Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2019	Oct. 31, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	MTB
Entity Registrant Name	M&T BANK CORP
Entity Central Index Key	0000036270
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		131,960,084
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	1-9861
Entity Tax Identification Number	16-0968385
Entity Address, Address Line One	One M & T Plaza
Entity Address, City or Town	Buffalo
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	14203
City Area Code	716
Local Phone Number	635-4000
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $.50 par value
Security Exchange Name	NYSE
Entity Incorporation, State or Country Code	NY
Document Quarterly Report	true
Document Transition Report	false

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 1,818,861	$ 1,605,439
Interest-bearing deposits at banks	12,495,524	8,105,197
Federal funds sold	200
Trading account	614,256	185,584
Investment securities (includes pledged securities that can be sold or repledged of $196,419 at September 30, 2019; $487,365 at December 31, 2018)
Available for sale (cost: $6,934,709 at September 30, 2019; $8,869,423 at December 31, 2018)	6,985,417	8,682,509
Held to maturity (fair value: $3,075,304 at September 30, 2019; $3,255,483 at December 31, 2018)	3,031,299	3,316,640
Equity and other securities (cost: $619,894 at September 30, 2019; $677,187 at December 31, 2018)	660,867	693,664
Total investment securities	10,677,583	12,692,813
Loans and leases	90,084,230	88,733,492
Unearned discount	(261,037)	(267,015)
Loans and leases, net of unearned discount	89,823,193	88,466,477
Allowance for credit losses	(1,038,437)	(1,019,444)
Loans and leases, net	88,784,756	87,447,033
Premises and equipment	1,074,181	647,408
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	33,339	47,067
Accrued interest and other assets	5,409,114	4,773,750
Total assets	125,500,926	120,097,403
Liabilities
Noninterest-bearing deposits	31,766,724	32,256,668
Savings and interest-checking deposits	55,581,533	50,963,744
Time deposits	6,203,679	6,124,254
Deposits at Cayman Islands office	1,561,997	811,906
Total deposits	95,113,933	90,156,572
Short-term borrowings	5,513,896	4,398,378
Accrued interest and other liabilities	2,090,762	1,637,348
Long-term borrowings	7,002,524	8,444,914
Total liabilities	109,721,115	104,637,212
Shareholders' equity
Preferred stock, $1.00 par, 1,000,000 shares authorized; Issued and outstanding: Liquidation preference of $1,000 per share: 350,000 shares at September 30, 2019 and 731,500 shares at December 31, 2018; Liquidation preference of $10,000 per share: 90,000 shares at September 30, 2019 and 50,000 shares at December 31, 2018	1,250,000	1,231,500
Common stock, $.50 par, 250,000,000 shares authorized, 159,741,898 shares issued at September 30, 2019; 159,765,044 shares issued at December 31, 2018	79,871	79,883
Common stock issuable, 21,461 shares at September 30, 2019; 24,563 shares at December 31, 2018	1,547	1,726
Additional paid-in capital	6,584,705	6,579,342
Retained earnings	12,490,233	11,516,672
Accumulated other comprehensive income (loss), net	(80,308)	(420,081)
Treasury stock — common, at cost — 27,485,996 shares at September 30, 2019; 21,255,275 shares at December 31, 2018	(4,546,237)	(3,528,851)
Total shareholders’ equity	15,779,811	15,460,191
Total liabilities and shareholders’ equity	$ 125,500,926	$ 120,097,403

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Pledged securities that can be sold or repledged	$ 196,419	$ 487,365
Investment securities, available for sale, amortized cost	6,934,709	8,869,423
Investment securities, held to maturity, fair value	3,075,304	3,255,483
Equity and other securities, cost	$ 619,894	$ 677,187
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	159,741,898	159,765,044
Common stock issuable, shares	21,461	24,563
Treasury stock, common shares	27,485,996	21,255,275
Series A Series C Series And E Preferred Stock [Member]
Preferred stock, shares issued	350,000	731,500
Preferred stock, shares outstanding	350,000	731,500
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series F And Series G Preferred Stock [Member]
Preferred stock, shares issued	90,000	50,000
Preferred stock, shares outstanding	90,000	50,000
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000

Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest income
Loans and leases, including fees	$ 1,119,662	$ 1,060,832	$ 3,363,152	$ 3,065,272
Investment securities
Fully taxable	69,059	80,118	225,048	244,989
Exempt from federal taxes	98	153	270	573
Deposits at banks	40,388	26,000	104,120	66,546
Other	262	272	1,101	1,050
Total interest income	1,229,469	1,167,375	3,693,691	3,378,430
Interest expense
Savings and interest-checking deposits	104,724	56,156	272,419	145,421
Time deposits	25,456	12,976	71,468	35,274
Deposits at Cayman Islands office	6,218	1,556	16,995	2,479
Short-term borrowings	6,967	1,600	21,573	3,866
Long-term borrowings	56,214	66,049	189,805	178,048
Total interest expense	199,579	138,337	572,260	365,088
Net interest income	1,029,890	1,029,038	3,121,431	3,013,342
Provision for credit losses	45,000	16,000	122,000	94,000
Net interest income after provision for credit losses	984,890	1,013,038	2,999,431	2,919,342
Other income
Brokerage services income	12,077	12,267	37,031	38,288
Trading account and foreign exchange gains	16,072	6,073	45,327	15,965
Gain (loss) on bank investment securities	3,737	(3,415)	24,489	(10,520)
Other revenues from operations	103,882	113,769	351,082	340,351
Total other income	527,779	459,294	1,540,639	1,375,404
Other expense
Salaries and employee benefits	476,780	431,371	1,431,717	1,313,336
Equipment and net occupancy	82,690	77,481	241,187	225,309
Outside data processing and software	60,360	50,678	168,011	148,819
FDIC assessments	9,906	18,849	29,104	58,689
Advertising and marketing	22,088	21,784	66,409	59,800
Printing, postage and supplies	10,201	8,843	30,380	26,881
Amortization of core deposit and other intangible assets	5,088	6,143	15,185	19,163
Other costs of operations	210,506	160,830	663,006	633,903
Total other expense	877,619	775,979	2,644,999	2,485,900
Income before taxes	635,050	696,353	1,895,071	1,808,846
Income taxes	154,969	170,262	458,988	436,985
Net income	480,081	526,091	1,436,083	1,371,861
Net income available to common shareholders
Basic	461,410	505,363	1,376,128	1,310,697
Diluted	$ 461,410	$ 505,365	$ 1,376,129	$ 1,310,703
Net income per common share
Basic	$ 3.47	$ 3.54	$ 10.16	$ 9.01
Diluted	$ 3.47	$ 3.53	$ 10.16	$ 9.00
Average common shares outstanding
Basic	132,965	142,822	135,411	145,424
Diluted	132,999	142,976	135,443	145,605
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 137,004	$ 88,408	$ 339,636	$ 268,213
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	111,092	108,647	321,991	320,546
Trust Income [Member]
Other income
Revenue from contract with customer	$ 143,915	$ 133,545	$ 421,083	$ 402,561

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Partners Capital [Abstract]
Net income	$ 480,081	$ 526,091	$ 1,436,083	$ 1,371,861
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	22,605	(30,381)	177,049	(167,798)
Cash flow hedges adjustments	8,695	(961)	155,666	(13,972)
Foreign currency translation adjustments	(1,704)	(265)	(2,104)	(1,409)
Defined benefit plans liability adjustments	3,054	7,149	9,162	21,447
Total other comprehensive income (loss)	32,650	(24,458)	339,773	(161,732)
Total comprehensive income	$ 512,731	$ 501,633	$ 1,775,856	$ 1,210,129

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net income	$ 1,436,083	$ 1,371,861
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	122,000	94,000
Depreciation and amortization of premises and equipment	155,721	80,186
Amortization of capitalized servicing rights	53,137	36,567
Amortization of core deposit and other intangible assets	15,185	19,163
Provision for deferred income taxes	16,683	(73,410)
Asset write-downs	53,850	7,398
Net gain on sales of assets	(13,938)	(17,681)
Net change in accrued interest receivable, payable	8,771	(30,178)
Net change in other accrued income and expense	(75,564)	125,478
Net change in loans originated for sale	(20,325)	(252,981)
Net change in trading account assets and liabilities	(524,755)	179,214
Net cash provided by operating activities	1,226,848	1,539,617
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale		418
Proceeds from sales of investment securities equity and other	878,405	649,204
Proceeds from maturities of investment securities Available for sale	1,932,168	1,415,214
Proceeds from maturities of investment securities Held to maturity	787,655	374,718
Purchases of investment securities Available for sale	(9,791)	(9,197)
Purchases of investment securities Held to maturity	(495,277)	(444,703)
Purchases of investment securities equity and other	(821,120)	(644,404)
Net (increase) decrease in loans and leases	(1,484,135)	1,443,623
Net increase in interest-bearing deposits at banks	(4,390,327)	(1,444,843)
Capital expenditures, net	(119,522)	(59,302)
Net (increase) decrease in loan servicing advances	(333,079)	267,074
Other, net	55,356	(11,072)
Net cash provided (used) by investing activities	(3,999,667)	1,536,730
Cash flows from financing activities
Net increase (decrease) in deposits	4,959,327	(3,289,371)
Net increase in short-term borrowings	1,115,518	1,135,011
Proceeds from long-term borrowings		1,773,189
Payments on long-term borrowings	(1,552,533)	(707,594)
Purchases of treasury stock	(1,067,575)	(1,694,562)
Dividends paid — common	(406,967)	(371,380)
Dividends paid — preferred	(54,642)	(53,628)
Redemption of Series A and Series C preferred stock	(381,500)
Other, net	(21,187)	22,711
Net cash provided (used) by financing activities	2,986,441	(3,185,624)
Net increase (decrease) in cash, cash equivalents and restricted cash	213,622	(109,277)
Cash, cash equivalents and restricted cash at beginning of period	1,605,439	1,420,888
Cash, cash equivalents and restricted cash at end of period	1,819,061	1,311,611
Supplemental disclosure of cash flow information
Interest received during the period	3,700,206	3,360,710
Interest paid during the period	577,291	381,137
Income taxes paid during the period	302,441	197,247
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	66,018	50,849
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	5,379	17,606
Securitization of residential mortgage loans allocated to capitalized servicing rights	83	$ 275
Adoption of lease accounting standard - Right-of-use assets	393,877
Adoption of lease accounting standard - Other liabilities	398,810
Additions to right-of-use assets under operating leases	69,305
Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock	$ 396,000

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Series A And Series C [Member]	Series G Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member] Series A And Series C [Member]	Preferred Stock [Member] Series G Preferred Stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series G Preferred Stock [Member]	Additional Paid-in Capital [Member] Series A Warrants [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]	Treasury Stock [Member] Series A Warrants [Member]
Beginning balance at Dec. 31, 2017	$ 16,250,819			$ 1,231,500			$ 79,909	$ 1,847	$ 6,590,855			$ 10,164,804	$ (363,814)	$ (1,454,282)
Cumulative effect of change in accounting principle — equity securities	(16,853)											16,853	(16,853)
Total comprehensive income	1,210,129											1,371,861	(161,732)
Preferred stock cash dividends	(54,390)											(54,390)
Exercise of stock warrants into common stock											$ (7,240)				$ 7,240
Purchases of treasury stock	(1,694,562)													(1,694,562)
Stock-based compensation plans:
Compensation expense, net	25,148						(26)		2,836					22,338
Stock purchase plan	11,124								2,358					8,766
Exercises of stock options, net	56,793								(3,282)					60,075
Directors’ stock plan	1,796								168					1,628
Deferred compensation plans, net, including dividend equivalents	(49)							(131)	(248)			(62)		392
Common stock cash dividends	(370,723)											(370,723)
Ending balance at Sep. 30, 2018	15,436,085			1,231,500			79,883	1,716	6,585,447			11,128,343	(542,399)	(3,048,405)
Beginning balance at Jun. 30, 2018	15,577,885			1,231,500			79,884	1,691	6,579,395			10,763,638	(517,941)	(2,560,282)
Total comprehensive income	501,633											526,091	(24,458)
Preferred stock cash dividends	(18,130)											(18,130)
Exercise of stock warrants into common stock											$ (2,117)				$ 2,117
Purchases of treasury stock	(498,500)													(498,500)
Stock-based compensation plans:
Compensation expense, net	9,702						(1)		9,030					673
Exercises of stock options, net	6,122								(880)					7,002
Directors’ stock plan	604								19					585
Deferred compensation plans, net, including dividend equivalents								25				(25)
Common stock cash dividends	(143,231)											(143,231)
Ending balance at Sep. 30, 2018	15,436,085			1,231,500			79,883	1,716	6,585,447			11,128,343	(542,399)	(3,048,405)
Beginning balance at Dec. 31, 2018	15,460,191			1,231,500			79,883	1,726	6,579,342			11,516,672	(420,081)	(3,528,851)
Total comprehensive income	1,775,856											1,436,083	339,773
Preferred stock cash dividends	(55,404)											(55,404)
Redemption of Series A and Series C preferred stock		$ (381,500)			$ (381,500)
Issuance of Series G preferred stock			$ 396,000			$ 400,000				$ (4,000)
Purchases of treasury stock	(1,067,575)													(1,067,575)
Stock-based compensation plans:
Compensation expense, net	40,552						(12)		12,728					27,836
Stock purchase plan	11,832								(67)					11,899
Exercises of stock options, net	5,326								(2,953)					8,279
Directors’ stock plan	1,564								(105)					1,669
Deferred compensation plans, net, including dividend equivalents	(64)							(179)	(327)			(64)		506
Performance share unit dividends									87			(87)
Common stock cash dividends	(406,967)											(406,967)
Ending balance at Sep. 30, 2019	15,779,811			1,250,000			79,871	1,547	6,584,705			12,490,233	(80,308)	(4,546,237)
Beginning balance at Jun. 30, 2019	15,691,827			1,231,500			79,871	1,526	6,577,603			12,162,278	(112,958)	(4,247,993)
Total comprehensive income	512,731											480,081	32,650
Preferred stock cash dividends	(19,144)											(19,144)
Redemption of Series A and Series C preferred stock		$ (381,500)			$ (381,500)
Issuance of Series G preferred stock			$ 396,000			$ 400,000				$ (4,000)
Purchases of treasury stock	(299,963)													(299,963)
Stock-based compensation plans:
Compensation expense, net	11,697								11,197					500
Exercises of stock options, net	599								(135)					734
Directors’ stock plan	496								11					485
Deferred compensation plans, net, including dividend equivalents								21				(21)
Performance share unit dividends									29			(29)
Common stock cash dividends	(132,932)											(132,932)
Ending balance at Sep. 30, 2019	$ 15,779,811			$ 1,250,000			$ 79,871	$ 1,547	$ 6,584,705			$ 12,490,233	$ (80,308)	$ (4,546,237)

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Retained Earnings [Member]
Common stock per share dividend amount	$ 1.00	$ 1.00	$ 3.00	$ 2.55
Treasury Stock [Member] \| Series A Warrants [Member]
Exercise of warrants into shares of common stock		22,291		76,517
Exercise of warrants into shares of common stock		12,758		45,426

Investment securities

9 Months Ended

Sep. 30, 2019

Investments Debt And Equity Securities [Abstract]

Investment securities

2. Investment securities

On January 1, 2018, the Company adopted amended guidance requiring equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in the consolidated statement of income. This amended guidance excludes equity method investments, investments in consolidated subsidiaries, exchange membership ownership interests, and Federal Home Loan Bank of New York and Federal Reserve Bank of New York capital stock. Upon adoption the Company reclassified $17 million, after-tax effect, from accumulated other comprehensive income to retained earnings, representing the difference between fair value and the cost basis of equity investments with readily determinable fair values at January 1, 2018.

The amortized cost and estimated fair value of investment securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
September 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	359,723	$	66	$	395	$	359,394
Obligations of states and political subdivisions		933		4		3		934
Mortgage-backed securities:
Government issued or guaranteed		6,435,730		88,522		29,352		6,494,900
Privately issued		16		—		—		16
Other debt securities		138,307		1,373		9,507		130,173
		6,934,709		89,965		39,257		6,985,417
Investment securities held to maturity:
U.S. Treasury and federal agencies		498,776		956		—		499,732
Obligations of states and political subdivisions		4,775		21		—		4,796
Mortgage-backed securities:
Government issued or guaranteed		2,424,716		53,076		1,879		2,475,913
Privately issued		99,679		11,791		19,960		91,510
Other debt securities		3,353		—		—		3,353
		3,031,299		65,844		21,839		3,075,304
Total debt securities	$	9,966,008	$	155,809	$	61,096	$	10,060,721
Equity and other securities:
Readily marketable equity — at fair value	$	109,131	$	41,152	$	179	$	150,104
Other — at cost		510,763		—		—		510,763
Total equity and other securities	$	619,894	$	41,152	$	179	$	660,867

2. Investment securities, continued

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,346,782	$	—	$	9,851	$	1,336,931
Obligations of states and political subdivisions		1,660		4		5		1,659
Mortgage-backed securities:
Government issued or guaranteed		7,383,340		15,754		182,103		7,216,991
Privately issued		24		—		2		22
Other debt securities		137,617		770		11,481		126,906
		8,869,423		16,528		203,442		8,682,509
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,542		—		239		446,303
Obligations of states and political subdivisions		7,494		22		12		7,504
Mortgage-backed securities:
Government issued or guaranteed		2,745,776		4,165		55,111		2,694,830
Privately issued		113,160		12,345		22,327		103,178
Other debt securities		3,668		—		—		3,668
		3,316,640		16,532		77,689		3,255,483
Total debt securities	$	12,186,063	$	33,060	$	281,131	$	11,937,992
Equity and other securities:
Readily marketable equity — at fair value	$	77,440	$	17,295	$	818	$	93,917
Other — at cost		599,747		—		—		599,747
Total equity and other securities	$	677,187	$	17,295	$	818	$	693,664

There were no significant gross realized gains or losses from sales of investment securities for the three-month and nine-month periods ended September 30, 2019 and 2018. Net unrealized gains recorded as gain (loss) on bank investment securities in the consolidated statement of income during the three months and nine months ended September 30, 2019 were $4 million and $24 million, respectively, compared with net unrealized losses of $3 million and $11 million during the three months and nine months ended September 30, 2018, respectively.

2. Investment securities, continued

At September 30, 2019, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:

	Amortized Cost		Estimated Fair Value
	(In thousands)
Debt securities available for sale:
Due in one year or less	$	355,210		354,825
Due after one year through five years		11,470		11,585
Due after five years through ten years		102,283		100,091
Due after ten years		30,000		24,000
		498,963		490,501
Mortgage-backed securities available for sale		6,435,746		6,494,916
	$	6,934,709		6,985,417
Debt securities held to maturity:
Due in one year or less	$	500,476		501,438
Due after one year through five years		3,075		3,090
Due after ten years		3,353		3,353
		506,904		507,881
Mortgage-backed securities held to maturity		2,524,395		2,567,423
	$	3,031,299		3,075,304

2. Investment securities, continued

A summary of investment securities that as of September 30, 2019 and December 31, 2018 had been in a continuous unrealized loss position for less than twelve months and those that had been in a continuous unrealized loss position for twelve months or longer follows:

	Less Than 12 Months					12 Months or More
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
September 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	—		—			352,482		(395	)
Obligations of states and political subdivisions		—		—			375		(3	)
Mortgage-backed securities:
Government issued or guaranteed		240,208		(589	)		2,107,684		(28,763	)
Other debt securities		20,290		(563	)		77,140		(8,944	)
		260,498		(1,152	)		2,537,681		(38,105	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		—		—			165,983		(1,879	)
Privately issued		—		—			49,824		(19,960	)
		—		—			215,807		(21,839	)
Total	$	260,498		(1,152	)		2,753,488		(59,944	)

December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	273		(2	)		1,335,559		(9,849	)
Obligations of states and political subdivisions		629		(5	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		405,558		(2,892	)		5,646,773		(179,211	)
Privately issued		22		(2	)		—		—
Other debt securities		53,478		(2,187	)		66,014		(9,294	)
		459,960		(5,088	)		7,048,346		(198,354	)
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,303		(239	)		—		—
Obligations of states and political subdivisions		—		—			3,126		(12	)
Mortgage-backed securities:
Government issued or guaranteed		179,354		(989	)		2,082,723		(54,122	)
Privately issued		—		—			51,943		(22,327	)
		625,657		(1,228	)		2,137,792		(76,461	)
Total	$	1,085,617		(6,316	)		9,186,138		(274,815	)

The Company owned 657 individual debt securities with aggregate gross unrealized losses of $61 million at September 30, 2019. Based on a review of each of the securities in the investment securities portfolio at September 30, 2019, the Company concluded that it expected to recover the amortized cost basis of its investment. As of September 30, 2019, the Company does not intend to sell nor is it anticipated that it would be required to sell any of its impaired investment securities at a loss. At September 30, 2019, the Company has not identified events or changes in circumstances which may have a significant adverse effect on the fair value of the $511 million of cost method equity securities.

Loans and leases and the allowance for credit losses

9 Months Ended

Sep. 30, 2019

Receivables [Abstract]

Loans and leases and the allowance for credit losses

3. Loans and leases and the allowance for credit losses

A summary of current, past due and nonaccrual loans as of September 30, 2019 and December 31, 2018 follows:

	Current		30-89 Days Past Due		Accruing Loans Past Due 90 Days or More (a)		Accruing Loans Acquired at a Discount Past Due 90 days or More (b)		Purchased Impaired (c)		Nonaccrual		Total
	(In thousands)
September 30, 2019
Commercial, financial, leasing, etc.	$	22,689,923		125,742		2,898		—		—		382,809	$	23,201,372
Real estate:
Commercial		25,613,988		186,157		8,387		15		14,406		184,632		26,007,585
Residential builder and developer		1,546,570		6,300		—		—		639		4,975		1,558,484
Other commercial construction		7,229,925		112,651		4,291		—		854		31,441		7,379,162
Residential		12,975,992		495,831		439,649		5,246		162,475		223,566		14,302,759
Residential — limited documentation		1,968,580		72,815		—		—		75,122		81,679		2,198,196
Consumer:
Home equity lines and loans		4,486,664		29,826		—		3,387		—		59,915		4,579,792
Recreational finance		5,262,857		27,880		—		—		—		11,852		5,302,589
Automobile		3,767,965		74,504		—		—		—		21,039		3,863,508
Other		1,373,612		14,771		5,937		32,085		—		3,341		1,429,746
Total	$	86,916,076		1,146,477		461,162		40,733		253,496		1,005,249	$	89,823,193

December 31, 2018
Commercial, financial, leasing, etc.	$	22,701,020		39,798		2,567		168		—		234,423	$	22,977,976
Real estate:
Commercial		25,250,983		134,474		11,457		10		9,769		203,672		25,610,365
Residential builder and developer		1,665,178		20,333		—		—		—		4,798		1,690,309
Other commercial construction		6,982,077		43,615		14,344		—		641		22,205		7,062,882
Residential		13,591,790		404,808		189,682		6,650		203,044		233,352		14,629,326
Residential — limited documentation		2,278,040		72,544		—		—		89,851		84,685		2,525,120
Consumer:
Home equity lines and loans		4,758,513		25,416		—		5,033		—		71,292		4,860,254
Recreational finance		4,085,781		29,947		—		235		—		11,199		4,127,162
Automobile		3,555,757		79,804		—		—		—		23,359		3,658,920
Other		1,271,811		15,598		4,477		27,654		—		4,623		1,324,163
Total	$	86,140,950		866,337		222,527		39,750		303,305		893,608	$	88,466,477

(a)	Excludes loans acquired at a discount.

(b)	Loans acquired at a discount that were recorded at fair value at acquisition date. This category does not include purchased impaired loans that are presented separately.

(c)	Accruing loans acquired at a discount that were impaired at acquisition date and recorded at fair value.

3. Loans and leases and the allowance for credit losses, continued

One-to-four family residential mortgage loans held for sale were $391 million and $205 million at September 30, 2019 and December 31, 2018, respectively. Commercial real estate loans held for sale were $197 million at September 30, 2019 and $347 million at December 31, 2018.

The outstanding principal balance and the carrying amount of loans acquired at a discount that were recorded at fair value at the acquisition date and included in the consolidated balance sheet were as follows:

	September 30,		December 31,
	2019		2018
	(In thousands)

Outstanding principal balance	$	869,636	$	1,016,785
Carrying amount:
Commercial, financial, leasing, etc.		22,829		27,073
Commercial real estate		110,430		135,047
Residential real estate		398,563		473,511
Consumer		89,157		91,860
	$	620,979	$	727,491

Purchased impaired loans included in the table above totaled $253 million at September 30, 2019 and $303 million at December 31, 2018, representing less than 1% of the Company’s assets as of each date. A summary of changes in the accretable yield for loans acquired at a discount for the three months and nine months ended September 30, 2019 and 2018 follows:

	Three Months Ended September 30
	2019						2018
	Purchased			Other			Purchased			Other
	Impaired			Acquired			Impaired			Acquired
	(In thousands)

Balance at beginning of period	$	147,104		$	90,911		$	149,388		$	117,715
Interest income		(9,564	)		(9,238	)		(8,105	)		(18,001	)
Reclassifications from nonaccretable balance		9,079			3,990			8,445			25
Other (a)		—			41			—			2,001
Balance at end of period	$	146,619		$	85,704		$	149,728		$	101,740

	Nine Months Ended September 30
	2019						2018
	Purchased			Other			Purchased			Other
	Impaired			Acquired			Impaired			Acquired
	(In thousands)

Balance at beginning of period	$	147,210		$	96,907		$	157,918		$	133,162
Interest income		(37,278	)		(28,621	)		(25,893	)		(48,507	)
Reclassifications from nonaccretable balance		36,687			12,312			17,703			11,230
Other (a)		—			5,106			—			5,855
Balance at end of period	$	146,619		$	85,704		$	149,728		$	101,740

(a)	Other changes in expected cash flows including changes in interest rates and prepayment assumptions.

3. Loans and leases and the allowance for credit losses, continued

Changes in the allowance for credit losses for the three months ended September 30, 2019 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated			Total
	(In thousands)

Beginning balance	$	335,855			343,296			61,011			211,220			78,485		$	1,029,867
Provision for credit losses		24,538			(16,713	)		(309	)		37,735			(251	)		45,000
Net charge-offs
Charge-offs		(15,678	)		(1,107	)		(2,721	)		(40,735	)		—			(60,241	)
Recoveries		6,730			1,656			1,511			13,914			—			23,811
Net (charge-offs) recoveries		(8,948	)		549			(1,210	)		(26,821	)		—			(36,430	)
Ending balance	$	351,445			327,132			59,492			222,134			78,234		$	1,038,437

Changes in the allowance for credit losses for the three months ended September 30, 2018 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated		Total
	(In thousands)

Beginning balance	$	328,830			353,761			76,123			182,987			77,547	$	1,019,248
Provision for credit losses		(6,972	)		(11,394	)		741			32,887			738		16,000
Net charge-offs
Charge-offs		(11,792	)		(1,941	)		(3,338	)		(34,995	)		—		(52,066	)
Recoveries		7,123			14,577			1,655			12,951			—		36,306
Net (charge-offs) recoveries		(4,669	)		12,636			(1,683	)		(22,044	)		—		(15,760	)
Ending balance	$	317,189			355,003			75,181			193,830			78,285	$	1,019,488

Changes in the allowance for credit losses for the nine months ended September 30, 2019 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated		Total
	(In thousands)

Beginning balance	$	330,055			341,655			69,125			200,564			78,045	$	1,019,444
Provision for credit losses		41,146			(6,415	)		(5,132	)		92,212			189		122,000
Net charge-offs
Charge-offs		(40,786	)		(11,555	)		(9,356	)		(113,050	)		—		(174,747	)
Recoveries		21,030			3,447			4,855			42,408			—		71,740
Net charge-offs		(19,756	)		(8,108	)		(4,501	)		(70,642	)		—		(103,007	)
Ending balance	$	351,445			327,132			59,492			222,134			78,234	$	1,038,437

3. Loans and leases and the allowance for credit losses, continued

Changes in the allowance for credit losses for the nine months ended September 30, 2018 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated			Total
	(In thousands)

Beginning balance	$	328,599			374,085			65,405			170,809			78,300		$	1,017,198
Provision for credit losses		11,508			(27,464	)		16,469			93,502			(15	)		94,000
Net charge-offs
Charge-offs		(41,273	)		(7,855	)		(11,658	)		(105,479	)		—			(166,265	)
Recoveries		18,355			16,237			4,965			34,998			—			74,555
Net (charge-offs) recoveries		(22,918	)		8,382			(6,693	)		(70,481	)		—			(91,710	)
Ending balance	$	317,189			355,003			75,181			193,830			78,285		$	1,019,488

Despite the allocation in the preceding tables, the allowance for credit losses is general in nature and is available to absorb losses from any loan or lease type.

In establishing the allowance for credit losses, the Company estimates losses attributable to specific troubled credits identified through both normal and targeted credit review processes and also estimates losses inherent in other loans and leases on a collective basis. For purposes of determining the level of the allowance for credit losses, the Company evaluates its loan and lease portfolio by loan type. The amounts of loss components in the Company’s loan and lease portfolios are determined through a loan-by-loan analysis of larger balance commercial loans and commercial real estate loans that are in nonaccrual status and by applying loss factors to groups of loan balances based on loan type and management’s classification of such loans under the Company’s loan grading system. Measurement of the specific loss components is typically based on expected future cash flows, collateral values and other factors that may impact the borrower’s ability to pay. In determining the allowance for credit losses, the Company utilizes a loan grading system which is applied to commercial and commercial real estate credits on an individual loan basis. Loan grades are assigned loss component factors that reflect the Company’s loss estimate for each group of loans and leases. Factors considered in assigning loan grades and loss component factors include borrower-specific information related to expected future cash flows and operating results, collateral values, geographic location, financial condition and performance, payment status, and other information; levels of and trends in portfolio charge-offs and recoveries; levels of and trends in portfolio delinquencies and impaired loans; changes in the risk profile of specific portfolios; trends in volume and terms of loans; effects of changes in credit concentrations; and observed trends and practices in the banking industry.

3. Loans and leases and the allowance for credit losses, continued

Information with respect to loans and leases that were considered impaired as of September 30, 2019 and December 31, 2018 and for the three-month and nine-month periods ended September 30, 2019 and 2018 follows.

	September 30, 2019						December 31, 2018
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Recorded Investment		Unpaid Principal Balance		Related Allowance
	(In thousands)
With an allowance recorded:
Commercial, financial, leasing, etc.	$	245,355		273,931		60,410		153,478		175,549		46,034
Real estate:
Commercial		60,489		67,104		7,711		110,253		125,117		11,937
Residential builder and developer		8,893		9,311		319		5,981		6,557		462
Other commercial construction		12,821		25,437		1,477		10,563		11,113		640
Residential		125,498		146,098		6,748		124,974		147,817		5,402
Residential — limited documentation		67,729		81,918		2,600		74,156		90,066		3,000
Consumer:
Home equity lines and loans		46,858		51,759		8,923		47,982		53,248		9,135
Recreational finance		5,483		9,481		1,153		6,138		9,163		1,261
Automobile		3,478		3,526		708		3,527		3,599		729
Other		4,699		9,620		943		5,203		8,380		1,046
		581,303		678,185		90,992		542,255		630,609		79,646
With no related allowance recorded:
Commercial, financial, leasing, etc.		159,991		172,191		—		105,507		136,128		—
Real estate:
Commercial		144,554		163,120		—		113,376		124,657		—
Residential builder and developer		3,378		3,378		—		2,593		2,602		—
Other commercial construction		18,620		19,614		—		11,710		11,880		—
Residential		18,949		24,350		—		15,379		20,496		—
Residential — limited documentation		4,007		7,324		—		5,631		9,796		—
		349,499		389,977		—		254,196		305,559		—
Total:
Commercial, financial, leasing, etc.		405,346		446,122		60,410		258,985		311,677		46,034
Real estate:
Commercial		205,043		230,224		7,711		223,629		249,774		11,937
Residential builder and developer		12,271		12,689		319		8,574		9,159		462
Other commercial construction		31,441		45,051		1,477		22,273		22,993		640
Residential		144,447		170,448		6,748		140,353		168,313		5,402
Residential — limited documentation		71,736		89,242		2,600		79,787		99,862		3,000
Consumer:
Home equity lines and loans		46,858		51,759		8,923		47,982		53,248		9,135
Recreational finance		5,483		9,481		1,153		6,138		9,163		1,261
Automobile		3,478		3,526		708		3,527		3,599		729
Other		4,699		9,620		943		5,203		8,380		1,046
Total	$	930,802		1,068,162		90,992		796,451		936,168		79,646

3. Loans and leases and the allowance for credit losses, continued

	Three Months Ended September 30, 2019						Three Months Ended September 30, 2018
			Interest Income Recognized						Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis		Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	288,516		836		836		256,196		1,985		1,985
Real estate:
Commercial		201,931		1,798		1,798		204,315		1,489		1,489
Residential builder and developer		11,837		89		89		9,000		—		—
Other commercial construction		32,458		13		13		9,623		3,379		3,379
Residential		143,508		2,353		984		133,337		1,959		773
Residential — limited documentation		72,926		1,348		229		81,729		1,607		481
Consumer:
Home equity lines and loans		46,982		416		74		48,542		421		62
Recreational finance		5,562		147		4		3,531		65		1
Automobile		3,413		54		18		7,805		181		20
Other		5,220		145		1		3,919		61		5
Total	$	812,353		7,199		4,046		757,997		11,147		8,195

	Nine Months Ended September 30, 2019						Nine Months Ended September 30, 2018
			Interest Income Recognized						Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis		Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	275,896		7,501		7,501		266,594		4,101		4,101
Real estate:
Commercial		214,027		4,921		4,921		184,795		8,447		8,447
Residential builder and developer		10,101		239		239		9,111		1,682		1,682
Other commercial construction		25,126		589		589		9,056		3,438		3,438
Residential		142,155		6,765		2,654		126,910		6,190		2,612
Residential — limited documentation		75,702		4,153		655		83,700		4,763		1,494
Consumer:
Home equity lines and loans		47,325		1,238		193		48,661		1,268		220
Recreational finance		5,799		414		12		2,156		193		6
Automobile		3,465		161		55		11,189		630		49
Other		5,155		409		10		2,389		106		6
Total	$	804,751		26,390		16,829		744,561		30,818		22,055

Commercial loans and commercial real estate loans with a lower expectation of default are assigned one of ten possible “pass” loan grades and are generally ascribed lower loss factors when determining the allowance for credit losses. Loans with an elevated level of credit risk are classified as “criticized” and are ascribed a higher loss factor when determining the allowance for credit losses. Criticized loans may be classified as “nonaccrual” if the Company no longer expects to collect all amounts according to the contractual terms of the loan agreement or the loan is delinquent 90 days or more. Furthermore, criticized nonaccrual commercial loans and commercial real estate loans are considered impaired and, as a result, specific loss allowances on such loans are established within the allowance for credit losses to the extent appropriate in each individual instance.

3. Loans and leases and the allowance for credit losses, continued

The following table summarizes the loan grades applied to the various classes of the Company’s commercial loans and commercial real estate loans.

			Real Estate
	Commercial,				Residential		Other
	Financial,				Builder and		Commercial
	Leasing, etc.		Commercial		Developer		Construction
	(In thousands)
September 30, 2019
Pass	$	21,893,239		25,095,663		1,447,978		7,122,983
Criticized accrual		925,324		727,291		105,531		224,738
Criticized nonaccrual		382,809		184,632		4,975		31,441
Total	$	23,201,372		26,007,586		1,558,484		7,379,162
December 31, 2018
Pass	$	21,693,705		24,539,706		1,546,002		6,890,562
Criticized accrual		1,049,848		866,987		139,509		150,115
Criticized nonaccrual		234,423		203,672		4,798		22,205
Total	$	22,977,976		25,610,365		1,690,309		7,062,882

In determining the allowance for credit losses, residential real estate loans and consumer loans are generally evaluated collectively after considering such factors as payment performance and recent loss experience and trends, which are mainly driven by current collateral values in the market place as well as the amount of loan defaults. Loss rates on such loans are determined by reference to recent charge-off history and are evaluated (and adjusted if deemed appropriate) through consideration of other factors including near-term forecasted loss estimates developed by the Company’s credit department. In arriving at such forecasts, the Company considers the current estimated fair value of its collateral based on geographical adjustments for home price depreciation/appreciation and overall borrower repayment performance. With regard to collateral values, the realizability of such values by the Company contemplates repayment of any first lien position prior to recovering amounts on a second lien position. However, residential real estate loans and outstanding balances of home equity loans and lines of credit that are more than 150 days past due are generally evaluated for collectibility on a loan-by-loan basis giving consideration to estimated collateral values. The carrying value of residential real estate loans and home equity loans and lines of credit for which a partial charge-off has been recognized totaled $26 million and $20 million, respectively, at September 30, 2019 and $29 million and $23 million, respectively, at December 31, 2018. Residential real estate loans and home equity loans and lines of credit that were more than 150 days past due but did not require a partial charge-off because the net realizable value of the collateral exceeded the outstanding customer balance were $19 million and $29 million, respectively, at September 30, 2019 and $21 million and $31 million, respectively, at December 31, 2018.

The Company also measures additional losses for purchased impaired loans when it is probable that the Company will be unable to collect all cash flows expected at acquisition plus additional cash flows expected to be collected arising from changes in estimates after acquisition. The determination of the allocated portion of the allowance for credit losses is very subjective. Given that inherent subjectivity and potential imprecision involved in determining the allocated portion of the allowance for credit losses, the Company also provides an inherent unallocated portion of the allowance. The unallocated portion of the allowance is intended to recognize probable losses that are not otherwise identifiable and includes management’s subjective determination of amounts necessary to provide for the possible use of imprecise estimates in determining the allocated portion of the allowance. Therefore, the level of the unallocated portion of the allowance is primarily reflective of the inherent imprecision in the various calculations used in determining the allocated portion of the allowance for credit losses. Other factors that could also lead to changes in the unallocated portion include the effects of expansion into new markets for which the Company does not have the same degree of familiarity and experience regarding portfolio performance in changing market conditions, the introduction of new loan and lease product types, and other risks associated with the Company’s loan portfolio that may not be specifically identifiable.

3. Loans and leases and the allowance for credit losses, continued

The allocation of the allowance for credit losses summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
September 30, 2019
Individually evaluated for impairment	$	60,410		9,507		9,348		11,727	$	90,992
Collectively evaluated for impairment		291,035		317,625		44,766		210,407		863,833
Purchased impaired		—		—		5,378		—		5,378
Allocated	$	351,445		327,132		59,492		222,134		960,203
Unallocated										78,234
Total									$	1,038,437
December 31, 2018
Individually evaluated for impairment	$	46,034		13,039		8,402		12,171	$	79,646
Collectively evaluated for impairment		284,021		328,616		48,326		188,393		849,356
Purchased impaired		—		—		12,397		—		12,397
Allocated	$	330,055		341,655		69,125		200,564		941,399
Unallocated										78,045
Total									$	1,019,444

The recorded investment in loans and leases summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
September 30, 2019
Individually evaluated for impairment	$	405,346		248,755		216,183		60,518	$	930,802
Collectively evaluated for impairment		22,796,026		34,680,577		16,047,175		15,115,117		88,638,895
Purchased impaired		—		15,899		237,597		—		253,496
Total	$	23,201,372		34,945,231		16,500,955		15,175,635	$	89,823,193
December 31, 2018
Individually evaluated for impairment	$	258,985		254,476		220,140		62,850	$	796,451
Collectively evaluated for impairment		22,718,991		34,098,670		16,641,411		13,907,649		87,366,721
Purchased impaired		—		10,410		292,895		—		303,305
Total	$	22,977,976		34,363,556		17,154,446		13,970,499	$	88,466,477

During the normal course of business, the Company modifies loans to maximize recovery efforts. If the borrower is experiencing financial difficulty and a concession is granted, the Company considers such modifications as troubled debt restructurings and classifies those loans as either nonaccrual loans or renegotiated loans. The types of concessions that the Company grants typically include principal deferrals and interest rate concessions, but may also include other types of concessions.

3. Loans and leases and the allowance for credit losses, continued

The table that follows summarizes the Company’s loan modification activities that were considered troubled debt restructurings for the three-month and nine-month periods ended September 30, 2019 and 2018:

					Post-modification (a)
	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
Three Months Ended September 30, 2019	(Dollars in thousands)

Commercial, financial, leasing, etc.	26		$	6,145	$	1,441	$	—	$	—	$	4,666	$	6,107
Real estate:
Commercial		9		2,986		383		—		—		2,589		2,972
Residential		20		5,161		3,046		—		—		2,535		5,581
Residential — limited documentation		1		236		—		—		—		240		240
Consumer:
Home equity lines and loans		12		1,392		—		—		—		1,399		1,399
Recreational finance		3		61		61		—		—		—		61
Automobile		26		485		457		—		—		28		485
Total		97	$	16,466	$	5,388	$	—	$	—	$	11,457	$	16,845

Three Months Ended September 30, 2018

Commercial, financial, leasing, etc.		47	$	6,837	$	1,683	$	5	$	—	$	5,018	$	6,706
Real estate:
Commercial		18		11,581		1,493		—		3,475		6,297		11,265
Residential		34		8,182		6,026		—		—		3,002		9,028
Residential — limited documentation		3		716		—		—		—		847		847
Consumer:
Home equity lines and loans		17		1,651		220		—		—		1,450		1,670
Recreational finance		2		44		44		—		—		—		44
Automobile		30		526		526		—		—		—		526
Total		151	$	29,537	$	9,992	$	5	$	3,475	$	16,614	$	30,086

3. Loans and leases and the allowance for credit losses, continued

					Post-modification (a)
Nine Months Ended September 30, 2019	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
	(Dollars in thousands)

Commercial, financial, leasing, etc.		115	$	39,357	$	8,582	$	—	$	—	$	30,827	$	39,409
Real estate:
Commercial		38		22,567		3,947		—		—		18,197		22,144
Residential builder and developer		2		1,330		1,068		—		—		—		1,068
Other commercial construction		2		1,456		—		—		—		1,399		1,399
Residential		63		16,490		8,805		—		—		8,842		17,647
Residential — limited documentation		4		1,084		399		—		—		705		1,104
Consumer:
Home equity lines and loans		32		3,141		90		—		—		3,078		3,168
Recreational finance		8		164		164		—		—		—		164
Automobile		58		991		926		—		—		65		991
Total		322	$	86,580	$	23,981	$	—	$	—	$	63,113	$	87,094

Nine Months Ended September 30, 2018

Commercial, financial, leasing, etc.		150	$	96,221	$	47,029	$	658	$	6,111	$	43,086	$	96,884
Real estate:
Commercial		66		25,561		14,693		175		3,869		7,224		25,961
Other commercial construction		1		752		746		—		—		—		746
Residential		111		28,769		15,785		—		—		15,670		31,455
Residential — limited documentation		8		1,595		467		—		—		1,423		1,890
Consumer:
Home equity lines and loans		41		3,554		224		—		—		3,357		3,581
Recreational finance		4		93		93		—		—		—		93
Automobile		57		1,007		995		—		—		12		1,007
Total		438	$	157,552	$	80,032	$	833	$	9,980	$	70,772	$	161,617

(a)	Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages. The present value of interest rate concessions, discounted at the effective rate of the original loan, was not material.

Troubled debt restructurings are considered to be impaired loans and for purposes of establishing the allowance for credit losses are evaluated for impairment giving consideration to the impact of the modified loan terms on the present value of the loan’s expected cash flows. Impairment of troubled debt restructurings that have subsequently defaulted may also be measured based on the loan’s observable market price or the fair value of collateral if the loan is collateral-dependent. Charge-offs may also be recognized on troubled debt restructurings that have subsequently defaulted. Loans that were modified as troubled debt restructurings during the twelve months ended September 30, 2019 and 2018 and for which there was a subsequent payment default during the nine-month periods ended September 30, 2019 and 2018, respectively, were not material.

The amount of foreclosed residential real estate property held by the Company was $70 million and $77 million at September 30, 2019 and December 31, 2018, respectively. There were $391 million in loans secured by residential real estate that were in the process of foreclosure at both September 30, 2019 and December 31, 2018. Of all loans in the process of foreclosure at September 30, 2019, approximately 27% were classified as purchased impaired and 33% were government guaranteed.

3. Loans and leases and the allowance for credit losses, continued

The Company’s loan and lease portfolio includes commercial lease financing receivables consisting of direct financing and leveraged leases for machinery and equipment, railroad equipment, commercial trucks and trailers, and aircraft. Certain leases contain payment schedules that are tied to variable interest rate indices. In general, early termination options are provided if the lessee is not in default, returns the leased equipment and pays an early termination fee. Additionally, options to purchase the underlying asset by the lessee are generally at the fair market value of the equipment. Effective January 1, 2019, the Company adopted new guidance related to lease accounting published by the Financial Accounting Standards Board (“FASB”). Under the new guidance, the accounting applied by lessors is largely unchanged from previous GAAP, however, the guidance eliminates the accounting model for leveraged leases that commence after the effective date of the guidance. A summary of lease financing receivables follows:

	September 30,			December 31,
	2019			2018
	(In thousands)
Commercial leases:
Direct financings:
Lease payments receivable	$	1,177,518		$	1,155,464
Estimated residual value of leased assets		84,692			85,169
Unearned income		(105,774	)		(110,458	)
Investment in direct financings		1,156,436			1,130,175
Leveraged leases:
Lease payments receivable		82,127			85,007
Estimated residual value of leased assets		81,163			81,261
Unearned income		(32,220	)		(33,717	)
Investment in leveraged leases		131,070			132,551
Total investment in leases	$	1,287,506		$	1,262,726
Deferred taxes payable arising from leveraged leases	$	71,432		$	74,995

Included within the estimated residual value of leased assets at September 30, 2019 and December 31, 2018 were $38 million and $39 million, respectively, in residual value associated with direct financing leases that are guaranteed by the lessees or others.

At September 30, 2019, the minimum future lease payments to be received from lease financings were as follows:

	(In thousands)
Twelve-month period ending September 30:
2020	$	346,223
2021		305,385
2022		216,018
2023		164,490
2024		82,455
Later years		145,074
	$	1,259,645

Operating Leases

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Operating leases

4. Operating leases

The January 1, 2019 adoption of new lease accounting guidance resulted in the Company recording right-of-use assets and lease liabilities in the consolidated balance sheet for all operating leases with a term greater than twelve months. In addition, the Company elected the practical expedients that (1) reassessment is not needed for whether any existing contracts are or contain leases, (2) reassessment of the classification of existing operating and finance leases is not required, and (3) a lease that has a term of twelve months or less is not required to apply the asset and liability recognition requirements.

The Company determines whether a contract contains a lease based on whether a contract, or a part of a contract, conveys the right to control the use of an identified asset for a period of time in exchange for consideration. If it is determined that a contract contains a lease, the consideration in the contract is separated between lease and nonlease components (for example, taxes or common area maintenance). In calculating the present value of the lease payments, the Company has utilized its incremental borrowing rate based on electing the original lease term to account for each lease component.

The right-of-use assets and lease liabilities relate to banking offices and other space occupied by the Company and use of certain equipment under noncancelable operating lease agreements, which prior to the adoption of the guidance were not reflected in the consolidated balance sheet.

As of September 30, 2019, the Company reported right-of-use assets recognized as a component of “premises and equipment” and lease liabilities recognized as a component of “accrued interest and other liabilities” in the consolidated balance sheet, as follows:

	September 30, 2019
	(In thousands)

Right-of-use assets	$	392,324
Lease liabilities		424,854

The Company’s noncancelable operating lease agreements expire at various dates over the next 22 years. Real estate leases generally consist of fixed monthly rental payments with certain leases containing escalation clauses. Any variable lease payments or payments for nonlease components are recognized in the consolidated statement of income as a component of “equipment and net occupancy” expense based on actual costs incurred. Some of these real estate leases contain lessee options to extend the term. Those options are included in the lease term when it is determined that it is reasonably certain the option will be exercised.

The Company has noncancelable operating lease agreements for certain equipment related to ATMs, servers, printers and mail machines that are used in the normal course of operations. The ATM leases are either based on the rights to a specific square footage or a license agreement whereby the Company has the right to operate an ATM in a landlord's location. The lease terms generally contain both fixed payments and variable payments that are transaction-based. Given the transaction-based nature of the variable payments, they are excluded from the measurement of the right-of-use asset and lease liability and are recognized in the consolidated statement of income as a component of “equipment and net occupancy” expense when incurred.

4. Operating leases, continued

The following table presents information about the Company’s lease costs for operating leases recorded in the consolidated balance sheet, cash paid toward lease liabilities, and the weighted-average remaining term and discount rates of the operating leases.

	Three Months Ended			Nine Months Ended
	September 30, 2019			September 30, 2019
	(Dollars in thousands)
Lease cost
Operating lease cost	$	25,058		$	74,599
Short-term lease cost		20			82
Variable lease cost		644			1,733
Sublease income		(1,903	)		(5,724	)
Total net lease cost	$	23,819		$	70,690

Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	$	24,377		$	69,305
Cash paid toward lease liabilities		25,189			76,050
Weighted-average remaining lease term	7 years			7 years
Weighted-average discount rate		3.1	%		3.1	%

Minimum lease payments under noncancelable operating leases are summarized in the following table. These minimum lease payments are not materially different from those reported in the 2018 Annual Report.

	(In thousands)
Twelve-month period ending September 30:
2020	$	97,712
2021		87,106
2022		72,577
2023		56,821
2024		42,770
Later years		116,467
Total lease payments	$	473,453
Less: imputed interest		48,599
Total	$	424,854

All other operating leasing activities were not material to the Company’s consolidated results of operations.

Borrowings

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Borrowings

5. Borrowings

M&T had $524 million of fixed and variable rate junior subordinated deferrable interest debentures ("Junior Subordinated Debentures") outstanding at September 30, 2019 that are held by various trusts that were issued in connection with the issuance by those trusts of preferred capital securities ("Capital Securities") and common securities ("Common Securities"). The proceeds from the issuances of the Capital Securities and the Common Securities were used by the trusts to purchase the Junior Subordinated Debentures. The Common Securities of each of those trusts are wholly owned by M&T and are the only class of each trust's securities possessing general voting powers. The Capital Securities represent preferred undivided interests in the assets of the corresponding trust. Under the Federal Reserve Board’s risk-based capital guidelines, the securities are includable in M&T’s Tier 2 regulatory capital.

Holders of the Capital Securities receive preferential cumulative cash distributions unless M&T exercises its right to extend the payment of interest on the Junior Subordinated Debentures as allowed by the terms of each such debenture, in which case payment of distributions on the respective Capital Securities will be deferred for comparable periods. During an extended interest period, M&T may not pay dividends or distributions on, or repurchase, redeem or acquire any shares of its capital stock. In general, the agreements governing the Capital Securities, in the aggregate, provide a full, irrevocable and unconditional guarantee by M&T of the payment of distributions on, the redemption of, and any liquidation distribution with respect to the Capital Securities. The obligations under such guarantee and the Capital Securities are subordinate and junior in right of payment to all senior indebtedness of M&T.

The Capital Securities will remain outstanding until the Junior Subordinated Debentures are repaid at maturity, are redeemed prior to maturity or are distributed in liquidation to the trusts. The Capital Securities are mandatorily redeemable in whole, but not in part, upon repayment at the stated maturity dates (ranging from 2027 to 2033) of the Junior Subordinated Debentures or the earlier redemption of the Junior Subordinated Debentures in whole upon the occurrence of one or more events set forth in the indentures relating to the Capital Securities, and in whole or in part at any time after an optional redemption prior to contractual maturity contemporaneously with the optional redemption of the related Junior Subordinated Debentures in whole or in part, subject to possible regulatory approval.

Also included in long-term borrowings are agreements to repurchase securities of $102 million and $409 million at September 30, 2019 and December 31, 2018, respectively. The repurchase agreement held at September 30, 2019 matures in 2020, however, the contractual maturities of the underlying investment securities extend beyond such repurchase date. The agreements are subject to legally enforceable master netting arrangements, however, the Company has not offset any amounts related to these agreements in its consolidated financial statements. The Company posted collateral consisting primarily of government guaranteed mortgage-backed securities of $108 million and $428 million at September 30, 2019 and December 31, 2018, respectively.

Shareholders’ equity

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Shareholders’ equity

6. Shareholders’ equity

M&T is authorized to issue 1,000,000 shares of preferred stock with a $1.00 par value per share. Preferred shares outstanding rank senior to common shares both as to dividends and liquidation preference, but have no general voting rights.

Issued and outstanding preferred stock of M&T as of September 30, 2019 and December 31, 2018 is presented below:

	September 30, 2019				December 31,2018
	Shares Issued and Outstanding		Carrying Value		Shares Issued and Outstanding		Carrying Value
	(Dollars in thousands)
Series A (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		230,000	$	230,000
Series C (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		151,500	$	151,500
Series E (b)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		350,000	$	350,000		350,000	$	350,000
Series F (c)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		50,000	$	500,000		50,000	$	500,000
Series G (d)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		40,000	$	400,000		—		—

(a)The shares were fully redeemed in August 2019, having received the approval of the Federal Reserve to redeem such shares after issuing the Series G

preferred stock.

(b)Dividends, if declared, are paid semi-annually at a rate of 6.45% through February 14, 2024 and thereafter will be paid quarterly at a rate of the

three-month LIBOR plus 361 basis points. The shares are redeemable in whole or in part on or after February 15, 2024. Notwithstanding M&T’s

option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90

days following that occurrence.

(c)Dividends, if declared, are paid semi-annually at a rate of 5.125% through October 31, 2026 and thereafter will be paid quarterly at a rate of the

three-month LIBOR plus 352 basis points. The shares are redeemable in whole or in part on or after November 1, 2026. Notwithstanding M&T’s

option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90

days following that occurrence.

(d)	Dividends, if declared, are paid semi-annually at a rate of 5.0% through July 31, 2024 and thereafter will be paid semiannually at a rate of the five-year U.S. Treasury rate plus 3.174%. The shares are redeemable in whole or in part on or after August 1, 2024. Notwithstanding M&T’s

option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90

days following that occurrence.

For each of the three-month periods ended September 30, 2019 and 2018, dividends declared per share were: Series A- $15.9375; Series C - $15.9375; Series E - $16.125; and Series F - $128.125. For each of the nine-month periods ended September 30, 2019 and 2018, dividends per share were: Series A- $47.8125; Series C - $47.8125; Series E - $48.375; and Series F - $384.375.

Revenue from contracts with customers

9 Months Ended

Sep. 30, 2019

Revenue From Contract With Customer [Abstract]

Revenue from contracts with customers

7. Revenue from contracts with customers

A significant amount of the Company’s revenues are derived from net interest income on financial assets and liabilities, mortgage banking revenues, trading account and foreign exchange gains, investment securities gains, loan and letter of credit fees, income from bank-owned life insurance, and certain other revenues that are generally excluded from the scope of accounting guidance for revenue from contracts with customers.

For noninterest income revenue streams, the Company recognizes the expected amount of consideration as revenue when the performance obligations related to the services under the terms of a contract are satisfied. The Company’s contracts generally do not contain terms that necessitate significant judgment to determine the amount of revenue to recognize.

The Company generally charges customer accounts or otherwise bills customers upon completion of its services. Typically the Company’s contracts with customers have a duration of one year or less and payment for services is received at least annually, but oftentimes more frequently as services are provided. At September 30, 2019 and December 31, 2018, the Company had $59 million and $56 million, respectively, of uncollected amounts receivable related to recognized revenue from the sources in the accompanying tables. Such amounts are classified in accrued interest and other assets in the Company’s consolidated balance sheet. In certain situations the Company is paid in advance of providing services and defers the recognition of revenue until its service obligation is satisfied. At September 30, 2019 and December 31, 2018, the Company had deferred revenue of $43 million related to the sources in the accompanying tables recorded in accrued interest and other liabilities in the consolidated balance sheet.

The following tables summarize sources of the Company’s noninterest income during the three-month and nine-month periods ended September 30, 2019 and 2018 that are subject to the noted accounting guidance.

	Business Banking		Commercial Banking		Commercial Real Estate		Discretionary Portfolio		Residential Mortgage Banking		Retail Banking		All Other		Total
Three Months Ended September 30, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,131		23,427		2,415		—		—		68,455		1,664	$	111,092
Trust income		9		242		—		—		—		—		143,664		143,915
Brokerage services income		—		—		—		—		—		—		12,077		12,077
Other revenues from operations:
Merchant discount and credit card fees		9,692		13,409		670		—		—		4,150		269		28,190
Other		—		1,239		1,372		503		816		9,347		7,076		20,353
	$	24,832		38,317		4,457		503		816		81,952		164,750	$	315,627
Three Months Ended September 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,767		24,167		2,374		—		2		64,709		1,628	$	108,647
Trust income		—		—		—		—		—		—		133,545		133,545
Brokerage services income		—		—		—		—		—		—		12,267		12,267
Other revenues from operations:
Merchant discount and credit card fees		9,238		13,520		643		—		—		3,908		462		27,771
Other		—		1,662		1,822		386		916		9,397		6,723		20,906
	$	25,005		39,349		4,839		386		918		78,014		154,625	$	303,136

7. Revenue from contracts with customers, continued

	Business Banking		Commercial Banking		Commercial Real Estate		Discretionary Portfolio		Residential Mortgage Banking		Retail Banking		All Other		Total
Nine Months Ended September 30, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	45,415		69,731		7,303		—		4		195,267		4,271	$	321,991
Trust income		21		680		—		—		—		—		420,382		421,083
Brokerage services income		—		—		—		—		—		—		37,031		37,031
Other revenues from operations:
Merchant discount and credit card fees		28,469		38,630		1,772		—		—		11,854		1,291		82,016
Other		—		5,386		5,840		1,545		2,913		27,170		26,159		69,013
	$	73,905		114,427		14,915		1,545		2,917		234,291		489,134	$	931,134
Nine Months Ended September 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	46,782		73,091		7,589		—		8		188,325		4,751	$	320,546
Trust income		—		—		—		—		—		—		402,561		402,561
Brokerage services income		—		—		—		—		—		—		38,288		38,288
Other revenues from operations:
Merchant discount and credit card fees		25,075		38,774		1,625		—		—		11,436		1,695		78,605
Other		—		6,871		4,896		1,251		2,886		28,875		23,429		68,208
	$	71,857		118,736		14,110		1,251		2,894		228,636		470,724	$	908,208

Pension plans and other postretirement benefits

9 Months Ended

Sep. 30, 2019

Compensation And Retirement Disclosure [Abstract]

Pension plans and other postretirement benefits

8. Pension plans and other postretirement benefits

The Company provides defined benefit pension and other postretirement benefits (including health care and life insurance benefits) to qualified retired employees. Net periodic defined benefit cost for defined benefit plans consisted of the following:

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended September 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	4,324			5,086			215		234
Interest cost on projected benefit obligation		20,394			18,676			586			573
Expected return on plan assets		(30,534	)		(30,781	)		—			—
Amortization of prior service cost (credit)		139			139			(1,182	)		(1,182	)
Amortization of net actuarial loss (gain)		5,498			10,948			(312	)		(206	)
Net periodic cost (benefit)	$	(179	)		4,068			(693	)		(581	)

	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended September 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	12,970			15,258			644			703
Interest cost on projected benefit obligation		61,184			56,029			1,758			1,719
Expected return on plan assets		(91,604	)		(92,344	)		—			—
Amortization of prior service cost (credit)		418			417			(3,547	)		(3,546	)
Amortization of net actuarial loss (gain)		16,494			32,844			(935	)		(619	)
Net periodic cost (benefit)	$	(538	)		12,204			(2,080	)		(1,743	)

Service cost is reflected in salaries and employee benefits expense in the consolidated statement of income. The other components of net periodic cost (benefit) are reflected in other costs of operations. Expenses incurred in connection with the Company's defined contribution pension and retirement savings plans totaled $21 million and $17 million for the three months ended September 30, 2019 and 2018, respectively, and $61 million and $55 million for the nine months ended September 30, 2019 and 2018, respectively, and are included in salaries and employee benefits expense.

Earnings per common share

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Earnings per common share

9. Earnings per common share

The computations of basic earnings per common share follow:

	Three Months Ended September 30						Nine Months Ended September 30
	2019			2018			2019			2018
	(In thousands, except per share)

Income available to common shareholders:
Net income	$	480,081			526,091			1,436,083			1,371,861
Less: Preferred stock dividends (a)		(16,103	)		(18,130	)		(52,364	)		(54,390	)
Net income available to common equity		463,978			507,961			1,383,719			1,317,471
Less: Income attributable to unvested stock-based compensation awards		(2,568	)		(2,598	)		(7,591	)		(6,774	)
Net income available to common shareholders	$	461,410			505,363			1,376,128			1,310,697
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		133,703			143,556			136,156			146,177
Less: Unvested stock-based compensation awards		(738	)		(734	)		(745	)		(753	)
Weighted-average shares outstanding		132,965			142,822			135,411			145,424

Basic earnings per common share	$	3.47			3.54			10.16			9.01

(a)Including impact of not as yet declared cumulative dividends.

The computations of diluted earnings per common share follow:

	Three Months Ended September 30						Nine Months Ended September 30
	2019			2018			2019			2018
	(In thousands, except per share)

Net income available to common equity	$	463,978			507,961			1,383,719			1,317,471
Less: Income attributable to unvested stock-based compensation awards		(2,568	)		(2,596	)		(7,590	)		(6,768	)
Net income available to common shareholders	$	461,410			505,365			1,376,129			1,310,703
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards		133,703			143,556			136,156			146,177
Less: Unvested stock-based compensation awards		(738	)		(734	)		(745	)		(753	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		34			154			32			181
Adjusted weighted-average shares outstanding		132,999			142,976			135,443			145,605

Diluted earnings per common share	$	3.47			3.53			10.16			9.00

GAAP defines unvested share-based awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) as participating securities that shall be included in the computation of earnings per common share pursuant to the two-class method. The Company has issued stock-based compensation awards in the form of restricted stock and restricted stock units which, in accordance with GAAP, are considered participating securities.

Stock-based compensation awards and warrants to purchase common stock of M&T representing 277,840 and 212,407 common shares during the three-month periods ended September 30, 2019 and 2018, respectively, and 224,639 and 220,653 common shares during the nine-month periods ended September 30, 2019 and 2018, respectively, were not included in the computations of diluted earnings per common share because the effect on those periods would have been antidilutive.

Comprehensive income

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Comprehensive income

10. Comprehensive income

The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other comprehensive income (loss) to net income:

	Investment			Defined Benefit						Total Amount				Income
	Securities			Plans			Other			Before Tax				Tax			Net
	(In thousands)

Balance — January 1, 2019	$	(200,107	)		(354,502	)		(14,719	)	$	(569,328	)			149,247		$	(420,081	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		237,615			—			—			237,615				(62,432	)		175,183
Foreign currency translation adjustment		—			—			(2,663	)		(2,663	)			559			(2,104	)
Unrealized gains on cash flow hedges		—			—			204,587			204,587				(53,786	)		150,801
Total other comprehensive income before reclassifications		237,615			—			201,924			439,539				(115,659	)		323,880
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities		2,524			—			—			2,524		(a)		(663	)		1,861
Losses realized in net income		7			—			—			7		(b)		(2	)		5
Accretion of net gain on terminated cash flow hedges		—			—			(93	)		(93	)	(c)		25			(68	)
Net yield adjustment from cash flow hedges currently in effect		—			—			6,693			6,693		(a)		(1,760	)		4,933
Amortization of prior service credit		—			(3,129	)		—			(3,129	)	(d)		823			(2,306	)
Amortization of actuarial losses		—			15,559			—			15,559		(d)		(4,091	)		11,468
Total other comprehensive income		240,146			12,430			208,524			461,100				(121,327	)		339,773
Balance — September 30, 2019	$	40,039			(342,072	)		193,805		$	(108,228	)			27,920		$	(80,308	)


Balance — January 1, 2018	$	(59,957	)		(413,168	)		(20,165	)	$	(493,290	)			129,476		$	(363,814	)
Cumulative effect of change in accounting principle — equity securities		(22,795	)		—			—			(22,795	)			5,942			(16,853	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(230,135	)		—			—			(230,135	)			60,494			(169,641	)
Foreign currency translation adjustment		—			—			(1,783	)		(1,783	)			374			(1,409	)
Unrealized losses on cash flow hedges		—			—			(26,522	)		(26,522	)			6,972			(19,550	)
Total other comprehensive income (loss) before reclassifications		(230,135	)		—			(28,305	)		(258,440	)			67,840			(190,600	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		2,519			—			—			2,519		(a)		(662	)		1,857
Gains realized in net income		(18	)		—			—			(18	)	(b)		4			(14	)
Accretion of net gain on terminated cash flow hedges		—			—			(83	)		(83	)	(c)		22			(61	)
Net yield adjustment from cash flow hedges currently in effect		—			—			7,650			7,650		(a)		(2,011	)		5,639
Amortization of prior service credit		—			(3,129	)		—			(3,129	)	(d)		823			(2,306	)
Amortization of actuarial losses		—			32,225			—			32,225		(d)		(8,472	)		23,753
Total other comprehensive income (loss)		(227,634	)		29,096			(20,738	)		(219,276	)			57,544			(161,732	)
Balance — September 30, 2018	$	(310,386	)		(384,072	)		(40,903	)	$	(735,361	)			192,962		$	(542,399	)

(a)	Included in interest income.

(b)	Included in gain (loss) on bank investment securities.

(c)	Included in interest expense.

(d)	Included in other costs of operations.

Accumulated other comprehensive income (loss), net consisted of the following:

	Investment			Defined Benefit
	Securities			Plans			Other			Total
	(In thousands)

Balance — December 31, 2018	$	(147,526	)		(261,303	)		(11,252	)	$	(420,081	)
Net gain during period		177,049			9,162			153,562			339,773
Balance — September 30, 2019	$	29,523			(252,141	)		142,310		$	(80,308	)

Derivative financial instruments

9 Months Ended

Sep. 30, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Derivative financial instruments

11. Derivative financial instruments

As part of managing interest rate risk, the Company enters into interest rate swap agreements to modify the repricing characteristics of certain portions of the Company’s portfolios of earning assets and interest-bearing liabilities. The Company designates interest rate swap agreements utilized in the management of interest rate risk as either fair value hedges or cash flow hedges. Interest rate swap agreements are generally entered into with counterparties that meet established credit standards and most contain master netting, collateral and/or settlement provisions protecting the at-risk party. Based on adherence to the Company’s credit standards and the presence of the netting, collateral or settlement provisions, the Company believes that the credit risk inherent in these contracts was not material as of September 30, 2019.

The net effect of interest rate swap agreements was to increase net interest income by $1 million during the three-month period ended September 30, 2019 and decrease net interest income by $23 million during the nine-month period ended September 30, 2019, compared with decreases of $8 million and $12 million during the three-month and nine-month periods ended September 30, 2018, respectively.

Information about interest rate swap agreements entered into for interest rate risk management purposes summarized by type of financial instrument the swap agreements were intended to hedge follows:

					Weighted-
					Average Rate
	Notional		Average								Estimated Fair Value
	Amount		Maturity		Fixed			Variable			Gain (Loss) (a)
	(In thousands)		(In years)								(In thousands)
September 30, 2019
Fair value hedges:
Fixed rate long-term borrowings (b)	$	3,800,000		2.5		2.51	%		2.55	%	$	(1,086	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(c)		43,600,000		1.4		2.38	%		2.06	%		(5,056	)
Total	$	47,400,000		1.5							$	(6,142	)
December 31, 2018
Fair value hedges:
Fixed rate long-term borrowings (b)	$	4,450,000		2.8		2.47	%		3.02	%	$	4,219
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(d)		15,400,000		1.3		1.52	%		2.35	%		1,311
Total	$	19,850,000		1.7							$	5,530

(a)

Certain clearinghouse exchanges consider payments by counterparties for variation margin on derivative instruments to be settlements of those positions. The impact of such treatment at September 30, 2019 and December 31, 2018 was a reduction of the estimated fair value gains on interest rate swap agreements designated as fair value hedges of $64.0 million and fair value losses of $54.7 million, respectively, and on interest rate swaps designated as cash flow hedges a reduction of fair value gains of $208.5 million and a reduction of fair value losses of $9.1 million, respectively.

(b)	Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate.

(c)	Includes notional amount and terms of $30.3 billion of forward-starting interest rate swap agreements that become effective in 2019, 2020 and 2021.

(d)	Includes notional amount and terms of $12.6 billion of forward-starting interest rate swap agreements that become effective in 2019 and 2020.

The Company utilizes commitments to sell residential and commercial real estate loans to hedge the exposure to changes in the fair value of real estate loans held for sale. Such commitments have generally been designated as fair value hedges. The Company also utilizes commitments to sell real estate loans to offset the exposure to changes in fair value of certain commitments to originate real estate loans for sale.

Derivative financial instruments used for trading account purposes included interest rate contracts, foreign exchange and other option contracts, foreign exchange forward and spot contracts, and financial futures. Interest rate contracts entered into for trading account purposes had notional values of $47.6 billion and $42.9 billion at September 30, 2019 and December 31, 2018, respectively. The notional amounts of foreign currency and other

11. Derivative financial instruments, continued

option and futures contracts entered into for trading account purposes aggregated $843 million and $763 million at September 30, 2019 and December 31, 2018, respectively.

Information about the fair values of derivative instruments in the Company’s consolidated balance sheet and consolidated statement of income follows:

	Asset Derivatives				Liability Derivatives
	Fair Value				Fair Value
	September 30,		December 31,		September 30,		December 31,
	2019		2018		2019		2018
	(In thousands)
Derivatives designated and qualifying as hedging instruments
Interest rate swap agreements (a)	$	47	$	5,530	$	6,189	$	—
Commitments to sell real estate loans (a)		1,339		1,090		1,928		6,434
		1,386		6,620		8,117		6,434
Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		24,463		9,304		189		1,592
Commitments to sell real estate loans (a)		2,079		3,702		13,402		4,535
Trading:
Interest rate contracts (b)		532,070		118,687		72,098		169,255
Foreign exchange and other option and futures contracts (b)		11,280		10,549		9,944		8,870
		569,892		142,242		95,633		184,252
Total derivatives	$	571,278	$	148,862	$	103,750	$	190,686

(a)	Asset derivatives are reported in other assets and liability derivatives are reported in other liabilities.

(b)

Asset derivatives are reported in trading account assets and liability derivatives are reported in other liabilities. The impact of variation margin payments at September 30, 2019 and December 31, 2018 was a reduction of the estimated fair value of interest rate contracts in the trading account in an asset position of $17.2 million and $170.7 million, respectively, and in a liability position of $390.6 million and $49.7 million, respectively.

	Amount of Gain (Loss) Recognized
	Three Months Ended September 30, 2019					Three Months Ended September 30, 2018
	Derivative		Hedged Item			Derivative			Hedged Item
	(In thousands)
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	22,582		(22,412	)	$	(12,568	)		12,607
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	6,435				$	(1,348	)
Foreign exchange and other option and futures contracts (b)		2,598					782
Total	$	9,033				$	(566	)

11. Derivative financial instruments, continued

	Amount of Gain (Loss) Recognized
	Nine Months Ended September 30, 2019					Nine Months Ended September 30, 2018
	Derivative		Hedged Item			Derivative			Hedged Item
	(In thousands)
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	113,441		(112,884	)	$	(68,315	)		68,861
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	17,639				$	(5,639	)
Foreign exchange and other option and futures contracts (b)		6,690					5,778
Total	$	24,329				$	139

(a)

Reported as interest expense.

(b)

Reported as trading account and foreign exchange gains.

	Carrying Amount of the Hedged Item				Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item
	September 30, 2019		December 31, 2018		September 30, 2019		December 31, 2018
	(In thousands)
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges

Long-term debt	$	3,858,490	$	4,394,109	$	61,782	$	(51,102	)

The Company also has commitments to sell and commitments to originate residential and commercial real estate loans that are considered derivatives. The Company designates certain of the commitments to sell real estate loans as fair value hedges of real estate loans held for sale. The Company also utilizes commitments to sell real estate loans to offset the exposure to changes in the fair value of certain commitments to originate real estate loans for sale. As a result of these activities, net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans were approximately $24 million and $18 million at September 30, 2019 and December 31, 2018, respectively. Changes in unrealized gains and losses are included in mortgage banking revenues and, in general, are realized in subsequent periods as the related loans are sold and commitments satisfied.

The Company does not offset derivative asset and liability positions in its consolidated financial statements. The Company’s exposure to credit risk by entering into derivative contracts is mitigated through master netting agreements and collateral posting or settlement requirements. Master netting agreements covering interest rate and foreign exchange contracts with the same party include a right to set-off that becomes enforceable in the event of default, early termination or under other specific conditions.

11. Derivative financial instruments, continued

The aggregate fair value of derivative financial instruments in a liability position and the net liability positions with counterparties, which are subject to enforceable master netting arrangements, was $70 million and $21 million at September 30, 2019 and December 31, 2018, respectively. The Company was required to post collateral relating to those positions of $68 million and $18 million at September 30, 2019 and December 31, 2018, respectively. Certain of the Company’s derivative financial instruments contain provisions that require the Company to maintain specific credit ratings from credit rating agencies to avoid higher collateral posting requirements. If the Company’s debt rating were to fall below specified ratings, the counterparties of the derivative financial instruments could demand immediate incremental collateralization on those instruments in a net liability position, however, the aggregate fair value of such derivative financial instruments in a net liability position and the amount of incremental collateralization that could be required was not significant at September 30, 2019.

The aggregate fair value of derivative financial instruments in an asset position and the net asset positions with counterparties, which are subject to enforceable master netting arrangements, was $639 thousand and $18 million at September 30, 2019 and December 31, 2018, respectively. Counterparties posted collateral relating to those positions of $81 thousand and $16 million at September 30, 2019 and December 31, 2018, respectively. Trading account interest rate swap agreements entered into with customers are subject to the Company’s credit risk standards and often contain collateral provisions.

In addition to the derivative contracts noted above, the Company clears certain derivative transactions through a clearinghouse, rather than directly with counterparties. Those transactions cleared through a clearinghouse require initial margin collateral and variation margin payments depending on the contracts being in a net asset or liability position. The amount of initial margin collateral posted by the Company was $129 million and $65 million at September 30, 2019 and December 31, 2018, respectively. The fair value asset and liability amounts of derivative contracts have been reduced by variation margin payments treated as settlements as described herein. Variation margin on derivative contracts not treated as settlements continues to represent collateral posted or received by the Company.

Variable interest entities and asset securitizations

9 Months Ended

Sep. 30, 2019

Text Block [Abstract]

Variable interest entities and asset securitizations

12. Variable interest entities and asset securitizations

The Company’s securitization activity has consisted of securitizing loans originated for sale into government issued or guaranteed mortgage-backed securities. The amounts of those securitizations during the nine-month periods ended September 30, 2019 and 2018 are presented in the Company’s consolidated statement of cash flows. The Company has not recognized any losses as a result of having securitized assets.

As described in note 5, M&T has issued junior subordinated debentures payable to various trusts that have issued Capital Securities. M&T owns the common securities of those trust entities. The Company is not considered to be the primary beneficiary of those entities and, accordingly, the trusts are not included in the Company’s consolidated financial statements. At each of September 30, 2019 and December 31, 2018, the Company included the junior subordinated debentures as “long-term borrowings” in its consolidated balance sheet and recognized $23 million in other assets for its “investment” in the common securities of the trusts that will be concomitantly repaid to M&T by the respective trust from the proceeds of M&T’s repayment of the junior subordinated debentures associated with preferred capital securities described in note 5.

The Company has invested as a limited partner in various partnerships that collectively had total assets of approximately $1.4 billion at September 30, 2019 and $1.1 billion at December 31, 2018. Those partnerships generally construct or acquire properties for which the investing partners are eligible to receive certain federal income tax credits in accordance with government guidelines. Such investments may also provide tax deductible losses to the partners. The partnership investments also assist the Company in achieving its community reinvestment initiatives. As a limited partner, there is no recourse to the Company by creditors of the partnerships. However, the tax credits that result from the Company’s investments in such partnerships are generally subject to recapture should a partnership fail to comply with the respective government regulations. The Company’s carrying amount of its investments in such partnerships at September 30, 2019 and December 31, 2018 was $604 million and $523 million, respectively, including $390 million of unfunded commitments at September 30, 2019 and $280 million of unfunded commitments at December 31, 2018. Contingent commitments to provide additional capital contributions to these partnerships were not material at September 30, 2019. The Company has not provided financial or other support to the partnerships that was not contractually required. The Company’s maximum exposure to loss from its investments in such partnerships as of September 30, 2019 was $803 million, including possible recapture of certain tax credits. Management currently estimates that no material losses are probable as a result of the Company’s involvement with such entities. The Company, in its position as limited partner, does not direct the activities that most significantly impact the economic performance of the partnerships and, therefore, in accordance with the accounting provisions for variable interest entities, the partnership entities are not included in the Company’s consolidated financial statements. The Company’s investment in qualified affordable housing projects is amortized to income taxes in the consolidated statement of income as tax credits and other tax benefits resulting from deductible losses associated with the projects are received. The Company amortized $17 million and $51 million of its investments in qualified affordable housing projects to income tax expense during the three-month and nine-month periods ended September 30, 2019, respectively, and recognized $21 million and $62 million of tax credits and other tax benefits during those periods. Similarly, for the three-month and nine-month periods ended September 30, 2018, the Company amortized $13 million and $39 million, respectively, of its investments in qualified affordable housing projects to income tax expense and recognized $15 million and $47 million of tax credits and other tax benefits during those respective periods.

The Company serves as investment advisor for certain registered money-market funds. The Company has no explicit arrangement to provide support to those funds but may waive portions of its allowable management fees because of market conditions.

Fair value measurements

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Fair value measurements

13. Fair value measurements

GAAP permits an entity to choose to measure eligible financial instruments and other items at fair value. The Company has not made any fair value elections at September 30, 2019.

Pursuant to GAAP, fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A three-level hierarchy exists in GAAP for fair value measurements based upon the inputs to the valuation of an asset or liability.

•

Level 1 — Valuation is based on quoted prices in active markets for identical assets and liabilities.

•

Level 2 — Valuation is determined from quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar instruments in markets that are not active or by model-based techniques in which all significant inputs are observable in the market.

•

Level 3 — Valuation is derived from model-based and other techniques in which at least one significant input is unobservable and which may be based on the Company's own estimates about the assumptions that market participants would use to value the asset or liability.

When available, the Company attempts to use quoted market prices in active markets to determine fair value and classifies such items as Level 1 or Level 2. If quoted market prices in active markets are not available, fair value is often determined using model-based techniques incorporating various assumptions including interest rates, prepayment speeds and credit losses. Assets and liabilities valued using model-based techniques are classified as either Level 2 or Level 3, depending on the lowest level classification of an input that is considered significant to the overall valuation. The following is a description of the valuation methodologies used for the Company's assets and liabilities that are measured on a recurring basis at estimated fair value.

Trading account assets and liabilities

Trading account assets and liabilities consist primarily of interest rate contracts and foreign exchange contracts with customers who require such services with offsetting positions with third parties to minimize the Company's risk with respect to such transactions. The Company generally determines the fair value of its derivative trading account assets and liabilities using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2. Mutual funds held in connection with deferred compensation and other arrangements have been classified as Level 1 valuations. Valuations of investments in municipal and other bonds can generally be obtained through reference to quoted prices in less active markets for the same or similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2.

Investment securities available for sale and equity securities

The majority of the Company's available-for-sale investment securities have been valued by reference to prices for similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2. Certain investments in mutual funds and equity securities are actively traded and, therefore, have been classified as Level 1 valuations.

Real estate loans held for sale

The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in fair value of real estate loans held for sale. The carrying value of hedged real estate loans held for sale includes changes in estimated fair value during the hedge period. Typically, the Company attempts to hedge real estate loans held for sale from the date of close through the sale date. The fair value of hedged real estate loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans with similar characteristics and, accordingly, such loans have been classified as a Level 2 valuation.

13. Fair value measurements, continued

Commitments to originate real estate loans for sale and commitments to sell real estate loans

The Company enters into various commitments to originate real estate loans for sale and commitments to sell real estate loans. Such commitments are considered to be derivative financial instruments and, therefore, are carried at estimated fair value on the consolidated balance sheet. The estimated fair values of such commitments were generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans to certain government-sponsored entities and other parties. The fair valuations of commitments to sell real estate loans generally result in a Level 2 classification. The estimated fair value of commitments to originate real estate loans for sale are adjusted to reflect the Company's anticipated commitment expirations. The estimated commitment expirations are considered significant unobservable inputs contributing to the Level 3 classification of commitments to originate real estate loans for sale. Significant unobservable inputs used in the determination of estimated fair value of commitments to originate real estate loans for sale are included in the accompanying table of significant unobservable inputs to Level 3 measurements.

Interest rate swap agreements used for interest rate risk management

The Company utilizes interest rate swap agreements as part of the management of interest rate risk to modify the repricing characteristics of certain portions of its portfolios of earning assets and interest-bearing liabilities. The Company generally determines the fair value of its interest rate swap agreements using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2. The Company has considered counterparty credit risk in the valuation of its interest rate swap agreement assets and has considered its own credit risk in the valuation of its interest rate swap agreement liabilities.

13. Fair value measurements, continued

The following tables present assets and liabilities at September 30, 2019 and December 31, 2018 measured at estimated fair value on a recurring basis:

	Fair Value Measurements		Level 1 (a)		Level 2 (a)		Level 3
	(In thousands)
September 30, 2019
Trading account assets	$	614,256	$	48,724	$	565,532	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		359,394		—		359,394		—
Obligations of states and political subdivisions		934		—		934		—
Mortgage-backed securities:
Government issued or guaranteed		6,494,900		—		6,494,900		—
Privately issued		16		—		—		16
Other debt securities		130,173		—		130,173		—
		6,985,417		—		6,985,401		16
Equity securities		150,104		104,199		45,905		—
Real estate loans held for sale		588,233		—		588,233		—
Other assets (b)		27,928		—		3,465		24,463
Total assets	$	8,365,938	$	152,923	$	8,188,536	$	24,479
Trading account liabilities	$	82,042	$	—	$	82,042	$	—
Other liabilities (b)		21,708		—		21,519		189
Total liabilities	$	103,750	$	—	$	103,561	$	189

December 31, 2018
Trading account assets	$	185,584	$	46,018	$	139,566	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		1,336,931		—		1,336,931		—
Obligations of states and political subdivisions		1,659		—		1,659		—
Mortgage-backed securities:
Government issued or guaranteed		7,216,991		—		7,216,991		—
Privately issued		22		—		—		22
Other debt securities		126,906		—		126,906		—
		8,682,509		—		8,682,487		22
Equity securities		93,917		71,989		21,928		—
Real estate loans held for sale		551,697		—		551,697		—
Other assets (b)		19,626		—		10,322		9,304
Total assets	$	9,533,333	$	118,007	$	9,406,000	$	9,326
Trading account liabilities	$	178,125	$	—	$	178,125	$	—
Other liabilities (b)		12,561		—		10,969		1,592
Total liabilities	$	190,686	$	—	$	189,094	$	1,592

(a)	There were no significant transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2019 and the year ended December 31, 2018.

(b)	Comprised predominantly of interest rate swap agreements used for interest rate risk management (Level 2), commitments to sell real estate loans (Level 2) and commitments to originate real estate loans to be held for sale (Level 3).

13. Fair value measurements, continued

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during three months ended September 30, 2019 and 2018 were as follows:

	Investment Securities Available for Sale
	Privately Issued Mortgage-Backed Securities		Other Assets and Other Liabilities
2019	(In thousands)

Balance — June 30, 2019	$	16		17,200
Total gains realized/unrealized:
Included in earnings		—		62,178		(b)
Settlements		—		—
Transfers out of Level 3 (a)		—		(55,104	)	(c)
Balance — September 30, 2019	$	16		24,274
Changes in unrealized gains included in earnings related to assets still held at September 30, 2019	$	—		19,350		(b)

2018

Balance — June 30, 2018	$	24		10,751
Total gains realized/unrealized:
Included in earnings		—		10,284		(b)
Settlements		(1	)	—
Transfers out of Level 3 (a)		—		(16,849	)	(c)
Balance — September 30, 2018	$	23		4,186
Changes in unrealized gains included in earnings related to assets still held at September 30, 2018	$	—		4,508		(b)

13. Fair value measurements, continued

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the nine months ended September 30, 2019 and 2018 were as follows:

	Investment Securities Available for Sale
	Privately Issued Mortgage-Backed Securities			Other Assets and Other Liabilities
2019	(In thousands)

Balance — January 1, 2019	$	22			7,712
Total gains realized/unrealized:
Included in earnings		—			115,187		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(98,625	)	(c)
Balance — September 30, 2019	$	16			24,274
Changes in unrealized gains included in earnings related to assets still held at September 30, 2019	$	—			24,981		(b)

2018

Balance — January 1, 2018	$	28		8,303
Total gains realized/unrealized:
Included in earnings		—		38,691		(b)
Settlements		(5	)	—
Transfers out of Level 3 (a)		—		(42,808	)	(c)
Balance — September 30, 2018	$	23		4,186
Changes in unrealized gains included in earnings related to assets still held at September 30, 2018	$	—		3,663		(b)

(a)	The Company’s policy for transfers between fair value levels is to recognize the transfer as of the actual date of the event or change in circumstances that caused the transfer.

(b)	Reported as mortgage banking revenues in the consolidated statement of income and includes the fair value of commitment issuances and expirations.

(c)	Transfers out of Level 3 consist of interest rate locks transferred to closed loans.

13. Fair value measurements, continued

The Company is required, on a nonrecurring basis, to adjust the carrying value of certain assets or provide valuation allowances related to certain assets using fair value measurements. The more significant of those assets follow.

Loans

Loans are generally not recorded at fair value on a recurring basis. Periodically, the Company records nonrecurring adjustments to the carrying value of loans based on fair value measurements for partial charge-offs of the uncollectible portions of those loans. Nonrecurring adjustments also include certain impairment amounts for collateral-dependent loans when establishing the allowance for credit losses. Such amounts are generally based on the fair value of the underlying collateral supporting the loan and, as a result, the carrying value of the loan less the calculated valuation amount does not necessarily represent the fair value of the loan. Real estate collateral is typically valued using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace and the related nonrecurring fair value measurement adjustments have been classified as Level 2, unless significant adjustments have been made to the valuation that are not readily observable by market participants. Non-real estate collateral supporting commercial loans generally consists of business assets such as receivables, inventory and equipment. Fair value estimations are typically determined by discounting recorded values of those assets to reflect estimated net realizable value considering specific borrower facts and circumstances and the experience of credit personnel in their dealings with similar borrower collateral liquidations. Such discounts were in the range of 15% to 85% at September 30, 2019. As these discounts are not readily observable and are considered significant, the valuations have been classified as Level 3. Automobile collateral is typically valued by reference to independent pricing sources based on recent sales transactions of similar vehicles and the related nonrecurring fair value measurement adjustments have been classified as Level 2. Collateral values for other consumer installment loans are generally estimated based on historical recovery rates for similar types of loans. As these recovery rates are not readily observable by market participants, such valuation adjustments have been classified as Level 3. Loans subject to nonrecurring fair value measurement were $302 million at September 30, 2019 ($122 million and $180 million of which were classified as Level 2 and Level 3, respectively), $268 million at December 31, 2018 ($120 million and $148 million of which were classified as Level 2 and Level 3, respectively) and $292 million at September 30, 2018 ($128 million and $164 million of which were classified as Level 2 and Level 3, respectively). Changes in fair value recognized for partial charge-offs of loans and loan impairment reserves on loans held by the Company on September 30, 2019 were decreases of $51 million and $85 million for the three-month and nine-month periods ended September 30, 2019, respectively. Changes in fair value recognized for partial charge-offs of loans and loan impairment reserves on loans held by the Company on September 30, 2018 were decreases of $35 million and $69 million for the three-month and nine-month periods ended September 30, 2018, respectively.

Assets taken in foreclosure of defaulted loans

Assets taken in foreclosure of defaulted loans are primarily comprised of commercial and residential real property and are generally measured at the lower of cost or fair value less costs to sell. The fair value of the real property is generally determined using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace, and the related nonrecurring fair value measurement adjustments have generally been classified as Level 2. Assets taken in foreclosure of defaulted loans subject to nonrecurring fair value measurement were $17 million and $32 million at September 30, 2019 and 2018, respectively. Changes in fair value recognized for those foreclosed assets held by the Company were not material during the three-month and nine-month periods ended September 30, 2019 and 2018.

13. Fair value measurements, continued

Capitalized servicing rights

Capitalized servicing rights are initially measured at fair value in the Company’s consolidated balance sheet. The Company utilizes the amortization method to subsequently measure its capitalized servicing assets. In accordance with GAAP, the Company must record impairment charges, on a nonrecurring basis, when the carrying value of certain strata exceed their estimated fair value. To estimate the fair value of servicing rights, the Company considers market prices for similar assets, if available, and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate, and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceed estimated fair value. Impairment is recognized through a valuation allowance. The determination of fair value of capitalized servicing rights is considered a Level 3 valuation. At September 30, 2019, $193 million of capitalized servicing rights required a valuation allowance of approximately $23 million. No stratum of capitalized servicing rights required a valuation allowance at December 31, 2018 or September 30, 2018. Changes in fair value recognized for impairment of capitalized servicing rights were $14 million and $23 million for the three months and nine months ended September 30, 2019, respectively. No changes in fair value were recognized in 2018.

Significant unobservable inputs to Level 3 measurements

The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for certain Level 3 assets and liabilities at September 30, 2019 and December 31, 2018:

Fair Value

Valuation

Technique

Unobservable

Inputs/Assumptions

Range

(Weighted-

Average)

(In thousands)

September 30, 2019

Recurring fair value measurements

Privately issued mortgage-backed

securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

24,274

Discounted cash flow

Commitment expirations

0%-96% (11%)

December 31, 2018

Recurring fair value measurements

Privately issued mortgage-backed

securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

7,712

Discounted cash flow

Commitment expirations

0%-95% (13%)

(a)	Other Level 3 assets (liabilities) consist of commitments to originate real estate loans.

13. Fair value measurements, continued

Sensitivity of fair value measurements to changes in unobservable inputs

An increase (decrease) in the estimate of expirations for commitments to originate real estate loans would generally result in a lower (higher) fair value measurement. Estimated commitment expirations are derived considering loan type, changes in interest rates and remaining length of time until closing.

Disclosures of fair value of financial instruments

The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following table:

	September 30, 2019
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
	(In thousands)
Financial assets:
Cash and cash equivalents	$	1,818,861			1,818,861			1,765,090		53,771			—
Interest-bearing deposits at banks		12,495,524			12,495,524			—		12,495,524			—
Federal funds sold		200			200			—		200			—
Trading account assets		614,256			614,256			48,724		565,532			—
Investment securities		10,677,583			10,721,588			104,199		10,525,863			91,526
Loans and leases:
Commercial loans and leases		23,201,372			22,844,883			—		—			22,844,883
Commercial real estate loans		34,945,231			34,772,982			—		197,141			34,575,841
Residential real estate loans		16,500,955			16,575,991			—		4,021,885			12,554,106
Consumer loans		15,175,635			15,157,025			—		—			15,157,025
Allowance for credit losses		(1,038,437	)		—			—		—			—
Loans and leases, net		88,784,756			89,350,881			—		4,219,026			85,131,855
Accrued interest receivable		340,543			340,543			—		340,543			—
Financial liabilities:
Noninterest-bearing deposits	$	(31,766,724	)		(31,766,724	)		—		(31,766,724	)		—
Savings and interest-checking deposits		(55,581,533	)		(55,581,533	)		—		(55,581,533	)		—
Time deposits		(6,203,679	)		(6,289,534	)		—		(6,289,534	)		—
Deposits at Cayman Islands office		(1,561,997	)		(1,561,997	)		—		(1,561,997	)		—
Short-term borrowings		(5,513,896	)		(5,513,896	)		—		(5,513,896	)		—
Long-term borrowings		(7,002,524	)		(7,056,344	)		—		(7,056,344	)		—
Accrued interest payable		(90,623	)		(90,623	)		—		(90,623	)		—
Trading account liabilities		(82,042	)		(82,042	)		—		(82,042	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	24,274			24,274			—		—			24,274
Commitments to sell real estate loans		(11,912	)		(11,912	)		—		(11,912	)		—
Other credit-related commitments		(130,413	)		(130,413	)		—		—			(130,413	)
Interest rate swap agreements used for interest rate risk management		(6,142	)		(6,142	)		—		(6,142	)		—

13. Fair value measurements, continued

	December 31, 2018
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
				(In thousands)
Financial assets:
Cash and cash equivalents	$	1,605,439			1,605,439			1,528,302		77,137			—
Interest-bearing deposits at banks		8,105,197			8,105,197			—		8,105,197			—
Trading account assets		185,584			185,584			46,018		139,566			—
Investment securities		12,692,813			12,631,656			71,989		12,456,467			103,200
Loans and leases:
Commercial loans and leases		22,977,976			22,587,387			—		—			22,587,387
Commercial real estate loans		34,363,556			33,832,558			—		346,775			33,485,783
Residential real estate loans		17,154,446			16,974,545			—		3,920,447			13,054,098
Consumer loans		13,970,499			13,819,545			—		—			13,819,545
Allowance for credit losses		(1,019,444	)		—			—		—			—
Loans and leases, net		87,447,033			87,214,035			—		4,267,222			82,946,813
Accrued interest receivable		353,965			353,965			—		353,965			—
Financial liabilities:
Noninterest-bearing deposits	$	(32,256,668	)		(32,256,668	)		—		(32,256,668	)		—
Savings and interest-checking deposits		(50,963,744	)		(50,963,744	)		—		(50,963,744	)		—
Time deposits		(6,124,254	)		(6,201,957	)		—		(6,201,957	)		—
Deposits at Cayman Islands office		(811,906	)		(811,906	)		—		(811,906	)		—
Short-term borrowings		(4,398,378	)		(4,398,378	)		—		(4,398,378	)		—
Long-term borrowings		(8,444,914	)		(8,385,289	)		—		(8,385,289	)		—
Accrued interest payable		(95,274	)		(95,274	)		—		(95,274	)		—
Trading account liabilities		(178,125	)		(178,125	)		—		(178,125	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	7,712			7,712			—		—			7,712
Commitments to sell real estate loans		(6,177	)		(6,177	)		—		(6,177	)		—
Other credit-related commitments		(131,688	)		(131,688	)		—		—			(131,688	)
Interest rate swap agreements used for interest rate risk management		5,530			5,530			—		5,530			—

With the exception of marketable securities, certain off-balance sheet financial instruments and mortgage loans originated for sale, the Company’s financial instruments are not readily marketable and market prices do not exist. The Company, in attempting to comply with the provisions of GAAP that require disclosures of fair value of financial instruments, has not attempted to market its financial instruments to potential buyers, if any exist. Since negotiated prices in illiquid markets depend greatly upon the then present motivations of the buyer and seller, it is reasonable to assume that actual sales prices could vary widely from any estimate of fair value made without the benefit of negotiations. Additionally, changes in market interest rates can dramatically impact the value of financial instruments in a short period of time.

The Company does not believe that the estimated information presented herein is representative of the earnings power or value of the Company. The preceding analysis, which is inherently limited in depicting fair value, also does not consider any value associated with existing customer relationships nor the ability of the Company to create value through loan origination, deposit gathering or fee generating activities. Many of the estimates presented herein are based upon the use of highly subjective information and assumptions and, accordingly, the results may not be precise. Management believes that fair value estimates may not be comparable between financial institutions due to the wide range of permitted valuation techniques and numerous estimates which must be made. Furthermore, because the disclosed fair value amounts were estimated as of the balance sheet date, the amounts actually realized or paid upon maturity or settlement of the various financial instruments could be significantly different.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and contingencies

9 Months Ended

Sep. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and contingencies

14. Commitments and contingencies

In the normal course of business, various commitments and contingent liabilities are outstanding. Certain of these commitments are not included in the Company's consolidated balance sheet.

	September 30,		December 31,
	2019		2018
	(In thousands)
Commitments to extend credit
Home equity lines of credit	$	5,451,328		5,484,197
Commercial real estate loans to be sold		393,397		229,401
Other commercial real estate		8,222,395		7,556,722
Residential real estate loans to be sold		530,093		245,211
Other residential real estate		511,854		219,351
Commercial and other		16,313,801		14,363,803
Standby letters of credit		2,373,846		2,326,991
Commercial letters of credit		38,633		55,808
Financial guarantees and indemnification contracts		3,996,029		3,529,136
Commitments to sell real estate loans		1,350,292		940,692

Commitments to extend credit are agreements to lend to customers, generally having fixed expiration dates or other termination clauses that may require payment of a fee. In addition to the amounts in the preceding table, the Company had discretionary funding commitments to commercial customers of $8.9 billion and $8.6 billion at September 30, 2019 and December 31, 2018, respectively, that the Company had the unconditional right to cancel prior to funding. Standby and commercial letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party, whereas commercial letters of credit are issued to facilitate commerce and typically result in the commitment being funded when the underlying transaction is consummated between the customer and a third party. The credit risk associated with commitments to extend credit and standby and commercial letters of credit is essentially the same as that involved with extending loans to customers and is subject to normal credit policies. Collateral may be obtained based on management's assessment of the customer's creditworthiness.

Financial guarantees and indemnification contracts are oftentimes similar to standby letters of credit and include mandatory purchase agreements issued to ensure that customer obligations are fulfilled, recourse obligations associated with sold loans, and other guarantees of customer performance or compliance with designated rules and regulations. Included in financial guarantees and indemnification contracts are loan principal amounts sold with recourse in conjunction with the Company's involvement in the Fannie Mae Delegated Underwriting and Servicing program. The Company's maximum credit risk for recourse associated with loans sold under this program totaled approximately $3.8 billion and $3.4 billion at September 30, 2019 and December 31, 2018, respectively.

Since many loan commitments, standby letters of credit, and guarantees and indemnification contracts expire without being funded in whole or in part, the contract amounts are not necessarily indicative of future cash flows.

The Company utilizes commitments to sell real estate loans to hedge exposure to changes in the fair value of real estate loans held for sale. Such commitments are considered derivatives and along with commitments to originate real estate loans to be held for sale are generally recorded in the consolidated balance sheet at estimated fair market value.

14. Commitments and contingencies, continued

The Company is contractually obligated to repurchase previously sold residential real estate loans that do not ultimately meet investor sale criteria related to underwriting procedures or loan documentation. When required to do so, the Company may reimburse loan purchasers for losses incurred or may repurchase certain loans. The Company reduces residential mortgage banking revenues by an estimate for losses related to its obligations to loan purchasers. The amount of those charges is based on the volume of loans sold, the level of reimbursement requests received from loan purchasers and estimates of losses that may be associated with previously sold loans. At September 30, 2019, the Company believes that its obligation to loan purchasers was not material to the Company’s consolidated financial position.

As previously disclosed, Wilmington Trust Corporation, a wholly-owned subsidiary of M&T, was the subject of a class action lawsuit alleging that Wilmington Trust Corporation’s financial reporting and securities filings prior to its acquisition by M&T in 2011 were in violation of securities laws. In April 2018, the parties reached an agreement in principle and a formal settlement agreement was executed and filed with the court later in the second quarter of 2018. The proposed settlement was preliminarily approved by the court in July 2018. In the first quarter of 2018, the Company increased its reserve for litigation matters in anticipation of the settlement. The settlement amount of $200 million was paid, pursuant to the settlement agreement, during the third quarter of 2018. The settlement agreement was approved by the court in the fourth quarter of 2018.

Wilmington Trust, N.A., a wholly owned bank subsidiary of M&T, provides retirement services, including serving in certain trustee roles relating to Employee Stock Ownership Plans (“ESOPs”). Beginning in 2010, the U.S. Department of Labor (“DOL”) announced that it would increase its focus on ESOP transactions, particularly with regard to valuation issues relating to ESOP transactions. Beginning in late 2013, Wilmington Trust, N.A. began receiving requests for information and subpoenas relating to certain ESOP transactions for which it acted as trustee. In June 2016, Wilmington Trust, N.A. received a DOL subpoena seeking information on its global ESOP trustee business. In addition to these investigations, the DOL has commenced three lawsuits against Wilmington Trust, N.A. relating to its role as trustee of three ESOP transactions. In July 2019, Wilmington Trust, N.A. reached a settlement in principle with the DOL to resolve certain pending DOL ESOP matters. Although a formal settlement agreement has yet to be prepared and executed, the Company does not expect that the agreed-upon settlement will have a material incremental impact on the Company’s consolidated financial position or results of operations. Wilmington Trust, N.A. has also been named as a defendant in five private party lawsuits relating to its role as trustee for five ESOP transactions. Under applicable transaction documents, Wilmington Trust, N.A. may be entitled to indemnification by the ESOP plan sponsors. These matters could result in damages, settlements, penalties, restitution, reputational damage or additional costs and expenses.

M&T and its subsidiaries are subject in the normal course of business to various other pending and threatened legal proceedings and matters in which claims for monetary damages are asserted. On an on-going basis management, after consultation with legal counsel, assesses the Company’s liabilities and contingencies in connection with such proceedings. For those matters where it is probable that the Company will incur losses and the amounts of the losses can be reasonably estimated, the Company records an expense and corresponding liability in its consolidated financial statements. Such expense was $50 million and $135 million during the three months ended March 31, 2019 and 2018, respectively. To the extent pending or threatened litigation could result in exposure in excess of the recorded liability, the amount of such excess is not currently estimable. Although not considered probable, the range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability, was estimated to be between $0 and $50 million as of September 30, 2019. Although the Company does not believe that the outcome of pending legal matters will be material to the Company’s consolidated financial position, it cannot rule out the possibility that such outcomes will be material to the consolidated results of operations for a particular reporting period in the future.

Segment information

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Segment information

15. Segment information

Reportable segments have been determined based upon the Company's internal profitability reporting system, which is organized by strategic business unit. Certain strategic business units have been combined for segment information reporting purposes where the nature of the products and services, the type of customer and the distribution of those products and services are similar. The reportable segments are Business Banking, Commercial Banking, Commercial Real Estate, Discretionary Portfolio, Residential Mortgage Banking and Retail Banking.

The financial information of the Company's segments was compiled utilizing the accounting policies described in note 22 of Notes to Financial Statements in the 2018 Annual Report. The management accounting policies and processes utilized in compiling segment financial information are highly subjective and, unlike financial accounting, are not based on authoritative guidance similar to GAAP. As a result, the financial information of the reported segments is not necessarily comparable with similar information reported by other financial institutions. Furthermore, changes in management structure or allocation methodologies and procedures may result in changes in reported segment financial data.

Information about the Company's segments is presented in the following table:

	Three Months Ended September 30
	2019								2018
	Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)			Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)
	(In thousands)

Business Banking	$	143,741		912			46,147		$	138,898		920			43,730
Commercial Banking		282,757		980			132,668			280,671		875			147,910
Commercial Real Estate		238,364		458			131,161			214,266		371			116,386
Discretionary Portfolio		50,871		(10,550	)		29,604			53,061		(10,270	)		39,723
Residential Mortgage Banking		115,239		19,363			15,846			79,603		15,402			13,289
Retail Banking		432,339		1,808			131,638			427,452		2,862			141,612
All Other		294,358		(12,971	)		(6,983	)		294,381		(10,160	)		23,441
Total	$	1,557,669		—			480,081		$	1,488,332		—			526,091

	Nine Months Ended September 30
	2019								2018
	Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)			Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)
	(In thousands)

Business Banking	$	423,830		2,772			131,668		$	402,811		2,750			124,455
Commercial Banking		828,357		2,707			388,393			816,566		2,653			399,766
Commercial Real Estate		682,979		1,218			370,288			622,414		1,096			337,380
Discretionary Portfolio		175,764		(29,140	)		106,816			162,075		(31,656	)		88,575
Residential Mortgage Banking		295,449		51,027			36,429			244,228		46,870			43,637
Retail Banking		1,299,823		7,106			417,198			1,241,468		8,434			408,081
All Other		955,868		(35,690	)		(14,709	)		899,184		(30,147	)		(30,033	)
Total	$	4,662,070		—			1,436,083		$	4,388,746		—			1,371,861

15. Segment information, continued

	Average Total Assets
	Nine Months Ended September 30				Year Ended December 31
	2019		2018		2018
	(In millions)

Business Banking	$	5,758		5,637		5,631
Commercial Banking		28,089		26,524		26,626
Commercial Real Estate		23,893		22,899		22,885
Discretionary Portfolio		29,355		32,659		32,123
Residential Mortgage Banking		2,444		2,123		2,161
Retail Banking		14,839		13,522		13,656
All Other		14,206		13,312		13,877
Total	$	118,584		116,676		116,959

(a)

Total revenues are comprised of net interest income and other income. Net interest income is the difference between taxable-equivalent interest earned on assets and interest paid on liabilities owed by a segment and a funding charge (credit) based on the Company's internal funds transfer and allocation methodology. Segments are charged a cost to fund any assets (e.g. loans) and are paid a funding credit for any funds provided (e.g. deposits). The taxable-equivalent adjustment aggregated $5,579,000 and $5,733,000 for the three-month periods ended September 30, 2019 and 2018, respectively, and $17,471,000 and $15,939,000 for the nine-month periods ended September 30, 2019 and 2018, respectively, and is eliminated in "All Other" total revenues. Intersegment revenues are included in total revenues of the reportable segments. The elimination of intersegment revenues is included in the determination of "All Other" total revenues.

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.

9 Months Ended

Sep. 30, 2019

Text Block [Abstract]

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.

16. Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.

M&T holds a 20% minority interest in Bayview Lending Group LLC ("BLG"), a privately-held commercial mortgage company. M&T recognizes income or loss from BLG using the equity method of accounting. That investment had no remaining carrying value at September 30, 2019 as a result of cumulative losses recognized and cash distributions received in prior years. Income recognized by M&T is included in other revenues from operations and was not significant during the three-month periods ended September 30, 2019 and 2018. Income recognized during the nine month-periods ended September 30, 2019 and 2018 totaled $37 million and $24 million, respectively.

Bayview Financial Holdings, L.P. (together with its affiliates, "Bayview Financial"), a privately-held specialty finance company, is BLG's majority investor. In addition to their common investment in BLG, the Company and Bayview Financial conduct other business activities with each other. The Company has obtained loan servicing rights for mortgage loans from BLG and Bayview Financial having outstanding principal balances of $2.3 billion and $2.5 billion at September 30, 2019 and December 31, 2018, respectively. Revenues from those servicing rights were $3 million and $4 million for the three-month periods ended September 30, 2019 and 2018, respectively, and $9 million and $11 million for the nine-month periods ended September 30, 2019 and 2018, respectively. The Company sub-services residential mortgage loans for Bayview Financial having outstanding principal balances of $65.1 billion and $56.8 billion at September 30, 2019 and December 31, 2018, respectively. Revenues earned for sub-servicing loans for Bayview Financial were $33 million and $28 million for the three-month periods ended September 30, 2019 and 2018, respectively, and $90 million and $86 million for the nine-month periods ended September 30, 2019 and 2018, respectively. In addition, the Company held $100 million and $113 million of mortgage-backed securities in its held-to-maturity portfolio at September 30, 2019 and December 31, 2018, respectively, that were securitized by Bayview Financial. At September 30, 2019, the Company held $90 million of Bayview Financial’s $714 million syndicated loan facility.

Recent accounting developments

9 Months Ended

Sep. 30, 2019

Accounting Changes And Error Corrections [Abstract]

Recent accounting developments

17. Recent accounting developments

The following table provides a description of accounting standards that were adopted by the Company in 2019 as well as standards that are not effective that could have an impact to M&T’s consolidated financial statements upon adoption.

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Adopted in 2019
Leases	The new guidance requires lessees to record a right-of-use asset and a lease liability for all leases with a term greater than 12 months. While the guidance requires all leases to be recognized in the balance sheet, there continues to be a differentiation between finance leases and operating leases for purposes of income statement recognition and cash flow statement presentation. For finance leases, interest on the lease liability and amortization of the right-of-use asset is recognized separately in the statement of income. Repayments of principal on those lease liabilities are classified within financing activities and payments of interest on the lease liability are classified within operating activities in the statement of cash flows. For operating leases, a single lease cost is recognized in the statement of income and allocated over the lease term, generally on a straight-line basis. All cash payments are presented within operating activities in the statement of cash flows. The accounting applied by lessors is largely unchanged, however, the guidance eliminates the accounting model for leveraged leases for leases that commence after the effective date of the guidance.	January 1, 2019 Early adoption permitted	The Company adopted the guidance on January 1, 2019 and applied the guidance retrospectively at the beginning of the period of adoption. The Company occupies certain banking offices and uses certain equipment under noncancelable operating lease agreements which prior to the adoption of the guidance were not reflected in its consolidated balance sheet. Upon adoption, the Company recognized a right-of-use asset of $394 million and increased liabilities by $399 million as a result of recognizing lease liabilities in its consolidated balance sheet. The new guidance did not have a material impact on the Company’s consolidated statement of income.
Premium Amortization on Purchased Callable Debt Securities	The amended guidance requires the premium on callable debt securities to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity.	January 1, 2019 Early adoption permitted	The Company adopted the amended guidance effective January 1, 2019 and applied the modified retrospective approach for reporting purposes. The adoption did not have a material effect on the Company’s consolidated financial position nor on its results of operations.

17. Recent accounting developments, continued

Standard

Description

Required date

of adoption

Effect on consolidated financial statements

Standards Not Yet Adopted as of September 30, 2019

Measurement of Credit Losses on Financial Instruments

The amended guidance replaces the current incurred loss model for determining the allowance for credit losses. The guidance requires financial assets measured at amortized cost to be presented at the net amount expected to be collected. The allowance for credit losses will represent a valuation account that is deducted from the amortized cost basis of the financial assets to present their net carrying value at the amount expected to be collected. The income statement will reflect the measurement of credit losses for newly recognized financial assets as well as expected increases or decreases of expected credit losses that have taken place during the period. When determining the allowance, expected credit losses over the contractual term of the financial asset(s) (taking into account prepayments) will be estimated considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The amended guidance also requires recording an allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination. The initial allowance for these assets will be added to the purchase price at acquisition rather than being reported as an expense. Subsequent changes in the allowance will be recorded through the income statement as an expense adjustment. In addition, the amended guidance requires credit losses relating to available-for-sale debt securities to be recorded through an allowance for credit losses. The calculation of credit losses for available-for-sale securities will be similar to how it is determined under existing guidance.

January 1, 2020

The Company has completed its second parallel run of its approach for determining expected credit losses under the new guidance. The Company’s cross-functional implementation team continues to refine its models and the qualitative framework and to build out the technology platform to support the estimation process. The Company is also completing its documentation and internal controls testing. The Company’s current planned approach for estimating expected credit losses for loans includes utilizing macro-economic assumptions to project losses over a two-year reasonable and supportable forecast period. Subsequent to the forecast period, the Company reverts to longer term historical loss experience to estimate expected credit losses over the remaining contractual life.

The Company anticipates an increase to the allowance for credit losses that could range from 5 to 15 percent upon adoption of the standard. The amount of the change will be affected by economic conditions, reasonable forecasts of such conditions and the composition of the Company’s portfolio as of the date of adoption.

The estimated effect on the allowance for credit losses is primarily attributable to increases in reserves for residential mortgage loans and consumer loans, which generally have longer estimated lives as compared to commercial and commercial real estate loans. The allowance for credit losses associated with commercial and commercial real estate loans is expected to remain similar to current levels. The Company does not expect a material allowance for credit losses on held-to-maturity debt securities as most of this portfolio consists of U.S. Treasury and federal agency securities.

Simplifying the Test for Goodwill Impairment

The amended guidance eliminates step 2 from the goodwill impairment test.

January 1, 2020

The amendments should be applied using a prospective transition method. The Company does not expect the guidance will have a material impact on its consolidated financial statements, unless at some point in the future one of its reporting units were to fail step 1 of the goodwill impairment test.

17. Recent accounting developments, continued

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Not Yet Adopted as of September 30, 2019
Changes to the Disclosure Requirements for Fair Value Measurements	The amended guidance modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurements. The amendments are a result of the disclosure framework project that focuses on improvements to the effectiveness of disclosures in the notes to financial statements. The amendments remove, modify, and add certain disclosure requirements. The disclosure requirements being removed relating to public companies are (1) the amount and reason for transfers between Level 1 and Level 2 of the fair value hierarchy, (2) the policy for timing of transfers between levels, and (3) the valuation process for Level 3 fair value measurements. The disclosure requirements being modified relating to public companies are (1) for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s asset and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly, and (2) the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as a result of the use of unobservable inputs. The disclosure requirements being added relating to public companies are (1) to disclose the changes in unrealized gains and losses for the period for recurring Level 3 fair value measurements, and (2) to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements.	January 1, 2020 Early adoption permitted	The amendments relating to changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurements uncertainty should be applied prospectively. All other amendments should be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements.
Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract	The amended guidance requires a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which implementation costs to capitalize and which costs to expense.	January 1, 2020 Early adoption permitted	The amendments should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company expects to implement the guidance on a prospective basis and does not expect the guidance to have a material impact on its consolidated financial statements.

17. Recent accounting developments, continued

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Not Yet Adopted as of September 30, 2019
Improvements to Related Party Guidance for VIEs	The amended guidance requires that indirect interests held through related parties in common control arrangements should be considered on a proportional basis for determining whether fees paid to decision makers and service providers are variable interests.	January 1, 2020 Early adoption permitted	The amendments should be applied retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Company does not expect the guidance to have a material impact on its consolidated financial statements.
Changes to the Disclosure Requirements for Defined Benefit Plans	The amended guidance modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments are a result of the disclosure framework project that focuses on improvements to the effectiveness of disclosures in the notes to financial statements. The amendments remove and add certain disclosure requirements. The disclosure requirements being removed relating to public companies are (1) the amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost over the next fiscal year, (2) the amount and timing of plan assets expected to be returned to the employer, (3) the 2001 disclosure requirement relating to Japanese Welfare Pension Insurance Law, (4) related party disclosures about the amount of future annual benefits covered by insurance, and (5) the effects of a one-percentage-point change in assumed health care cost trends on the benefit cost and obligation. The disclosure requirements being added relating to public companies are (1) the weighted-average interest crediting rates for cash balance plans , and (2) an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period.	January 1, 2021 Early adoption permitted	The amendments should be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements.

Investment securities (Tables)

9 Months Ended

Sep. 30, 2019

Investments Debt And Equity Securities [Abstract]

Amortized Cost and Estimated Fair Value of Investment Securities

The amortized cost and estimated fair value of investment securities were as follows:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
September 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	359,723	$	66	$	395	$	359,394
Obligations of states and political subdivisions		933		4		3		934
Mortgage-backed securities:
Government issued or guaranteed		6,435,730		88,522		29,352		6,494,900
Privately issued		16		—		—		16
Other debt securities		138,307		1,373		9,507		130,173
		6,934,709		89,965		39,257		6,985,417
Investment securities held to maturity:
U.S. Treasury and federal agencies		498,776		956		—		499,732
Obligations of states and political subdivisions		4,775		21		—		4,796
Mortgage-backed securities:
Government issued or guaranteed		2,424,716		53,076		1,879		2,475,913
Privately issued		99,679		11,791		19,960		91,510
Other debt securities		3,353		—		—		3,353
		3,031,299		65,844		21,839		3,075,304
Total debt securities	$	9,966,008	$	155,809	$	61,096	$	10,060,721
Equity and other securities:
Readily marketable equity — at fair value	$	109,131	$	41,152	$	179	$	150,104
Other — at cost		510,763		—		—		510,763
Total equity and other securities	$	619,894	$	41,152	$	179	$	660,867

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
	(In thousands)
December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	1,346,782	$	—	$	9,851	$	1,336,931
Obligations of states and political subdivisions		1,660		4		5		1,659
Mortgage-backed securities:
Government issued or guaranteed		7,383,340		15,754		182,103		7,216,991
Privately issued		24		—		2		22
Other debt securities		137,617		770		11,481		126,906
		8,869,423		16,528		203,442		8,682,509
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,542		—		239		446,303
Obligations of states and political subdivisions		7,494		22		12		7,504
Mortgage-backed securities:
Government issued or guaranteed		2,745,776		4,165		55,111		2,694,830
Privately issued		113,160		12,345		22,327		103,178
Other debt securities		3,668		—		—		3,668
		3,316,640		16,532		77,689		3,255,483
Total debt securities	$	12,186,063	$	33,060	$	281,131	$	11,937,992
Equity and other securities:
Readily marketable equity — at fair value	$	77,440	$	17,295	$	818	$	93,917
Other — at cost		599,747		—		—		599,747
Total equity and other securities	$	677,187	$	17,295	$	818	$	693,664

Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity

At September 30, 2019, the amortized cost and estimated fair value of debt securities by contractual maturity were as follows:

	Amortized Cost		Estimated Fair Value
	(In thousands)
Debt securities available for sale:
Due in one year or less	$	355,210		354,825
Due after one year through five years		11,470		11,585
Due after five years through ten years		102,283		100,091
Due after ten years		30,000		24,000
		498,963		490,501
Mortgage-backed securities available for sale		6,435,746		6,494,916
	$	6,934,709		6,985,417
Debt securities held to maturity:
Due in one year or less	$	500,476		501,438
Due after one year through five years		3,075		3,090
Due after ten years		3,353		3,353
		506,904		507,881
Mortgage-backed securities held to maturity		2,524,395		2,567,423
	$	3,031,299		3,075,304

Investment Securities in Continuous Unrealized Loss Position

	Less Than 12 Months					12 Months or More
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
September 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	—		—			352,482		(395	)
Obligations of states and political subdivisions		—		—			375		(3	)
Mortgage-backed securities:
Government issued or guaranteed		240,208		(589	)		2,107,684		(28,763	)
Other debt securities		20,290		(563	)		77,140		(8,944	)
		260,498		(1,152	)		2,537,681		(38,105	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		—		—			165,983		(1,879	)
Privately issued		—		—			49,824		(19,960	)
		—		—			215,807		(21,839	)
Total	$	260,498		(1,152	)		2,753,488		(59,944	)

December 31, 2018
Investment securities available for sale:
U.S. Treasury and federal agencies	$	273		(2	)		1,335,559		(9,849	)
Obligations of states and political subdivisions		629		(5	)		—		—
Mortgage-backed securities:
Government issued or guaranteed		405,558		(2,892	)		5,646,773		(179,211	)
Privately issued		22		(2	)		—		—
Other debt securities		53,478		(2,187	)		66,014		(9,294	)
		459,960		(5,088	)		7,048,346		(198,354	)
Investment securities held to maturity:
U.S. Treasury and federal agencies		446,303		(239	)		—		—
Obligations of states and political subdivisions		—		—			3,126		(12	)
Mortgage-backed securities:
Government issued or guaranteed		179,354		(989	)		2,082,723		(54,122	)
Privately issued		—		—			51,943		(22,327	)
		625,657		(1,228	)		2,137,792		(76,461	)
Total	$	1,085,617		(6,316	)		9,186,138		(274,815	)

Loans and leases and the allowance for credit losses (Tables)

9 Months Ended

Sep. 30, 2019

Receivables [Abstract]

Summary of Current, Past Due and Nonaccrual Loans

A summary of current, past due and nonaccrual loans as of September 30, 2019 and December 31, 2018 follows:

	Current		30-89 Days Past Due		Accruing Loans Past Due 90 Days or More (a)		Accruing Loans Acquired at a Discount Past Due 90 days or More (b)		Purchased Impaired (c)		Nonaccrual		Total
	(In thousands)
September 30, 2019
Commercial, financial, leasing, etc.	$	22,689,923		125,742		2,898		—		—		382,809	$	23,201,372
Real estate:
Commercial		25,613,988		186,157		8,387		15		14,406		184,632		26,007,585
Residential builder and developer		1,546,570		6,300		—		—		639		4,975		1,558,484
Other commercial construction		7,229,925		112,651		4,291		—		854		31,441		7,379,162
Residential		12,975,992		495,831		439,649		5,246		162,475		223,566		14,302,759
Residential — limited documentation		1,968,580		72,815		—		—		75,122		81,679		2,198,196
Consumer:
Home equity lines and loans		4,486,664		29,826		—		3,387		—		59,915		4,579,792
Recreational finance		5,262,857		27,880		—		—		—		11,852		5,302,589
Automobile		3,767,965		74,504		—		—		—		21,039		3,863,508
Other		1,373,612		14,771		5,937		32,085		—		3,341		1,429,746
Total	$	86,916,076		1,146,477		461,162		40,733		253,496		1,005,249	$	89,823,193

December 31, 2018
Commercial, financial, leasing, etc.	$	22,701,020		39,798		2,567		168		—		234,423	$	22,977,976
Real estate:
Commercial		25,250,983		134,474		11,457		10		9,769		203,672		25,610,365
Residential builder and developer		1,665,178		20,333		—		—		—		4,798		1,690,309
Other commercial construction		6,982,077		43,615		14,344		—		641		22,205		7,062,882
Residential		13,591,790		404,808		189,682		6,650		203,044		233,352		14,629,326
Residential — limited documentation		2,278,040		72,544		—		—		89,851		84,685		2,525,120
Consumer:
Home equity lines and loans		4,758,513		25,416		—		5,033		—		71,292		4,860,254
Recreational finance		4,085,781		29,947		—		235		—		11,199		4,127,162
Automobile		3,555,757		79,804		—		—		—		23,359		3,658,920
Other		1,271,811		15,598		4,477		27,654		—		4,623		1,324,163
Total	$	86,140,950		866,337		222,527		39,750		303,305		893,608	$	88,466,477

(a)	Excludes loans acquired at a discount.

(b)	Loans acquired at a discount that were recorded at fair value at acquisition date. This category does not include purchased impaired loans that are presented separately.

(c)	Accruing loans acquired at a discount that were impaired at acquisition date and recorded at fair value.

Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet

	September 30,		December 31,
	2019		2018
	(In thousands)

Outstanding principal balance	$	869,636	$	1,016,785
Carrying amount:
Commercial, financial, leasing, etc.		22,829		27,073
Commercial real estate		110,430		135,047
Residential real estate		398,563		473,511
Consumer		89,157		91,860
	$	620,979	$	727,491

Summary of Changes in Accretable Yield for Acquired Loans

A summary of changes in the accretable yield for loans acquired at a discount for the three months and nine months ended September 30, 2019 and 2018 follows:

	Three Months Ended September 30
	2019						2018
	Purchased			Other			Purchased			Other
	Impaired			Acquired			Impaired			Acquired
	(In thousands)

Balance at beginning of period	$	147,104		$	90,911		$	149,388		$	117,715
Interest income		(9,564	)		(9,238	)		(8,105	)		(18,001	)
Reclassifications from nonaccretable balance		9,079			3,990			8,445			25
Other (a)		—			41			—			2,001
Balance at end of period	$	146,619		$	85,704		$	149,728		$	101,740

	Nine Months Ended September 30
	2019						2018
	Purchased			Other			Purchased			Other
	Impaired			Acquired			Impaired			Acquired
	(In thousands)

Balance at beginning of period	$	147,210		$	96,907		$	157,918		$	133,162
Interest income		(37,278	)		(28,621	)		(25,893	)		(48,507	)
Reclassifications from nonaccretable balance		36,687			12,312			17,703			11,230
Other (a)		—			5,106			—			5,855
Balance at end of period	$	146,619		$	85,704		$	149,728		$	101,740

(a)	Other changes in expected cash flows including changes in interest rates and prepayment assumptions.

Changes in Allowance for Credit Losses

Changes in the allowance for credit losses for the three months ended September 30, 2019 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated			Total
	(In thousands)

Beginning balance	$	335,855			343,296			61,011			211,220			78,485		$	1,029,867
Provision for credit losses		24,538			(16,713	)		(309	)		37,735			(251	)		45,000
Net charge-offs
Charge-offs		(15,678	)		(1,107	)		(2,721	)		(40,735	)		—			(60,241	)
Recoveries		6,730			1,656			1,511			13,914			—			23,811
Net (charge-offs) recoveries		(8,948	)		549			(1,210	)		(26,821	)		—			(36,430	)
Ending balance	$	351,445			327,132			59,492			222,134			78,234		$	1,038,437

Changes in the allowance for credit losses for the three months ended September 30, 2018 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated		Total
	(In thousands)

Beginning balance	$	328,830			353,761			76,123			182,987			77,547	$	1,019,248
Provision for credit losses		(6,972	)		(11,394	)		741			32,887			738		16,000
Net charge-offs
Charge-offs		(11,792	)		(1,941	)		(3,338	)		(34,995	)		—		(52,066	)
Recoveries		7,123			14,577			1,655			12,951			—		36,306
Net (charge-offs) recoveries		(4,669	)		12,636			(1,683	)		(22,044	)		—		(15,760	)
Ending balance	$	317,189			355,003			75,181			193,830			78,285	$	1,019,488

Changes in the allowance for credit losses for the nine months ended September 30, 2019 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated		Total
	(In thousands)

Beginning balance	$	330,055			341,655			69,125			200,564			78,045	$	1,019,444
Provision for credit losses		41,146			(6,415	)		(5,132	)		92,212			189		122,000
Net charge-offs
Charge-offs		(40,786	)		(11,555	)		(9,356	)		(113,050	)		—		(174,747	)
Recoveries		21,030			3,447			4,855			42,408			—		71,740
Net charge-offs		(19,756	)		(8,108	)		(4,501	)		(70,642	)		—		(103,007	)
Ending balance	$	351,445			327,132			59,492			222,134			78,234	$	1,038,437

Changes in the allowance for credit losses for the nine months ended September 30, 2018 were as follows:

	Commercial, Financial,			Real Estate
	Leasing, etc.			Commercial			Residential			Consumer			Unallocated			Total
	(In thousands)

Beginning balance	$	328,599			374,085			65,405			170,809			78,300		$	1,017,198
Provision for credit losses		11,508			(27,464	)		16,469			93,502			(15	)		94,000
Net charge-offs
Charge-offs		(41,273	)		(7,855	)		(11,658	)		(105,479	)		—			(166,265	)
Recoveries		18,355			16,237			4,965			34,998			—			74,555
Net (charge-offs) recoveries		(22,918	)		8,382			(6,693	)		(70,481	)		—			(91,710	)
Ending balance	$	317,189			355,003			75,181			193,830			78,285		$	1,019,488

Impaired Loans and Leases

	September 30, 2019						December 31, 2018
	Recorded Investment		Unpaid Principal Balance		Related Allowance		Recorded Investment		Unpaid Principal Balance		Related Allowance
	(In thousands)
With an allowance recorded:
Commercial, financial, leasing, etc.	$	245,355		273,931		60,410		153,478		175,549		46,034
Real estate:
Commercial		60,489		67,104		7,711		110,253		125,117		11,937
Residential builder and developer		8,893		9,311		319		5,981		6,557		462
Other commercial construction		12,821		25,437		1,477		10,563		11,113		640
Residential		125,498		146,098		6,748		124,974		147,817		5,402
Residential — limited documentation		67,729		81,918		2,600		74,156		90,066		3,000
Consumer:
Home equity lines and loans		46,858		51,759		8,923		47,982		53,248		9,135
Recreational finance		5,483		9,481		1,153		6,138		9,163		1,261
Automobile		3,478		3,526		708		3,527		3,599		729
Other		4,699		9,620		943		5,203		8,380		1,046
		581,303		678,185		90,992		542,255		630,609		79,646
With no related allowance recorded:
Commercial, financial, leasing, etc.		159,991		172,191		—		105,507		136,128		—
Real estate:
Commercial		144,554		163,120		—		113,376		124,657		—
Residential builder and developer		3,378		3,378		—		2,593		2,602		—
Other commercial construction		18,620		19,614		—		11,710		11,880		—
Residential		18,949		24,350		—		15,379		20,496		—
Residential — limited documentation		4,007		7,324		—		5,631		9,796		—
		349,499		389,977		—		254,196		305,559		—
Total:
Commercial, financial, leasing, etc.		405,346		446,122		60,410		258,985		311,677		46,034
Real estate:
Commercial		205,043		230,224		7,711		223,629		249,774		11,937
Residential builder and developer		12,271		12,689		319		8,574		9,159		462
Other commercial construction		31,441		45,051		1,477		22,273		22,993		640
Residential		144,447		170,448		6,748		140,353		168,313		5,402
Residential — limited documentation		71,736		89,242		2,600		79,787		99,862		3,000
Consumer:
Home equity lines and loans		46,858		51,759		8,923		47,982		53,248		9,135
Recreational finance		5,483		9,481		1,153		6,138		9,163		1,261
Automobile		3,478		3,526		708		3,527		3,599		729
Other		4,699		9,620		943		5,203		8,380		1,046
Total	$	930,802		1,068,162		90,992		796,451		936,168		79,646

Interest Income Recognized on Impaired Loans

	Three Months Ended September 30, 2019						Three Months Ended September 30, 2018
			Interest Income Recognized						Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis		Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	288,516		836		836		256,196		1,985		1,985
Real estate:
Commercial		201,931		1,798		1,798		204,315		1,489		1,489
Residential builder and developer		11,837		89		89		9,000		—		—
Other commercial construction		32,458		13		13		9,623		3,379		3,379
Residential		143,508		2,353		984		133,337		1,959		773
Residential — limited documentation		72,926		1,348		229		81,729		1,607		481
Consumer:
Home equity lines and loans		46,982		416		74		48,542		421		62
Recreational finance		5,562		147		4		3,531		65		1
Automobile		3,413		54		18		7,805		181		20
Other		5,220		145		1		3,919		61		5
Total	$	812,353		7,199		4,046		757,997		11,147		8,195

	Nine Months Ended September 30, 2019						Nine Months Ended September 30, 2018
			Interest Income Recognized						Interest Income Recognized
	Average Recorded Investment		Total		Cash Basis		Average Recorded Investment		Total		Cash Basis
	(In thousands)

Commercial, financial, leasing, etc.	$	275,896		7,501		7,501		266,594		4,101		4,101
Real estate:
Commercial		214,027		4,921		4,921		184,795		8,447		8,447
Residential builder and developer		10,101		239		239		9,111		1,682		1,682
Other commercial construction		25,126		589		589		9,056		3,438		3,438
Residential		142,155		6,765		2,654		126,910		6,190		2,612
Residential — limited documentation		75,702		4,153		655		83,700		4,763		1,494
Consumer:
Home equity lines and loans		47,325		1,238		193		48,661		1,268		220
Recreational finance		5,799		414		12		2,156		193		6
Automobile		3,465		161		55		11,189		630		49
Other		5,155		409		10		2,389		106		6
Total	$	804,751		26,390		16,829		744,561		30,818		22,055

Summary of Loan Grades

3. Loans and leases and the allowance for credit losses, continued

The following table summarizes the loan grades applied to the various classes of the Company’s commercial loans and commercial real estate loans.

			Real Estate
	Commercial,				Residential		Other
	Financial,				Builder and		Commercial
	Leasing, etc.		Commercial		Developer		Construction
	(In thousands)
September 30, 2019
Pass	$	21,893,239		25,095,663		1,447,978		7,122,983
Criticized accrual		925,324		727,291		105,531		224,738
Criticized nonaccrual		382,809		184,632		4,975		31,441
Total	$	23,201,372		26,007,586		1,558,484		7,379,162
December 31, 2018
Pass	$	21,693,705		24,539,706		1,546,002		6,890,562
Criticized accrual		1,049,848		866,987		139,509		150,115
Criticized nonaccrual		234,423		203,672		4,798		22,205
Total	$	22,977,976		25,610,365		1,690,309		7,062,882

Allocation of Allowance for Credit Losses on Basis of Company's Impairment Methodology

The allocation of the allowance for credit losses summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
September 30, 2019
Individually evaluated for impairment	$	60,410		9,507		9,348		11,727	$	90,992
Collectively evaluated for impairment		291,035		317,625		44,766		210,407		863,833
Purchased impaired		—		—		5,378		—		5,378
Allocated	$	351,445		327,132		59,492		222,134		960,203
Unallocated										78,234
Total									$	1,038,437
December 31, 2018
Individually evaluated for impairment	$	46,034		13,039		8,402		12,171	$	79,646
Collectively evaluated for impairment		284,021		328,616		48,326		188,393		849,356
Purchased impaired		—		—		12,397		—		12,397
Allocated	$	330,055		341,655		69,125		200,564		941,399
Unallocated										78,045
Total									$	1,019,444

Recorded Investment in Loans and Leases on Basis of Company's Impairment Methodology

The recorded investment in loans and leases summarized on the basis of the Company’s impairment methodology was as follows:

	Commercial, Financial,		Real Estate
	Leasing, etc.		Commercial		Residential		Consumer		Total
	(In thousands)
September 30, 2019
Individually evaluated for impairment	$	405,346		248,755		216,183		60,518	$	930,802
Collectively evaluated for impairment		22,796,026		34,680,577		16,047,175		15,115,117		88,638,895
Purchased impaired		—		15,899		237,597		—		253,496
Total	$	23,201,372		34,945,231		16,500,955		15,175,635	$	89,823,193
December 31, 2018
Individually evaluated for impairment	$	258,985		254,476		220,140		62,850	$	796,451
Collectively evaluated for impairment		22,718,991		34,098,670		16,641,411		13,907,649		87,366,721
Purchased impaired		—		10,410		292,895		—		303,305
Total	$	22,977,976		34,363,556		17,154,446		13,970,499	$	88,466,477

Loan Modification Activities that were Considered Troubled Debt Restructurings

					Post-modification (a)
	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
Three Months Ended September 30, 2019	(Dollars in thousands)

Commercial, financial, leasing, etc.	26		$	6,145	$	1,441	$	—	$	—	$	4,666	$	6,107
Real estate:
Commercial		9		2,986		383		—		—		2,589		2,972
Residential		20		5,161		3,046		—		—		2,535		5,581
Residential — limited documentation		1		236		—		—		—		240		240
Consumer:
Home equity lines and loans		12		1,392		—		—		—		1,399		1,399
Recreational finance		3		61		61		—		—		—		61
Automobile		26		485		457		—		—		28		485
Total		97	$	16,466	$	5,388	$	—	$	—	$	11,457	$	16,845

Three Months Ended September 30, 2018

Commercial, financial, leasing, etc.		47	$	6,837	$	1,683	$	5	$	—	$	5,018	$	6,706
Real estate:
Commercial		18		11,581		1,493		—		3,475		6,297		11,265
Residential		34		8,182		6,026		—		—		3,002		9,028
Residential — limited documentation		3		716		—		—		—		847		847
Consumer:
Home equity lines and loans		17		1,651		220		—		—		1,450		1,670
Recreational finance		2		44		44		—		—		—		44
Automobile		30		526		526		—		—		—		526
Total		151	$	29,537	$	9,992	$	5	$	3,475	$	16,614	$	30,086

3. Loans and leases and the allowance for credit losses, continued

					Post-modification (a)
Nine Months Ended September 30, 2019	Number		Pre- modification Recorded Investment		Principal Deferral		Interest Rate Reduction		Other		Combination of Concession Types		Total
	(Dollars in thousands)

Commercial, financial, leasing, etc.		115	$	39,357	$	8,582	$	—	$	—	$	30,827	$	39,409
Real estate:
Commercial		38		22,567		3,947		—		—		18,197		22,144
Residential builder and developer		2		1,330		1,068		—		—		—		1,068
Other commercial construction		2		1,456		—		—		—		1,399		1,399
Residential		63		16,490		8,805		—		—		8,842		17,647
Residential — limited documentation		4		1,084		399		—		—		705		1,104
Consumer:
Home equity lines and loans		32		3,141		90		—		—		3,078		3,168
Recreational finance		8		164		164		—		—		—		164
Automobile		58		991		926		—		—		65		991
Total		322	$	86,580	$	23,981	$	—	$	—	$	63,113	$	87,094

Nine Months Ended September 30, 2018

Commercial, financial, leasing, etc.		150	$	96,221	$	47,029	$	658	$	6,111	$	43,086	$	96,884
Real estate:
Commercial		66		25,561		14,693		175		3,869		7,224		25,961
Other commercial construction		1		752		746		—		—		—		746
Residential		111		28,769		15,785		—		—		15,670		31,455
Residential — limited documentation		8		1,595		467		—		—		1,423		1,890
Consumer:
Home equity lines and loans		41		3,554		224		—		—		3,357		3,581
Recreational finance		4		93		93		—		—		—		93
Automobile		57		1,007		995		—		—		12		1,007
Total		438	$	157,552	$	80,032	$	833	$	9,980	$	70,772	$	161,617

(a)	Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages. The present value of interest rate concessions, discounted at the effective rate of the original loan, was not material.

Summary of Lease Financing Receivables

A summary of lease financing receivables follows:

	September 30,			December 31,
	2019			2018
	(In thousands)
Commercial leases:
Direct financings:
Lease payments receivable	$	1,177,518		$	1,155,464
Estimated residual value of leased assets		84,692			85,169
Unearned income		(105,774	)		(110,458	)
Investment in direct financings		1,156,436			1,130,175
Leveraged leases:
Lease payments receivable		82,127			85,007
Estimated residual value of leased assets		81,163			81,261
Unearned income		(32,220	)		(33,717	)
Investment in leveraged leases		131,070			132,551
Total investment in leases	$	1,287,506		$	1,262,726
Deferred taxes payable arising from leveraged leases	$	71,432		$	74,995

Minimum Future Lease Payments to be Received from Lease Financings

At September 30, 2019, the minimum future lease payments to be received from lease financings were as follows:

	(In thousands)
Twelve-month period ending September 30:
2020	$	346,223
2021		305,385
2022		216,018
2023		164,490
2024		82,455
Later years		145,074
	$	1,259,645

Operating Leases (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Summary of Right-of-Use Assets Recognized as Component of Premises and Equipment and Lease Liabilities Recognized as Component of Accrued Interest and Other Liabilities in Consolidated Balance Sheet

	September 30, 2019
	(In thousands)

Right-of-use assets	$	392,324
Lease liabilities		424,854

Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases

	Three Months Ended			Nine Months Ended
	September 30, 2019			September 30, 2019
	(Dollars in thousands)
Lease cost
Operating lease cost	$	25,058		$	74,599
Short-term lease cost		20			82
Variable lease cost		644			1,733
Sublease income		(1,903	)		(5,724	)
Total net lease cost	$	23,819		$	70,690

Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	$	24,377		$	69,305
Cash paid toward lease liabilities		25,189			76,050
Weighted-average remaining lease term	7 years			7 years
Weighted-average discount rate		3.1	%		3.1	%

Summary of Minimum Lease Payments Under Noncancelable Operating Leases

	(In thousands)
Twelve-month period ending September 30:
2020	$	97,712
2021		87,106
2022		72,577
2023		56,821
2024		42,770
Later years		116,467
Total lease payments	$	473,453
Less: imputed interest		48,599
Total	$	424,854

Shareholders’ equity (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Issued and Outstanding Preferred Stock

Issued and outstanding preferred stock of M&T as of September 30, 2019 and December 31, 2018 is presented below:

	September 30, 2019				December 31,2018
	Shares Issued and Outstanding		Carrying Value		Shares Issued and Outstanding		Carrying Value
	(Dollars in thousands)
Series A (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		230,000	$	230,000
Series C (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		—		—		151,500	$	151,500
Series E (b)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		350,000	$	350,000		350,000	$	350,000
Series F (c)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		50,000	$	500,000		50,000	$	500,000
Series G (d)
Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		40,000	$	400,000		—		—

(a)The shares were fully redeemed in August 2019, having received the approval of the Federal Reserve to redeem such shares after issuing the Series G

preferred stock.

(b)Dividends, if declared, are paid semi-annually at a rate of 6.45% through February 14, 2024 and thereafter will be paid quarterly at a rate of the

three-month LIBOR plus 361 basis points. The shares are redeemable in whole or in part on or after February 15, 2024. Notwithstanding M&T’s

option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90

days following that occurrence.

(c)Dividends, if declared, are paid semi-annually at a rate of 5.125% through October 31, 2026 and thereafter will be paid quarterly at a rate of the

three-month LIBOR plus 352 basis points. The shares are redeemable in whole or in part on or after November 1, 2026. Notwithstanding M&T’s

option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90

days following that occurrence.

(d)	Dividends, if declared, are paid semi-annually at a rate of 5.0% through July 31, 2024 and thereafter will be paid semiannually at a rate of the five-year U.S. Treasury rate plus 3.174%. The shares are redeemable in whole or in part on or after August 1, 2024. Notwithstanding M&T’s

option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90

days following that occurrence.

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Subparagraph (SX 210.5-02(28))
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
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-Section S99
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-Subparagraph (SX 210.5-02(27))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644

Reference 14: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Revenue from contracts with customers (Tables)

9 Months Ended

Sep. 30, 2019

ASU 2014-09 [Member]

Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance

	Business Banking		Commercial Banking		Commercial Real Estate		Discretionary Portfolio		Residential Mortgage Banking		Retail Banking		All Other		Total
Three Months Ended September 30, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,131		23,427		2,415		—		—		68,455		1,664	$	111,092
Trust income		9		242		—		—		—		—		143,664		143,915
Brokerage services income		—		—		—		—		—		—		12,077		12,077
Other revenues from operations:
Merchant discount and credit card fees		9,692		13,409		670		—		—		4,150		269		28,190
Other		—		1,239		1,372		503		816		9,347		7,076		20,353
	$	24,832		38,317		4,457		503		816		81,952		164,750	$	315,627
Three Months Ended September 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,767		24,167		2,374		—		2		64,709		1,628	$	108,647
Trust income		—		—		—		—		—		—		133,545		133,545
Brokerage services income		—		—		—		—		—		—		12,267		12,267
Other revenues from operations:
Merchant discount and credit card fees		9,238		13,520		643		—		—		3,908		462		27,771
Other		—		1,662		1,822		386		916		9,397		6,723		20,906
	$	25,005		39,349		4,839		386		918		78,014		154,625	$	303,136

	Business Banking		Commercial Banking		Commercial Real Estate		Discretionary Portfolio		Residential Mortgage Banking		Retail Banking		All Other		Total
Nine Months Ended September 30, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	45,415		69,731		7,303		—		4		195,267		4,271	$	321,991
Trust income		21		680		—		—		—		—		420,382		421,083
Brokerage services income		—		—		—		—		—		—		37,031		37,031
Other revenues from operations:
Merchant discount and credit card fees		28,469		38,630		1,772		—		—		11,854		1,291		82,016
Other		—		5,386		5,840		1,545		2,913		27,170		26,159		69,013
	$	73,905		114,427		14,915		1,545		2,917		234,291		489,134	$	931,134
Nine Months Ended September 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	46,782		73,091		7,589		—		8		188,325		4,751	$	320,546
Trust income		—		—		—		—		—		—		402,561		402,561
Brokerage services income		—		—		—		—		—		—		38,288		38,288
Other revenues from operations:
Merchant discount and credit card fees		25,075		38,774		1,625		—		—		11,436		1,695		78,605
Other		—		6,871		4,896		1,251		2,886		28,875		23,429		68,208
	$	71,857		118,736		14,110		1,251		2,894		228,636		470,724	$	908,208

Pension plans and other postretirement benefits (Tables)

9 Months Ended

Sep. 30, 2019

Compensation And Retirement Disclosure [Abstract]

Net Periodic Defined Benefit Cost for Defined Benefit Plans

Net periodic defined benefit cost for defined benefit plans consisted of the following:

	Pension Benefits						Other Postretirement Benefits
	Three Months Ended September 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	4,324			5,086			215		234
Interest cost on projected benefit obligation		20,394			18,676			586			573
Expected return on plan assets		(30,534	)		(30,781	)		—			—
Amortization of prior service cost (credit)		139			139			(1,182	)		(1,182	)
Amortization of net actuarial loss (gain)		5,498			10,948			(312	)		(206	)
Net periodic cost (benefit)	$	(179	)		4,068			(693	)		(581	)

	Pension Benefits						Other Postretirement Benefits
	Nine Months Ended September 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	12,970			15,258			644			703
Interest cost on projected benefit obligation		61,184			56,029			1,758			1,719
Expected return on plan assets		(91,604	)		(92,344	)		—			—
Amortization of prior service cost (credit)		418			417			(3,547	)		(3,546	)
Amortization of net actuarial loss (gain)		16,494			32,844			(935	)		(619	)
Net periodic cost (benefit)	$	(538	)		12,204			(2,080	)		(1,743	)

Earnings per common share (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Computations of Basic Earnings Per Common Share

The computations of basic earnings per common share follow:

	Three Months Ended September 30						Nine Months Ended September 30
	2019			2018			2019			2018
	(In thousands, except per share)

Income available to common shareholders:
Net income	$	480,081			526,091			1,436,083			1,371,861
Less: Preferred stock dividends (a)		(16,103	)		(18,130	)		(52,364	)		(54,390	)
Net income available to common equity		463,978			507,961			1,383,719			1,317,471
Less: Income attributable to unvested stock-based compensation awards		(2,568	)		(2,598	)		(7,591	)		(6,774	)
Net income available to common shareholders	$	461,410			505,363			1,376,128			1,310,697
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		133,703			143,556			136,156			146,177
Less: Unvested stock-based compensation awards		(738	)		(734	)		(745	)		(753	)
Weighted-average shares outstanding		132,965			142,822			135,411			145,424

Basic earnings per common share	$	3.47			3.54			10.16			9.01

(a)Including impact of not as yet declared cumulative dividends.

Computations of Diluted Earnings Per Common Share

The computations of diluted earnings per common share follow:

	Three Months Ended September 30						Nine Months Ended September 30
	2019			2018			2019			2018
	(In thousands, except per share)

Net income available to common equity	$	463,978			507,961			1,383,719			1,317,471
Less: Income attributable to unvested stock-based compensation awards		(2,568	)		(2,596	)		(7,590	)		(6,768	)
Net income available to common shareholders	$	461,410			505,365			1,376,129			1,310,703
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards		133,703			143,556			136,156			146,177
Less: Unvested stock-based compensation awards		(738	)		(734	)		(745	)		(753	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		34			154			32			181
Adjusted weighted-average shares outstanding		132,999			142,976			135,443			145,605

Diluted earnings per common share	$	3.47			3.53			10.16			9.00

Comprehensive income (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income

The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other comprehensive income (loss) to net income:

	Investment			Defined Benefit						Total Amount				Income
	Securities			Plans			Other			Before Tax				Tax			Net
	(In thousands)

Balance — January 1, 2019	$	(200,107	)		(354,502	)		(14,719	)	$	(569,328	)			149,247		$	(420,081	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		237,615			—			—			237,615				(62,432	)		175,183
Foreign currency translation adjustment		—			—			(2,663	)		(2,663	)			559			(2,104	)
Unrealized gains on cash flow hedges		—			—			204,587			204,587				(53,786	)		150,801
Total other comprehensive income before reclassifications		237,615			—			201,924			439,539				(115,659	)		323,880
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities		2,524			—			—			2,524		(a)		(663	)		1,861
Losses realized in net income		7			—			—			7		(b)		(2	)		5
Accretion of net gain on terminated cash flow hedges		—			—			(93	)		(93	)	(c)		25			(68	)
Net yield adjustment from cash flow hedges currently in effect		—			—			6,693			6,693		(a)		(1,760	)		4,933
Amortization of prior service credit		—			(3,129	)		—			(3,129	)	(d)		823			(2,306	)
Amortization of actuarial losses		—			15,559			—			15,559		(d)		(4,091	)		11,468
Total other comprehensive income		240,146			12,430			208,524			461,100				(121,327	)		339,773
Balance — September 30, 2019	$	40,039			(342,072	)		193,805		$	(108,228	)			27,920		$	(80,308	)


Balance — January 1, 2018	$	(59,957	)		(413,168	)		(20,165	)	$	(493,290	)			129,476		$	(363,814	)
Cumulative effect of change in accounting principle — equity securities		(22,795	)		—			—			(22,795	)			5,942			(16,853	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(230,135	)		—			—			(230,135	)			60,494			(169,641	)
Foreign currency translation adjustment		—			—			(1,783	)		(1,783	)			374			(1,409	)
Unrealized losses on cash flow hedges		—			—			(26,522	)		(26,522	)			6,972			(19,550	)
Total other comprehensive income (loss) before reclassifications		(230,135	)		—			(28,305	)		(258,440	)			67,840			(190,600	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		2,519			—			—			2,519		(a)		(662	)		1,857
Gains realized in net income		(18	)		—			—			(18	)	(b)		4			(14	)
Accretion of net gain on terminated cash flow hedges		—			—			(83	)		(83	)	(c)		22			(61	)
Net yield adjustment from cash flow hedges currently in effect		—			—			7,650			7,650		(a)		(2,011	)		5,639
Amortization of prior service credit		—			(3,129	)		—			(3,129	)	(d)		823			(2,306	)
Amortization of actuarial losses		—			32,225			—			32,225		(d)		(8,472	)		23,753
Total other comprehensive income (loss)		(227,634	)		29,096			(20,738	)		(219,276	)			57,544			(161,732	)
Balance — September 30, 2018	$	(310,386	)		(384,072	)		(40,903	)	$	(735,361	)			192,962		$	(542,399	)

(a)	Included in interest income.

(b)	Included in gain (loss) on bank investment securities.

(c)	Included in interest expense.

(d)	Included in other costs of operations.

Accumulated Other Comprehensive Income (Loss), Net

Accumulated other comprehensive income (loss), net consisted of the following:

	Investment			Defined Benefit
	Securities			Plans			Other			Total
	(In thousands)

Balance — December 31, 2018	$	(147,526	)		(261,303	)		(11,252	)	$	(420,081	)
Net gain during period		177,049			9,162			153,562			339,773
Balance — September 30, 2019	$	29,523			(252,141	)		142,310		$	(80,308	)

Derivative financial instruments (Tables)

9 Months Ended

Sep. 30, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Information about Interest Rate Swap Agreements

Information about interest rate swap agreements entered into for interest rate risk management purposes summarized by type of financial instrument the swap agreements were intended to hedge follows:

					Weighted-
					Average Rate
	Notional		Average								Estimated Fair Value
	Amount		Maturity		Fixed			Variable			Gain (Loss) (a)
	(In thousands)		(In years)								(In thousands)
September 30, 2019
Fair value hedges:
Fixed rate long-term borrowings (b)	$	3,800,000		2.5		2.51	%		2.55	%	$	(1,086	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(c)		43,600,000		1.4		2.38	%		2.06	%		(5,056	)
Total	$	47,400,000		1.5							$	(6,142	)
December 31, 2018
Fair value hedges:
Fixed rate long-term borrowings (b)	$	4,450,000		2.8		2.47	%		3.02	%	$	4,219
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(d)		15,400,000		1.3		1.52	%		2.35	%		1,311
Total	$	19,850,000		1.7							$	5,530

(a)

(b)	Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate.

(c)	Includes notional amount and terms of $30.3 billion of forward-starting interest rate swap agreements that become effective in 2019, 2020 and 2021.

(d)	Includes notional amount and terms of $12.6 billion of forward-starting interest rate swap agreements that become effective in 2019 and 2020.

Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet

Information about the fair values of derivative instruments in the Company’s consolidated balance sheet and consolidated statement of income follows:

	Asset Derivatives				Liability Derivatives
	Fair Value				Fair Value
	September 30,		December 31,		September 30,		December 31,
	2019		2018		2019		2018
	(In thousands)
Derivatives designated and qualifying as hedging instruments
Interest rate swap agreements (a)	$	47	$	5,530	$	6,189	$	—
Commitments to sell real estate loans (a)		1,339		1,090		1,928		6,434
		1,386		6,620		8,117		6,434
Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		24,463		9,304		189		1,592
Commitments to sell real estate loans (a)		2,079		3,702		13,402		4,535
Trading:
Interest rate contracts (b)		532,070		118,687		72,098		169,255
Foreign exchange and other option and futures contracts (b)		11,280		10,549		9,944		8,870
		569,892		142,242		95,633		184,252
Total derivatives	$	571,278	$	148,862	$	103,750	$	190,686

(a)	Asset derivatives are reported in other assets and liability derivatives are reported in other liabilities.

(b)

	Carrying Amount of the Hedged Item				Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item
	September 30, 2019		December 31, 2018		September 30, 2019		December 31, 2018
	(In thousands)
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges

Long-term debt	$	3,858,490	$	4,394,109	$	61,782	$	(51,102	)

Information about Fair Values of Derivative Instruments in Consolidated Statement of Income

	Amount of Gain (Loss) Recognized
	Three Months Ended September 30, 2019					Three Months Ended September 30, 2018
	Derivative		Hedged Item			Derivative			Hedged Item
	(In thousands)
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	22,582		(22,412	)	$	(12,568	)		12,607
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	6,435				$	(1,348	)
Foreign exchange and other option and futures contracts (b)		2,598					782
Total	$	9,033				$	(566	)

11. Derivative financial instruments, continued

	Amount of Gain (Loss) Recognized
	Nine Months Ended September 30, 2019					Nine Months Ended September 30, 2018
	Derivative		Hedged Item			Derivative			Hedged Item
	(In thousands)
Derivatives in fair value hedging relationships
Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	113,441		(112,884	)	$	(68,315	)		68,861
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	17,639				$	(5,639	)
Foreign exchange and other option and futures contracts (b)		6,690					5,778
Total	$	24,329				$	139

(a)

Reported as interest expense.

(b)

Reported as trading account and foreign exchange gains.

Fair value measurements (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis

The following tables present assets and liabilities at September 30, 2019 and December 31, 2018 measured at estimated fair value on a recurring basis:

	Fair Value Measurements		Level 1 (a)		Level 2 (a)		Level 3
	(In thousands)
September 30, 2019
Trading account assets	$	614,256	$	48,724	$	565,532	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		359,394		—		359,394		—
Obligations of states and political subdivisions		934		—		934		—
Mortgage-backed securities:
Government issued or guaranteed		6,494,900		—		6,494,900		—
Privately issued		16		—		—		16
Other debt securities		130,173		—		130,173		—
		6,985,417		—		6,985,401		16
Equity securities		150,104		104,199		45,905		—
Real estate loans held for sale		588,233		—		588,233		—
Other assets (b)		27,928		—		3,465		24,463
Total assets	$	8,365,938	$	152,923	$	8,188,536	$	24,479
Trading account liabilities	$	82,042	$	—	$	82,042	$	—
Other liabilities (b)		21,708		—		21,519		189
Total liabilities	$	103,750	$	—	$	103,561	$	189

December 31, 2018
Trading account assets	$	185,584	$	46,018	$	139,566	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		1,336,931		—		1,336,931		—
Obligations of states and political subdivisions		1,659		—		1,659		—
Mortgage-backed securities:
Government issued or guaranteed		7,216,991		—		7,216,991		—
Privately issued		22		—		—		22
Other debt securities		126,906		—		126,906		—
		8,682,509		—		8,682,487		22
Equity securities		93,917		71,989		21,928		—
Real estate loans held for sale		551,697		—		551,697		—
Other assets (b)		19,626		—		10,322		9,304
Total assets	$	9,533,333	$	118,007	$	9,406,000	$	9,326
Trading account liabilities	$	178,125	$	—	$	178,125	$	—
Other liabilities (b)		12,561		—		10,969		1,592
Total liabilities	$	190,686	$	—	$	189,094	$	1,592

(a)	There were no significant transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2019 and the year ended December 31, 2018.

(b)	Comprised predominantly of interest rate swap agreements used for interest rate risk management (Level 2), commitments to sell real estate loans (Level 2) and commitments to originate real estate loans to be held for sale (Level 3).

Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during three months ended September 30, 2019 and 2018 were as follows:

	Investment Securities Available for Sale
	Privately Issued Mortgage-Backed Securities		Other Assets and Other Liabilities
2019	(In thousands)

Balance — June 30, 2019	$	16		17,200
Total gains realized/unrealized:
Included in earnings		—		62,178		(b)
Settlements		—		—
Transfers out of Level 3 (a)		—		(55,104	)	(c)
Balance — September 30, 2019	$	16		24,274
Changes in unrealized gains included in earnings related to assets still held at September 30, 2019	$	—		19,350		(b)

2018

Balance — June 30, 2018	$	24		10,751
Total gains realized/unrealized:
Included in earnings		—		10,284		(b)
Settlements		(1	)	—
Transfers out of Level 3 (a)		—		(16,849	)	(c)
Balance — September 30, 2018	$	23		4,186
Changes in unrealized gains included in earnings related to assets still held at September 30, 2018	$	—		4,508		(b)

	Investment Securities Available for Sale
	Privately Issued Mortgage-Backed Securities			Other Assets and Other Liabilities
2019	(In thousands)

Balance — January 1, 2019	$	22			7,712
Total gains realized/unrealized:
Included in earnings		—			115,187		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(98,625	)	(c)
Balance — September 30, 2019	$	16			24,274
Changes in unrealized gains included in earnings related to assets still held at September 30, 2019	$	—			24,981		(b)

2018

Balance — January 1, 2018	$	28		8,303
Total gains realized/unrealized:
Included in earnings		—		38,691		(b)
Settlements		(5	)	—
Transfers out of Level 3 (a)		—		(42,808	)	(c)
Balance — September 30, 2018	$	23		4,186
Changes in unrealized gains included in earnings related to assets still held at September 30, 2018	$	—		3,663		(b)

(a)	The Company’s policy for transfers between fair value levels is to recognize the transfer as of the actual date of the event or change in circumstances that caused the transfer.

(b)	Reported as mortgage banking revenues in the consolidated statement of income and includes the fair value of commitment issuances and expirations.

(c)	Transfers out of Level 3 consist of interest rate locks transferred to closed loans.

Quantitative Information Related to Significant Unobservable Inputs

Fair Value

Valuation

Technique

Unobservable

Inputs/Assumptions

Range

(Weighted-

Average)

(In thousands)

September 30, 2019

Recurring fair value measurements

Privately issued mortgage-backed

securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

24,274

Discounted cash flow

Commitment expirations

0%-96% (11%)

December 31, 2018

Recurring fair value measurements

Privately issued mortgage-backed

securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

7,712

Discounted cash flow

Commitment expirations

0%-95% (13%)

(a)	Other Level 3 assets (liabilities) consist of commitments to originate real estate loans.

Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities)

The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following table:

	September 30, 2019
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
	(In thousands)
Financial assets:
Cash and cash equivalents	$	1,818,861			1,818,861			1,765,090		53,771			—
Interest-bearing deposits at banks		12,495,524			12,495,524			—		12,495,524			—
Federal funds sold		200			200			—		200			—
Trading account assets		614,256			614,256			48,724		565,532			—
Investment securities		10,677,583			10,721,588			104,199		10,525,863			91,526
Loans and leases:
Commercial loans and leases		23,201,372			22,844,883			—		—			22,844,883
Commercial real estate loans		34,945,231			34,772,982			—		197,141			34,575,841
Residential real estate loans		16,500,955			16,575,991			—		4,021,885			12,554,106
Consumer loans		15,175,635			15,157,025			—		—			15,157,025
Allowance for credit losses		(1,038,437	)		—			—		—			—
Loans and leases, net		88,784,756			89,350,881			—		4,219,026			85,131,855
Accrued interest receivable		340,543			340,543			—		340,543			—
Financial liabilities:
Noninterest-bearing deposits	$	(31,766,724	)		(31,766,724	)		—		(31,766,724	)		—
Savings and interest-checking deposits		(55,581,533	)		(55,581,533	)		—		(55,581,533	)		—
Time deposits		(6,203,679	)		(6,289,534	)		—		(6,289,534	)		—
Deposits at Cayman Islands office		(1,561,997	)		(1,561,997	)		—		(1,561,997	)		—
Short-term borrowings		(5,513,896	)		(5,513,896	)		—		(5,513,896	)		—
Long-term borrowings		(7,002,524	)		(7,056,344	)		—		(7,056,344	)		—
Accrued interest payable		(90,623	)		(90,623	)		—		(90,623	)		—
Trading account liabilities		(82,042	)		(82,042	)		—		(82,042	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	24,274			24,274			—		—			24,274
Commitments to sell real estate loans		(11,912	)		(11,912	)		—		(11,912	)		—
Other credit-related commitments		(130,413	)		(130,413	)		—		—			(130,413	)
Interest rate swap agreements used for interest rate risk management		(6,142	)		(6,142	)		—		(6,142	)		—

	December 31, 2018
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
				(In thousands)
Financial assets:
Cash and cash equivalents	$	1,605,439			1,605,439			1,528,302		77,137			—
Interest-bearing deposits at banks		8,105,197			8,105,197			—		8,105,197			—
Trading account assets		185,584			185,584			46,018		139,566			—
Investment securities		12,692,813			12,631,656			71,989		12,456,467			103,200
Loans and leases:
Commercial loans and leases		22,977,976			22,587,387			—		—			22,587,387
Commercial real estate loans		34,363,556			33,832,558			—		346,775			33,485,783
Residential real estate loans		17,154,446			16,974,545			—		3,920,447			13,054,098
Consumer loans		13,970,499			13,819,545			—		—			13,819,545
Allowance for credit losses		(1,019,444	)		—			—		—			—
Loans and leases, net		87,447,033			87,214,035			—		4,267,222			82,946,813
Accrued interest receivable		353,965			353,965			—		353,965			—
Financial liabilities:
Noninterest-bearing deposits	$	(32,256,668	)		(32,256,668	)		—		(32,256,668	)		—
Savings and interest-checking deposits		(50,963,744	)		(50,963,744	)		—		(50,963,744	)		—
Time deposits		(6,124,254	)		(6,201,957	)		—		(6,201,957	)		—
Deposits at Cayman Islands office		(811,906	)		(811,906	)		—		(811,906	)		—
Short-term borrowings		(4,398,378	)		(4,398,378	)		—		(4,398,378	)		—
Long-term borrowings		(8,444,914	)		(8,385,289	)		—		(8,385,289	)		—
Accrued interest payable		(95,274	)		(95,274	)		—		(95,274	)		—
Trading account liabilities		(178,125	)		(178,125	)		—		(178,125	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	7,712			7,712			—		—			7,712
Commitments to sell real estate loans		(6,177	)		(6,177	)		—		(6,177	)		—
Other credit-related commitments		(131,688	)		(131,688	)		—		—			(131,688	)
Interest rate swap agreements used for interest rate risk management		5,530			5,530			—		5,530			—

Commitments and contingencies (Tables)

9 Months Ended

Sep. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingent Liabilities Outstanding

In the normal course of business, various commitments and contingent liabilities are outstanding. Certain of these commitments are not included in the Company's consolidated balance sheet.

	September 30,		December 31,
	2019		2018
	(In thousands)
Commitments to extend credit
Home equity lines of credit	$	5,451,328		5,484,197
Commercial real estate loans to be sold		393,397		229,401
Other commercial real estate		8,222,395		7,556,722
Residential real estate loans to be sold		530,093		245,211
Other residential real estate		511,854		219,351
Commercial and other		16,313,801		14,363,803
Standby letters of credit		2,373,846		2,326,991
Commercial letters of credit		38,633		55,808
Financial guarantees and indemnification contracts		3,996,029		3,529,136
Commitments to sell real estate loans		1,350,292		940,692

Segment information (Tables)

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Information about Company's Segments

Information about the Company's segments is presented in the following table:

	Three Months Ended September 30
	2019								2018
	Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)			Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)
	(In thousands)

Business Banking	$	143,741		912			46,147		$	138,898		920			43,730
Commercial Banking		282,757		980			132,668			280,671		875			147,910
Commercial Real Estate		238,364		458			131,161			214,266		371			116,386
Discretionary Portfolio		50,871		(10,550	)		29,604			53,061		(10,270	)		39,723
Residential Mortgage Banking		115,239		19,363			15,846			79,603		15,402			13,289
Retail Banking		432,339		1,808			131,638			427,452		2,862			141,612
All Other		294,358		(12,971	)		(6,983	)		294,381		(10,160	)		23,441
Total	$	1,557,669		—			480,081		$	1,488,332		—			526,091

	Nine Months Ended September 30
	2019								2018
	Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)			Total Revenues(a)		Inter- segment Revenues			Net Income (Loss)
	(In thousands)

Business Banking	$	423,830		2,772			131,668		$	402,811		2,750			124,455
Commercial Banking		828,357		2,707			388,393			816,566		2,653			399,766
Commercial Real Estate		682,979		1,218			370,288			622,414		1,096			337,380
Discretionary Portfolio		175,764		(29,140	)		106,816			162,075		(31,656	)		88,575
Residential Mortgage Banking		295,449		51,027			36,429			244,228		46,870			43,637
Retail Banking		1,299,823		7,106			417,198			1,241,468		8,434			408,081
All Other		955,868		(35,690	)		(14,709	)		899,184		(30,147	)		(30,033	)
Total	$	4,662,070		—			1,436,083		$	4,388,746		—			1,371,861

15. Segment information, continued

	Average Total Assets
	Nine Months Ended September 30				Year Ended December 31
	2019		2018		2018
	(In millions)

Business Banking	$	5,758		5,637		5,631
Commercial Banking		28,089		26,524		26,626
Commercial Real Estate		23,893		22,899		22,885
Discretionary Portfolio		29,355		32,659		32,123
Residential Mortgage Banking		2,444		2,123		2,161
Retail Banking		14,839		13,522		13,656
All Other		14,206		13,312		13,877
Total	$	118,584		116,676		116,959

(a)

Investment Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended
Investment Securities - Additional Information (Detail)	Sep. 30, 2019 USD ($) Security	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Security	Sep. 30, 2018 USD ($)
Investment Holdings [Line Items]
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0	$ 0	$ 0
Gain (loss) on bank investment securities	$ 3,737,000	$ (3,415,000)	$ 24,489,000	$ (10,520,000)
Number of debt securities with aggregate gross unrealized losses \| Security	657		657
Unrealized losses on individual debt securities			$ (61,000,000)
Cost method equity securities	$ 511,000,000		511,000,000
Retained Earnings [Member] \| Adjustments for New Accounting Pronouncement [Member]
Investment Holdings [Line Items]
Reclassification from accumulated comprehensive income to retained earnings, net of tax	$ 17,000,000		$ 17,000,000

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	$ 6,934,709	$ 8,869,423
Investment securities available for sale, gross unrealized gains	89,965	16,528
Investment securities available for sale, gross unrealized losses	39,257	203,442
Investment securities available for sale, estimated fair value	6,985,417	8,682,509
Amortized cost for held to maturity	3,031,299	3,316,640
Gross unrealized gains for held to maturity	65,844	16,532
Gross unrealized losses for held to maturity	21,839	77,689
Estimated fair value for held to maturity	3,075,304	3,255,483
Equity and other securities, Amortized Cost	619,894	677,187
Equity securities, Gross Unrealized Gains	41,152	17,295
Equity securities, Gross Unrealized Losses	179	818
Equity and other securities, Estimated Fair Value	660,867	693,664
Other securities, Amortized cost	510,763	599,747
Other securities, Estimated fair value	510,763	599,747
Total debt securities Amortized cost	9,966,008	12,186,063
Total debt securities Gross unrealized gains	155,809	33,060
Total debt securities Gross unrealized losses	61,096	281,131
Total debt securities Estimated fair value	10,060,721	11,937,992
Readily marketable securities Amortized cost	109,131	77,440
Readily marketable securities Gross unrealized gains	41,152	17,295
Readily marketable securities Gross unrealized losses	179	818
Readily marketable securities Estimated fair value	150,104	93,917
U.S. Treasury and Federal Agencies [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	359,723	1,346,782
Investment securities available for sale, gross unrealized gains	66
Investment securities available for sale, gross unrealized losses	395	9,851
Investment securities available for sale, estimated fair value	359,394	1,336,931
Amortized cost for held to maturity	498,776	446,542
Gross unrealized gains for held to maturity	956
Gross unrealized losses for held to maturity		239
Estimated fair value for held to maturity	499,732	446,303
Obligations of States and Political Subdivisions [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	933	1,660
Investment securities available for sale, gross unrealized gains	4	4
Investment securities available for sale, gross unrealized losses	3	5
Investment securities available for sale, estimated fair value	934	1,659
Amortized cost for held to maturity	4,775	7,494
Gross unrealized gains for held to maturity	21	22
Gross unrealized losses for held to maturity		12
Estimated fair value for held to maturity	4,796	7,504
Government Issued or Guaranteed [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	6,435,730	7,383,340
Investment securities available for sale, gross unrealized gains	88,522	15,754
Investment securities available for sale, gross unrealized losses	29,352	182,103
Investment securities available for sale, estimated fair value	6,494,900	7,216,991
Amortized cost for held to maturity	2,424,716	2,745,776
Gross unrealized gains for held to maturity	53,076	4,165
Gross unrealized losses for held to maturity	1,879	55,111
Estimated fair value for held to maturity	2,475,913	2,694,830
Privately Issued [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	16	24
Investment securities available for sale, gross unrealized losses		2
Investment securities available for sale, estimated fair value	16	22
Amortized cost for held to maturity	99,679	113,160
Gross unrealized gains for held to maturity	11,791	12,345
Gross unrealized losses for held to maturity	19,960	22,327
Estimated fair value for held to maturity	91,510	103,178
Other Debt Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	138,307	137,617
Investment securities available for sale, gross unrealized gains	1,373	770
Investment securities available for sale, gross unrealized losses	9,507	11,481
Investment securities available for sale, estimated fair value	130,173	126,906
Amortized cost for held to maturity	3,353	3,668
Estimated fair value for held to maturity	$ 3,353	$ 3,668

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt securities available for sale:
Due in one year or less	$ 355,210
Due after one year through five years	11,470
Due after five years through ten years	102,283
Due after ten years	30,000
Total available for sale (amortized cost)	498,963
Mortgage-backed securities available for sale	6,435,746
Investment securities available for sale, amortized cost	6,934,709	$ 8,869,423
Debt securities held to maturity:
Due in one year or less	500,476
Due after one year through five years	3,075
Due after ten years	3,353
Total available for held to maturity (amortized cost)	506,904
Mortgage-backed securities held to maturity	2,524,395
Amortized cost for held to maturity	3,031,299	3,316,640
Debt securities available for sale:
Due in one year or less	354,825
Due after one year through five years	11,585
Due after five years through ten years	100,091
Due after ten years	24,000
Total available for sale (fair value)	490,501
Mortgage-backed securities available for sale	6,494,916
Total	6,985,417	8,682,509
Debt securities held to maturity:
Due in one year or less	501,438
Due after one year through five years	3,090
Due after ten years	3,353
Total available for held to maturity (fair value)	507,881
Mortgage-backed securities held to maturity	2,567,423
Total	$ 3,075,304	$ 3,255,483

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 260,498	$ 459,960
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(1,152)	(5,088)
Estimated fair value, 12 months or more	2,537,681	7,048,346
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(38,105)	(198,354)
Held to maturity, Estimated fair value, Less than 12 months		625,657
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		(1,228)
Held to maturity, Estimated fair value, 12 months or more	215,807	2,137,792
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(21,839)	(76,461)
Total investment securities, fair value less than 12 months	260,498	1,085,617
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(1,152)	(6,316)
Total of investment securities, fair value, 12 Months or More	2,753,488	9,186,138
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(59,944)	(274,815)
U.S. Treasury and Federal Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months		273
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		(2)
Estimated fair value, 12 months or more	352,482	1,335,559
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(395)	(9,849)
Held to maturity, Estimated fair value, Less than 12 months		446,303
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		(239)
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months		629
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		(5)
Estimated fair value, 12 months or more	375
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(3)
Held to maturity, Estimated fair value, 12 months or more		3,126
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses		(12)
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	240,208	405,558
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(589)	(2,892)
Estimated fair value, 12 months or more	2,107,684	5,646,773
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(28,763)	(179,211)
Held to maturity, Estimated fair value, Less than 12 months		179,354
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		(989)
Held to maturity, Estimated fair value, 12 months or more	165,983	2,082,723
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(1,879)	(54,122)
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	20,290	53,478
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(563)	(2,187)
Estimated fair value, 12 months or more	77,140	66,014
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(8,944)	(9,294)
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months		22
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		(2)
Held to maturity, Estimated fair value, 12 months or more	49,824	51,943
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	$ (19,960)	$ (22,327)

Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 86,916,076	$ 86,140,950
30-89 Days Past Due	1,146,477	866,337
Accruing Loans Past Due 90 Days or More	461,162	222,527
Purchased Impaired	253,496	303,305
Nonaccrual	1,005,249	893,608
Loans and leases, net of unearned discount	89,823,193	88,466,477
Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	40,733	39,750
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	22,689,923	22,701,020
30-89 Days Past Due	125,742	39,798
Accruing Loans Past Due 90 Days or More	2,898	2,567
Nonaccrual	382,809	234,423
Loans and leases, net of unearned discount	23,201,372	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More		168
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	25,613,988	25,250,983
30-89 Days Past Due	186,157	134,474
Accruing Loans Past Due 90 Days or More	8,387	11,457
Purchased Impaired	14,406	9,769
Nonaccrual	184,632	203,672
Loans and leases, net of unearned discount	26,007,585	25,610,365
Commercial [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	15	10
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,546,570	1,665,178
30-89 Days Past Due	6,300	20,333
Purchased Impaired	639
Nonaccrual	4,975	4,798
Loans and leases, net of unearned discount	1,558,484	1,690,309
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	7,229,925	6,982,077
30-89 Days Past Due	112,651	43,615
Accruing Loans Past Due 90 Days or More	4,291	14,344
Purchased Impaired	854	641
Nonaccrual	31,441	22,205
Loans and leases, net of unearned discount	7,379,162	7,062,882
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	12,975,992	13,591,790
30-89 Days Past Due	495,831	404,808
Accruing Loans Past Due 90 Days or More	439,649	189,682
Purchased Impaired	162,475	203,044
Nonaccrual	223,566	233,352
Loans and leases, net of unearned discount	14,302,759	14,629,326
Residential [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	5,246	6,650
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,968,580	2,278,040
30-89 Days Past Due	72,815	72,544
Purchased Impaired	75,122	89,851
Nonaccrual	81,679	84,685
Loans and leases, net of unearned discount	2,198,196	2,525,120
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,486,664	4,758,513
30-89 Days Past Due	29,826	25,416
Nonaccrual	59,915	71,292
Loans and leases, net of unearned discount	4,579,792	4,860,254
Home Equity Lines and Loans [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	3,387	5,033
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,262,857	4,085,781
30-89 Days Past Due	27,880	29,947
Nonaccrual	11,852	11,199
Loans and leases, net of unearned discount	5,302,589	4,127,162
Recreational Finance [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More		235
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,767,965	3,555,757
30-89 Days Past Due	74,504	79,804
Nonaccrual	21,039	23,359
Loans and leases, net of unearned discount	3,863,508	3,658,920
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,373,612	1,271,811
30-89 Days Past Due	14,771	15,598
Accruing Loans Past Due 90 Days or More	5,937	4,477
Nonaccrual	3,341	4,623
Loans and leases, net of unearned discount	1,429,746	1,324,163
Other [Member] \| Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	$ 32,085	$ 27,654

Loans and Leases and the Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Loans And Leases Receivable [Line Items]
Contractual principal and interest payments	$ 253	$ 303
Minimum delinquency period for loan level collectability analysis consumer mortgage	150 days
Amount of foreclosed residential real estate property held	$ 70	77
Loans secured by residential real estate that were in the process of foreclosure	$ 391	391
Percentage loans in the process of foreclosure, serviced by other entities, classified as purchased impaired	27.00%
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	33.00%
Guaranteed amount included in the estimated residual value of leased assets associated with direct financing leases	$ 38	39
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Carrying value of loans for which partial charge-off has been recognized	26	29
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount	19	21
Home Equity Loans and Lines of Credit [Member]
Loans And Leases Receivable [Line Items]
Carrying value of loans for which partial charge-off has been recognized	20	23
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount	$ 29	$ 31
Maximum [Member]
Loans And Leases Receivable [Line Items]
Purchased impaired loans as a percentage of total assets	1.00%	1.00%
Minimum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	90 days
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	$ 391	$ 205
Commercial Real Estate Loans [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	$ 197	$ 347

Loans and Leases and the Allowance for Credit Losses - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 147,104	$ 149,388	$ 147,210	$ 157,918
Interest income	(9,564)	(8,105)	(37,278)	(25,893)
Reclassifications from nonaccretable balance	9,079	8,445	36,687	17,703
Balance at end of period	146,619	149,728	146,619	149,728
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	90,911	117,715	96,907	133,162
Interest income	(9,238)	(18,001)	(28,621)	(48,507)
Reclassifications from nonaccretable balance	3,990	25	12,312	11,230
Other	41	2,001	5,106	5,855
Balance at end of period	$ 85,704	$ 101,740	$ 85,704	$ 101,740

Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,029,867	$ 1,019,248	$ 1,019,444	$ 1,017,198
Provision for credit losses	45,000	16,000	122,000	94,000
Net charge-offs
Charge-offs	(60,241)	(52,066)	(174,747)	(166,265)
Recoveries	23,811	36,306	71,740	74,555
Net (charge-offs) recoveries	(36,430)	(15,760)	(103,007)	(91,710)
Ending balance	1,038,437	1,019,488	1,038,437	1,019,488
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	335,855	328,830	330,055	328,599
Provision for credit losses	24,538	(6,972)	41,146	11,508
Net charge-offs
Charge-offs	(15,678)	(11,792)	(40,786)	(41,273)
Recoveries	6,730	7,123	21,030	18,355
Net (charge-offs) recoveries	(8,948)	(4,669)	(19,756)	(22,918)
Ending balance	351,445	317,189	351,445	317,189
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	343,296	353,761	341,655	374,085
Provision for credit losses	(16,713)	(11,394)	(6,415)	(27,464)
Net charge-offs
Charge-offs	(1,107)	(1,941)	(11,555)	(7,855)
Recoveries	1,656	14,577	3,447	16,237
Net (charge-offs) recoveries	549	12,636	(8,108)	8,382
Ending balance	327,132	355,003	327,132	355,003
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	61,011	76,123	69,125	65,405
Provision for credit losses	(309)	741	(5,132)	16,469
Net charge-offs
Charge-offs	(2,721)	(3,338)	(9,356)	(11,658)
Recoveries	1,511	1,655	4,855	4,965
Net (charge-offs) recoveries	(1,210)	(1,683)	(4,501)	(6,693)
Ending balance	59,492	75,181	59,492	75,181
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	211,220	182,987	200,564	170,809
Provision for credit losses	37,735	32,887	92,212	93,502
Net charge-offs
Charge-offs	(40,735)	(34,995)	(113,050)	(105,479)
Recoveries	13,914	12,951	42,408	34,998
Net (charge-offs) recoveries	(26,821)	(22,044)	(70,642)	(70,481)
Ending balance	222,134	193,830	222,134	193,830
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	78,485	77,547	78,045	78,300
Provision for credit losses	(251)	738	189	(15)
Net charge-offs
Ending balance	$ 78,234	$ 78,285	$ 78,234	$ 78,285

Loans and Leases and the Allowance for Credit Losses - Impaired Loans and Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	$ 581,303	$ 542,255
Unpaid principal balance with related allowance	678,185	630,609
Related allowance	90,992	79,646
Recorded investment with no related allowance	349,499	254,196
Unpaid principal balance with no related allowance	389,977	305,559
Recorded investment	930,802	796,451
Unpaid principal balance	1,068,162	936,168
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	60,489	110,253
Unpaid principal balance with related allowance	67,104	125,117
Related allowance	7,711	11,937
Recorded investment with no related allowance	144,554	113,376
Unpaid principal balance with no related allowance	163,120	124,657
Recorded investment	205,043	223,629
Unpaid principal balance	230,224	249,774
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	3,478	3,527
Unpaid principal balance with related allowance	3,526	3,599
Related allowance	708	729
Recorded investment	3,478	3,527
Unpaid principal balance	3,526	3,599
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	245,355	153,478
Unpaid principal balance with related allowance	273,931	175,549
Related allowance	60,410	46,034
Recorded investment with no related allowance	159,991	105,507
Unpaid principal balance with no related allowance	172,191	136,128
Recorded investment	405,346	258,985
Unpaid principal balance	446,122	311,677
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	8,893	5,981
Unpaid principal balance with related allowance	9,311	6,557
Related allowance	319	462
Recorded investment with no related allowance	3,378	2,593
Unpaid principal balance with no related allowance	3,378	2,602
Recorded investment	12,271	8,574
Unpaid principal balance	12,689	9,159
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	12,821	10,563
Unpaid principal balance with related allowance	25,437	11,113
Related allowance	1,477	640
Recorded investment with no related allowance	18,620	11,710
Unpaid principal balance with no related allowance	19,614	11,880
Recorded investment	31,441	22,273
Unpaid principal balance	45,051	22,993
Residential [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	125,498	124,974
Unpaid principal balance with related allowance	146,098	147,817
Related allowance	6,748	5,402
Recorded investment with no related allowance	18,949	15,379
Unpaid principal balance with no related allowance	24,350	20,496
Recorded investment	144,447	140,353
Unpaid principal balance	170,448	168,313
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	67,729	74,156
Unpaid principal balance with related allowance	81,918	90,066
Related allowance	2,600	3,000
Recorded investment with no related allowance	4,007	5,631
Unpaid principal balance with no related allowance	7,324	9,796
Recorded investment	71,736	79,787
Unpaid principal balance	89,242	99,862
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	46,858	47,982
Unpaid principal balance with related allowance	51,759	53,248
Related allowance	8,923	9,135
Recorded investment	46,858	47,982
Unpaid principal balance	51,759	53,248
Recreational Finance [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	5,483	6,138
Unpaid principal balance with related allowance	9,481	9,163
Related allowance	1,153	1,261
Recorded investment	5,483	6,138
Unpaid principal balance	9,481	9,163
Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	4,699	5,203
Unpaid principal balance with related allowance	9,620	8,380
Related allowance	943	1,046
Recorded investment	4,699	5,203
Unpaid principal balance	$ 9,620	$ 8,380

Loans and Leases and the Allowance for Credit Losses - Interest Income Recognized on Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	$ 812,353	$ 757,997	$ 804,751	$ 744,561
Interest income recognized, Total	7,199	11,147	26,390	30,818
Interest income recognized, Cash basis	4,046	8,195	16,829	22,055
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	201,931	204,315	214,027	184,795
Interest income recognized, Total	1,798	1,489	4,921	8,447
Interest income recognized, Cash basis	1,798	1,489	4,921	8,447
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	288,516	256,196	275,896	266,594
Interest income recognized, Total	836	1,985	7,501	4,101
Interest income recognized, Cash basis	836	1,985	7,501	4,101
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	11,837	9,000	10,101	9,111
Interest income recognized, Total	89		239	1,682
Interest income recognized, Cash basis	89		239	1,682
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	32,458	9,623	25,126	9,056
Interest income recognized, Total	13	3,379	589	3,438
Interest income recognized, Cash basis	13	3,379	589	3,438
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	143,508	133,337	142,155	126,910
Interest income recognized, Total	2,353	1,959	6,765	6,190
Interest income recognized, Cash basis	984	773	2,654	2,612
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	72,926	81,729	75,702	83,700
Interest income recognized, Total	1,348	1,607	4,153	4,763
Interest income recognized, Cash basis	229	481	655	1,494
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	46,982	48,542	47,325	48,661
Interest income recognized, Total	416	421	1,238	1,268
Interest income recognized, Cash basis	74	62	193	220
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	5,562	3,531	5,799	2,156
Interest income recognized, Total	147	65	414	193
Interest income recognized, Cash basis	4	1	12	6
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	3,413	7,805	3,465	11,189
Interest income recognized, Total	54	181	161	630
Interest income recognized, Cash basis	18	20	55	49
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	5,220	3,919	5,155	2,389
Interest income recognized, Total	145	61	409	106
Interest income recognized, Cash basis	$ 1	$ 5	$ 10	$ 6

Loans and Leases and the Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 89,823,193	$ 88,466,477
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,201,372	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	21,893,239	21,693,705
Commercial, Financial, Leasing, etc. [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	925,324	1,049,848
Commercial, Financial, Leasing, etc. [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	382,809	234,423
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,007,586	25,610,365
Commercial [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	25,095,663	24,539,706
Commercial [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	727,291	866,987
Commercial [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	184,632	203,672
Residential Builder and Developer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,558,484	1,690,309
Residential Builder and Developer [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,447,978	1,546,002
Residential Builder and Developer [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	105,531	139,509
Residential Builder and Developer [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	4,975	4,798
Other Commercial Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,379,162	7,062,882
Other Commercial Construction [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,122,983	6,890,562
Other Commercial Construction [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	224,738	150,115
Other Commercial Construction [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 31,441	$ 22,205

Loans and Leases and the Allowance for Credit Losses - Allocation of Allowance for Credit Losses on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 90,992		$ 79,646
Allowance for credit losses	863,833		849,356
Allowance for credit losses	1,038,437	$ 1,029,867	1,019,444	$ 1,019,488	$ 1,019,248	$ 1,017,198
Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	5,378		12,397
Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	960,203		941,399
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	78,234	$ 78,485	78,045	$ 78,285	$ 77,547	$ 78,300
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	60,410		46,034
Allowance for credit losses	291,035		284,021
Commercial, Financial, Leasing, etc. [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	351,445		330,055
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	9,507		13,039
Allowance for credit losses	317,625		328,616
Commercial Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	327,132		341,655
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	9,348		8,402
Allowance for credit losses	44,766		48,326
Residential Real Estate [Member] \| Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	5,378		12,397
Residential Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	59,492		69,125
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	11,727		12,171
Allowance for credit losses	210,407		188,393
Consumer Loans [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 222,134		$ 200,564

Loans and Leases and the Allowance for Credit Losses - Recorded Investment in Loans and Leases on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 89,823,193	$ 88,466,477
Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	930,802	796,451
Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	88,638,895	87,366,721
Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	253,496	303,305
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,201,372	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	405,346	258,985
Commercial, Financial, Leasing, etc. [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	22,796,026	22,718,991
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	34,945,231	34,363,556
Commercial Real Estate [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	248,755	254,476
Commercial Real Estate [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	34,680,577	34,098,670
Commercial Real Estate [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	15,899	10,410
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,500,955	17,154,446
Residential Real Estate [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	216,183	220,140
Residential Real Estate [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,047,175	16,641,411
Residential Real Estate [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	237,597	292,895
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	15,175,635	13,970,499
Consumer Loans [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	60,518	62,850
Consumer Loans [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 15,115,117	$ 13,907,649

Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) Modification	Sep. 30, 2018 USD ($) Modification	Sep. 30, 2019 USD ($) Modification	Sep. 30, 2018 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	97	151	322	438
Pre-modification Recorded Investment	$ 16,466	$ 29,537	$ 86,580	$ 157,552
Post- modification	$ 16,845	$ 30,086	$ 87,094	$ 161,617
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	9	18	38	66
Pre-modification Recorded Investment	$ 2,986	$ 11,581	$ 22,567	$ 25,561
Post- modification	2,972	11,265	22,144	25,961
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	5,388	9,992	23,981	80,032
Principal Deferral [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	383	1,493	3,947	14,693
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		5		833
Interest Rate Reduction [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification				175
Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		3,475		9,980
Other [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		3,475		3,869
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	11,457	16,614	63,113	70,772
Combination of Concession Types [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 2,589	$ 6,297	$ 18,197	$ 7,224
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	26	47	115	150
Pre-modification Recorded Investment	$ 6,145	$ 6,837	$ 39,357	$ 96,221
Post- modification	6,107	6,706	39,409	96,884
Commercial, Financial, Leasing, etc. [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,441	1,683	8,582	47,029
Commercial, Financial, Leasing, etc. [Member] \| Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		5		658
Commercial, Financial, Leasing, etc. [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification				6,111
Commercial, Financial, Leasing, etc. [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 4,666	$ 5,018	$ 30,827	$ 43,086
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification			2
Pre-modification Recorded Investment			$ 1,330
Post- modification			1,068
Residential Builder and Developer [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 1,068
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	20	34	63	111
Pre-modification Recorded Investment	$ 5,161	$ 8,182	$ 16,490	$ 28,769
Post- modification	5,581	9,028	17,647	31,455
Residential [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	3,046	6,026	8,805	15,785
Residential [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 2,535	$ 3,002	$ 8,842	$ 15,670
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	1	3	4	8
Pre-modification Recorded Investment	$ 236	$ 716	$ 1,084	$ 1,595
Post- modification	240	847	1,104	1,890
Residential Limited Documentation [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			399	467
Residential Limited Documentation [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 240	$ 847	$ 705	$ 1,423
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	12	17	32	41
Pre-modification Recorded Investment	$ 1,392	$ 1,651	$ 3,141	$ 3,554
Post- modification	1,399	1,670	3,168	3,581
Home Equity Lines and Loans [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		220	90	224
Home Equity Lines and Loans [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 1,399	$ 1,450	$ 3,078	$ 3,357
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	26	30	58	57
Pre-modification Recorded Investment	$ 485	$ 526	$ 991	$ 1,007
Post- modification	485	526	991	1,007
Automobile [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	457	$ 526	926	995
Automobile [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 28		$ 65	$ 12
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	3	2	8	4
Pre-modification Recorded Investment	$ 61	$ 44	$ 164	$ 93
Post- modification	61	44	164	93
Recreational Finance [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 61	$ 44	$ 164	$ 93
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification			2	1
Pre-modification Recorded Investment			$ 1,456	$ 752
Post- modification			1,399	746
Other Commercial Construction [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification				$ 746
Other Commercial Construction [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 1,399

Loans and Leases and the Allowance for Credit Losses - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Direct financings:
Lease payments receivable	$ 1,177,518	$ 1,155,464
Estimated residual value of leased assets	84,692	85,169
Unearned income	(105,774)	(110,458)
Investment in direct financings	1,156,436	1,130,175
Leveraged leases:
Lease payments receivable	82,127	85,007
Estimated residual value of leased assets	81,163	81,261
Unearned income	(32,220)	(33,717)
Investment in leveraged leases	131,070	132,551
Total investment in leases	1,287,506	1,262,726
Deferred taxes payable arising from leveraged leases	$ 71,432	$ 74,995

Loans and Leases and the Allowance for Credit Losses - Minimum Future Lease Payments to be Received from Lease Financings (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Receivables [Abstract]
2020	$ 346,223
2021	305,385
2022	216,018
2023	164,490
2024	82,455
Later years	145,074
Total	$ 1,259,645

Operating Leases - Summary of Right-of-Use Assets Recognized as Component of Premises and Equipment and Lease Liabilities Recognized as Component of Accrued Interest and Other Liabilities in Consolidated Balance Sheet (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Lessee Disclosure [Abstract]
Right-of-use assets	$ 392,324
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet
Lease liabilities	$ 424,854
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities

Operating Leases - Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases (Detail) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Lease cost
Operating lease cost	$ 25,058	$ 74,599
Short-term lease cost	20	82
Variable lease cost	644	1,733
Sublease income	(1,903)	(5,724)
Total net lease cost	23,819	70,690
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	24,377	69,305
Cash paid toward lease liabilities	$ 25,189	$ 76,050
Weighted-average remaining lease term	7 years	7 years
Weighted-average discount rate	3.10%	3.10%

Operating Leases - Summary of Minimum Lease Payments Under Noncancelable Operating Leases (Detail) $ in Thousands	Sep. 30, 2019 USD ($)
Leases [Abstract]
2020	$ 97,712
2021	87,106
2022	72,577
2023	56,821
2024	42,770
Later years	116,467
Total lease payments	473,453
Less: imputed interest	48,599
Lease liabilities	$ 424,854

Borrowings - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Debt Instruments [Abstract]
Junior subordinated debentures	$ 524
Debt Maturity, Start Year	Jan. 01, 2027
Debt Maturity, End Year	Dec. 31, 2033
Agreements to repurchase securities	$ 102	$ 409
Collateral posted	$ 108	$ 428

Shareholders' Equity - Additional Information (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Class Of Stock [Line Items]
Preferred stock, shares authorized	1,000,000		1,000,000		1,000,000
Preferred stock, par value	$ 1.00		$ 1.00		$ 1.00
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	15.9375	$ 15.9375	47.8125	$ 47.8125
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	15.9375	15.9375	47.8125	47.8125
Series E Fixed-To-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	16.125	16.125	48.375	48.375
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 128.125	$ 128.125	$ 384.375	$ 384.375

Shareholders' Equity - Issued and Outstanding Preferred Stock (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Carrying Value	$ 1,250,000	$ 1,231,500
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued		230,000
Preferred stock, Shares Outstanding		230,000
Carrying Value		$ 230,000
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued		151,500
Preferred stock, Shares Outstanding		151,500
Carrying Value		$ 151,500
Series E Fixed-To-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	350,000	350,000
Preferred stock, Shares Outstanding	350,000	350,000
Carrying Value	$ 350,000	$ 350,000
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	50,000	50,000
Preferred stock, Shares Outstanding	50,000	50,000
Carrying Value	$ 500,000	$ 500,000
Series G Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	40,000
Preferred stock, Shares Outstanding	40,000
Carrying Value	$ 400,000

Shareholders' Equity - Issued and Outstanding Preferred Stock (Parenthetical) (Detail) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	1,000	1,000
Series E Fixed-To-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Preferred stock dividend rate	6.45%	6.45%
Date of change in the dividend rate	Feb. 14, 2024	Feb. 14, 2024
London Interbank offered rate plus basis points	3.61%	3.61%
Preferred shares redemption date	Feb. 15, 2024	Feb. 15, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	5.125%	5.125%
Date of change in the dividend rate	Oct. 31, 2026	Oct. 31, 2026
London Interbank offered rate plus basis points	3.52%	3.52%
Preferred shares redemption date	Nov. 01, 2026	Nov. 01, 2026
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Series G Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	5.00%	5.00%
Date of change in the dividend rate	Jul. 31, 2024	Jul. 31, 2024
Preferred shares redemption date	Aug. 01, 2024	Aug. 01, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
U S treasury rate plus additional rate	3.174%	3.174%
Dividend payment terms	five-year	five-year

Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 12,077	$ 12,267	$ 37,031	$ 38,288
Other revenues from operations:
Total other income	527,779	459,294	1,540,639	1,375,404
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	111,092	108,647	321,991	320,546
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	143,915	133,545	421,083	402,561
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	12,077	12,267	37,031	38,288
Other revenues from operations:
Merchant discount and credit card fees	28,190	27,771	82,016	78,605
Other	20,353	20,906	69,013	68,208
Total other income	315,627	303,136	931,134	908,208
ASU 2014-09 [Member] \| Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	9,692	9,238	28,469	25,075
Total other income	24,832	25,005	73,905	71,857
ASU 2014-09 [Member] \| Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	13,409	13,520	38,630	38,774
Other	1,239	1,662	5,386	6,871
Total other income	38,317	39,349	114,427	118,736
ASU 2014-09 [Member] \| Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	670	643	1,772	1,625
Other	1,372	1,822	5,840	4,896
Total other income	4,457	4,839	14,915	14,110
ASU 2014-09 [Member] \| Discretionary Portfolio [Member]
Other revenues from operations:
Other	503	386	1,545	1,251
Total other income	503	386	1,545	1,251
ASU 2014-09 [Member] \| Residential Mortgage Banking [Member]
Other revenues from operations:
Other	816	916	2,913	2,886
Total other income	816	918	2,917	2,894
ASU 2014-09 [Member] \| Retail Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	4,150	3,908	11,854	11,436
Other	9,347	9,397	27,170	28,875
Total other income	81,952	78,014	234,291	228,636
ASU 2014-09 [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	12,077	12,267	37,031	38,288
Other revenues from operations:
Merchant discount and credit card fees	269	462	1,291	1,695
Other	7,076	6,723	26,159	23,429
Total other income	164,750	154,625	489,134	470,724
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	111,092	108,647	321,991	320,546
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Business Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	15,131	15,767	45,415	46,782
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	23,427	24,167	69,731	73,091
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Commercial Real Estate [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	2,415	2,374	7,303	7,589
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Residential Mortgage Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer		2	4	8
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Retail Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	68,455	64,709	195,267	188,325
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1,664	1,628	4,271	4,751
ASU 2014-09 [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	143,915	133,545	421,083	402,561
ASU 2014-09 [Member] \| Trust Income [Member] \| Business Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	9		21
ASU 2014-09 [Member] \| Trust Income [Member] \| Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	242		680
ASU 2014-09 [Member] \| Trust Income [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 143,664	$ 133,545	$ 420,382	$ 402,561

Pension Plans and Other Postretirement Benefits - Net Periodic Defined Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,324	$ 5,086	$ 12,970	$ 15,258
Interest cost on projected benefit obligation	20,394	18,676	61,184	56,029
Expected return on plan assets	(30,534)	(30,781)	(91,604)	(92,344)
Amortization of prior service cost (credit)	139	139	418	417
Amortization of net actuarial loss (gain)	5,498	10,948	16,494	32,844
Net periodic cost (benefit)	(179)	4,068	(538)	12,204
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	215	234	644	703
Interest cost on projected benefit obligation	586	573	1,758	1,719
Amortization of prior service cost (credit)	(1,182)	(1,182)	(3,547)	(3,546)
Amortization of net actuarial loss (gain)	(312)	(206)	(935)	(619)
Net periodic cost (benefit)	$ (693)	$ (581)	$ (2,080)	$ (1,743)

Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income available to common shareholders:
Net income	$ 480,081	$ 526,091	$ 1,436,083	$ 1,371,861
Less: Preferred stock dividends	(16,103)	(18,130)	(52,364)	(54,390)
Net income available to common equity	463,978	507,961	1,383,719	1,317,471
Less: Income attributable to unvested stock-based compensation awards	(2,568)	(2,598)	(7,591)	(6,774)
Net income available to common shareholders	$ 461,410	$ 505,363	$ 1,376,128	$ 1,310,697
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	133,703	143,556	136,156	146,177
Less: Unvested stock-based compensation awards	(738)	(734)	(745)	(753)
Weighted-average shares outstanding	132,965	142,822	135,411	145,424
Basic earnings per common share	$ 3.47	$ 3.54	$ 10.16	$ 9.01

Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income available to common equity	$ 463,978	$ 507,961	$ 1,383,719	$ 1,317,471
Less: Income attributable to unvested stock-based compensation awards	(2,568)	(2,596)	(7,590)	(6,768)
Net income available to common shareholders	$ 461,410	$ 505,365	$ 1,376,129	$ 1,310,703
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	133,703	143,556	136,156	146,177
Less: Unvested stock-based compensation awards	(738)	(734)	(745)	(753)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	34	154	32	181
Adjusted weighted-average shares outstanding	132,999	142,976	135,443	145,605
Diluted earnings per common share	$ 3.47	$ 3.53	$ 10.16	$ 9.00

Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			$ (569,328)	$ (493,290)
Cumulative effect of change in accounting principle — equity securities, before tax				(22,795)
Unrealized holding gains (losses), net, before tax			237,615	(230,135)
Foreign currency translation adjustment, before tax			(2,663)	(1,783)
Unrealized gains (losses) on cash flow hedges, before tax			204,587	(26,522)
Total other comprehensive income (loss) before reclassifications, before tax			439,539	(258,440)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			2,524	2,519
(Gains) losses realized in net income, before tax			7	(18)
Accretion of net gain on terminated cash flow hedges, before tax			(93)	(83)
Net yield adjustment from cash flow hedges currently in effect, before tax			6,693	7,650
Amortization of prior service credit, before tax			(3,129)	(3,129)
Amortization of actuarial losses, before tax			15,559	32,225
Total other comprehensive income (loss), before tax			461,100	(219,276)
Ending balance, before tax	$ (108,228)	$ (735,361)	(108,228)	(735,361)
Beginning balance, tax			149,247	129,476
Cumulative effect of change in accounting principle — equity securities, tax				5,942
Unrealized holding gains (losses), net, tax			(62,432)	60,494
Foreign currency translation adjustment, tax			559	374
Unrealized gains (losses) on cash flow hedges, tax			(53,786)	6,972
Total other comprehensive income (loss) before reclassifications, tax			(115,659)	67,840
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, tax			(663)	(662)
(Gains) losses realized in net income, tax			(2)	4
Accretion of net gain on terminated cash flow hedges, tax			25	22
Net yield adjustment from cash flow hedges currently in effect, tax			(1,760)	(2,011)
Amortization of prior service credit, tax			823	823
Amortization of actuarial losses, tax			(4,091)	(8,472)
Total other comprehensive income (loss), tax			(121,327)	57,544
Ending balance, tax	27,920	192,962	27,920	192,962
Beginning balance, net of tax			(420,081)	(363,814)
Cumulative effect of change in accounting principle — equity securities				(16,853)
Unrealized holding gains (losses), net of tax			175,183	(169,641)
Foreign currency translation adjustment	(1,704)	(265)	(2,104)	(1,409)
Unrealized gains (losses) on cash flow hedges, net of tax			150,801	(19,550)
Total other comprehensive income (loss) before reclassifications, net of tax			323,880	(190,600)
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, net of tax			1,861	1,857
(Gains) losses realized in net income, net of tax			5	(14)
Accretion of net gain on terminated cash flow hedges, net of tax			(68)	(61)
Net yield adjustment from cash flow hedges currently in effect, net of tax			4,933	5,639
Amortization of prior service credit, net of tax			(2,306)	(2,306)
Amortization of actuarial losses, net of tax			11,468	23,753
Total other comprehensive income (loss)	32,650	(24,458)	339,773	(161,732)
Ending balance, net of tax	(80,308)	(542,399)	(80,308)	(542,399)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(200,107)	(59,957)
Cumulative effect of change in accounting principle — equity securities, before tax				(22,795)
Unrealized holding gains (losses), net, before tax			237,615	(230,135)
Total other comprehensive income (loss) before reclassifications, before tax			237,615	(230,135)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			2,524	2,519
(Gains) losses realized in net income, before tax			7	(18)
Total other comprehensive income (loss), before tax			240,146	(227,634)
Ending balance, before tax	40,039	(310,386)	40,039	(310,386)
Total other comprehensive income (loss)			177,049
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(354,502)	(413,168)
Amortization of prior service credit, before tax			(3,129)	(3,129)
Amortization of actuarial losses, before tax			15,559	32,225
Total other comprehensive income (loss), before tax			12,430	29,096
Ending balance, before tax	(342,072)	(384,072)	(342,072)	(384,072)
Total other comprehensive income (loss)			9,162
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(14,719)	(20,165)
Foreign currency translation adjustment, before tax			(2,663)	(1,783)
Unrealized gains (losses) on cash flow hedges, before tax			204,587	(26,522)
Total other comprehensive income (loss) before reclassifications, before tax			201,924	(28,305)
Accretion of net gain on terminated cash flow hedges, before tax			(93)	(83)
Net yield adjustment from cash flow hedges currently in effect, before tax			6,693	7,650
Total other comprehensive income (loss), before tax			208,524	(20,738)
Ending balance, before tax	$ 193,805	$ (40,903)	$ 193,805	$ (40,903)

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 15,691,827	$ 15,577,885	$ 15,460,191	$ 16,250,819
Net gain during period	32,650	(24,458)	339,773	(161,732)
Ending balance	15,779,811	15,436,085	15,779,811	15,436,085
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(147,526)
Net gain during period			177,049
Ending balance	29,523		29,523
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(261,303)
Net gain during period			9,162
Ending balance	(252,141)		(252,141)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(11,252)
Net gain during period			153,562
Ending balance	142,310		142,310
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(112,958)	(517,941)	(420,081)	(363,814)
Net gain during period			339,773
Ending balance	$ (80,308)	$ (542,399)	$ (80,308)	$ (542,399)

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 47,400,000,000		$ 47,400,000,000		$ 19,850,000,000
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	24,000,000		24,000,000		18,000,000
Aggregate fair value of derivative financial instruments in a liability position	70,000,000		70,000,000		21,000,000
Net liability positions with counterparties	70,000,000		70,000,000		21,000,000
Aggregate fair value of derivative financial instruments in asset position	639,000		639,000		18,000,000
Net fair value of derivative financial instruments in a net asset position	639,000		639,000		18,000,000
Collateral relating to net asset positions	81,000		81,000		16,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	68,000,000		68,000,000		18,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	129,000,000		129,000,000		65,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	(1,000,000)	$ (8,000,000)	(23,000,000)	$ (12,000,000)
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	47,600,000,000		47,600,000,000		42,900,000,000
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	843,000,000		843,000,000		$ 763,000,000
Credit Risk Derivative [Member]
Derivative [Line Items]
Fair value of additional collateral to be posted for derivative financial instruments	$ 0		$ 0

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount	$ 47,400,000,000	$ 19,850,000,000
Average Maturity (in years)	1 year 6 months	1 year 8 months 12 days
Estimated Fair Value Gain (Loss)	$ (6,142,000)	$ 5,530,000
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] \| Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 43,600,000,000	$ 15,400,000,000
Average Maturity (in years)	1 year 4 months 24 days	1 year 3 months 18 days
Weighted-Average Rate, Fixed	2.38%	1.52%
Weighted-Average Rate, Variable	2.06%	2.35%
Estimated Fair Value Gain (Loss)	$ (5,056,000)	$ 1,311,000
Fixed Rate Long-Term Borrowings [Member] \| Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 3,800,000,000	$ 4,450,000,000
Average Maturity (in years)	2 years 3 months 18 days	2 years 9 months 18 days
Weighted-Average Rate, Fixed	2.51%	2.47%
Weighted-Average Rate, Variable	2.55%	3.02%
Estimated Fair Value Gain (Loss)	$ (1,086,000)	$ 4,219,000

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 571,278	$ 148,862
Liability Derivatives, Fair Value	103,750	190,686
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	569,892	142,242
Liability Derivatives, Fair Value	95,633	184,252
Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,386	6,620
Liability Derivatives, Fair Value	8,117	6,434
Interest Rate Swap Agreements [Member] \| Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	47	5,530
Liability Derivatives, Fair Value	6,189
Commitments to Sell Real Estate Loans [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	2,079	3,702
Liability Derivatives, Fair Value	13,402	4,535
Commitments to Sell Real Estate Loans [Member] \| Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,339	1,090
Liability Derivatives, Fair Value	1,928	6,434
Mortgage-Related Commitments to Originate Real Estate Loans for Sale [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	24,463	9,304
Liability Derivatives, Fair Value	189	1,592
Interest Rate Contracts [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	532,070	118,687
Liability Derivatives, Fair Value	72,098	169,255
Foreign Exchange and Other Option and Futures Contracts [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	11,280	10,549
Liability Derivatives, Fair Value	$ 9,944	$ 8,870

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 9,033	$ (566)	$ 24,329	$ 139
Interest Rate Swap Agreements [Member] \| Fixed Rate Long-Term Borrowings [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member] \| Fair Value Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, Derivatives	22,582	(12,568)	113,441	(68,315)
Derivatives in fair value hedging relationships, Hedged item	(22,412)	12,607	(112,884)	68,861
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	6,435	(1,348)	17,639	(5,639)
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 2,598	$ 782	$ 6,690	$ 5,778

Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Variable Interest Entity Disclosure [Abstract]
Loss on securitization of assets			$ 0	$ 0
Other assets for its "investment" in the common securities recognized by the company of various trusts	$ 23,000,000		23,000,000		$ 23,000,000
Total assets of partnerships in which the company invested	1,400,000,000		1,400,000,000		1,100,000,000
Maximum exposure to loss of investments in real estate partnerships	803,000,000		803,000,000
Investment in partnership carrying amount	604,000,000		604,000,000		523,000,000
Unfunded commitments includes carrrying amount of its investments	390,000,000		390,000,000		$ 280,000,000
Investments amortized to income tax expense	17,000,000	$ 13,000,000	51,000,000	39,000,000
Federal tax credits and other federal tax benefits recognized	21,000,000	$ 15,000,000	62,000,000	$ 47,000,000
Material losses related to involvement with partnership entities	$ 0		$ 0

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 6,985,417	$ 8,682,509
U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	359,394	1,336,931
Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	934	1,659
Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,494,900	7,216,991
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	130,173	126,906
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	614,256	185,584
Investment securities	6,985,417	8,682,509
Equity securities	150,104	93,917
Real estate loans held for sale	588,233	551,697
Other assets	27,928	19,626
Total assets	8,365,938	9,533,333
Trading account liabilities	82,042	178,125
Other liabilities	21,708	12,561
Total liabilities	103,750	190,686
Fair Value Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	48,724	46,018
Equity securities	104,199	71,989
Total assets	152,923	118,007
Fair Value Measurements, Recurring [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	565,532	139,566
Investment securities	6,985,401	8,682,487
Equity securities	45,905	21,928
Real estate loans held for sale	588,233	551,697
Other assets	3,465	10,322
Total assets	8,188,536	9,406,000
Trading account liabilities	82,042	178,125
Other liabilities	21,519	10,969
Total liabilities	103,561	189,094
Fair Value Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	22
Other assets	24,463	9,304
Total assets	24,479	9,326
Other liabilities	189	1,592
Total liabilities	189	1,592
Fair Value Measurements, Recurring [Member] \| U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	359,394	1,336,931
Fair Value Measurements, Recurring [Member] \| U.S. Treasury and Federal Agencies [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	359,394	1,336,931
Fair Value Measurements, Recurring [Member] \| Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	934	1,659
Fair Value Measurements, Recurring [Member] \| Obligations of States and Political Subdivisions [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	934	1,659
Fair Value Measurements, Recurring [Member] \| Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,494,900	7,216,991
Fair Value Measurements, Recurring [Member] \| Government Issued or Guaranteed [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,494,900	7,216,991
Fair Value Measurements, Recurring [Member] \| Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	22
Fair Value Measurements, Recurring [Member] \| Privately Issued Mortgage-Backed Securities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	22
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	130,173	126,906
Fair Value Measurements, Recurring [Member] \| Other Debt Securities [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 130,173	$ 126,906

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Parenthetical) (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Transfer of asset from level 1 to 2	$ 0	$ 0
Transfer of asset from level 2 to 1	0	0
Transfer of liabilities from level 1 to 2	0	0
Transfer of liabilities from level 2 to 1	$ 0	$ 0

Fair Value Measurements - Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - Fair Value Measurements, Recurring [Member] - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 16	$ 24	$ 22	$ 28
Total gains realized/unrealized:
Settlements		(1)	(6)	(5)
Ending Balance	16	23	16	23
Other Assets and Other Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	17,200	10,751	7,712	8,303
Total gains realized/unrealized:
Included in earnings	62,178	10,284	115,187	38,691
Transfers out of Level 3	(55,104)	(16,849)	(98,625)	(42,808)
Ending Balance	24,274	4,186	24,274	4,186
Changes in unrealized gains included in earnings related to assets still held at end of period	$ 19,350	$ 4,508	$ 24,981	$ 3,663

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input [Extensible List]	us-gaap:MeasurementInputComparabilityAdjustmentMember		us-gaap:MeasurementInputComparabilityAdjustmentMember
Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations			15.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations			85.00%
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value of nonrecurring fair value measured loans for charge-offs and impairment reserves	$ 51,000,000	$ 35,000,000	$ 85,000,000	$ 69,000,000
Capitalized servicing rights	193,000,000	0	193,000,000	0	$ 0
Capitalized servicing rights, valuation allowance			23,000,000	0	0
Changes in fair value recognized for impairment of capitalized servicing rights	14,000,000		23,000,000		0
Fair Value, Measurements, Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	302,000,000	292,000,000	302,000,000	292,000,000	268,000,000
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	17,000,000	32,000,000	17,000,000	32,000,000
Fair Value, Measurements, Nonrecurring [Member] \| Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	122,000,000	128,000,000	122,000,000	128,000,000	120,000,000
Fair Value, Measurements, Nonrecurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	$ 180,000,000	$ 164,000,000	$ 180,000,000	$ 164,000,000	$ 148,000,000

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Privately Issued Mortgage-Backed Securities [Member] \| Two Independent Pricing Quotes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements for certain Level 3 Assets and Liabilities	$ 16	$ 22
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements for certain Level 3 Assets and Liabilities	$ 24,274	$ 7,712
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member] \| Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member] \| Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	96.00%	95.00%
Other Assets and Other Liabilities [Member] \| Discounted Cash Flows [Member] \| Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	11.00%	13.00%

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Financial assets:
Interest-bearing deposits at banks	$ 12,495,524		$ 8,105,197
Federal funds sold	200
Investment securities	10,677,583		12,692,813
Loans and leases:
Allowance for credit losses	(1,038,437)	$ (1,029,867)	(1,019,444)	$ (1,019,488)	$ (1,019,248)	$ (1,017,198)
Loans and leases, net	88,784,756		87,447,033
Financial liabilities:
Noninterest-bearing deposits	(31,766,724)		(32,256,668)
Savings and interest-checking deposits	(55,581,533)		(50,963,744)
Time deposits	(6,203,679)		(6,124,254)
Deposits at Cayman Islands office	(1,561,997)		(811,906)
Long-term borrowings	(7,002,524)		(8,444,914)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,818,861		1,605,439
Interest-bearing deposits at banks	12,495,524		8,105,197
Federal funds sold	200
Trading account assets	614,256		185,584
Investment securities	10,677,583		12,692,813
Loans and leases:
Consumer loans	15,175,635		13,970,499
Allowance for credit losses	(1,038,437)		(1,019,444)
Loans and leases, net	88,784,756		87,447,033
Accrued interest receivable	340,543		353,965
Financial liabilities:
Noninterest-bearing deposits	(31,766,724)		(32,256,668)
Savings and interest-checking deposits	(55,581,533)		(50,963,744)
Time deposits	(6,203,679)		(6,124,254)
Deposits at Cayman Islands office	(1,561,997)		(811,906)
Short-term borrowings	(5,513,896)		(4,398,378)
Long-term borrowings	(7,002,524)		(8,444,914)
Accrued interest payable	(90,623)		(95,274)
Trading account liabilities	(82,042)		(178,125)
Other financial instruments:
Commitments to originate real estate loans for sale	24,274		7,712
Commitments to sell real estate loans	(11,912)		(6,177)
Other credit-related commitments	(130,413)		(131,688)
Interest rate swap agreements used for interest rate risk management	(6,142)		5,530
Carrying Amount [Member] \| Commercial Loans And Leases
Loans and leases:
Commercial loans and leases	23,201,372		22,977,976
Commercial real estate loans	23,201,372		22,977,976
Carrying Amount [Member] \| Commercial [Member]
Loans and leases:
Commercial loans and leases	34,945,231		34,363,556
Commercial real estate loans	34,945,231		34,363,556
Carrying Amount [Member] \| Residential Real Estate Loans
Loans and leases:
Commercial loans and leases	16,500,955		17,154,446
Commercial real estate loans	16,500,955		17,154,446
Estimate Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,818,861		1,605,439
Interest-bearing deposits at banks	12,495,524		8,105,197
Federal funds sold	200
Trading account assets	614,256		185,584
Investment securities	10,721,588		12,631,656
Loans and leases:
Consumer loans	15,157,025		13,819,545
Loans and leases, net	89,350,881		87,214,035
Accrued interest receivable	340,543		353,965
Financial liabilities:
Noninterest-bearing deposits	(31,766,724)		(32,256,668)
Savings and interest-checking deposits	(55,581,533)		(50,963,744)
Time deposits	(6,289,534)		(6,201,957)
Deposits at Cayman Islands office	(1,561,997)		(811,906)
Short-term borrowings	(5,513,896)		(4,398,378)
Long-term borrowings	(7,056,344)		(8,385,289)
Accrued interest payable	(90,623)		(95,274)
Trading account liabilities	(82,042)		(178,125)
Other financial instruments:
Commitments to originate real estate loans for sale	24,274		7,712
Commitments to sell real estate loans	(11,912)		(6,177)
Other credit-related commitments	(130,413)		(131,688)
Interest rate swap agreements used for interest rate risk management	(6,142)		5,530
Estimate Fair Value [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,765,090		1,528,302
Trading account assets	48,724		46,018
Investment securities	104,199		71,989
Estimate Fair Value [Member] \| Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	53,771		77,137
Interest-bearing deposits at banks	12,495,524		8,105,197
Federal funds sold	200
Trading account assets	565,532		139,566
Investment securities	10,525,863		12,456,467
Loans and leases:
Loans and leases, net	4,219,026		4,267,222
Accrued interest receivable	340,543		353,965
Financial liabilities:
Noninterest-bearing deposits	(31,766,724)		(32,256,668)
Savings and interest-checking deposits	(55,581,533)		(50,963,744)
Time deposits	(6,289,534)		(6,201,957)
Deposits at Cayman Islands office	(1,561,997)		(811,906)
Short-term borrowings	(5,513,896)		(4,398,378)
Long-term borrowings	(7,056,344)		(8,385,289)
Accrued interest payable	(90,623)		(95,274)
Trading account liabilities	(82,042)		(178,125)
Other financial instruments:
Commitments to sell real estate loans	(11,912)		(6,177)
Interest rate swap agreements used for interest rate risk management	(6,142)		5,530
Estimate Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	91,526		103,200
Loans and leases:
Consumer loans	15,157,025		13,819,545
Loans and leases, net	85,131,855		82,946,813
Other financial instruments:
Commitments to originate real estate loans for sale	24,274		7,712
Other credit-related commitments	(130,413)		(131,688)
Estimate Fair Value [Member] \| Commercial Loans And Leases
Loans and leases:
Commercial loans and leases	22,844,883		22,587,387
Commercial real estate loans	22,844,883		22,587,387
Estimate Fair Value [Member] \| Commercial Loans And Leases \| Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	22,844,883		22,587,387
Commercial real estate loans	22,844,883		22,587,387
Estimate Fair Value [Member] \| Commercial [Member]
Loans and leases:
Commercial loans and leases	34,772,982		33,832,558
Commercial real estate loans	34,772,982		33,832,558
Estimate Fair Value [Member] \| Commercial [Member] \| Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Commercial loans and leases	197,141		346,775
Commercial real estate loans	197,141		346,775
Estimate Fair Value [Member] \| Commercial [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	34,575,841		33,485,783
Commercial real estate loans	34,575,841		33,485,783
Estimate Fair Value [Member] \| Residential Real Estate Loans
Loans and leases:
Commercial loans and leases	16,575,991		16,974,545
Commercial real estate loans	16,575,991		16,974,545
Estimate Fair Value [Member] \| Residential Real Estate Loans \| Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Commercial loans and leases	4,021,885		3,920,447
Commercial real estate loans	4,021,885		3,920,447
Estimate Fair Value [Member] \| Residential Real Estate Loans \| Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	12,554,106		13,054,098
Commercial real estate loans	$ 12,554,106		$ 13,054,098

Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Commitments to extend credit
Home equity lines of credit	$ 5,451,328	$ 5,484,197
Commercial real estate loans to be sold	393,397	229,401
Other commercial real estate	8,222,395	7,556,722
Residential real estate loans to be sold	530,093	245,211
Other residential real estate	511,854	219,351
Commercial and other	16,313,801	14,363,803
Standby letters of credit	2,373,846	2,326,991
Commercial letters of credit	38,633	55,808
Financial guarantees and indemnification contracts	3,996,029	3,529,136
Commitments to sell real estate loans	$ 1,350,292	$ 940,692

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers				$ 8,900,000,000	$ 8,600,000,000
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program				3,800,000,000	$ 3,400,000,000
Payment of legal settlement expense		$ 200,000,000
Legal expenses	$ 50,000,000		$ 135,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses				0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses				$ 50,000,000

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net Income (Loss)	$ 480,081	$ 526,091	$ 1,436,083	$ 1,371,861
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,557,669	1,488,332	4,662,070	4,388,746
Business Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	46,147	43,730	131,668	124,455
Business Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	143,741	138,898	423,830	402,811
Business Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	912	920	2,772	2,750
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	132,668	147,910	388,393	399,766
Commercial Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	282,757	280,671	828,357	816,566
Commercial Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	980	875	2,707	2,653
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	131,161	116,386	370,288	337,380
Commercial Real Estate [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	238,364	214,266	682,979	622,414
Commercial Real Estate [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	458	371	1,218	1,096
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	29,604	39,723	106,816	88,575
Discretionary Portfolio [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	50,871	53,061	175,764	162,075
Discretionary Portfolio [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(10,550)	(10,270)	(29,140)	(31,656)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	15,846	13,289	36,429	43,637
Residential Mortgage Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	115,239	79,603	295,449	244,228
Residential Mortgage Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	19,363	15,402	51,027	46,870
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	131,638	141,612	417,198	408,081
Retail Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	432,339	427,452	1,299,823	1,241,468
Retail Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,808	2,862	7,106	8,434
All Other [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	(6,983)	23,441	(14,709)	(30,033)
All Other [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	294,358	294,381	955,868	899,184
All Other [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ (12,971)	$ (10,160)	$ (35,690)	$ (30,147)

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 7,002,524,000		$ 7,002,524,000		$ 8,444,914,000
Bayview Lending Group [Member]
Schedule of Equity Method Investments [Line Items]
Minority interest in Bayview Lending Group LLC	20.00%		20.00%
Carrying value of minority interest investment in Bayview Lending Group LLC	$ 0		$ 0
Bayview Lending Group [Member] \| Other Revenues From Operations [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	0	$ 0	37,000,000	$ 24,000,000
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	2,300,000,000		2,300,000,000		2,500,000,000
Revenue from contract with customer	3,000,000	4,000,000	9,000,000	11,000,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	65,100,000,000		65,100,000,000		56,800,000,000
Revenues from sub-servicing	33,000,000	$ 28,000,000	90,000,000	$ 86,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	100,000,000		100,000,000		$ 113,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	714,000,000		714,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member] \| M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 90,000,000		$ 90,000,000

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Recognized right of use asset	$ 392,324
Recognizing lease liabilities	$ 424,854
ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lessee, operating lease term	12 months
Recognized right of use asset		$ 394,000
Recognizing lease liabilities		$ 399,000

Significant accounting policies (Policies)	9 Months Ended
Significant accounting policies (Policies)	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Accounting	The consolidated interim financial statements of M&T Bank Corporation (“M&T”) and subsidiaries (“the Company”) were compiled in accordance with generally accepted accounting principles (“GAAP”) using the accounting policies set forth in note 1 of Notes to Financial Statements included in Form 10-K for the year ended December 31, 2018 (“2018 Annual Report”), except that effective January 1, 2019 the Company adopted accounting guidance that is discussed in notes 3, 4 and 17 herein. The financial statements contain all adjustments which are, in the opinion of management, necessary for a fair statement of the Company’s financial position, results of operations and cash flows for the interim periods presented.

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ (17.2)	$ (170.7)
Reduction in estimated fair value of interest rate contracts in liability position	$ (390.6)	$ (49.7)

Loans and Leases and the Allowance for Credit Losses - Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 869,636	$ 1,016,785
Carrying amount	620,979	727,491
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	22,829	27,073
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	110,430	135,047
Residential Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	398,563	473,511
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 89,157	$ 91,860

Operating Leases - Additional Information (Detail)	9 Months Ended
Operating Leases - Additional Information (Detail)	Sep. 30, 2019
Leases [Abstract]
Period of noncancelable operating lease in years	22 years

Revenue from Contracts with Customers - Additional Information (Detail1)	Sep. 30, 2019
Maximum [Member] \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01
Disaggregation Of Revenue [Line Items]
Period of satisfaction of contract with customer	1 year

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Uncollected amounts receivable	$ 59	$ 56
Accrued interest and other liabilities [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue	$ 43	$ 43

Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Segment Reporting Information [Line Items]
Average Total Assets	$ 118,584	$ 116,959	$ 116,676
Business Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	5,758	5,631	5,637
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	28,089	26,626	26,524
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average Total Assets	23,893	22,885	22,899
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Average Total Assets	29,355	32,123	32,659
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	2,444	2,161	2,123
Retail Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	14,839	13,656	13,522
All Other [Member]
Segment Reporting Information [Line Items]
Average Total Assets	$ 14,206	$ 13,877	$ 13,312