0001564590-19-028777 | 10-Q | XBRL Viewer

Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2019

Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis

The following tables present assets and liabilities at June 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)
June 30, 2019
Trading account assets	$	479,403	$	47,344	$	432,059	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		429,813		—		429,813		—
Obligations of states and political subdivisions		1,015		—		1,015		—
Mortgage-backed securities:
Government issued or guaranteed		6,818,333		—		6,818,333		—
Privately issued		16		—		—		16
Other debt securities		131,163		—		131,163		—
		7,380,340		—		7,380,324		16
Equity securities		151,801		109,377		42,424		—
Real estate loans held for sale		797,474		—		797,474		—
Other assets (b)		18,661		—		1,250		17,411
Total assets	$	8,827,679	$	156,721	$	8,653,531	$	17,427
Trading account liabilities	$	73,392	$	—	$	73,392	$	—
Other liabilities (b)		30,688		—		30,477		211
Total liabilities	$	104,080	$	—	$	103,869	$	211

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 six months ended June 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 June 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 — March 31 , 2019	$	16		7,433
Total gains realized/unrealized:
Included in earnings		—		36,463		(b)
Settlements		—		—
Transfers out of Level 3 (a)		—		(26,696	)	(c)
Balance — June 30, 2019	$	16		17,200
Changes in unrealized gains included in earnings related to assets still held at June 30, 2019	$	—		17,464		(b)

2018

Balance — March 31 , 2018	$	27		8,760
Total gains realized/unrealized:
Included in earnings		—		20,277		(b)
Settlements		(3	)	—
Transfers out of Level 3 (a)		—		(18,286	)	(c)
Balance — June 30, 2018	$	24		10,751
Changes in unrealized gains included in earnings related to assets still held at June 30, 2018	$	—		10,686		(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		—			53,009		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(43,521	)	(c)
Balance — June 30, 2019	$	16			17,200
Changes in unrealized gains included in earnings related to assets still held at June 30, 2019	$	—			17,372		(b)

2018

Balance — January 1, 2018	$	28		8,303
Total gains realized/unrealized:
Included in earnings		—		28,407		(b)
Settlements		(4	)	—
Transfers out of Level 3 (a)		—		(25,959	)	(c)
Balance — June 30, 2018	$	24		10,751
Changes in unrealized gains included in earnings related to assets still held at June 30, 2018	$	—		10,686		(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

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

Fair Value

Valuation

Technique

Unobservable

Inputs/Assumptions

Range

(Weighted-

Average)

(In thousands)

June 30, 2019

Recurring fair value measurements

Privately issued mortgage-backed

securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

17,200

Discounted cash flow

Commitment expirations

0%-98% (16%)

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:

	June 30, 2019
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
	(In thousands)
Financial assets:
Cash and cash equivalents	$	1,271,611			1,271,611			1,214,826		56,785			—
Interest-bearing deposits at banks		8,791,753			8,791,753			—		8,791,753			—
Trading account assets		479,403			479,403			47,344		432,059			—
Investment securities		11,580,249			11,606,174			109,377		11,400,933			95,864
Loans and leases:
Commercial loans and leases		23,431,408			23,095,155			—		—			23,095,155
Commercial real estate loans		35,194,375			34,932,104			—		503,599			34,428,505
Residential real estate loans		16,693,737			16,734,846			—		3,965,011			12,769,835
Consumer loans		14,558,538			14,537,432			—		—			14,537,432
Allowance for credit losses		(1,029,867	)		—			—		—			—
Loans and leases, net		88,848,191			89,299,537			—		4,468,610			84,830,927
Accrued interest receivable		362,012			362,012			—		362,012			—
Financial liabilities:
Noninterest-bearing deposits	$	(30,747,946	)		(30,747,946	)		—		(30,747,946	)		—
Savings and interest-checking deposits		(53,221,672	)		(53,221,672	)		—		(53,221,672	)		—
Time deposits		(6,346,551	)		(6,447,027	)		—		(6,447,027	)		—
Deposits at Cayman Islands office		(1,364,855	)		(1,364,855	)		—		(1,364,855	)		—
Short-term borrowings		(4,611,390	)		(4,611,390	)		—		(4,611,390	)		—
Long-term borrowings		(7,655,507	)		(7,703,957	)		—		(7,703,957	)		—
Accrued interest payable		(108,971	)		(108,971	)		—		(108,971	)		—
Trading account liabilities		(73,392	)		(73,392)			—		(73,392	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	17,200			17,200			—		—			17,200
Commitments to sell real estate loans		(23,447	)		(23,447	)		—		(23,447	)		—
Other credit-related commitments		(127,699	)		(127,699	)		—		—			(127,699	)
Interest rate swap agreements used for interest rate risk management		(5,780	)		(5,780	)		—		(5,780	)		—

	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			—

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Assets
Cash and due from banks	$ 1,271,611	$ 1,605,439
Interest-bearing deposits at banks	8,791,753	8,105,197
Trading account	479,403	185,584
Investment securities (includes pledged securities that can be sold or repledged of $167,935 at June 30, 2019; $487,365 at December 31, 2018)
Available for sale (cost: $7,359,445 at June 30, 2019; $8,869,423 at December 31, 2018)	7,380,340	8,682,509
Held to maturity (fair value: $3,630,158 at June 30, 2019; $3,255,483 at December 31, 2018)	3,604,233	3,316,640
Equity and other securities (cost: $558,440 at June 30, 2019; $677,187 at December 31, 2018)	595,676	693,664
Total investment securities	11,580,249	12,692,813
Loans and leases	90,142,482	88,733,492
Unearned discount	(264,424)	(267,015)
Loans and leases, net of unearned discount	89,878,058	88,466,477
Allowance for credit losses	(1,029,867)	(1,019,444)
Loans and leases, net	88,848,191	87,447,033
Premises and equipment	1,066,511	647,408
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	38,428	47,067
Accrued interest and other assets	4,885,637	4,773,750
Total assets	121,554,895	120,097,403
Liabilities
Noninterest-bearing deposits	30,747,946	32,256,668
Savings and interest-checking deposits	53,221,672	50,963,744
Time deposits	6,346,551	6,124,254
Deposits at Cayman Islands office	1,364,855	811,906
Total deposits	91,681,024	90,156,572
Short-term borrowings	4,611,390	4,398,378
Accrued interest and other liabilities	1,915,147	1,637,348
Long-term borrowings	7,655,507	8,444,914
Total liabilities	105,863,068	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: 731,500 shares at June 30, 2019 and December 31, 2018; Liquidation preference of $10,000 per share: 50,000 shares at June 30, 2019 and December 31, 2018	1,231,500	1,231,500
Common stock, $.50 par, 250,000,000 shares authorized, 159,741,898 shares issued at June 30, 2019; 159,765,044 shares issued at December 31, 2018	79,871	79,883
Common stock issuable, 21,327 shares at June 30, 2019; 24,563 shares at December 31, 2018	1,526	1,726
Additional paid-in capital	6,577,603	6,579,342
Retained earnings	12,162,278	11,516,672
Accumulated other comprehensive income (loss), net	(112,958)	(420,081)
Treasury stock — common, at cost — 25,563,347 shares at June 30, 2019; 21,255,275 shares at December 31, 2018	(4,247,993)	(3,528,851)
Total shareholders’ equity	15,691,827	15,460,191
Total liabilities and shareholders’ equity	$ 121,554,895	$ 120,097,403

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Partners Capital [Abstract]
Net income	$ 473,260	$ 493,160	$ 956,002	$ 845,770
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	69,853	(36,733)	154,444	(137,417)
Cash flow hedges adjustments	102,050	(2,569)	146,971	(13,011)
Foreign currency translation adjustment	(675)	(2,434)	(400)	(1,144)
Defined benefit plans liability adjustments	3,823	7,038	6,108	14,298
Total other comprehensive income (loss)	175,051	(34,698)	307,123	(137,274)
Total comprehensive income	$ 648,311	$ 458,462	$ 1,263,125	$ 708,496

- Definition

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

+ References + Details

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	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 89,878,058	$ 88,466,477
Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	803,979	796,451
Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	88,811,054	87,366,721
Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	263,025	303,305
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,431,408	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	265,907	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	23,165,499	22,718,991
Commercial, Financial, Leasing, etc. [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	2
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	35,194,375	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	258,854	254,476
Commercial Real Estate [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	34,921,561	34,098,670
Commercial Real Estate [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	13,960	10,410
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,693,737	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	217,874	220,140
Residential Real Estate [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,226,800	16,641,411
Residential Real Estate [Member] \| Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	249,063	292,895
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	14,558,538	13,970,499
Consumer Loans [Member] \| Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	61,344	62,850
Consumer Loans [Member] \| Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 14,497,194	$ 13,907,649

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Parenthetical) (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount	$ 39,200,000,000	$ 19,850,000,000
Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	21,400,000,000	12,600,000,000
Fair Value Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value gains (loss) on hedging instruments	41,600,000	(54,700,000)
Cash Flow Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value gains (loss) on hedging instruments	$ 196,200,000	$ (9,100,000)

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Preferred Series A [Member]
Preferred stock per share dividend amount	$ 15.9375	$ 15.9375	$ 31.875	$ 31.875
Preferred Series C [Member]
Preferred stock per share dividend amount	15.9375	15.9375	31.875	31.875
Preferred Series E [Member]
Preferred stock per share dividend amount	16.125	16.125	32.25	32.25
Series F Preferred Stock [Member]
Preferred stock per share dividend amount	128.125	128.125	256.25	256.25
Retained Earnings [Member]
Common stock per share dividend amount	$ 1.00	$ 0.80	$ 2.00	$ 1.55
Treasury Stock [Member] \| Series A Warrants [Member]
Exercise of warrants into shares of common stock		17,252		54,226
Exercise of warrants into shares of common stock		10,115		32,668

Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income available to common equity	$ 455,130	$ 475,030	$ 919,742	$ 809,510
Less: Income attributable to unvested stock-based compensation awards	(2,497)	(2,430)	(5,023)	(4,168)
Net income available to common shareholders	$ 452,633	$ 472,600	$ 914,719	$ 805,342
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	136,182	145,571	137,403	147,510
Less: Unvested stock-based compensation awards	(749)	(746)	(749)	(764)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	31	173	31	195
Adjusted weighted-average shares outstanding	135,464	144,998	136,685	146,941
Diluted earnings per common share	$ 3.34	$ 3.26	$ 6.69	$ 5.48

Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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	1,100,000,000		1,100,000,000		1,100,000,000
Maximum exposure to loss of investments in real estate partnerships	573,000,000		573,000,000		523,000,000
Unfunded commitments included in company's maximum exposure to loss of investments in real estate partnerships	267,000,000		267,000,000		$ 280,000,000
Investments amortized to income tax expense	17,000,000	$ 13,000,000	34,000,000	26,000,000
Federal tax credits and other federal tax benefits recognized	21,000,000	$ 16,000,000	41,000,000	$ 32,000,000
Material losses related to involvement with partnership entities	$ 0		$ 0

- Definition

A gain (loss) realized on a transfer, accounted for as a sale, of all or a portion of financial assets in which the transferor surrenders control and receives consideration other than a beneficial interest in the assets transferred. Reflects the amount of sales proceeds in excess of, or deficient from, the sum of the carrying amounts of transferred financial assets plus transaction costs.

+ References + Details

Loans and Leases and the Allowance for Credit Losses - Interest Income Recognized on Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	$ 801,024	$ 729,881	$ 800,947	$ 737,845
Interest income recognized, Total	10,274	9,700	19,191	19,671
Interest income recognized, Cash basis	7,012	6,540	12,783	13,860
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	214,775	168,224	220,075	175,035
Interest income recognized, Total	2,032	3,811	3,123	6,958
Interest income recognized, Cash basis	2,032	3,811	3,123	6,958
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	273,924	271,413	269,586	271,793
Interest income recognized, Total	3,627	1,333	6,665	2,116
Interest income recognized, Cash basis	3,627	1,333	6,665	2,116
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	9,590	8,494	9,233	9,167
Interest income recognized, Total	35		150	1,682
Interest income recognized, Cash basis	35		150	1,682
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	22,521	7,443	21,460	8,773
Interest income recognized, Total	12	53	576	59
Interest income recognized, Cash basis	12	53	576	59
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	142,555	126,185	141,479	123,697
Interest income recognized, Total	2,390	2,329	4,412	4,231
Interest income recognized, Cash basis	1,004	937	1,670	1,839
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	75,940	83,776	77,089	84,686
Interest income recognized, Total	1,452	1,428	2,805	3,156
Interest income recognized, Cash basis	218	317	426	1,013
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	47,435	48,644	47,496	48,721
Interest income recognized, Total	406	433	822	847
Interest income recognized, Cash basis	57	72	119	158
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	5,808	1,480	5,917	1,469
Interest income recognized, Total	125	65	267	128
Interest income recognized, Cash basis	4	3	8	5
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	3,450	12,636	3,490	12,881
Interest income recognized, Total	53	225	107	449
Interest income recognized, Cash basis	18	14	37	29
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	5,026	1,586	5,122	1,623
Interest income recognized, Total	142	$ 23	264	45
Interest income recognized, Cash basis	$ 5		$ 9	$ 1

Pension plans and other postretirement benefits

6 Months Ended

Jun. 30, 2019

Compensation And Retirement Disclosure [Abstract]

Pension plans and other postretirement benefits

7. 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 June 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	4,559			5,069			229		243
Interest cost on projected benefit obligation		20,590			18,548			569			589
Expected return on plan assets		(30,470	)		(30,688	)		—			—
Amortization of prior service cost (credit)		154			153			(1,190	)		(1,189	)
Amortization of net actuarial loss (gain)		6,546			10,796			(323	)		(213	)
Net periodic cost (benefit)	$	1,379			3,878			(715	)		(570	)

	Pension Benefits						Other Postretirement Benefits
	Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	8,646			10,172			429			469
Interest cost on projected benefit obligation		40,790			37,353			1,172			1,146
Expected return on plan assets		(61,070	)		(61,563	)		—			—
Amortization of prior service cost (credit)		279			278			(2,365	)		(2,364	)
Amortization of net actuarial loss (gain)		10,996			21,896			(623	)		(413	)
Net periodic cost (benefit)	$	(359	)		8,136			(1,387	)		(1,162	)

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 $19 million and $17 million for the three months ended June 30, 2019 and 2018, respectively, and $41 million and $38 million for the six months ended June 30, 2019 and 2018, respectively, and are included in salaries and employee benefits expense.

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Defined contribution pension and retirement savings plans total expense	$ 19	$ 17	$ 41	$ 38

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Financial assets:
Interest-bearing deposits at banks	$ 8,791,753		$ 8,105,197
Trading account assets	479,403		185,584
Investment securities	11,580,249		12,692,813
Loans and leases:
Allowance for credit losses	(1,029,867)	$ (1,019,337)	(1,019,444)	$ (1,019,248)	$ (1,019,671)	$ (1,017,198)
Loans and leases, net	88,848,191		87,447,033
Financial liabilities:
Noninterest-bearing deposits	(30,747,946)		(32,256,668)
Savings and interest-checking deposits	(53,221,672)		(50,963,744)
Time deposits	(6,346,551)		(6,124,254)
Deposits at Cayman Islands office	(1,364,855)		(811,906)
Long-term borrowings	(7,655,507)		(8,444,914)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,271,611		1,605,439
Interest-bearing deposits at banks	8,791,753		8,105,197
Trading account assets	479,403		185,584
Investment securities	11,580,249		12,692,813
Loans and leases:
Commercial loans and leases	23,431,408		22,977,976
Commercial real estate loans	35,194,375		34,363,556
Residential real estate loans	16,693,737		17,154,446
Consumer loans	14,558,538		13,970,499
Allowance for credit losses	(1,029,867)		(1,019,444)
Loans and leases, net	88,848,191		87,447,033
Accrued interest receivable	362,012		353,965
Financial liabilities:
Noninterest-bearing deposits	(30,747,946)		(32,256,668)
Savings and interest-checking deposits	(53,221,672)		(50,963,744)
Time deposits	(6,346,551)		(6,124,254)
Deposits at Cayman Islands office	(1,364,855)		(811,906)
Short-term borrowings	(4,611,390)		(4,398,378)
Long-term borrowings	(7,655,507)		(8,444,914)
Accrued interest payable	(108,971)		(95,274)
Trading account liabilities	(73,392)		(178,125)
Other financial instruments:
Commitments to originate real estate loans for sale	17,200		7,712
Commitments to sell real estate loans	(23,447)		(6,177)
Other credit-related commitments	(127,699)		(131,688)
Interest rate swap agreements used for interest rate risk management	(5,780)		5,530
Estimate Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,271,611		1,605,439
Interest-bearing deposits at banks	8,791,753		8,105,197
Trading account assets	479,403		185,584
Investment securities	11,606,174		12,631,656
Loans and leases:
Commercial loans and leases	23,095,155		22,587,387
Commercial real estate loans	34,932,104		33,832,558
Residential real estate loans	16,734,846		16,974,545
Consumer loans	14,537,432		13,819,545
Loans and leases, net	89,299,537		87,214,035
Accrued interest receivable	362,012		353,965
Financial liabilities:
Noninterest-bearing deposits	(30,747,946)		(32,256,668)
Savings and interest-checking deposits	(53,221,672)		(50,963,744)
Time deposits	(6,447,027)		(6,201,957)
Deposits at Cayman Islands office	(1,364,855)		(811,906)
Short-term borrowings	(4,611,390)		(4,398,378)
Long-term borrowings	(7,703,957)		(8,385,289)
Accrued interest payable	(108,971)		(95,274)
Trading account liabilities	(73,392)		(178,125)
Other financial instruments:
Commitments to originate real estate loans for sale	17,200		7,712
Commitments to sell real estate loans	(23,447)		(6,177)
Other credit-related commitments	(127,699)		(131,688)
Interest rate swap agreements used for interest rate risk management	(5,780)		5,530
Estimate Fair Value [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,214,826		1,528,302
Trading account assets	47,344		46,018
Investment securities	109,377		71,989
Estimate Fair Value [Member] \| Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	56,785		77,137
Interest-bearing deposits at banks	8,791,753		8,105,197
Trading account assets	432,059		139,566
Investment securities	11,400,933		12,456,467
Loans and leases:
Commercial real estate loans	503,599		346,775
Residential real estate loans	3,965,011		3,920,447
Loans and leases, net	4,468,610		4,267,222
Accrued interest receivable	362,012		353,965
Financial liabilities:
Noninterest-bearing deposits	(30,747,946)		(32,256,668)
Savings and interest-checking deposits	(53,221,672)		(50,963,744)
Time deposits	(6,447,027)		(6,201,957)
Deposits at Cayman Islands office	(1,364,855)		(811,906)
Short-term borrowings	(4,611,390)		(4,398,378)
Long-term borrowings	(7,703,957)		(8,385,289)
Accrued interest payable	(108,971)		(95,274)
Trading account liabilities	(73,392)		(178,125)
Other financial instruments:
Commitments to sell real estate loans	(23,447)		(6,177)
Interest rate swap agreements used for interest rate risk management	(5,780)		5,530
Estimate Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	95,864		103,200
Loans and leases:
Commercial loans and leases	23,095,155		22,587,387
Commercial real estate loans	34,428,505		33,485,783
Residential real estate loans	12,769,835		13,054,098
Consumer loans	14,537,432		13,819,545
Loans and leases, net	84,830,927		82,946,813
Other financial instruments:
Commitments to originate real estate loans for sale	17,200		7,712
Other credit-related commitments	$ (127,699)		$ (131,688)

Segment Information - Summary of Segment Information (Parenthetical) (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting [Abstract]
Taxable-equivalent adjustment	$ 5,925,000	$ 5,397,000	$ 11,892,000	$ 10,206,000

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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 16	$ 27	$ 22	$ 28
Total gains realized/unrealized:
Settlements		(3)	(6)	(4)
Ending Balance	16	24	16	24
Other Assets and Other Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	7,433	8,760	7,712	8,303
Total gains realized/unrealized:
Included in earnings	36,463	20,277	53,009	28,407
Transfers out of Level 3	(26,696)	(18,286)	(43,521)	(25,959)
Ending Balance	17,200	10,751	17,200	10,751
Changes in unrealized gains included in earnings related to assets still held at end of period	$ 17,464	$ 10,686	$ 17,372	$ 10,686

Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) Modification	Jun. 30, 2018 USD ($) Modification	Jun. 30, 2019 USD ($) Modification	Jun. 30, 2018 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	93	137	225	287
Pre-modification Recorded Investment	$ 23,577	$ 58,013	$ 70,114	$ 128,015
Post- modification	$ 23,958	$ 58,909	$ 70,249	$ 131,531
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	14	28	29	48
Pre-modification Recorded Investment	$ 10,340	$ 7,200	$ 19,581	$ 13,980
Post- modification	10,218	7,945	19,172	14,696
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	7,669	20,384	18,593	70,040
Principal Deferral [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	2,577	7,376	3,564	13,200
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		204		828
Interest Rate Reduction [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		175		175
Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		6,505		6,505
Other [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		394		394
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	16,289	$ 31,816	51,656	54,158
Combination of Concession Types [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 7,641		$ 15,608	$ 927
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	24	47	89	103
Pre-modification Recorded Investment	$ 2,597	$ 41,390	$ 33,212	$ 89,384
Post- modification	2,558	40,834	33,302	90,178
Commercial, Financial, Leasing, etc. [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	667	9,673	7,141	45,346
Commercial, Financial, Leasing, etc. [Member] \| Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		29		653
Commercial, Financial, Leasing, etc. [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		6,111		6,111
Commercial, Financial, Leasing, etc. [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 1,891	$ 25,021	$ 26,161	$ 38,068
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
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	1		2	1
Pre-modification Recorded Investment	$ 1,038		$ 1,456	$ 752
Post- modification	1,033		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	$ 1,033		$ 1,399
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	26	30	43	77
Pre-modification Recorded Investment	$ 7,513	$ 7,951	$ 11,329	$ 20,587
Post- modification	8,042	8,580	12,066	22,427
Residential [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	4,008	2,814	5,759	9,759
Residential [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 4,034	$ 5,766	$ 6,307	$ 12,668
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	2	3	3	5
Pre-modification Recorded Investment	$ 612	$ 584	$ 848	$ 879
Post- modification	625	658	864	1,043
Residential Limited Documentation [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	160	200	399	467
Residential Limited Documentation [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 465	$ 458	$ 465	$ 576
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	13	10	20	24
Pre-modification Recorded Investment	$ 1,273	$ 555	$ 1,749	$ 1,903
Post- modification	1,278	559	1,769	1,911
Home Equity Lines and Loans [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	53		90	4
Home Equity Lines and Loans [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 1,225	$ 559	$ 1,679	$ 1,907
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	12	19	32	27
Pre-modification Recorded Investment	$ 189	$ 333	$ 506	$ 481
Post- modification	189	333	506	481
Automobile [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 189	321	469	469
Automobile [Member] \| Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		$ 12	$ 37	$ 12
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	1		5	2
Pre-modification Recorded Investment	$ 15		$ 103	$ 49
Post- modification	15		103	49
Recreational Finance [Member] \| Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 15		$ 103	$ 49

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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			$ (569,328)	$ (493,290)
Cumulative effect of change in accounting principles — equity securities, before tax				(22,795)
Unrealized holding gains (losses), net, before tax			207,802	(187,989)
Foreign currency translation adjustment, before tax			(507)	(1,448)
Unrealized gains (losses) on cash flow hedges, before tax			188,272	(21,065)
Total other comprehensive income (loss) before reclassifications, before tax			395,567	(210,502)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			1,691	1,590
(Gains) losses realized in net income, before tax			7	(18)
Accretion of net gain on terminated cash flow hedges, before tax			(56)	(56)
Net yield adjustment from cash flow hedges currently in effect, before tax			11,176	3,469
Amortization of prior service credit, before tax			(2,086)	(2,086)
Amortization of actuarial losses, before tax			10,373	21,483
Total other comprehensive income (loss), before tax			416,672	(186,120)
Ending balance, before tax	$ (152,656)	$ (702,205)	(152,656)	(702,205)
Beginning balance, tax			149,247	129,476
Cumulative effect of change in accounting principles — equity securities, tax				5,942
Unrealized holding gains (losses), net, tax			(54,609)	49,414
Foreign currency translation adjustment, tax			107	304
Unrealized gains (losses) on cash flow hedges, tax			(49,497)	5,538
Total other comprehensive income (loss) before reclassifications, tax			(103,999)	55,256
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, tax			(445)	(418)
(Gains) losses realized in net income, tax			(2)	4
Accretion of net gain on terminated cash flow hedges, tax			14	15
Net yield adjustment from cash flow hedges currently in effect, tax			(2,938)	(912)
Amortization of prior service credit, tax			548	549
Amortization of actuarial losses, tax			(2,727)	(5,648)
Total other comprehensive income (loss), tax			(109,549)	48,846
Ending balance, tax	39,698	184,264	39,698	184,264
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			153,193	(138,575)
Foreign currency translation adjustment	(675)	(2,434)	(400)	(1,144)
Unrealized gains (losses) on cash flow hedges, net of tax			138,775	(15,527)
Total other comprehensive income (loss) before reclassifications, net of tax			291,568	(155,246)
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, net of tax			1,246	1,172
(Gains) losses realized in net income, net of tax			5	(14)
Accretion of net gain on terminated cash flow hedges, net of tax			(42)	(41)
Net yield adjustment from cash flow hedges currently in effect, net of tax			8,238	2,557
Amortization of prior service credit, net of tax			(1,538)	(1,537)
Amortization of actuarial losses, net of tax			7,646	15,835
Total other comprehensive income (loss)	175,051	(34,698)	307,123	(137,274)
Ending balance, net of tax	(112,958)	(517,941)	(112,958)	(517,941)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(200,107)	(59,957)
Cumulative effect of change in accounting principles — equity securities, before tax				(22,795)
Unrealized holding gains (losses), net, before tax			207,802	(187,989)
Total other comprehensive income (loss) before reclassifications, before tax			207,802	(187,989)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			1,691	1,590
(Gains) losses realized in net income, before tax			7	(18)
Total other comprehensive income (loss), before tax			209,500	(186,417)
Ending balance, before tax	9,393	(269,169)	9,393	(269,169)
Total other comprehensive income (loss)			154,444
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			(2,086)	(2,086)
Amortization of actuarial losses, before tax			10,373	21,483
Total other comprehensive income (loss), before tax			8,287	19,397
Ending balance, before tax	(346,215)	(393,771)	(346,215)	(393,771)
Total other comprehensive income (loss)			6,108
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(14,719)	(20,165)
Foreign currency translation adjustment, before tax			(507)	(1,448)
Unrealized gains (losses) on cash flow hedges, before tax			188,272	(21,065)
Total other comprehensive income (loss) before reclassifications, before tax			187,765	(22,513)
Accretion of net gain on terminated cash flow hedges, before tax			(56)	(56)
Net yield adjustment from cash flow hedges currently in effect, before tax			11,176	3,469
Total other comprehensive income (loss), before tax			198,885	(19,100)
Ending balance, before tax	$ 184,166	$ (39,265)	$ 184,166	$ (39,265)

Recent accounting developments

6 Months Ended

Jun. 30, 2019

Accounting Changes And Error Corrections [Abstract]

Recent accounting developments

16. 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.

16. Recent accounting developments, continued

Standard

Description

Required date

of adoption

Effect on consolidated financial statements

Standards Not Yet Adopted as of June 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

Early adoption permitted as of January 1, 2019

The Company is continuing the development of its approach for determining expected credit losses under the new guidance. The Company has a cross-functional implementation team working on model development, model validation, and development of a qualitative framework, data sourcing, and technology enhancements. The Company expects that the new guidance will result in an increase in its allowance for credit losses as a result of considering credit losses over the expected life of its loan portfolios, in particular its consumer and residential real estate loan portfolios. The expected changes to the allowance for credit losses and the impact to the Company’s financial statements are still to be determined. 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.

Simplifying the Test for Goodwill Impairment

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

January 1, 2020

Early adoption permitted

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.

16. Recent accounting developments, continued

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Not Yet Adopted as of June 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 is evaluating the impact that the guidance will have on its consolidated financial statements.

16. Recent accounting developments, continued

Standard	Description	Required date of adoption	Effect on consolidated financial statements
Standards Not Yet Adopted as of June 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.

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	Jun. 30, 2019	Dec. 31, 2018
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 920,481	$ 1,016,785
Carrying amount	655,037	727,491
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	23,648	27,073
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	125,737	135,047
Residential Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	415,242	473,511
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 90,410	$ 91,860

Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income available to common shareholders:
Net income	$ 473,260	$ 493,160	$ 956,002	$ 845,770
Less: Preferred stock dividends	(18,130)	(18,130)	(36,260)	(36,260)
Net income available to common equity	455,130	475,030	919,742	809,510
Less: Income attributable to unvested stock-based compensation awards	(2,498)	(2,432)	(5,024)	(4,172)
Net income available to common shareholders	$ 452,632	$ 472,598	$ 914,718	$ 805,338
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	136,182	145,571	137,403	147,510
Less: Unvested stock-based compensation awards	(749)	(746)	(749)	(764)
Weighted-average shares outstanding	135,433	144,825	136,654	146,746
Basic earnings per common share	$ 3.34	$ 3.26	$ 6.69	$ 5.49

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

6 Months Ended

Jun. 30, 2019

Text Block [Abstract]

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

15. 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 June 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 totaled $37 million and $23 million for the three-month periods ended March 31, 2019 and 2018, respectively. There was no similar income recognized during the three-month periods ended June 30, 2019 and 2018.

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 $2.4 billion and $2.5 billion at each of June 30, 2019 and December 31, 2018, respectively. Revenues from those servicing rights were $3 million and $4 million for the three-month periods ended June 30, 2019 and 2018, respectively, and $6 million and $7 million for the six-month periods ended June 30, 2019 and 2018, respectively. The Company sub-services residential mortgage loans for Bayview Financial having outstanding principal balances of $68.7 billion and $56.8 billion at June 30, 2019 and December 31, 2018, respectively. Revenues earned for sub-servicing loans for Bayview Financial were $29 million and $28 million for the three-month periods ended June 30, 2019 and 2018, respectively, and $57 million and $58 million for the six-month periods ended June 30, 2019 and 2018, respectively. In addition, the Company held $105 million and $113 million of mortgage-backed securities in its held-to-maturity portfolio at June 30, 2019 and December 31, 2018, respectively, that were securitized by Bayview Financial. At June 30, 2019, the Company held $112 million of Bayview Financial’s $826 million syndicated loan facility. The Company and Bayview Financial entered into arrangements whereby the Company added approximately $16.6 billion to its residential mortgage loan sub-servicing portfolio during the second quarter of 2019.

Loans and Leases and the Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 89,878,058	$ 88,466,477
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,431,408	22,977,976
Commercial, Financial, Leasing, etc. [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	22,112,126	21,693,705
Commercial, Financial, Leasing, etc. [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,095,549	1,049,848
Commercial, Financial, Leasing, etc. [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	223,733	234,423
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,204,849	25,610,365
Commercial [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	25,213,055	24,539,706
Commercial [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	788,678	866,987
Commercial [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	203,116	203,672
Residential Builder and Developer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,678,899	1,690,309
Residential Builder and Developer [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,476,023	1,546,002
Residential Builder and Developer [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	196,891	139,509
Residential Builder and Developer [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	5,985	4,798
Other Commercial Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,310,627	7,062,882
Other Commercial Construction [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,024,168	6,890,562
Other Commercial Construction [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	253,690	150,115
Other Commercial Construction [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 32,769	$ 22,205

Loans and Leases and the Allowance for Credit Losses - Minimum Future Lease Payments to be Received from Lease Financings (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Receivables [Abstract]
2020	$ 356,518
2021	294,985
2022	223,456
2023	145,794
2024	105,567
Later years	145,258
Total	$ 1,271,578

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	Jun. 30, 2019 USD ($)
Lessee Disclosure [Abstract]
Right-of-use assets	$ 395,659
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet
Lease liabilities	$ 422,384
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities

Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,019,337	$ 1,019,671	$ 1,019,444	$ 1,017,198
Provision for credit losses	55,000	35,000	77,000	78,000
Net charge-offs
Charge-offs	(69,406)	(57,447)	(114,506)	(114,199)
Recoveries	24,936	22,024	47,929	38,249
Net charge-offs	(44,470)	(35,423)	(66,577)	(75,950)
Ending balance	1,029,867	1,019,248	1,029,867	1,019,248
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	335,620	326,071	330,055	328,599
Provision for credit losses	10,337	11,250	16,608	18,480
Net charge-offs
Charge-offs	(16,608)	(14,900)	(25,108)	(29,481)
Recoveries	6,506	6,409	14,300	11,232
Net charge-offs	(10,102)	(8,491)	(10,808)	(18,249)
Ending balance	335,855	328,830	335,855	328,830
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	337,995	367,717	341,655	374,085
Provision for credit losses	14,501	(10,845)	10,298	(16,070)
Net charge-offs
Charge-offs	(10,165)	(4,548)	(10,448)	(5,914)
Recoveries	965	1,437	1,791	1,660
Net charge-offs	(9,200)	(3,111)	(8,657)	(4,254)
Ending balance	343,296	353,761	343,296	353,761
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	65,136	73,047	69,125	65,405
Provision for credit losses	(2,376)	5,242	(4,823)	15,728
Net charge-offs
Charge-offs	(3,263)	(3,966)	(6,635)	(8,320)
Recoveries	1,514	1,800	3,344	3,310
Net charge-offs	(1,749)	(2,166)	(3,291)	(5,010)
Ending balance	61,011	76,123	61,011	76,123
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	203,045	173,841	200,564	170,809
Provision for credit losses	31,594	30,801	54,477	60,615
Net charge-offs
Charge-offs	(39,370)	(34,033)	(72,315)	(70,484)
Recoveries	15,951	12,378	28,494	22,047
Net charge-offs	(23,419)	(21,655)	(43,821)	(48,437)
Ending balance	211,220	182,987	211,220	182,987
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	77,541	78,995	78,045	78,300
Provision for credit losses	944	(1,448)	440	(753)
Net charge-offs
Ending balance	$ 78,485	$ 77,547	$ 78,485	$ 77,547

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Uncollected amounts receivable	$ 58	$ 56
Accrued interest and other liabilities [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue	$ 43	$ 43

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount	$ 39,200,000,000	$ 19,850,000,000
Average Maturity (in years)	1 year 6 months	1 year 8 months 12 days
Estimated Fair Value Gain (Loss)	$ (5,780,000)	$ 5,530,000
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] \| Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 34,750,000,000	$ 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	2.42%	2.35%
Estimated Fair Value Gain (Loss)	$ (4,556,000)	$ 1,311,000
Fixed Rate Long-Term Borrowings [Member] \| Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 4,450,000,000	$ 4,450,000,000
Average Maturity (in years)	2 years 3 months 18 days	2 years 9 months 18 days
Weighted-Average Rate, Fixed	2.47%	2.47%
Weighted-Average Rate, Variable	2.95%	3.02%
Estimated Fair Value Gain (Loss)	$ (1,224,000)	$ 4,219,000

Derivative financial instruments

6 Months Ended

Jun. 30, 2019

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Derivative financial instruments

10. 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 June 30, 2019.

The net effect of interest rate swap agreements was to decrease net interest income by $11 million and $24 million during the three-month and six-month periods ended June 30, 2019, respectively, compared with decreases of $5 million and $4 million during the three-month and six-month periods ended June 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)
June 30, 2019
Fair value hedges:
Fixed rate long-term borrowings (b)	$	4,450,000		2.3		2.47	%		2.95	%	$	(1,224	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(c)		34,750,000		1.4		2.38	%		2.42	%		(4,556	)
Total	$	39,200,000		1.5							$	(5,780	)
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 June 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 $41.6 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 $196.2 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 $21.4 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 $44.4 billion and $42.9 billion at June 30, 2019 and December 31, 2018, respectively. The notional amounts of foreign currency and other option and futures

10. Derivative financial instruments, continued

contracts entered into for trading account purposes aggregated $949 million and $763 million at June 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
	June 30,		December 31,		June 30,		December 31,
	2019		2018		2019		2018
	(In thousands)
Derivatives designated and qualifying as hedging instruments
Interest rate swap agreements (a)	$	70	$	5,530	$	5,850	$	—
Commitments to sell real estate loans (a)		665		1,090		16,607		6,434
		735		6,620		22,457		6,434
Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		17,411		9,304		211		1,592
Commitments to sell real estate loans (a)		515		3,702		8,020		4,535
Trading:
Interest rate contracts (b)		399,155		118,687		66,897		169,255
Foreign exchange and other option and futures contracts (b)		7,305		10,549		6,495		8,870
		424,386		142,242		81,623		184,252
Total derivatives	$	425,121	$	148,862	$	104,080	$	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 June 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 $29.2 million and $170.7 million, respectively, and in a liability position of $281.2 million and $49.7 million, respectively.

	Amount of Gain (Loss) Recognized
	Three Months Ended June 30, 2019					Three Months Ended June 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)	$	56,679		(56,458	)	$	(13,357	)		13,884
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	8,493				$	(2,686	)
Foreign exchange and other option and futures contracts (b)		2,479					2,365
Total	$	10,972				$	(321	)

10. Derivative financial instruments, continued

	Amount of Gain (Loss) Recognized
	Six Months Ended June 30, 2019					Six Months Ended June 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)	$	90,859		(90,472	)	$	(55,747	)		56,254
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	11,204				$	(4,291	)
Foreign exchange and other option and futures contracts (b)		4,092					4,996
Total	$	15,296				$	705

(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
	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
	(In thousands)
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges

Long-term debt	$	4,485,626	$	4,394,109	$	39,370	$	(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 $25 million and $18 million at June 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.

10. 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 $52 million and $21 million at June 30, 2019 and December 31, 2018, respectively. The Company was required to post collateral relating to those positions of $48 million and $18 million at June 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 June 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 $4 million and $18 million at June 30, 2019 and December 31, 2018, respectively. Counterparties posted collateral relating to those positions of $2 million and $16 million at June 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 $98 million and $65 million at June 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.

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 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	$ 20,000,000	$ 21,000,000	$ 36,000,000	$ 45,000,000
Capitalized servicing rights	199,000,000	0	199,000,000	0	$ 0
Capitalized servicing rights, valuation allowance			9,000,000	0	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	212,000,000	206,000,000	212,000,000	206,000,000	268,000,000
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	17,000,000	30,000,000	17,000,000	30,000,000
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	155,000,000	119,000,000	155,000,000	119,000,000	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	$ 57,000,000	$ 87,000,000	$ 57,000,000	$ 87,000,000	$ 148,000,000

Loans and Leases and the Allowance for Credit Losses - Impaired Loans and Leases (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	$ 542,528	$ 542,255
Unpaid principal balance with related allowance	639,016	630,609
Related allowance	67,677	79,646
Recorded investment with no related allowance	261,451	254,196
Unpaid principal balance with no related allowance	292,631	305,559
Recorded investment	803,979	796,451
Unpaid principal balance	931,647	936,168
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	63,236	110,253
Unpaid principal balance with related allowance	70,777	125,117
Related allowance	8,276	11,937
Recorded investment with no related allowance	150,804	113,376
Unpaid principal balance with no related allowance	168,046	124,657
Recorded investment	214,040	223,629
Unpaid principal balance	238,823	249,774
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	3,374	3,527
Unpaid principal balance with related allowance	3,458	3,599
Related allowance	686	729
Recorded investment	3,374	3,527
Unpaid principal balance	3,458	3,599
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	192,660	153,478
Unpaid principal balance with related allowance	220,662	175,549
Related allowance	36,496	46,034
Recorded investment with no related allowance	73,247	105,507
Unpaid principal balance with no related allowance	77,171	136,128
Recorded investment	265,907	258,985
Unpaid principal balance	297,833	311,677
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	7,490	5,981
Unpaid principal balance with related allowance	8,059	6,557
Related allowance	286	462
Recorded investment with no related allowance	4,555	2,593
Unpaid principal balance with no related allowance	4,602	2,602
Recorded investment	12,045	8,574
Unpaid principal balance	12,661	9,159
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	22,851	10,563
Unpaid principal balance with related allowance	34,782	11,113
Related allowance	1,901	640
Recorded investment with no related allowance	9,918	11,710
Unpaid principal balance with no related allowance	10,313	11,880
Recorded investment	32,769	22,273
Unpaid principal balance	45,095	22,993
Residential [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	125,607	124,974
Unpaid principal balance with related allowance	147,097	147,817
Related allowance	6,220	5,402
Recorded investment with no related allowance	17,530	15,379
Unpaid principal balance with no related allowance	23,155	20,496
Recorded investment	143,137	140,353
Unpaid principal balance	170,252	168,313
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	69,340	74,156
Unpaid principal balance with related allowance	83,920	90,066
Related allowance	2,600	3,000
Recorded investment with no related allowance	5,397	5,631
Unpaid principal balance with no related allowance	9,344	9,796
Recorded investment	74,737	79,787
Unpaid principal balance	93,264	99,862
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	47,437	47,982
Unpaid principal balance with related allowance	52,838	53,248
Related allowance	9,060	9,135
Recorded investment	47,437	47,982
Unpaid principal balance	52,838	53,248
Recreational Finance [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	5,701	6,138
Unpaid principal balance with related allowance	9,248	9,163
Related allowance	1,178	1,261
Recorded investment	5,701	6,138
Unpaid principal balance	9,248	9,163
Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	4,832	5,203
Unpaid principal balance with related allowance	8,175	8,380
Related allowance	974	1,046
Recorded investment	4,832	5,203
Unpaid principal balance	$ 8,175	$ 8,380

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers				$ 8,600,000,000	$ 8,600,000,000
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program				3,600,000,000	$ 3,400,000,000
Payment of legal settlement expense		$ 200,000,000
Increased recorded liability for legal-related matters	$ 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

Borrowings

6 Months Ended

Jun. 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 June 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 $103 million and $409 million at June 30, 2019 and December 31, 2018, respectively. The agreements reflect various repurchase dates through 2020, however, the contractual maturities of the underlying investment securities extend beyond such repurchase dates. 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 $109 million and $428 million at June 30, 2019 and December 31, 2018, respectively.

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net Income (Loss)	$ 473,260	$ 493,160	$ 956,002	$ 845,770
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,553,576	1,466,201	3,104,401	2,900,414
Business Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	42,250	43,007	85,521	80,725
Business Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	140,767	136,029	280,089	263,913
Business Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,004	912	1,860	1,830
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	123,507	126,391	255,725	251,856
Commercial Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	278,110	269,499	545,600	535,895
Commercial Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	887	928	1,727	1,778
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	121,629	112,691	239,127	220,994
Commercial Real Estate [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	225,442	205,541	444,615	408,148
Commercial Real Estate [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	406	385	760	725
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	38,040	29,113	77,212	48,852
Discretionary Portfolio [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	60,976	58,976	124,893	109,014
Discretionary Portfolio [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(9,291)	(10,554)	(18,590)	(21,386)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	7,642	15,402	20,583	30,348
Residential Mortgage Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	96,449	82,167	180,210	164,625
Residential Mortgage Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	17,150	16,047	31,664	31,468
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	140,494	143,089	285,560	266,469
Retail Banking [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	436,593	420,540	867,484	814,016
Retail Banking [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	2,787	2,707	5,298	5,572
All Other [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	(302)	23,467	(7,726)	(53,474)
All Other [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	315,239	293,449	661,510	604,803
All Other [Member] \| Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ (12,943)	$ (10,425)	$ (22,719)	$ (19,987)

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Parenthetical) (Detail) - USD ($)	Jun. 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

Commitments and contingencies

6 Months Ended

Jun. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and contingencies

13. 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.

	June 30,		December 31,
	2019		2018
	(In thousands)
Commitments to extend credit
Home equity lines of credit	$	5,489,356		5,484,197
Commercial real estate loans to be sold		247,494		229,401
Other commercial real estate		7,771,353		7,556,722
Residential real estate loans to be sold		473,275		245,211
Other residential real estate		414,375		219,351
Commercial and other		15,188,645		14,363,803
Standby letters of credit		2,353,515		2,326,991
Commercial letters of credit		43,824		55,808
Financial guarantees and indemnification contracts		3,741,060		3,529,136
Commitments to sell real estate loans		1,377,712		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 $8.6 billion at each of June 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 $3.6 billion and $3.4 billion at June 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.

13. 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 June 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 four private party lawsuits relating to its role as trustee for four 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. The Company increased its recorded liability for legal-related matters by $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 June 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.

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 7,655,507,000				$ 7,655,507,000		$ 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	$ 37,000,000	$ 0	$ 23,000,000
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	2,400,000,000				2,400,000,000		2,500,000,000
Revenue from contract with customer	3,000,000		4,000,000		6,000,000	$ 7,000,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	68,700,000,000				68,700,000,000		56,800,000,000
Revenues from sub-servicing	29,000,000		$ 28,000,000		57,000,000	$ 58,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	105,000,000				105,000,000		$ 113,000,000
Addition on outstanding principal balances of residential mortgage loans from Bayview Financial	16,600,000,000				16,600,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	826,000,000				826,000,000
Bayview Financial [Member] \| Syndicated Loan Facility [Member] \| M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 112,000,000				$ 112,000,000

Revenue from contracts with customers

6 Months Ended

Jun. 30, 2019

Revenue From Contract With Customer [Abstract]

Revenue from contracts with customers

6. 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 June 30, 2019 and December 31, 2018, the Company had $58 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 June 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 six-month periods ended June 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 June 30, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,175		23,094		2,362		—		2		65,661		1,493	$	107,787
Trust income		7		224		—		—		—		—		144,151		144,382
Brokerage services income		—		—		—		—		—		—		12,478		12,478
Other revenues from operations:
Merchant discount and credit card fees		9,895		13,129		496		—		—		4,566		602		28,688
Other		—		3,145		2,680		641		1,033		9,329		8,595		25,423
	$	25,077		39,592		5,538		641		1,035		79,556		167,319	$	318,758
Three Months Ended June 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,611		24,270		2,451		—		3		63,015		1,434	$	106,784
Trust income		—		—		—		—		—		—		137,641		137,641
Brokerage services income		—		—		—		—		—		—		12,629		12,629
Other revenues from operations:
Merchant discount and credit card fees		8,334		12,542		428		—		—		4,140		618		26,062
Other		—		3,646		2,215		413		927		9,613		7,598		24,412
	$	23,945		40,458		5,094		413		930		76,768		159,920	$	307,528

6. Revenue from contracts with customers, continued

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

Classification in consolidated statement of income
Service charges on deposit accounts		30,284		46,304		4,888		—		4		126,812		2,607		210,899
Trust income		12		438		—		—		—		—		276,718		277,168
Brokerage services income		—		—		—		—		—		—		24,954		24,954
Other revenues from operations:
Merchant discount and credit card fees		18,777		25,221		1,102		—		—		7,704		1,022		53,826
Other		—		4,147		4,468		1,042		2,097		17,823		19,083		48,660
	$	49,073		76,110		10,458		1,042		2,101		152,339		324,384	$	615,507
Six Months Ended June 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	31,015		48,924		5,215		—		6		123,616		3,123	$	211,899
Trust income		—		—		—		—		—		—		269,016		269,016
Brokerage services income		—		—		—		—		—		—		26,021		26,021
Other revenues from operations:
Merchant discount and credit card fees		15,837		25,254		982		—		—		7,528		1,233		50,834
Other		—		5,209		3,074		865		1,970		19,478		16,706		47,302
	$	46,852		79,387		9,271		865		1,976		150,622		316,099	$	605,072

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 10,972	$ (321)	$ 15,296	$ 705
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	56,679	(13,357)	90,859	(55,747)
Derivatives in fair value hedging relationships, Hedged item	(56,458)	13,884	(90,472)	56,254
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	8,493	(2,686)	11,204	(4,291)
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 2,479	$ 2,365	$ 4,092	$ 4,996

Loans and Leases and the Allowance for Credit Losses - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Direct financings:
Lease payments receivable	$ 1,188,750	$ 1,155,464
Estimated residual value of leased assets	82,021	85,169
Unearned income	(107,409)	(110,458)
Investment in direct financings	1,163,362	1,130,175
Leveraged leases:
Lease payments receivable	82,828	85,007
Estimated residual value of leased assets	81,244	81,261
Unearned income	(32,774)	(33,717)
Investment in leveraged leases	131,298	132,551
Total investment in leases	1,294,660	1,262,726
Deferred taxes payable arising from leveraged leases	$ 72,620	$ 74,995

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Jun. 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	$ 7,359,445	$ 8,869,423
Investment securities available for sale, gross unrealized gains	67,944	16,528
Investment securities available for sale, gross unrealized losses	47,049	203,442
Investment securities available for sale, estimated fair value	7,380,340	8,682,509
Amortized cost for held to maturity	3,604,233	3,316,640
Gross unrealized gains for held to maturity	51,160	16,532
Gross unrealized losses for held to maturity	25,235	77,689
Estimated fair value for held to maturity	3,630,158	3,255,483
Equity and other securities, Amortized Cost	558,440	677,187
Equity securities, Gross Unrealized Gains	37,558	17,295
Equity securities, Gross Unrealized Losses	322	818
Equity and other securities, Estimated Fair Value	595,676	693,664
Other securities, Amortized cost	443,875	599,747
Other securities, Estimated fair value	443,875	599,747
Total debt securities Amortized cost	10,963,678	12,186,063
Total debt securities Gross unrealized gains	119,104	33,060
Total debt securities Gross unrealized losses	72,284	281,131
Total debt securities Estimated fair value	11,010,498	11,937,992
Readily marketable securities Amortized cost	114,565	77,440
Readily marketable securities Gross unrealized gains	37,558	17,295
Readily marketable securities Gross unrealized losses	322	818
Readily marketable securities Estimated fair value	151,801	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	431,334	1,346,782
Investment securities available for sale, gross unrealized gains	17
Investment securities available for sale, gross unrealized losses	1,538	9,851
Investment securities available for sale, estimated fair value	429,813	1,336,931
Amortized cost for held to maturity	946,782	446,542
Gross unrealized gains for held to maturity	1,547
Gross unrealized losses for held to maturity		239
Estimated fair value for held to maturity	948,329	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	1,015	1,660
Investment securities available for sale, gross unrealized gains	3	4
Investment securities available for sale, gross unrealized losses	3	5
Investment securities available for sale, estimated fair value	1,015	1,659
Amortized cost for held to maturity	5,415	7,494
Gross unrealized gains for held to maturity	32	22
Gross unrealized losses for held to maturity		12
Estimated fair value for held to maturity	5,447	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	6,789,309	7,383,340
Investment securities available for sale, gross unrealized gains	66,806	15,754
Investment securities available for sale, gross unrealized losses	37,782	182,103
Investment securities available for sale, estimated fair value	6,818,333	7,216,991
Amortized cost for held to maturity	2,543,906	2,745,776
Gross unrealized gains for held to maturity	37,595	4,165
Gross unrealized losses for held to maturity	4,505	55,111
Estimated fair value for held to maturity	2,576,996	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	104,592	113,160
Gross unrealized gains for held to maturity	11,986	12,345
Gross unrealized losses for held to maturity	20,730	22,327
Estimated fair value for held to maturity	95,848	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	137,771	137,617
Investment securities available for sale, gross unrealized gains	1,118	770
Investment securities available for sale, gross unrealized losses	7,726	11,481
Investment securities available for sale, estimated fair value	131,163	126,906
Amortized cost for held to maturity	3,538	3,668
Estimated fair value for held to maturity	$ 3,538	$ 3,668

Derivative financial instruments (Tables)

6 Months Ended

Jun. 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)
June 30, 2019
Fair value hedges:
Fixed rate long-term borrowings (b)	$	4,450,000		2.3		2.47	%		2.95	%	$	(1,224	)
Cash flow hedges:
Interest payments on variable rate commercial real estate loans (b)(c)		34,750,000		1.4		2.38	%		2.42	%		(4,556	)
Total	$	39,200,000		1.5							$	(5,780	)
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 $21.4 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
	June 30,		December 31,		June 30,		December 31,
	2019		2018		2019		2018
	(In thousands)
Derivatives designated and qualifying as hedging instruments
Interest rate swap agreements (a)	$	70	$	5,530	$	5,850	$	—
Commitments to sell real estate loans (a)		665		1,090		16,607		6,434
		735		6,620		22,457		6,434
Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		17,411		9,304		211		1,592
Commitments to sell real estate loans (a)		515		3,702		8,020		4,535
Trading:
Interest rate contracts (b)		399,155		118,687		66,897		169,255
Foreign exchange and other option and futures contracts (b)		7,305		10,549		6,495		8,870
		424,386		142,242		81,623		184,252
Total derivatives	$	425,121	$	148,862	$	104,080	$	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
	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
	(In thousands)
Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges

Long-term debt	$	4,485,626	$	4,394,109	$	39,370	$	(51,102	)

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

	Amount of Gain (Loss) Recognized
	Three Months Ended June 30, 2019					Three Months Ended June 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)	$	56,679		(56,458	)	$	(13,357	)		13,884
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	8,493				$	(2,686	)
Foreign exchange and other option and futures contracts (b)		2,479					2,365
Total	$	10,972				$	(321	)

10. Derivative financial instruments, continued

	Amount of Gain (Loss) Recognized
	Six Months Ended June 30, 2019					Six Months Ended June 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)	$	90,859		(90,472	)	$	(55,747	)		56,254
Derivatives not designated as hedging instruments
Trading:
Interest rate contracts (b)	$	11,204				$	(4,291	)
Foreign exchange and other option and futures contracts (b)		4,092					4,996
Total	$	15,296				$	705

(a)

Reported as interest expense.

(b)

Reported as trading account and foreign exchange gains.

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 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	$ 17,200	$ 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	98.00%	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	16.00%	13.00%

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 50,215	$ 459,960
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(502)	(5,088)
Estimated fair value, 12 months or more	3,408,196	7,048,346
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(46,547)	(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	369,556	2,137,792
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(25,235)	(76,461)
Total investment securities, fair value less than 12 months	50,215	1,085,617
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(502)	(6,316)
Total of investment securities, fair value, 12 Months or More	3,777,752	9,186,138
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(71,782)	(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	428,193	1,335,559
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(1,538)	(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	457
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	4,795	405,558
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(28)	(2,892)
Estimated fair value, 12 months or more	2,911,625	5,646,773
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(37,754)	(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	318,799	2,082,723
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(4,505)	(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	45,420	53,478
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(474)	(2,187)
Estimated fair value, 12 months or more	67,921	66,014
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(7,252)	(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	50,757	51,943
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	$ (20,730)	$ (22,327)

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2019	Jul. 31, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
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		133,666,679
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	1-9861
Entity Tax Identification Number	160968385
Entity Address, Address Line One	One M & T Plaza
Entity Address, City or Town	Buffalo
Entity Address, State or Province	New York
Entity Address, Postal Zip Code	14203
City Area Code	716
Local Phone Number	635-4000

Pension plans and other postretirement benefits (Tables)

6 Months Ended

Jun. 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 June 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	4,559			5,069			229		243
Interest cost on projected benefit obligation		20,590			18,548			569			589
Expected return on plan assets		(30,470	)		(30,688	)		—			—
Amortization of prior service cost (credit)		154			153			(1,190	)		(1,189	)
Amortization of net actuarial loss (gain)		6,546			10,796			(323	)		(213	)
Net periodic cost (benefit)	$	1,379			3,878			(715	)		(570	)

	Pension Benefits						Other Postretirement Benefits
	Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands)

Service cost	$	8,646			10,172			429			469
Interest cost on projected benefit obligation		40,790			37,353			1,172			1,146
Expected return on plan assets		(61,070	)		(61,563	)		—			—
Amortization of prior service cost (credit)		279			278			(2,365	)		(2,364	)
Amortization of net actuarial loss (gain)		10,996			21,896			(623	)		(413	)
Net periodic cost (benefit)	$	(359	)		8,136			(1,387	)		(1,162	)

Fair value measurements

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Fair value measurements

12. 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 June 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.

12. 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.

12. Fair value measurements, continued

The following tables present assets and liabilities at June 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)
June 30, 2019
Trading account assets	$	479,403	$	47,344	$	432,059	$	—
Investment securities available for sale:
U.S. Treasury and federal agencies		429,813		—		429,813		—
Obligations of states and political subdivisions		1,015		—		1,015		—
Mortgage-backed securities:
Government issued or guaranteed		6,818,333		—		6,818,333		—
Privately issued		16		—		—		16
Other debt securities		131,163		—		131,163		—
		7,380,340		—		7,380,324		16
Equity securities		151,801		109,377		42,424		—
Real estate loans held for sale		797,474		—		797,474		—
Other assets (b)		18,661		—		1,250		17,411
Total assets	$	8,827,679	$	156,721	$	8,653,531	$	17,427
Trading account liabilities	$	73,392	$	—	$	73,392	$	—
Other liabilities (b)		30,688		—		30,477		211
Total liabilities	$	104,080	$	—	$	103,869	$	211

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 six months ended June 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).

12. 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 June 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 — March 31 , 2019	$	16		7,433
Total gains realized/unrealized:
Included in earnings		—		36,463		(b)
Settlements		—		—
Transfers out of Level 3 (a)		—		(26,696	)	(c)
Balance — June 30, 2019	$	16		17,200
Changes in unrealized gains included in earnings related to assets still held at June 30, 2019	$	—		17,464		(b)

2018

Balance — March 31 , 2018	$	27		8,760
Total gains realized/unrealized:
Included in earnings		—		20,277		(b)
Settlements		(3	)	—
Transfers out of Level 3 (a)		—		(18,286	)	(c)
Balance — June 30, 2018	$	24		10,751
Changes in unrealized gains included in earnings related to assets still held at June 30, 2018	$	—		10,686		(b)

12. Fair value measurements, continued

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the six months ended June 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		—			53,009		(b)
Settlements		(6	)		—
Transfers out of Level 3 (a)		—			(43,521	)	(c)
Balance — June 30, 2019	$	16			17,200
Changes in unrealized gains included in earnings related to assets still held at June 30, 2019	$	—			17,372		(b)

2018

Balance — January 1, 2018	$	28		8,303
Total gains realized/unrealized:
Included in earnings		—		28,407		(b)
Settlements		(4	)	—
Transfers out of Level 3 (a)		—		(25,959	)	(c)
Balance — June 30, 2018	$	24		10,751
Changes in unrealized gains included in earnings related to assets still held at June 30, 2018	$	—		10,686		(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.

12. 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 June 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 $212 million at June 30, 2019 ($155 million and $57 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 $206 million at June 30, 2018 ($119 million and $87 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 June 30, 2019 were decreases of $20 million and $36 million for the three-month and six-month periods ended June 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 June 30, 2018 were decreases of $21 million and $45 million for the three-month and six-month periods ended June 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 $30 million at June 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 six-month periods ended June 30, 2019 and 2018.

12. 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 June 30, 2019, $199 million of capitalized servicing rights required a valuation allowance of approximately $9 million. No stratum of capitalized servicing rights required a valuation allowance at December 31, 2018 or June 30, 2018.

Significant unobservable inputs to Level 3 measurements

Fair Value

Valuation

Technique

Unobservable

Inputs/Assumptions

Range

(Weighted-

Average)

(In thousands)

June 30, 2019

Recurring fair value measurements

Privately issued mortgage-backed

securities

Two independent pricing quotes

—

Net other assets (liabilities) (a)

17,200

Discounted cash flow

Commitment expirations

0%-98% (16%)

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.

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.

12. Fair value measurements, continued

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:

	June 30, 2019
	Carrying Amount			Estimated Fair Value			Level 1		Level 2			Level 3
	(In thousands)
Financial assets:
Cash and cash equivalents	$	1,271,611			1,271,611			1,214,826		56,785			—
Interest-bearing deposits at banks		8,791,753			8,791,753			—		8,791,753			—
Trading account assets		479,403			479,403			47,344		432,059			—
Investment securities		11,580,249			11,606,174			109,377		11,400,933			95,864
Loans and leases:
Commercial loans and leases		23,431,408			23,095,155			—		—			23,095,155
Commercial real estate loans		35,194,375			34,932,104			—		503,599			34,428,505
Residential real estate loans		16,693,737			16,734,846			—		3,965,011			12,769,835
Consumer loans		14,558,538			14,537,432			—		—			14,537,432
Allowance for credit losses		(1,029,867	)		—			—		—			—
Loans and leases, net		88,848,191			89,299,537			—		4,468,610			84,830,927
Accrued interest receivable		362,012			362,012			—		362,012			—
Financial liabilities:
Noninterest-bearing deposits	$	(30,747,946	)		(30,747,946	)		—		(30,747,946	)		—
Savings and interest-checking deposits		(53,221,672	)		(53,221,672	)		—		(53,221,672	)		—
Time deposits		(6,346,551	)		(6,447,027	)		—		(6,447,027	)		—
Deposits at Cayman Islands office		(1,364,855	)		(1,364,855	)		—		(1,364,855	)		—
Short-term borrowings		(4,611,390	)		(4,611,390	)		—		(4,611,390	)		—
Long-term borrowings		(7,655,507	)		(7,703,957	)		—		(7,703,957	)		—
Accrued interest payable		(108,971	)		(108,971	)		—		(108,971	)		—
Trading account liabilities		(73,392	)		(73,392)			—		(73,392	)		—
Other financial instruments:
Commitments to originate real estate loans for sale	$	17,200			17,200			—		—			17,200
Commitments to sell real estate loans		(23,447	)		(23,447	)		—		(23,447	)		—
Other credit-related commitments		(127,699	)		(127,699	)		—		—			(127,699	)
Interest rate swap agreements used for interest rate risk management		(5,780	)		(5,780	)		—		(5,780	)		—

12. 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

Derivative Financial Instruments - Information about Hedged Items Included in Consolidated Balance Sheet (Detail) - Long-term Debt [Member] - Derivatives Designated and Qualifying as Hedging Instruments [Member] - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 4,485,626	$ 4,394,109
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 39,370	$ (51,102)

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Pledged securities that can be sold or repledged	$ 167,935	$ 487,365
Investment securities, available for sale, amortized cost	7,359,445	8,869,423
Investment securities, held to maturity, fair value	3,630,158	3,255,483
Equity and other securities, cost	$ 558,440	$ 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	21,327	24,563
Treasury stock, common shares	25,563,347	21,255,275
Series A Series C Series And E Preferred Stock [Member]
Preferred stock, shares issued	731,500	731,500
Preferred stock, shares outstanding	731,500	731,500
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series F Preferred Stock [Member]
Preferred stock, shares issued	50,000	50,000
Preferred stock, shares outstanding	50,000	50,000
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($)
$ in Thousands

Total

Preferred Stock [Member]

Common Stock [Member]

Common Stock Issuable [Member]

Additional Paid-in Capital [Member]

Series A Warrants [Member]

Retained Earnings [Member]

Accumulated Other Comprehensive Income (Loss), Net [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

708,496

845,770

(137,274)

Preferred stock cash dividends

^[1]

(36,260)

Exercise of stock warrants into common stock

$ (5,123)

$ 5,123

Purchases of treasury stock

(1,196,062)

Stock-based compensation plans:

Compensation expense, net

15,446

(25)

(6,194)

21,665

Exercises of stock options, net

50,671

(2,402)

53,073

Stock purchase plan

11,124

2,358

8,766

Directors’ stock plan

1,192

149

1,043

Deferred compensation plans, net, including dividend equivalents

(49)

(156)

(248)

(37)

392

Common stock cash dividends

(227,492)

Ending 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)

Beginning balance at Mar. 31, 2018

15,709,694

1,231,500

79,884

1,675

6,572,281

10,404,458

(483,243)

(2,096,861)

Total comprehensive income

458,462

493,160

(34,698)

Preferred stock cash dividends

^[1]

(18,130)

Exercise of stock warrants into common stock

$ (1,668)

$ 1,668

Purchases of treasury stock

(475,096)

Stock-based compensation plans:

Compensation expense, net

9,613

9,168

445

Exercises of stock options, net

8,571

(457)

9,028

Directors’ stock plan

603

528

Deferred compensation plans, net, including dividend equivalents

(1)

(4)

(19)

Common stock cash dividends

(115,831)

Ending 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)

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

1,263,125

956,002

307,123

Preferred stock cash dividends

^[1]

(36,260)

Purchases of treasury stock

(767,612)

Stock-based compensation plans:

Compensation expense, net

28,855

(12)

1,531

27,336

Exercises of stock options, net

4,727

(2,818)

7,545

Stock purchase plan

11,832

(67)

11,899

Directors’ stock plan

1,068

(116)

1,184

Deferred compensation plans, net, including dividend equivalents

(64)

(200)

(327)

(43)

506

Performance share unit dividends

(58)

Common stock cash dividends

(274,035)

Ending 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)

Beginning balance at Mar. 31, 2019

15,587,529

1,231,500

79,871

1,514

6,568,480

11,842,371

(288,009)

(3,848,198)

Total comprehensive income

648,311

473,260

175,051

Preferred stock cash dividends

^[1]

(18,130)

Purchases of treasury stock

(401,984)

Stock-based compensation plans:

Compensation expense, net

10,735

9,137

1,598

Directors’ stock plan

539

(32)

571

Deferred compensation plans, net, including dividend equivalents

(11)

(21)

Performance share unit dividends

(29)

Common stock cash dividends

(135,173)

Ending 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)

[1]

For each of the three-month periods ended June 30, 2019 and 2018, dividends per preferred share were: Preferred Series A- $15.9375; Preferred Series C - $15.9375; Preferred Series E - $16.125; and Preferred Series F - $128.125. For each of the six-month periods ended June 30, 2019 and 2018, dividends per preferred share were: Preferred Series A- $31.875; Preferred Series C - $31.875; Preferred Series E - $32.25; and Preferred Series F - $256.25.

Investment Securities - Additional Information (Detail)	3 Months Ended		6 Months Ended
Investment Securities - Additional Information (Detail)	Jun. 30, 2019 USD ($) Security	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Security	Jun. 30, 2018 USD ($)
Investment Holdings [Line Items]
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0	$ 0	$ 0
Gain (loss) on bank investment securities	$ 8,911,000	$ 2,326,000	$ 20,752,000	$ (7,105,000)
Number of debt securities with aggregate gross unrealized losses \| Security	801		801
Unrealized losses on individual debt securities			$ (72,000,000)
Cost method equity securities	$ 444,000,000		444,000,000
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

Subsequent Events

6 Months Ended

Jun. 30, 2019

Subsequent Events [Abstract]

Subsequent Events

17. Subsequent Events

On July 30, 2019, M&T issued 40,000 shares of Series G Perpetual Fixed-Rate Reset Non-cumulative Preferred Stock, par value $1.00 per share and liquidation preference of $10,000 per share. Through July 31, 2024 holders of the Series G preferred stock are entitled to receive, only when, as and if declared by M&T’s Board of Directors, non-cumulative cash dividends at an annual rate of 5.0%, payable semiannually in arrears. Subsequent to July 31, 2024 holders will be entitled to receive, only when, as and if declared by M&T’s Board of Directors, non-cumulative cash dividends at an annual rate of the five-year U.S. Treasury Rate plus 3.174%, payable semiannually in arrears. The Series G preferred stock may be redeemed at M&T’s option, in whole or in part, on any dividend payment date on or after August 1, 2024 or, in whole but not in part, at any time within 90 days following a regulatory capital treatment event whereby the full liquidation value of the shares no longer qualifies as “additional Tier 1 capital.”

In addition, M&T expects to redeem the 230,000 shares issued and outstanding of the Series A and 151,500 shares issued and outstanding of the Series C Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share on August 30, 2019, having received the approval of the Federal Reserve to redeem such shares after issuing the Series G preferred stock.

Comprehensive income (Tables)

6 Months Ended

Jun. 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		207,802			—			—			207,802				(54,609	)		153,193
Foreign currency translation adjustment		—			—			(507	)		(507	)			107			(400	)
Unrealized gains on cash flow hedges		—			—			188,272			188,272				(49,497	)		138,775
Total other comprehensive income before reclassifications		207,802			—			187,765			395,567				(103,999	)		291,568
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities		1,691			—			—			1,691		(a)		(445	)		1,246
Losses realized in net income		7			—			—			7		(b)		(2	)		5
Accretion of net gain on terminated cash flow hedges		—			—			(56	)		(56	)	(c)		14			(42	)
Net yield adjustment from cash flow hedges currently in effect		—			—			11,176			11,176		(a)		(2,938	)		8,238
Amortization of prior service credit		—			(2,086	)		—			(2,086	)	(d)		548			(1,538	)
Amortization of actuarial losses		—			10,373			—			10,373		(d)		(2,727	)		7,646
Total other comprehensive income		209,500			8,287			198,885			416,672				(109,549	)		307,123
Balance — June 30, 2019	$	9,393			(346,215	)		184,166		$	(152,656	)			39,698		$	(112,958	)


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		(187,989	)		—			—			(187,989	)			49,414			(138,575	)
Foreign currency translation adjustment		—			—			(1,448	)		(1,448	)			304			(1,144	)
Unrealized losses on cash flow hedges		—			—			(21,065	)		(21,065	)			5,538			(15,527	)
Total other comprehensive income (loss) before reclassifications		(187,989	)		—			(22,513	)		(210,502	)			55,256			(155,246	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		1,590			—			—			1,590		(a)		(418	)		1,172
Gains realized in net income		(18	)		—			—			(18	)	(b)		4			(14	)
Accretion of net gain on terminated cash flow hedges		—			—			(56	)		(56	)	(c)		15			(41	)
Net yield adjustment from cash flow hedges currently in effect		—			—			3,469			3,469		(a)		(912	)		2,557
Amortization of prior service credit		—			(2,086	)		—			(2,086	)	(d)		549			(1,537	)
Amortization of actuarial losses		—			21,483			—			21,483		(d)		(5,648	)		15,835
Total other comprehensive income (loss)		(186,417	)		19,397			(19,100	)		(186,120	)			48,846			(137,274	)
Balance — June 30, 2018	$	(269,169	)		(393,771	)		(39,265	)	$	(702,205	)			184,264		$	(517,941	)

(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		154,444			6,108			146,571			307,123
Balance — June 30, 2019	$	6,918			(255,195	)		135,319		$	(112,958	)

Comprehensive income

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

Comprehensive income

9. 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		207,802			—			—			207,802				(54,609	)		153,193
Foreign currency translation adjustment		—			—			(507	)		(507	)			107			(400	)
Unrealized gains on cash flow hedges		—			—			188,272			188,272				(49,497	)		138,775
Total other comprehensive income before reclassifications		207,802			—			187,765			395,567				(103,999	)		291,568
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities		1,691			—			—			1,691		(a)		(445	)		1,246
Losses realized in net income		7			—			—			7		(b)		(2	)		5
Accretion of net gain on terminated cash flow hedges		—			—			(56	)		(56	)	(c)		14			(42	)
Net yield adjustment from cash flow hedges currently in effect		—			—			11,176			11,176		(a)		(2,938	)		8,238
Amortization of prior service credit		—			(2,086	)		—			(2,086	)	(d)		548			(1,538	)
Amortization of actuarial losses		—			10,373			—			10,373		(d)		(2,727	)		7,646
Total other comprehensive income		209,500			8,287			198,885			416,672				(109,549	)		307,123
Balance — June 30, 2019	$	9,393			(346,215	)		184,166		$	(152,656	)			39,698		$	(112,958	)


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		(187,989	)		—			—			(187,989	)			49,414			(138,575	)
Foreign currency translation adjustment		—			—			(1,448	)		(1,448	)			304			(1,144	)
Unrealized losses on cash flow hedges		—			—			(21,065	)		(21,065	)			5,538			(15,527	)
Total other comprehensive income (loss) before reclassifications		(187,989	)		—			(22,513	)		(210,502	)			55,256			(155,246	)
Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:
Amortization of unrealized holding losses on HTM securities		1,590			—			—			1,590		(a)		(418	)		1,172
Gains realized in net income		(18	)		—			—			(18	)	(b)		4			(14	)
Accretion of net gain on terminated cash flow hedges		—			—			(56	)		(56	)	(c)		15			(41	)
Net yield adjustment from cash flow hedges currently in effect		—			—			3,469			3,469		(a)		(912	)		2,557
Amortization of prior service credit		—			(2,086	)		—			(2,086	)	(d)		549			(1,537	)
Amortization of actuarial losses		—			21,483			—			21,483		(d)		(5,648	)		15,835
Total other comprehensive income (loss)		(186,417	)		19,397			(19,100	)		(186,120	)			48,846			(137,274	)
Balance — June 30, 2018	$	(269,169	)		(393,771	)		(39,265	)	$	(702,205	)			184,264		$	(517,941	)

(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		154,444			6,108			146,571			307,123
Balance — June 30, 2019	$	6,918			(255,195	)		135,319		$	(112,958	)

Significant accounting policies (Policies)	6 Months Ended
Significant accounting policies (Policies)	Jun. 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 16 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.

Earnings per common share

6 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

Earnings per common share

8. Earnings per common share

The computations of basic earnings per common share follow:

	Three Months Ended June 30						Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands, except per share)

Income available to common shareholders:
Net income	$	473,260			493,160			956,002			845,770
Less: Preferred stock dividends (a)		(18,130	)		(18,130	)		(36,260	)		(36,260	)
Net income available to common equity		455,130			475,030			919,742			809,510
Less: Income attributable to unvested stock-based compensation awards		(2,498	)		(2,432	)		(5,024	)		(4,172	)
Net income available to common shareholders	$	452,632			472,598			914,718			805,338
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		136,182			145,571			137,403			147,510
Less: Unvested stock-based compensation awards		(749	)		(746	)		(749	)		(764	)
Weighted-average shares outstanding		135,433			144,825			136,654			146,746

Basic earnings per common share	$	3.34			3.26			6.69			5.49

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

The computations of diluted earnings per common share follow:

	Three Months Ended June 30						Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands, except per share)

Net income available to common equity	$	455,130			475,030			919,742			809,510
Less: Income attributable to unvested stock-based compensation awards		(2,497	)		(2,430	)		(5,023	)		(4,168	)
Net income available to common shareholders	$	452,633			472,600			914,719			805,342
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards		136,182			145,571			137,403			147,510
Less: Unvested stock-based compensation awards		(749	)		(746	)		(749	)		(764	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		31			173			31			195
Adjusted weighted-average shares outstanding		135,464			144,998			136,685			146,941

Diluted earnings per common share	$	3.34			3.26			6.69			5.48

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 115,293 and 212,244 common shares during the three-month periods ended June 30, 2019 and 2018, respectively, and 197,598 and 224,844 common shares during the six-month periods ended June 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.

Segment information

6 Months Ended

Jun. 30, 2019

Segment Reporting [Abstract]

Segment information

14. 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 June 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	$	140,767		1,004			42,250		$	136,029		912			43,007
Commercial Banking		278,110		887			123,507			269,499		928			126,391
Commercial Real Estate		225,442		406			121,629			205,541		385			112,691
Discretionary Portfolio		60,976		(9,291	)		38,040			58,976		(10,554	)		29,113
Residential Mortgage Banking		96,449		17,150			7,642			82,167		16,047			15,402
Retail Banking		436,593		2,787			140,494			420,540		2,707			143,089
All Other		315,239		(12,943	)		(302	)		293,449		(10,425	)		23,467
Total	$	1,553,576		—			473,260		$	1,466,201		—			493,160

	Six Months Ended June 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	$	280,089		1,860			85,521		$	263,913		1,830			80,725
Commercial Banking		545,600		1,727			255,725			535,895		1,778			251,856
Commercial Real Estate		444,615		760			239,127			408,148		725			220,994
Discretionary Portfolio		124,893		(18,590	)		77,212			109,014		(21,386	)		48,852
Residential Mortgage Banking		180,210		31,664			20,583			164,625		31,468			30,348
Retail Banking		867,484		5,298			285,560			814,016		5,572			266,469
All Other		661,510		(22,719	)		(7,726	)		604,803		(19,987	)		(53,474	)
Total	$	3,104,401		—			956,002		$	2,900,414		—			845,770

14. Segment information, continued

	Average Total Assets
	Six Months Ended June 30				Year Ended December 31
	2019		2018		2018
	(In millions)

Business Banking	$	5,724		5,656		5,631
Commercial Banking		27,981		26,542		26,626
Commercial Real Estate		23,720		22,848		22,885
Discretionary Portfolio		29,888		33,277		32,123
Residential Mortgage Banking		2,173		2,186		2,161
Retail Banking		14,580		13,403		13,656
All Other		13,601		13,109		13,877
Total	$	117,667		117,021		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 $5,925,000 and $5,397,000 for the three-month periods ended June 30, 2019 and 2018, respectively, and $11,892,000 and $10,206,000 for the six-month periods ended June 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.

Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Interest income
Loans and leases, including fees	$ 1,125,577	$ 1,024,471	$ 2,243,490	$ 2,004,440
Investment securities
Fully taxable	75,578	82,019	155,989	164,871
Exempt from federal taxes	77	172	172	420
Deposits at banks	36,325	21,869	63,732	40,546
Other	356	374	839	778
Total interest income	1,237,913	1,128,905	2,464,222	2,211,055
Interest expense
Savings and interest-checking deposits	91,557	48,738	167,695	89,265
Time deposits	24,931	11,362	46,012	22,298
Deposits at Cayman Islands office	6,039	542	10,777	923
Short-term borrowings	7,893	1,383	14,606	2,266
Long-term borrowings	66,012	58,093	133,591	111,999
Total interest expense	196,432	120,118	372,681	226,751
Net interest income	1,041,481	1,008,787	2,091,541	1,984,304
Provision for credit losses	55,000	35,000	77,000	78,000
Net interest income after provision for credit losses	986,481	973,787	2,014,541	1,906,304
Other income
Brokerage services income	12,478	12,629	24,954	26,021
Trading account and foreign exchange gains	18,453	5,255	29,255	9,892
Gain (loss) on bank investment securities	8,911	2,326	20,752	(7,105)
Other revenues from operations	112,763	100,280	247,200	226,582
Total other income	512,095	457,414	1,012,860	916,110
Other expense
Salaries and employee benefits	455,737	418,537	954,937	881,965
Equipment and net occupancy	79,150	73,031	158,497	147,828
Outside data processing and software	55,234	49,712	107,651	98,141
FDIC assessments	9,772	19,560	19,198	39,840
Advertising and marketing	24,046	21,768	44,321	38,016
Printing, postage and supplies	10,324	8,719	20,179	18,038
Amortization of core deposit and other intangible assets	5,077	6,388	10,097	13,020
Other costs of operations	233,692	178,862	452,500	473,073
Total other expense	873,032	776,577	1,767,380	1,709,921
Income before taxes	625,544	654,624	1,260,021	1,112,493
Income taxes	152,284	161,464	304,019	266,723
Net income	473,260	493,160	956,002	845,770
Net income available to common shareholders
Basic	452,632	472,598	914,718	805,338
Diluted	$ 452,633	$ 472,600	$ 914,719	$ 805,342
Net income per common share
Basic	$ 3.34	$ 3.26	$ 6.69	$ 5.49
Diluted	$ 3.34	$ 3.26	$ 6.69	$ 5.48
Average common shares outstanding
Basic	135,433	144,825	136,654	146,746
Diluted	135,464	144,998	136,685	146,941
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 107,321	$ 92,499	$ 202,632	$ 179,805
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	107,787	106,784	210,899	211,899
Trust Income [Member]
Other income
Revenue from contract with customer	$ 144,382	$ 137,641	$ 277,168	$ 269,016

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	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Lease cost
Operating lease cost	$ 24,902	$ 49,541
Short-term lease cost	28	62
Variable lease cost	623	1,089
Sublease income	(1,904)	(3,821)
Total net lease cost	23,649	46,871
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	24,518	44,928
Cash paid toward lease liabilities	$ 25,205	$ 50,861
Weighted-average remaining lease term	7 years	7 years
Weighted-average discount rate	3.20%	3.20%

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ (29.2)	$ (170.7)
Reduction in estimated fair value of interest rate contracts in liability position	$ (281.2)	$ (49.7)

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 15,587,529	$ 15,709,694	$ 15,460,191	$ 16,250,819
Net gain during period	175,051	(34,698)	307,123	(137,274)
Ending balance	15,691,827	15,577,885	15,691,827	15,577,885
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(147,526)
Net gain during period			154,444
Ending balance	6,918		6,918
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(261,303)
Net gain during period			6,108
Ending balance	(255,195)		(255,195)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(11,252)
Net gain during period			146,571
Ending balance	135,319		135,319
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(288,009)	(483,243)	(420,081)	(363,814)
Net gain during period			307,123
Ending balance	$ (112,958)	$ (517,941)	$ (112,958)	$ (517,941)

Variable interest entities and asset securitizations

6 Months Ended

Jun. 30, 2019

Text Block [Abstract]

Variable interest entities and asset securitizations

11. 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 six-month periods ended June 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 June 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 $1.2 billion at June 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 maximum exposure to loss of its investments in such partnerships was $573 million, including $267 million of unfunded commitments, at June 30, 2019 and $523 million, including $280 million of unfunded commitments, at December 31, 2018. Contingent commitments to provide additional capital contributions to these partnerships were not material at June 30, 2019. The Company has not provided financial or other support to the partnerships that was not contractually required. 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 $34 million of its investments in qualified affordable housing projects to income tax expense during the three-month and six-month periods ended June 30, 2019, respectively, and recognized $21 million and $41 million of tax credits and other tax benefits during those periods. Similarly, for the three-month and six-month periods ended June 30, 2018, the Company amortized $13 million and $26 million, respectively, of its investments in qualified affordable housing projects to income tax expense and recognized $16 million and $32 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.

Borrowings - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 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	$ 103	$ 409
Collateral posted	$ 109	$ 428

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

6 Months Ended

Jun. 30, 2019

Receivables [Abstract]

Summary of Current, Past Due and Nonaccrual Loans

A summary of current, past due and nonaccrual loans as of June 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)
June 30, 2019
Commercial, financial, leasing, etc.	$	23,177,367		26,974		3,332		—		2		223,733	$	23,431,408
Real estate:
Commercial		25,829,322		146,704		12,450		390		12,867		203,116		26,204,849
Residential builder and developer		1,665,951		6,495		—		—		468		5,985		1,678,899
Other commercial construction		7,217,573		55,060		4,600		—		625		32,769		7,310,627
Residential		13,206,787		462,391		321,810		5,981		172,718		210,922		14,380,609
Residential — limited documentation		2,067,375		81,857		—		—		76,345		87,551		2,313,128
Consumer:
Home equity lines and loans		4,562,840		29,972		—		4,360		—		66,927		4,664,099
Recreational finance		4,759,183		24,485		—		295		—		11,153		4,795,116
Automobile		3,639,155		70,177		—		—		—		20,170		3,729,502
Other		1,315,662		12,515		6,533		32,053		—		3,058		1,369,821
Total	$	87,441,215		916,630		348,725		43,079		263,025		865,384	$	89,878,058

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

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:

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

Outstanding principal balance	$	920,481	$	1,016,785
Carrying amount:
Commercial, financial, leasing, etc.		23,648		27,073
Commercial real estate		125,737		135,047
Residential real estate		415,242		473,511
Consumer		90,410		91,860
	$	655,037	$	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 six months ended June 30, 2019 and 2018 follows:

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

Balance at beginning of period	$	140,317		$	93,687		$	149,007		$	118,184
Interest income		(9,632	)		(9,666	)		(7,969	)		(15,394	)
Reclassifications from nonaccretable balance		16,419			3,457			8,350			10,998
Other (a)		—			3,433			—			3,927
Balance at end of period	$	147,104		$	90,911		$	149,388		$	117,715

	Six Months Ended June 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		(27,714	)		(19,383	)		(17,788	)		(30,506	)
Reclassifications from nonaccretable balance		27,608			8,322			9,258			11,205
Other (a)		—			5,065			—			3,854
Balance at end of period	$	147,104		$	90,911		$	149,388		$	117,715

(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 June 30, 2019 were as follows:

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

Beginning balance	$	335,620			337,995			65,136			203,045			77,541	$	1,019,337
Provision for credit losses		10,337			14,501			(2,376	)		31,594			944		55,000
Net charge-offs
Charge-offs		(16,608	)		(10,165	)		(3,263	)		(39,370	)		—		(69,406	)
Recoveries		6,506			965			1,514			15,951			—		24,936
Net charge-offs		(10,102	)		(9,200	)		(1,749	)		(23,419	)		—		(44,470	)
Ending balance	$	335,855			343,296			61,011			211,220			78,485	$	1,029,867

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

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

Beginning balance	$	326,071			367,717			73,047			173,841			78,995		$	1,019,671
Provision for credit losses		11,250			(10,845	)		5,242			30,801			(1,448	)		35,000
Net charge-offs
Charge-offs		(14,900	)		(4,548	)		(3,966	)		(34,033	)		—			(57,447	)
Recoveries		6,409			1,437			1,800			12,378			—			22,024
Net charge-offs		(8,491	)		(3,111	)		(2,166	)		(21,655	)		—			(35,423	)
Ending balance	$	328,830			353,761			76,123			182,987			77,547		$	1,019,248

Changes in the allowance for credit losses for the six months ended June 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		16,608			10,298			(4,823	)		54,477			440		77,000
Net charge-offs
Charge-offs		(25,108	)		(10,448	)		(6,635	)		(72,315	)		—		(114,506	)
Recoveries		14,300			1,791			3,344			28,494			—		47,929
Net charge-offs		(10,808	)		(8,657	)		(3,291	)		(43,821	)		—		(66,577	)
Ending balance	$	335,855			343,296			61,011			211,220			78,485	$	1,029,867

Changes in the allowance for credit losses for the six months ended June 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		18,480			(16,070	)		15,728			60,615			(753	)		78,000
Net charge-offs
Charge-offs		(29,481	)		(5,914	)		(8,320	)		(70,484	)		—			(114,199	)
Recoveries		11,232			1,660			3,310			22,047			—			38,249
Net charge-offs		(18,249	)		(4,254	)		(5,010	)		(48,437	)		—			(75,950	)
Ending balance	$	328,830			353,761			76,123			182,987			77,547		$	1,019,248

Impaired Loans and Leases

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

	June 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.	$	192,660		220,662		36,496		153,478		175,549		46,034
Real estate:
Commercial		63,236		70,777		8,276		110,253		125,117		11,937
Residential builder and developer		7,490		8,059		286		5,981		6,557		462
Other commercial construction		22,851		34,782		1,901		10,563		11,113		640
Residential		125,607		147,097		6,220		124,974		147,817		5,402
Residential — limited documentation		69,340		83,920		2,600		74,156		90,066		3,000
Consumer:
Home equity lines and loans		47,437		52,838		9,060		47,982		53,248		9,135
Recreational finance		5,701		9,248		1,178		6,138		9,163		1,261
Automobile		3,374		3,458		686		3,527		3,599		729
Other		4,832		8,175		974		5,203		8,380		1,046
		542,528		639,016		67,677		542,255		630,609		79,646
With no related allowance recorded:
Commercial, financial, leasing, etc.		73,247		77,171		—		105,507		136,128		—
Real estate:
Commercial		150,804		168,046		—		113,376		124,657		—
Residential builder and developer		4,555		4,602		—		2,593		2,602		—
Other commercial construction		9,918		10,313		—		11,710		11,880		—
Residential		17,530		23,155		—		15,379		20,496		—
Residential — limited documentation		5,397		9,344		—		5,631		9,796		—
		261,451		292,631		—		254,196		305,559		—
Total:
Commercial, financial, leasing, etc.		265,907		297,833		36,496		258,985		311,677		46,034
Real estate:
Commercial		214,040		238,823		8,276		223,629		249,774		11,937
Residential builder and developer		12,045		12,661		286		8,574		9,159		462
Other commercial construction		32,769		45,095		1,901		22,273		22,993		640
Residential		143,137		170,252		6,220		140,353		168,313		5,402
Residential — limited documentation		74,737		93,264		2,600		79,787		99,862		3,000
Consumer:
Home equity lines and loans		47,437		52,838		9,060		47,982		53,248		9,135
Recreational finance		5,701		9,248		1,178		6,138		9,163		1,261
Automobile		3,374		3,458		686		3,527		3,599		729
Other		4,832		8,175		974		5,203		8,380		1,046
Total	$	803,979		931,647		67,677		796,451		936,168		79,646

Interest Income Recognized on Impaired Loans

	Three Months Ended June 30, 2019						Three Months Ended June 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.	$	273,924		3,627		3,627		271,413		1,333		1,333
Real estate:
Commercial		214,775		2,032		2,032		168,224		3,811		3,811
Residential builder and developer		9,590		35		35		8,494		—		—
Other commercial construction		22,521		12		12		7,443		53		53
Residential		142,555		2,390		1,004		126,185		2,329		937
Residential — limited documentation		75,940		1,452		218		83,776		1,428		317
Consumer:
Home equity lines and loans		47,435		406		57		48,644		433		72
Recreational finance		5,808		125		4		1,480		65		3
Automobile		3,450		53		18		12,636		225		14
Other		5,026		142		5		1,586		23		—
Total	$	801,024		10,274		7,012		729,881		9,700		6,540

	Six Months Ended June 30, 2019						Six Months Ended June 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.	$	269,586		6,665		6,665		271,793		2,116		2,116
Real estate:
Commercial		220,075		3,123		3,123		175,035		6,958		6,958
Residential builder and developer		9,233		150		150		9,167		1,682		1,682
Other commercial construction		21,460		576		576		8,773		59		59
Residential		141,479		4,412		1,670		123,697		4,231		1,839
Residential — limited documentation		77,089		2,805		426		84,686		3,156		1,013
Consumer:
Home equity lines and loans		47,496		822		119		48,721		847		158
Recreational finance		5,917		267		8		1,469		128		5
Automobile		3,490		107		37		12,881		449		29
Other		5,122		264		9		1,623		45		1
Total	$	800,947		19,191		12,783		737,845		19,671		13,860

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)
June 30, 2019
Pass	$	22,112,126		25,213,055		1,476,023		7,024,168
Criticized accrual		1,095,549		788,678		196,891		253,690
Criticized nonaccrual		223,733		203,116		5,985		32,769
Total	$	23,431,408		26,204,849		1,678,899		7,310,627
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)
June 30, 2019
Individually evaluated for impairment	$	36,496		10,463		8,820		11,898	$	67,677
Collectively evaluated for impairment		299,359		332,833		45,666		199,322		877,180
Purchased impaired		—		—		6,525		—		6,525
Allocated	$	335,855		343,296		61,011		211,220		951,382
Unallocated										78,485
Total									$	1,029,867
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)
June 30, 2019
Individually evaluated for impairment	$	265,907		258,854		217,874		61,344	$	803,979
Collectively evaluated for impairment		23,165,499		34,921,561		16,226,800		14,497,194		88,811,054
Purchased impaired		2		13,960		249,063		—		263,025
Total	$	23,431,408		35,194,375		16,693,737		14,558,538	$	89,878,058
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

The table that follows summarizes the Company’s loan modification activities that were considered troubled debt restructurings for the three-month and six-month periods ended June 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 June 30, 2019	(Dollars in thousands)

Commercial, financial, leasing, etc.	24		$	2,597	$	667	$	—	$	—	$	1,891	$	2,558
Real estate:
Commercial		14		10,340		2,577		—		—		7,641		10,218
Other commercial construction		1		1,038		—		—		—		1,033		1,033
Residential		26		7,513		4,008		—		—		4,034		8,042
Residential — limited documentation		2		612		160		—		—		465		625
Consumer:
Home equity lines and loans		13		1,273		53		—		—		1,225		1,278
Recreational finance		1		15		15		—		—		—		15
Automobile		12		189		189		—		—		—		189
Total		93	$	23,577	$	7,669	$	—	$	—	$	16,289	$	23,958

Three Months Ended June 30, 2018

Commercial, financial, leasing, etc.		47	$	41,390	$	9,673	$	29	$	6,111	$	25,021	$	40,834
Real estate:
Commercial		28		7,200		7,376		175		394		—		7,945
Residential		30		7,951		2,814		—		—		5,766		8,580
Residential — limited documentation		3		584		200		—		—		458		658
Consumer:
Home equity lines and loans		10		555		—		—		—		559		559
Automobile		19		333		321		—		—		12		333
Total		137	$	58,013	$	20,384	$	204	$	6,505	$	31,816	$	58,909

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

					Post-modification (a)
Six Months Ended June 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.		89	$	33,212	$	7,141	$	—	$	—	$	26,161	$	33,302
Real estate:
Commercial		29		19,581		3,564		—		—		15,608		19,172
Residential builder and developer		2		1,330		1,068		—		—		—		1,068
Other commercial construction		2		1,456		—		—		—		1,399		1,399
Residential		43		11,329		5,759		—		—		6,307		12,066
Residential — limited documentation		3		848		399		—		—		465		864
Consumer:
Home equity lines and loans		20		1,749		90		—		—		1,679		1,769
Recreational finance		5		103		103		—		—		—		103
Automobile		32		506		469		—		—		37		506
Total		225	$	70,114	$	18,593	$	—	$	—	$	51,656	$	70,249

Six Months Ended June 30, 2018

Commercial, financial, leasing, etc.		103	$	89,384	$	45,346	$	653	$	6,111	$	38,068	$	90,178
Real estate:
Commercial		48		13,980		13,200		175		394		927		14,696
Other commercial construction		1		752		746		—		—		—		746
Residential		77		20,587		9,759		—		—		12,668		22,427
Residential — limited documentation		5		879		467		—		—		576		1,043
Consumer:
Home equity lines and loans		24		1,903		4		—		—		1,907		1,911
Recreational finance		2		49		49		—		—		—		49
Automobile		27		481		469		—		—		12		481
Total		287	$	128,015	$	70,040	$	828	$	6,505	$	54,158	$	131,531

(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:

	June 30,			December 31,
	2019			2018
	(In thousands)
Commercial leases:
Direct financings:
Lease payments receivable	$	1,188,750		$	1,155,464
Estimated residual value of leased assets		82,021			85,169
Unearned income		(107,409	)		(110,458	)
Investment in direct financings		1,163,362			1,130,175
Leveraged leases:
Lease payments receivable		82,828			85,007
Estimated residual value of leased assets		81,244			81,261
Unearned income		(32,774	)		(33,717	)
Investment in leveraged leases		131,298			132,551
Total investment in leases	$	1,294,660		$	1,262,726
Deferred taxes payable arising from leveraged leases	$	72,620		$	74,995

Minimum Future Lease Payments to be Received from Lease Financings

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

	(In thousands)
Twelve-month period ending June 30:
2020	$	356,518
2021		294,985
2022		223,456
2023		145,794
2024		105,567
Later years		145,258
	$	1,271,578

Significant accounting policies

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

Significant accounting policies

1. Significant accounting policies

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 16 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.

Loans and leases and the allowance for credit losses

6 Months Ended

Jun. 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 June 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)
June 30, 2019
Commercial, financial, leasing, etc.	$	23,177,367		26,974		3,332		—		2		223,733	$	23,431,408
Real estate:
Commercial		25,829,322		146,704		12,450		390		12,867		203,116		26,204,849
Residential builder and developer		1,665,951		6,495		—		—		468		5,985		1,678,899
Other commercial construction		7,217,573		55,060		4,600		—		625		32,769		7,310,627
Residential		13,206,787		462,391		321,810		5,981		172,718		210,922		14,380,609
Residential — limited documentation		2,067,375		81,857		—		—		76,345		87,551		2,313,128
Consumer:
Home equity lines and loans		4,562,840		29,972		—		4,360		—		66,927		4,664,099
Recreational finance		4,759,183		24,485		—		295		—		11,153		4,795,116
Automobile		3,639,155		70,177		—		—		—		20,170		3,729,502
Other		1,315,662		12,515		6,533		32,053		—		3,058		1,369,821
Total	$	87,441,215		916,630		348,725		43,079		263,025		865,384	$	89,878,058

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 $294 million and $205 million at June 30, 2019 and December 31, 2018, respectively. Commercial real estate loans held for sale were $504 million at June 30, 2019 and $347 million at December 31, 2018.

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

Outstanding principal balance	$	920,481	$	1,016,785
Carrying amount:
Commercial, financial, leasing, etc.		23,648		27,073
Commercial real estate		125,737		135,047
Residential real estate		415,242		473,511
Consumer		90,410		91,860
	$	655,037	$	727,491

Purchased impaired loans included in the table above totaled $263 million at June 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 six months ended June 30, 2019 and 2018 follows:

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

Balance at beginning of period	$	140,317		$	93,687		$	149,007		$	118,184
Interest income		(9,632	)		(9,666	)		(7,969	)		(15,394	)
Reclassifications from nonaccretable balance		16,419			3,457			8,350			10,998
Other (a)		—			3,433			—			3,927
Balance at end of period	$	147,104		$	90,911		$	149,388		$	117,715

	Six Months Ended June 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		(27,714	)		(19,383	)		(17,788	)		(30,506	)
Reclassifications from nonaccretable balance		27,608			8,322			9,258			11,205
Other (a)		—			5,065			—			3,854
Balance at end of period	$	147,104		$	90,911		$	149,388		$	117,715

(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 June 30, 2019 were as follows:

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

Beginning balance	$	335,620			337,995			65,136			203,045			77,541	$	1,019,337
Provision for credit losses		10,337			14,501			(2,376	)		31,594			944		55,000
Net charge-offs
Charge-offs		(16,608	)		(10,165	)		(3,263	)		(39,370	)		—		(69,406	)
Recoveries		6,506			965			1,514			15,951			—		24,936
Net charge-offs		(10,102	)		(9,200	)		(1,749	)		(23,419	)		—		(44,470	)
Ending balance	$	335,855			343,296			61,011			211,220			78,485	$	1,029,867

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

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

Beginning balance	$	326,071			367,717			73,047			173,841			78,995		$	1,019,671
Provision for credit losses		11,250			(10,845	)		5,242			30,801			(1,448	)		35,000
Net charge-offs
Charge-offs		(14,900	)		(4,548	)		(3,966	)		(34,033	)		—			(57,447	)
Recoveries		6,409			1,437			1,800			12,378			—			22,024
Net charge-offs		(8,491	)		(3,111	)		(2,166	)		(21,655	)		—			(35,423	)
Ending balance	$	328,830			353,761			76,123			182,987			77,547		$	1,019,248

Changes in the allowance for credit losses for the six months ended June 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		16,608			10,298			(4,823	)		54,477			440		77,000
Net charge-offs
Charge-offs		(25,108	)		(10,448	)		(6,635	)		(72,315	)		—		(114,506	)
Recoveries		14,300			1,791			3,344			28,494			—		47,929
Net charge-offs		(10,808	)		(8,657	)		(3,291	)		(43,821	)		—		(66,577	)
Ending balance	$	335,855			343,296			61,011			211,220			78,485	$	1,029,867

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

Changes in the allowance for credit losses for the six months ended June 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		18,480			(16,070	)		15,728			60,615			(753	)		78,000
Net charge-offs
Charge-offs		(29,481	)		(5,914	)		(8,320	)		(70,484	)		—			(114,199	)
Recoveries		11,232			1,660			3,310			22,047			—			38,249
Net charge-offs		(18,249	)		(4,254	)		(5,010	)		(48,437	)		—			(75,950	)
Ending balance	$	328,830			353,761			76,123			182,987			77,547		$	1,019,248

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

	June 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.	$	192,660		220,662		36,496		153,478		175,549		46,034
Real estate:
Commercial		63,236		70,777		8,276		110,253		125,117		11,937
Residential builder and developer		7,490		8,059		286		5,981		6,557		462
Other commercial construction		22,851		34,782		1,901		10,563		11,113		640
Residential		125,607		147,097		6,220		124,974		147,817		5,402
Residential — limited documentation		69,340		83,920		2,600		74,156		90,066		3,000
Consumer:
Home equity lines and loans		47,437		52,838		9,060		47,982		53,248		9,135
Recreational finance		5,701		9,248		1,178		6,138		9,163		1,261
Automobile		3,374		3,458		686		3,527		3,599		729
Other		4,832		8,175		974		5,203		8,380		1,046
		542,528		639,016		67,677		542,255		630,609		79,646
With no related allowance recorded:
Commercial, financial, leasing, etc.		73,247		77,171		—		105,507		136,128		—
Real estate:
Commercial		150,804		168,046		—		113,376		124,657		—
Residential builder and developer		4,555		4,602		—		2,593		2,602		—
Other commercial construction		9,918		10,313		—		11,710		11,880		—
Residential		17,530		23,155		—		15,379		20,496		—
Residential — limited documentation		5,397		9,344		—		5,631		9,796		—
		261,451		292,631		—		254,196		305,559		—
Total:
Commercial, financial, leasing, etc.		265,907		297,833		36,496		258,985		311,677		46,034
Real estate:
Commercial		214,040		238,823		8,276		223,629		249,774		11,937
Residential builder and developer		12,045		12,661		286		8,574		9,159		462
Other commercial construction		32,769		45,095		1,901		22,273		22,993		640
Residential		143,137		170,252		6,220		140,353		168,313		5,402
Residential — limited documentation		74,737		93,264		2,600		79,787		99,862		3,000
Consumer:
Home equity lines and loans		47,437		52,838		9,060		47,982		53,248		9,135
Recreational finance		5,701		9,248		1,178		6,138		9,163		1,261
Automobile		3,374		3,458		686		3,527		3,599		729
Other		4,832		8,175		974		5,203		8,380		1,046
Total	$	803,979		931,647		67,677		796,451		936,168		79,646

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

	Three Months Ended June 30, 2019						Three Months Ended June 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.	$	273,924		3,627		3,627		271,413		1,333		1,333
Real estate:
Commercial		214,775		2,032		2,032		168,224		3,811		3,811
Residential builder and developer		9,590		35		35		8,494		—		—
Other commercial construction		22,521		12		12		7,443		53		53
Residential		142,555		2,390		1,004		126,185		2,329		937
Residential — limited documentation		75,940		1,452		218		83,776		1,428		317
Consumer:
Home equity lines and loans		47,435		406		57		48,644		433		72
Recreational finance		5,808		125		4		1,480		65		3
Automobile		3,450		53		18		12,636		225		14
Other		5,026		142		5		1,586		23		—
Total	$	801,024		10,274		7,012		729,881		9,700		6,540

	Six Months Ended June 30, 2019						Six Months Ended June 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.	$	269,586		6,665		6,665		271,793		2,116		2,116
Real estate:
Commercial		220,075		3,123		3,123		175,035		6,958		6,958
Residential builder and developer		9,233		150		150		9,167		1,682		1,682
Other commercial construction		21,460		576		576		8,773		59		59
Residential		141,479		4,412		1,670		123,697		4,231		1,839
Residential — limited documentation		77,089		2,805		426		84,686		3,156		1,013
Consumer:
Home equity lines and loans		47,496		822		119		48,721		847		158
Recreational finance		5,917		267		8		1,469		128		5
Automobile		3,490		107		37		12,881		449		29
Other		5,122		264		9		1,623		45		1
Total	$	800,947		19,191		12,783		737,845		19,671		13,860

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)
June 30, 2019
Pass	$	22,112,126		25,213,055		1,476,023		7,024,168
Criticized accrual		1,095,549		788,678		196,891		253,690
Criticized nonaccrual		223,733		203,116		5,985		32,769
Total	$	23,431,408		26,204,849		1,678,899		7,310,627
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 $21 million, respectively, at June 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 $18 million and $31 million, respectively, at June 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)
June 30, 2019
Individually evaluated for impairment	$	36,496		10,463		8,820		11,898	$	67,677
Collectively evaluated for impairment		299,359		332,833		45,666		199,322		877,180
Purchased impaired		—		—		6,525		—		6,525
Allocated	$	335,855		343,296		61,011		211,220		951,382
Unallocated										78,485
Total									$	1,029,867
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)
June 30, 2019
Individually evaluated for impairment	$	265,907		258,854		217,874		61,344	$	803,979
Collectively evaluated for impairment		23,165,499		34,921,561		16,226,800		14,497,194		88,811,054
Purchased impaired		2		13,960		249,063		—		263,025
Total	$	23,431,408		35,194,375		16,693,737		14,558,538	$	89,878,058
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

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

Commercial, financial, leasing, etc.	24		$	2,597	$	667	$	—	$	—	$	1,891	$	2,558
Real estate:
Commercial		14		10,340		2,577		—		—		7,641		10,218
Other commercial construction		1		1,038		—		—		—		1,033		1,033
Residential		26		7,513		4,008		—		—		4,034		8,042
Residential — limited documentation		2		612		160		—		—		465		625
Consumer:
Home equity lines and loans		13		1,273		53		—		—		1,225		1,278
Recreational finance		1		15		15		—		—		—		15
Automobile		12		189		189		—		—		—		189
Total		93	$	23,577	$	7,669	$	—	$	—	$	16,289	$	23,958

Three Months Ended June 30, 2018

Commercial, financial, leasing, etc.		47	$	41,390	$	9,673	$	29	$	6,111	$	25,021	$	40,834
Real estate:
Commercial		28		7,200		7,376		175		394		—		7,945
Residential		30		7,951		2,814		—		—		5,766		8,580
Residential — limited documentation		3		584		200		—		—		458		658
Consumer:
Home equity lines and loans		10		555		—		—		—		559		559
Automobile		19		333		321		—		—		12		333
Total		137	$	58,013	$	20,384	$	204	$	6,505	$	31,816	$	58,909

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

					Post-modification (a)
Six Months Ended June 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.		89	$	33,212	$	7,141	$	—	$	—	$	26,161	$	33,302
Real estate:
Commercial		29		19,581		3,564		—		—		15,608		19,172
Residential builder and developer		2		1,330		1,068		—		—		—		1,068
Other commercial construction		2		1,456		—		—		—		1,399		1,399
Residential		43		11,329		5,759		—		—		6,307		12,066
Residential — limited documentation		3		848		399		—		—		465		864
Consumer:
Home equity lines and loans		20		1,749		90		—		—		1,679		1,769
Recreational finance		5		103		103		—		—		—		103
Automobile		32		506		469		—		—		37		506
Total		225	$	70,114	$	18,593	$	—	$	—	$	51,656	$	70,249

Six Months Ended June 30, 2018

Commercial, financial, leasing, etc.		103	$	89,384	$	45,346	$	653	$	6,111	$	38,068	$	90,178
Real estate:
Commercial		48		13,980		13,200		175		394		927		14,696
Other commercial construction		1		752		746		—		—		—		746
Residential		77		20,587		9,759		—		—		12,668		22,427
Residential — limited documentation		5		879		467		—		—		576		1,043
Consumer:
Home equity lines and loans		24		1,903		4		—		—		1,907		1,911
Recreational finance		2		49		49		—		—		—		49
Automobile		27		481		469		—		—		12		481
Total		287	$	128,015	$	70,040	$	828	$	6,505	$	54,158	$	131,531

(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 June 30, 2019 and 2018 and for which there was a subsequent payment default during the six-month periods ended June 30, 2019 and 2018, respectively, were not material.

The amount of foreclosed residential real estate property held by the Company was $72 million and $77 million at June 30, 2019 and December 31, 2018, respectively. There were $380 million and $391 million at June 30, 2019 and December 31, 2018, respectively, in loans secured by residential real estate that were in the process of foreclosure. Of all loans in the process of foreclosure at June 30, 2019, approximately 33% were classified as purchased impaired and 24% 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:

	June 30,			December 31,
	2019			2018
	(In thousands)
Commercial leases:
Direct financings:
Lease payments receivable	$	1,188,750		$	1,155,464
Estimated residual value of leased assets		82,021			85,169
Unearned income		(107,409	)		(110,458	)
Investment in direct financings		1,163,362			1,130,175
Leveraged leases:
Lease payments receivable		82,828			85,007
Estimated residual value of leased assets		81,244			81,261
Unearned income		(32,774	)		(33,717	)
Investment in leveraged leases		131,298			132,551
Total investment in leases	$	1,294,660		$	1,262,726
Deferred taxes payable arising from leveraged leases	$	72,620		$	74,995

Included within the estimated residual value of leased assets at June 30, 2019 and December 31, 2018 were $37 million and $39 million, respectively, in residual value associated with direct financing leases that are guaranteed by the lessees or others.

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

	(In thousands)
Twelve-month period ending June 30:
2020	$	356,518
2021		294,985
2022		223,456
2023		145,794
2024		105,567
Later years		145,258
	$	1,271,578

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Operating Leases - Summary of Minimum Lease Payments Under Noncancelable Operating Leases (Detail) $ in Thousands	Jun. 30, 2019 USD ($)
Leases [Abstract]
2020	$ 89,301
2021	87,300
2022	71,956
2023	57,685
2024	41,815
Later years	113,403
Total lease payments	461,460
Less: imputed interest	39,076
Lease liabilities	$ 422,384

Subsequent Events - Additional Information (Detail) - $ / shares	Aug. 30, 2019	Jul. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Preferred stock, par value			$ 1.00	$ 1.00
Scenario, Forecast [Member]
Subsequent Event [Line Items]
Preferred stock, liquidation preference per share	$ 1,000
Series G Perpetual Fixed-Rate Reset Non-cumulative Preferred Stock [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Preferred stock, shares issued		40,000
Preferred stock, par value		$ 1.00
Preferred stock, liquidation preference per share		$ 10,000
Preferred stock dividend rate		5.00%
Date of change in the dividend rate		Jul. 31, 2024
Dividend payment terms		five-year
U S treasury rate plus additional rate		3.174%
Preferred shares redemption date		Aug. 01, 2024
Preferred stock, redemption feature, redemption term		90 days
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member] \| Scenario, Forecast [Member]
Subsequent Event [Line Items]
Shares expects to redeem	230,000
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member] \| Scenario, Forecast [Member]
Subsequent Event [Line Items]
Shares expects to redeem	151,500

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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 140,317	$ 149,007	$ 147,210	$ 157,918
Interest income	(9,632)	(7,969)	(27,714)	(17,788)
Reclassifications from nonaccretable balance	16,419	8,350	27,608	9,258
Balance at end of period	147,104	149,388	147,104	149,388
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	93,687	118,184	96,907	133,162
Interest income	(9,666)	(15,394)	(19,383)	(30,506)
Reclassifications from nonaccretable balance	3,457	10,998	8,322	11,205
Other	3,433	3,927	5,065	3,854
Balance at end of period	$ 90,911	$ 117,715	$ 90,911	$ 117,715

Operating Leases (Tables)

6 Months Ended

Jun. 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

As of June 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:

	June 30, 2019
	(In thousands)

Right-of-use assets	$	395,659
Lease liabilities		422,384

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

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			Six Months Ended
	June 30, 2019			June 30, 2019
	(Dollars in thousands)
Lease cost
Operating lease cost	$	24,902		$	49,541
Short-term lease cost		28			62
Variable lease cost		623			1,089
Sublease income		(1,904	)		(3,821	)
Total net lease cost	$	23,649		$	46,871

Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	$	24,518		$	44,928
Cash paid toward lease liabilities		25,205			50,861
Weighted-average remaining lease term	7 years			7 years
Weighted-average discount rate		3.2	%		3.2	%

Summary of Minimum Lease Payments Under Noncancelable Operating Leases

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 June 30:
2020	$	89,301
2021		87,300
2022		71,956
2023		57,685
2024		41,815
Later years		113,403
Total lease payments	$	461,460
Less: imputed interest		39,076
Total	$	422,384

Operating Leases - Additional Information (Detail)	6 Months Ended
Operating Leases - Additional Information (Detail)	Jun. 30, 2019
Leases [Abstract]
Period of noncancelable operating lease in years	23 years

Investment securities (Tables)

6 Months Ended

Jun. 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)
June 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	431,334	$	17	$	1,538	$	429,813
Obligations of states and political subdivisions		1,015		3		3		1,015
Mortgage-backed securities:
Government issued or guaranteed		6,789,309		66,806		37,782		6,818,333
Privately issued		16		—		—		16
Other debt securities		137,771		1,118		7,726		131,163
		7,359,445		67,944		47,049		7,380,340
Investment securities held to maturity:
U.S. Treasury and federal agencies		946,782		1,547		—		948,329
Obligations of states and political subdivisions		5,415		32		—		5,447
Mortgage-backed securities:
Government issued or guaranteed		2,543,906		37,595		4,505		2,576,996
Privately issued		104,592		11,986		20,730		95,848
Other debt securities		3,538		—		—		3,538
		3,604,233		51,160		25,235		3,630,158
Total debt securities	$	10,963,678	$	119,104	$	72,284	$	11,010,498
Equity and other securities:
Readily marketable equity — at fair value	$	114,565	$	37,558	$	322	$	151,801
Other — at cost		443,875		—		—		443,875
Total equity and other securities	$	558,440	$	37,558	$	322	$	595,676

	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 June 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	$	429,891		428,384
Due after one year through five years		8,048		8,048
Due after five years through ten years		102,181		99,357
Due after ten years		30,000		26,202
		570,120		561,991
Mortgage-backed securities available for sale		6,789,325		6,818,349
	$	7,359,445		7,380,340
Debt securities held to maturity:
Due in one year or less	$	948,757		950,308
Due after one year through five years		3,440		3,468
Due after ten years		3,538		3,538
		955,735		957,314
Mortgage-backed securities held to maturity		2,648,498		2,672,844
	$	3,604,233		3,630,158

Investment Securities in Continuous Unrealized Loss Position

A summary of investment securities that as of June 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)
June 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	—		—			428,193		(1,538	)
Obligations of states and political subdivisions		—		—			457		(3	)
Mortgage-backed securities:
Government issued or guaranteed		4,795		(28	)		2,911,625		(37,754	)
Other debt securities		45,420		(474	)		67,921		(7,252	)
		50,215		(502	)		3,408,196		(46,547	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		—		—			318,799		(4,505	)
Privately issued		—		—			50,757		(20,730	)
		—		—			369,556		(25,235	)
Total	$	50,215		(502	)		3,777,752		(71,782	)

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	)

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net income	$ 956,002	$ 845,770
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	77,000	78,000
Depreciation and amortization of premises and equipment	101,983	54,092
Amortization of capitalized servicing rights	34,017	24,207
Amortization of core deposit and other intangible assets	10,097	13,020
Provision for deferred income taxes	15,817	(123,980)
Asset write-downs	52,324	5,237
Net gain on sales of assets	(10,521)	(8,738)
Net change in accrued interest receivable, payable	5,650	5,759
Net change in other accrued income and expense	(144,714)	255,124
Net change in loans originated for sale	(218,925)	(756,003)
Net change in trading account assets and liabilities	(398,552)	128,754
Net cash provided by operating activities	480,178	521,242
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale		418
Proceeds from sales of investment securities equity and other	580,489	505,841
Proceeds from maturities of investment securities Available for sale	1,506,273	950,071
Proceeds from maturities of investment securities Held to maturity	213,086	247,385
Purchases of investment securities Available for sale	(2,694)	(5,799)
Purchases of investment securities Held to maturity	(495,277)
Purchases of investment securities equity and other	(461,749)	(520,040)
Net (increase) decrease in loans and leases	(1,259,545)	859,071
Net increase in interest-bearing deposits at banks	(686,556)	(1,591,082)
Capital expenditures, net	(82,657)	(37,116)
Net decrease in loan servicing advances	23,663	262,947
Other, net	84,108	(8,708)
Net cash provided (used) by investing activities	(580,859)	662,988
Cash flows from financing activities
Net increase (decrease) in deposits	1,525,777	(3,157,898)
Net increase in short-term borrowings	213,012	3,064,317
Proceeds from long-term borrowings		999,594
Payments on long-term borrowings	(876,581)	(706,370)
Purchases of treasury stock	(767,612)	(1,196,062)
Dividends paid — common	(274,037)	(227,565)
Dividends paid — preferred	(36,260)	(36,260)
Other, net	(17,446)	24,220
Net cash used by financing activities	(233,147)	(1,236,024)
Net decrease in cash, cash equivalents and restricted cash	(333,828)	(51,794)
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	1,271,611	1,369,094
Supplemental disclosure of cash flow information
Interest received during the period	2,444,623	2,210,063
Interest paid during the period	361,179	218,731
Income taxes paid during the period	243,404	175,619
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	39,456	36,418
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	5,379	10,303
Securitization of residential mortgage loans allocated to capitalized servicing rights	83	$ 150
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	$ 44,928

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt securities available for sale:
Due in one year or less	$ 429,891
Due after one year through five years	8,048
Due after five years through ten years	102,181
Due after ten years	30,000
Total available for sale (amortized cost)	570,120
Mortgage-backed securities available for sale	6,789,325
Investment securities available for sale, amortized cost	7,359,445	$ 8,869,423
Debt securities held to maturity:
Due in one year or less	948,757
Due after one year through five years	3,440
Due after ten years	3,538
Total available for held to maturity (amortized cost)	955,735
Mortgage-backed securities held to maturity	2,648,498
Amortized cost for held to maturity	3,604,233	3,316,640
Debt securities available for sale:
Due in one year or less	428,384
Due after one year through five years	8,048
Due after five years through ten years	99,357
Due after ten years	26,202
Total available for sale (fair value)	561,991
Mortgage-backed securities available for sale	6,818,349
Total	7,380,340	8,682,509
Debt securities held to maturity:
Due in one year or less	950,308
Due after one year through five years	3,468
Due after ten years	3,538
Total available for held to maturity (fair value)	957,314
Mortgage-backed securities held to maturity	2,672,844
Total	$ 3,630,158	$ 3,255,483

Earnings per common share (Tables)

6 Months Ended

Jun. 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 June 30						Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands, except per share)

Income available to common shareholders:
Net income	$	473,260			493,160			956,002			845,770
Less: Preferred stock dividends (a)		(18,130	)		(18,130	)		(36,260	)		(36,260	)
Net income available to common equity		455,130			475,030			919,742			809,510
Less: Income attributable to unvested stock-based compensation awards		(2,498	)		(2,432	)		(5,024	)		(4,172	)
Net income available to common shareholders	$	452,632			472,598			914,718			805,338
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		136,182			145,571			137,403			147,510
Less: Unvested stock-based compensation awards		(749	)		(746	)		(749	)		(764	)
Weighted-average shares outstanding		135,433			144,825			136,654			146,746

Basic earnings per common share	$	3.34			3.26			6.69			5.49

(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 June 30						Six Months Ended June 30
	2019			2018			2019			2018
	(In thousands, except per share)

Net income available to common equity	$	455,130			475,030			919,742			809,510
Less: Income attributable to unvested stock-based compensation awards		(2,497	)		(2,430	)		(5,023	)		(4,168	)
Net income available to common shareholders	$	452,633			472,600			914,719			805,342
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards		136,182			145,571			137,403			147,510
Less: Unvested stock-based compensation awards		(749	)		(746	)		(749	)		(764	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		31			173			31			195
Adjusted weighted-average shares outstanding		135,464			144,998			136,685			146,941

Diluted earnings per common share	$	3.34			3.26			6.69			5.48

Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Commitments to extend credit
Home equity lines of credit	$ 5,489,356	$ 5,484,197
Commercial real estate loans to be sold	247,494	229,401
Other commercial real estate	7,771,353	7,556,722
Residential real estate loans to be sold	473,275	245,211
Other residential real estate	414,375	219,351
Commercial and other	15,188,645	14,363,803
Standby letters of credit	2,353,515	2,326,991
Commercial letters of credit	43,824	55,808
Financial guarantees and indemnification contracts	3,741,060	3,529,136
Commitments to sell real estate loans	$ 1,377,712	$ 940,692

Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 87,441,215	$ 86,140,950
30-89 Days Past Due	916,630	866,337
Accruing Loans Past Due 90 Days or More	348,725	222,527
Purchased Impaired	263,025	303,305
Nonaccrual	865,384	893,608
Loans and leases, net of unearned discount	89,878,058	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	43,079	39,750
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	23,177,367	22,701,020
30-89 Days Past Due	26,974	39,798
Accruing Loans Past Due 90 Days or More	3,332	2,567
Purchased Impaired	2
Nonaccrual	223,733	234,423
Loans and leases, net of unearned discount	23,431,408	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	25,829,322	25,250,983
30-89 Days Past Due	146,704	134,474
Accruing Loans Past Due 90 Days or More	12,450	11,457
Purchased Impaired	12,867	9,769
Nonaccrual	203,116	203,672
Loans and leases, net of unearned discount	26,204,849	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	390	10
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,665,951	1,665,178
30-89 Days Past Due	6,495	20,333
Purchased Impaired	468
Nonaccrual	5,985	4,798
Loans and leases, net of unearned discount	1,678,899	1,690,309
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	7,217,573	6,982,077
30-89 Days Past Due	55,060	43,615
Accruing Loans Past Due 90 Days or More	4,600	14,344
Purchased Impaired	625	641
Nonaccrual	32,769	22,205
Loans and leases, net of unearned discount	7,310,627	7,062,882
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	13,206,787	13,591,790
30-89 Days Past Due	462,391	404,808
Accruing Loans Past Due 90 Days or More	321,810	189,682
Purchased Impaired	172,718	203,044
Nonaccrual	210,922	233,352
Loans and leases, net of unearned discount	14,380,609	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	5,981	6,650
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	2,067,375	2,278,040
30-89 Days Past Due	81,857	72,544
Purchased Impaired	76,345	89,851
Nonaccrual	87,551	84,685
Loans and leases, net of unearned discount	2,313,128	2,525,120
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,562,840	4,758,513
30-89 Days Past Due	29,972	25,416
Nonaccrual	66,927	71,292
Loans and leases, net of unearned discount	4,664,099	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	4,360	5,033
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,759,183	4,085,781
30-89 Days Past Due	24,485	29,947
Nonaccrual	11,153	11,199
Loans and leases, net of unearned discount	4,795,116	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	295	235
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,639,155	3,555,757
30-89 Days Past Due	70,177	79,804
Nonaccrual	20,170	23,359
Loans and leases, net of unearned discount	3,729,502	3,658,920
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,315,662	1,271,811
30-89 Days Past Due	12,515	15,598
Accruing Loans Past Due 90 Days or More	6,533	4,477
Nonaccrual	3,058	4,623
Loans and leases, net of unearned discount	1,369,821	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	$ 32,053	$ 27,654

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	$ 479,403	$ 185,584
Investment securities	7,380,340	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	429,813	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	1,015	1,659
Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	6,818,333	7,216,991
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	131,163	126,906
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	479,403	185,584
Investment securities	7,380,340	8,682,509
Equity securities	151,801	93,917
Real estate loans held for sale	797,474	551,697
Other assets	18,661	19,626
Total assets	8,827,679	9,533,333
Trading account liabilities	73,392	178,125
Other liabilities	30,688	12,561
Total liabilities	104,080	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	47,344	46,018
Equity securities	109,377	71,989
Total assets	156,721	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	432,059	139,566
Investment securities	7,380,324	8,682,487
Equity securities	42,424	21,928
Real estate loans held for sale	797,474	551,697
Other assets	1,250	10,322
Total assets	8,653,531	9,406,000
Trading account liabilities	73,392	178,125
Other liabilities	30,477	10,969
Total liabilities	103,869	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	17,411	9,304
Total assets	17,427	9,326
Other liabilities	211	1,592
Total liabilities	211	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	429,813	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	429,813	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	1,015	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	1,015	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	6,818,333	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	6,818,333	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	131,163	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	$ 131,163	$ 126,906

Pension Plans and Other Postretirement Benefits - Net Periodic Defined Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,559	$ 5,069	$ 8,646	$ 10,172
Interest cost on projected benefit obligation	20,590	18,548	40,790	37,353
Expected return on plan assets	(30,470)	(30,688)	(61,070)	(61,563)
Amortization of prior service cost (credit)	154	153	279	278
Amortization of net actuarial loss (gain)	6,546	10,796	10,996	21,896
Net periodic cost (benefit)	1,379	3,878	(359)	8,136
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	229	243	429	469
Interest cost on projected benefit obligation	569	589	1,172	1,146
Amortization of prior service cost (credit)	(1,190)	(1,189)	(2,365)	(2,364)
Amortization of net actuarial loss (gain)	(323)	(213)	(623)	(413)
Net periodic cost (benefit)	$ (715)	$ (570)	$ (1,387)	$ (1,162)

Commitments and contingencies (Tables)

6 Months Ended

Jun. 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.

	June 30,		December 31,
	2019		2018
	(In thousands)
Commitments to extend credit
Home equity lines of credit	$	5,489,356		5,484,197
Commercial real estate loans to be sold		247,494		229,401
Other commercial real estate		7,771,353		7,556,722
Residential real estate loans to be sold		473,275		245,211
Other residential real estate		414,375		219,351
Commercial and other		15,188,645		14,363,803
Standby letters of credit		2,353,515		2,326,991
Commercial letters of credit		43,824		55,808
Financial guarantees and indemnification contracts		3,741,060		3,529,136
Commitments to sell real estate loans		1,377,712		940,692

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	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 67,677		$ 79,646
Allowance for credit losses	877,180		849,356
Allowance for credit losses	1,029,867	$ 1,019,337	1,019,444	$ 1,019,248	$ 1,019,671	$ 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	6,525		12,397
Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	951,382		941,399
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	78,485	$ 77,541	78,045	$ 77,547	$ 78,995	$ 78,300
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	36,496		46,034
Allowance for credit losses	299,359		284,021
Commercial, Financial, Leasing, etc. [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	335,855		330,055
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	10,463		13,039
Allowance for credit losses	332,833		328,616
Commercial Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	343,296		341,655
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	8,820		8,402
Allowance for credit losses	45,666		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	6,525		12,397
Residential Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	61,011		69,125
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	11,898		12,171
Allowance for credit losses	199,322		188,393
Consumer Loans [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 211,220		$ 200,564

Revenue from Contracts with Customers - Additional Information (Detail1)	Jun. 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

Investment securities

6 Months Ended

Jun. 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)
June 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	431,334	$	17	$	1,538	$	429,813
Obligations of states and political subdivisions		1,015		3		3		1,015
Mortgage-backed securities:
Government issued or guaranteed		6,789,309		66,806		37,782		6,818,333
Privately issued		16		—		—		16
Other debt securities		137,771		1,118		7,726		131,163
		7,359,445		67,944		47,049		7,380,340
Investment securities held to maturity:
U.S. Treasury and federal agencies		946,782		1,547		—		948,329
Obligations of states and political subdivisions		5,415		32		—		5,447
Mortgage-backed securities:
Government issued or guaranteed		2,543,906		37,595		4,505		2,576,996
Privately issued		104,592		11,986		20,730		95,848
Other debt securities		3,538		—		—		3,538
		3,604,233		51,160		25,235		3,630,158
Total debt securities	$	10,963,678	$	119,104	$	72,284	$	11,010,498
Equity and other securities:
Readily marketable equity — at fair value	$	114,565	$	37,558	$	322	$	151,801
Other — at cost		443,875		—		—		443,875
Total equity and other securities	$	558,440	$	37,558	$	322	$	595,676

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 six-month periods ended June 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 six months ended June 30, 2019 were $9 million and $21 million, respectively, compared with net unrealized gains of $2 million during the three months ended June 30, 2018 and net unrealized losses of $7 million during the six months ended June 30, 2018.

2. Investment securities, continued

At June 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	$	429,891		428,384
Due after one year through five years		8,048		8,048
Due after five years through ten years		102,181		99,357
Due after ten years		30,000		26,202
		570,120		561,991
Mortgage-backed securities available for sale		6,789,325		6,818,349
	$	7,359,445		7,380,340
Debt securities held to maturity:
Due in one year or less	$	948,757		950,308
Due after one year through five years		3,440		3,468
Due after ten years		3,538		3,538
		955,735		957,314
Mortgage-backed securities held to maturity		2,648,498		2,672,844
	$	3,604,233		3,630,158

2. Investment securities, continued

	Less Than 12 Months					12 Months or More
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(In thousands)
June 30, 2019
Investment securities available for sale:
U.S. Treasury and federal agencies	$	—		—			428,193		(1,538	)
Obligations of states and political subdivisions		—		—			457		(3	)
Mortgage-backed securities:
Government issued or guaranteed		4,795		(28	)		2,911,625		(37,754	)
Other debt securities		45,420		(474	)		67,921		(7,252	)
		50,215		(502	)		3,408,196		(46,547	)
Investment securities held to maturity:
Mortgage-backed securities:
Government issued or guaranteed		—		—			318,799		(4,505	)
Privately issued		—		—			50,757		(20,730	)
		—		—			369,556		(25,235	)
Total	$	50,215		(502	)		3,777,752		(71,782	)

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 801 individual debt securities with aggregate gross unrealized losses of $72 million at June 30, 2019. Based on a review of each of the securities in the investment securities portfolio at June 30, 2019, the Company concluded that it expected to recover the amortized cost basis of its investment. As of June 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 June 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 $444 million of cost method equity securities.

Segment information (Tables)

6 Months Ended

Jun. 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 June 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	$	140,767		1,004			42,250		$	136,029		912			43,007
Commercial Banking		278,110		887			123,507			269,499		928			126,391
Commercial Real Estate		225,442		406			121,629			205,541		385			112,691
Discretionary Portfolio		60,976		(9,291	)		38,040			58,976		(10,554	)		29,113
Residential Mortgage Banking		96,449		17,150			7,642			82,167		16,047			15,402
Retail Banking		436,593		2,787			140,494			420,540		2,707			143,089
All Other		315,239		(12,943	)		(302	)		293,449		(10,425	)		23,467
Total	$	1,553,576		—			473,260		$	1,466,201		—			493,160

	Six Months Ended June 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	$	280,089		1,860			85,521		$	263,913		1,830			80,725
Commercial Banking		545,600		1,727			255,725			535,895		1,778			251,856
Commercial Real Estate		444,615		760			239,127			408,148		725			220,994
Discretionary Portfolio		124,893		(18,590	)		77,212			109,014		(21,386	)		48,852
Residential Mortgage Banking		180,210		31,664			20,583			164,625		31,468			30,348
Retail Banking		867,484		5,298			285,560			814,016		5,572			266,469
All Other		661,510		(22,719	)		(7,726	)		604,803		(19,987	)		(53,474	)
Total	$	3,104,401		—			956,002		$	2,900,414		—			845,770

14. Segment information, continued

	Average Total Assets
	Six Months Ended June 30				Year Ended December 31
	2019		2018		2018
	(In millions)

Business Banking	$	5,724		5,656		5,631
Commercial Banking		27,981		26,542		26,626
Commercial Real Estate		23,720		22,848		22,885
Discretionary Portfolio		29,888		33,277		32,123
Residential Mortgage Banking		2,173		2,186		2,161
Retail Banking		14,580		13,403		13,656
All Other		13,601		13,109		13,877
Total	$	117,667		117,021		116,959

(a)

Earnings Per Common Share - Additional Information (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	115,293	212,244	197,598	224,844

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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 12,478	$ 12,629	$ 24,954	$ 26,021
Other revenues from operations:
Total other income	512,095	457,414	1,012,860	916,110
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	107,787	106,784	210,899	211,899
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	144,382	137,641	277,168	269,016
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	12,478	12,629	24,954	26,021
Other revenues from operations:
Merchant discount and credit card fees	28,688	26,062	53,826	50,834
Other	25,423	24,412	48,660	47,302
Total other income	318,758	307,528	615,507	605,072
ASU 2014-09 [Member] \| Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	9,895	8,334	18,777	15,837
Total other income	25,077	23,945	49,073	46,852
ASU 2014-09 [Member] \| Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	13,129	12,542	25,221	25,254
Other	3,145	3,646	4,147	5,209
Total other income	39,592	40,458	76,110	79,387
ASU 2014-09 [Member] \| Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	496	428	1,102	982
Other	2,680	2,215	4,468	3,074
Total other income	5,538	5,094	10,458	9,271
ASU 2014-09 [Member] \| Discretionary Portfolio [Member]
Other revenues from operations:
Other	641	413	1,042	865
Total other income	641	413	1,042	865
ASU 2014-09 [Member] \| Residential Mortgage Banking [Member]
Other revenues from operations:
Other	1,033	927	2,097	1,970
Total other income	1,035	930	2,101	1,976
ASU 2014-09 [Member] \| Retail Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	4,566	4,140	7,704	7,528
Other	9,329	9,613	17,823	19,478
Total other income	79,556	76,768	152,339	150,622
ASU 2014-09 [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	12,478	12,629	24,954	26,021
Other revenues from operations:
Merchant discount and credit card fees	602	618	1,022	1,233
Other	8,595	7,598	19,083	16,706
Total other income	167,319	159,920	324,384	316,099
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	107,787	106,784	210,899	211,899
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Business Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	15,175	15,611	30,284	31,015
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	23,094	24,270	46,304	48,924
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Commercial Real Estate [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	2,362	2,451	4,888	5,215
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	3	4	6
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| Retail Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	65,661	63,015	126,812	123,616
ASU 2014-09 [Member] \| Service Charges on Deposit Accounts [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1,493	1,434	2,607	3,123
ASU 2014-09 [Member] \| Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	144,382	137,641	277,168	269,016
ASU 2014-09 [Member] \| Trust Income [Member] \| Business Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	7		12
ASU 2014-09 [Member] \| Trust Income [Member] \| Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	224		438
ASU 2014-09 [Member] \| Trust Income [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 144,151	$ 137,641	$ 276,718	$ 269,016

Revenue from contracts with customers (Tables)

6 Months Ended

Jun. 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 June 30, 2019	(In thousands)

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,175		23,094		2,362		—		2		65,661		1,493	$	107,787
Trust income		7		224		—		—		—		—		144,151		144,382
Brokerage services income		—		—		—		—		—		—		12,478		12,478
Other revenues from operations:
Merchant discount and credit card fees		9,895		13,129		496		—		—		4,566		602		28,688
Other		—		3,145		2,680		641		1,033		9,329		8,595		25,423
	$	25,077		39,592		5,538		641		1,035		79,556		167,319	$	318,758
Three Months Ended June 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	15,611		24,270		2,451		—		3		63,015		1,434	$	106,784
Trust income		—		—		—		—		—		—		137,641		137,641
Brokerage services income		—		—		—		—		—		—		12,629		12,629
Other revenues from operations:
Merchant discount and credit card fees		8,334		12,542		428		—		—		4,140		618		26,062
Other		—		3,646		2,215		413		927		9,613		7,598		24,412
	$	23,945		40,458		5,094		413		930		76,768		159,920	$	307,528

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

Classification in consolidated statement of income
Service charges on deposit accounts		30,284		46,304		4,888		—		4		126,812		2,607		210,899
Trust income		12		438		—		—		—		—		276,718		277,168
Brokerage services income		—		—		—		—		—		—		24,954		24,954
Other revenues from operations:
Merchant discount and credit card fees		18,777		25,221		1,102		—		—		7,704		1,022		53,826
Other		—		4,147		4,468		1,042		2,097		17,823		19,083		48,660
	$	49,073		76,110		10,458		1,042		2,101		152,339		324,384	$	615,507
Six Months Ended June 30, 2018

Classification in consolidated statement of income
Service charges on deposit accounts	$	31,015		48,924		5,215		—		6		123,616		3,123	$	211,899
Trust income		—		—		—		—		—		—		269,016		269,016
Brokerage services income		—		—		—		—		—		—		26,021		26,021
Other revenues from operations:
Merchant discount and credit card fees		15,837		25,254		982		—		—		7,528		1,233		50,834
Other		—		5,209		3,074		865		1,970		19,478		16,706		47,302
	$	46,852		79,387		9,271		865		1,976		150,622		316,099	$	605,072

Operating Leases

6 Months Ended

Jun. 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.

	June 30, 2019
	(In thousands)

Right-of-use assets	$	395,659
Lease liabilities		422,384

The Company’s noncancelable operating lease agreements expire at various dates over the next 23 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

	Three Months Ended			Six Months Ended
	June 30, 2019			June 30, 2019
	(Dollars in thousands)
Lease cost
Operating lease cost	$	24,902		$	49,541
Short-term lease cost		28			62
Variable lease cost		623			1,089
Sublease income		(1,904	)		(3,821	)
Total net lease cost	$	23,649		$	46,871

Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	$	24,518		$	44,928
Cash paid toward lease liabilities		25,205			50,861
Weighted-average remaining lease term	7 years			7 years
Weighted-average discount rate		3.2	%		3.2	%

	(In thousands)
Twelve-month period ending June 30:
2020	$	89,301
2021		87,300
2022		71,956
2023		57,685
2024		41,815
Later years		113,403
Total lease payments	$	461,460
Less: imputed interest		39,076
Total	$	422,384

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

Loans and Leases and the Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Loans And Leases Receivable [Line Items]
Commercial real estate loans held for sale	$ 504	$ 347
Contractual principal and interest payments	$ 263	303
Minimum delinquency period for loan level collectability analysis consumer mortgage	150 days
Amount of foreclosed residential real estate property held	$ 72	77
Loans secured by residential real estate that were in the process of foreclosure	$ 380	391
Percentage loans in the process of foreclosure, serviced by other entities, classified as purchased impaired	33.00%
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	24.00%
Guaranteed amount included in the estimated residual value of leased assets associated with direct financing leases	$ 37	$ 39
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	$ 294	$ 205
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	18	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	21	23
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount	$ 31	$ 31

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Recognized right of use asset	$ 395,659
Recognizing lease liabilities	$ 422,384
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

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 425,121	$ 148,862
Liability Derivatives, Fair Value	104,080	190,686
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	424,386	142,242
Liability Derivatives, Fair Value	81,623	184,252
Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	735	6,620
Liability Derivatives, Fair Value	22,457	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	70	5,530
Liability Derivatives, Fair Value	5,850
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	515	3,702
Liability Derivatives, Fair Value	8,020	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	665	1,090
Liability Derivatives, Fair Value	16,607	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	17,411	9,304
Liability Derivatives, Fair Value	211	1,592
Interest Rate Contracts [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	399,155	118,687
Liability Derivatives, Fair Value	66,897	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	7,305	10,549
Liability Derivatives, Fair Value	$ 6,495	$ 8,870

Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Segment Reporting Information [Line Items]
Average Total Assets	$ 117,667	$ 116,959	$ 117,021
Business Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	5,724	5,631	5,656
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	27,981	26,626	26,542
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average Total Assets	23,720	22,885	22,848
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Average Total Assets	29,888	32,123	33,277
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	2,173	2,161	2,186
Retail Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	14,580	13,656	13,403
All Other [Member]
Segment Reporting Information [Line Items]
Average Total Assets	$ 13,601	$ 13,877	$ 13,109

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 39,200,000,000		$ 39,200,000,000		$ 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	25,000,000		25,000,000		18,000,000
Aggregate fair value of derivative financial instruments in a liability position	52,000,000		52,000,000		21,000,000
Net liability positions with counterparties	52,000,000		52,000,000		21,000,000
Aggregate fair value of derivative financial instruments in asset position	4,000,000		4,000,000		18,000,000
Net fair value of derivative financial instruments in a net asset position	4,000,000		4,000,000		18,000,000
Collateral relating to net asset positions	2,000,000		2,000,000		16,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	48,000,000		48,000,000		18,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	98,000,000		98,000,000		65,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	(11,000,000)	$ (5,000,000)	(24,000,000)	$ (4,000,000)
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	44,400,000,000		44,400,000,000		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	949,000,000		949,000,000		$ 763,000,000
Credit Risk Derivative [Member]
Derivative [Line Items]
Fair value of additional collateral to be posted for derivative financial instruments	$ 0		$ 0