Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2016	Apr. 22, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q1
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 Common Stock, Shares Outstanding		158,999,014

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets
Cash and due from banks	$ 1,178,175	$ 1,368,040
Interest-bearing deposits at banks	9,545,181	7,594,350
Trading account	467,987	273,783
Investment securities (includes pledged securities that can be sold or repledged of $2,133,492 at March 31, 2016; $2,136,712 at December 31, 2015)
Available for sale (cost: $11,937,326 at March 31, 2016; $12,138,636 at December 31, 2015)	12,200,647	12,242,671
Held to maturity (fair value: $2,769,343 at March 31, 2016; $2,864,147 at December 31, 2015)	2,730,611	2,859,709
Other (fair value: $536,062 at March 31, 2016; $554,059 at December 31, 2015)	536,062	554,059
Total investment securities	15,467,320	15,656,439
Loans and leases	88,104,830	87,719,234
Unearned discount	(232,364)	(229,735)
Loans and leases, net of unearned discount	87,872,466	87,489,499
Allowance for credit losses	(962,752)	(955,992)
Loans and leases, net	86,909,714	86,533,507
Premises and equipment	662,891	666,682
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	127,949	140,268
Accrued interest and other assets	5,673,303	5,961,703
Total assets	124,625,632	122,787,884
Liabilities
Noninterest-bearing deposits	29,709,218	29,110,635
Interest-checking deposits	2,848,126	2,939,274
Savings deposits	48,649,114	46,627,370
Time deposits	12,841,331	13,110,392
Deposits at Cayman Islands office	166,787	170,170
Total deposits	94,214,576	91,957,841
Federal funds purchased and agreements to repurchase securities	206,709	150,546
Other short-term borrowings	1,560,117	1,981,636
Accrued interest and other liabilities	1,948,142	1,870,714
Long-term borrowings	10,341,035	10,653,858
Total liabilities	108,270,579	106,614,595
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 March 31, 2016 and December 31, 2015; Liquidation preference of $10,000 per share: 50,000 shares at March 31, 2016 and December 31, 2015	1,231,500	1,231,500
Common stock, $.50 par, 250,000,000 shares authorized, 159,963,737 shares issued at March 31, 2016; 159,563,512 shares issued at December 31, 2015	79,982	79,782
Common stock issuable, 33,391 shares at March 31, 2016; 36,644 shares at December 31, 2015	2,180	2,364
Additional paid-in capital	6,683,499	6,680,768
Retained earnings	8,596,752	8,430,502
Accumulated other comprehensive income (loss), net	(150,189)	(251,627)
Treasury stock - common, at cost - 841,082 shares at March 31, 2016	(88,671)
Total shareholders' equity	16,355,053	16,173,289
Total liabilities and shareholders' equity	$ 124,625,632	$ 122,787,884

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Pledged securities that can be sold or repledged	$ 2,133,492	$ 2,136,712
Investment securities, available for sale, amortized cost	11,937,326	12,138,636
Investment securities, held to maturity, fair value	2,769,343	2,864,147
Other, fair value	$ 536,062	$ 554,059
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	159,963,737	159,563,512
Common stock issuable, shares	33,391	36,644
Treasury stock, shares	841,082
Series A and Series C [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 D 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 Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Interest income
Loans and leases, including fees	$ 863,385	$ 647,179
Investment securities
Fully taxable	98,015	85,957
Exempt from federal taxes	795	1,318
Deposits at banks	10,337	3,118
Other	302	515
Total interest income	972,834	738,087
Interest expense
Interest-checking deposits	414	311
Savings deposits	15,891	10,219
Time deposits	24,322	3,740
Deposits at Cayman Islands office	193	147
Short-term borrowings	2,162	34
Long-term borrowings	57,888	64,048
Total interest expense	100,870	78,499
Net interest income	871,964	659,588
Provision for credit losses	49,000	38,000
Net interest income after provision for credit losses	822,964	621,588
Other income
Mortgage banking revenues	82,063	101,601
Service charges on deposit accounts	102,405	102,344
Trust income	111,077	123,734
Brokerage services income	16,004	15,461
Trading account and foreign exchange gains	7,458	6,231
Gain (loss) on bank investment securities	4	(98)
Other revenues from operations	101,922	90,930
Total other income	420,933	440,203
Other expense
Salaries and employee benefits	431,785	389,893
Equipment and net occupancy	74,178	66,470
Printing, postage and supplies	11,986	9,590
Amortization of core deposit and other intangible assets	12,319	6,793
FDIC assessments	25,225	10,660
Other costs of operations	220,602	202,969
Total other expense	776,095	686,375
Income before taxes	467,802	375,416
Income taxes	169,274	133,803
Net income	298,528	241,613
Net income available to common shareholders
Basic	275,744	218,830
Diluted	$ 275,748	$ 218,837
Net income per common share
Basic	$ 1.74	$ 1.66
Diluted	1.73	1.65
Cash dividends per common share	$ 0.70	$ 0.70
Average common shares outstanding
Basic	158,734	132,049
Diluted	159,181	132,769

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Partners' Capital [Abstract]
Net income	$ 298,528	$ 241,613
Other comprehensive income, net of tax and reclassification adjustments:
Net unrealized gains on investment securities	97,194	25,339
Cash flow hedges adjustments	(24)	871
Foreign currency translation adjustment	(53)	(2,384)
Defined benefit plans liability adjustments	4,321	4,677
Total other comprehensive income	101,438	28,503
Total comprehensive income	$ 399,966	$ 270,116

- Definition

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

+ References + Details

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities
Net income	$ 298,528	$ 241,613
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	49,000	38,000
Depreciation and amortization of premises and equipment	27,141	24,178
Amortization of capitalized servicing rights	12,249	12,199
Amortization of core deposit and other intangible assets	12,319	6,793
Provision for deferred income taxes	50,075	37,052
Asset write-downs	8,940	2,379
Net gain on sales of assets	(5,399)	(1,066)
Net change in accrued interest receivable, payable	(16,530)	(2,200)
Net change in other accrued income and expense	70,766	(80,084)
Net change in loans originated for sale	211	197,708
Net change in trading account assets and liabilities	(59,080)	(18,206)
Net cash provided by operating activities	448,220	458,366
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale	518	693
Proceeds from sales of investment securities Other	18,121	132
Proceeds from maturities of investment securities Available for sale	511,549	369,649
Proceeds from maturities of investment securities Held to maturity	132,636	148,708
Purchases of investment securities Available for sale	(311,302)	(1,871,491)
Purchases of investment securities Held to maturity	(5,343)	(7,442)
Purchases of investment securities Other	(124)	(348)
Net increase in loans and leases	(439,712)	(666,220)
Net (increase) decrease in interest-bearing deposits at banks	(1,950,831)	179,376
Capital expenditures, net	(16,307)	(9,598)
Net decrease in loan servicing advances	37,600	76,145
Other, net	7,920	(21,940)
Net cash used by investing activities	(2,015,275)	(1,802,336)
Cash flows from financing activities
Net increase (decrease) in deposits	2,264,623	(4,543)
Net increase (decrease) in short-term borrowings	(343,838)	819
Proceeds from long-term borrowings		1,500,000
Payments on long-term borrowings	(317,187)	(1,797)
Purchases of treasury stock	(100,000)
Dividends paid - common	(112,000)	(93,631)
Dividends paid - preferred	(17,368)	(17,368)
Other, net	2,960	(46,014)
Net cash provided by financing activities	1,377,190	1,337,466
Net decrease in cash and cash equivalents	(189,865)	(6,504)
Cash and cash equivalents at beginning of period	1,368,040	1,373,357
Cash and cash equivalents at end of period	1,178,175	1,366,853
Supplemental disclosure of cash flow information
Interest received during the period	968,223	726,475
Interest paid during the period	146,568	75,776
Income taxes paid (refunded) during the period	(86,146)	88,578
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	33,737	10,846
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	8,452	12,920
Securitization of residential mortgage loans allocated to capitalized servicing rights	$ 92	$ 143

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series A Warrants [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series A Warrants [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2014	$ 12,335,896	$ 1,231,500	$ 66,157		$ 2,608	$ 3,409,506		$ 7,807,119	$ (180,994)
Total comprehensive income	270,116							241,613	28,503
Preferred stock cash dividends	(20,318)							(20,318)
Exercise of stock warrants into common stock				$ 1			$ (1)
Stock-based compensation plans:
Compensation expense, net	5,572		147			5,425
Exercises of stock options, net	19,479		101			19,378
Stock purchase plan	10,346		45			10,301
Directors' stock plan	425		2			423
Deferred compensation plans, net, including dividend equivalents	(51)		2		(298)	270		(25)
Other	405					405
Common stock cash dividends - $.70 per share	(93,569)							(93,569)
Ending balance at Mar. 31, 2015	12,528,301	1,231,500	66,455		2,310	3,445,707		7,934,820	(152,491)
Beginning balance at Dec. 31, 2015	16,173,289	1,231,500	79,782		2,364	6,680,768		8,430,502	(251,627)
Total comprehensive income	399,966							298,528	101,438
Preferred stock cash dividends	(20,318)							(20,318)
Purchases of treasury stock	(100,000)									$ (100,000)
Stock-based compensation plans:
Compensation expense, net	(55)		178			(978)				745
Exercises of stock options, net	2,618		18			2,335				265
Stock purchase plan	10,594					275				10,319
Directors' stock plan	473		2			471
Deferred compensation plans, net, including dividend equivalents	29		2		(184)	234		(23)
Other	394					394
Common stock cash dividends - $.70 per share	(111,937)							(111,937)
Ending balance at Mar. 31, 2016	$ 16,355,053	$ 1,231,500	$ 79,982		$ 2,180	$ 6,683,499		$ 8,596,752	$ (150,189)	$ (88,671)

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Common stock per share dividend amount	$ 0.70	$ 0.70
Common Stock [Member] \| Series A Warrants [Member]
Exercise of warrants into shares of common stock		2,315
Exercise of warrants into shares of common stock		904
Retained Earnings [Member]
Common stock per share dividend amount	$ 0.70	$ 0.70

Significant accounting policies

3 Months Ended

Mar. 31, 2016

Accounting Policies [Abstract]

Significant accounting policies

1.	Significant accounting policies

The consolidated 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, 2015 (“2015 Annual Report”). In the opinion of management, all adjustments necessary for a fair presentation have been made and were all of a normal recurring nature.

Acquisition

3 Months Ended

Mar. 31, 2016

Business Combinations [Abstract]

Acquisition

2.	Acquisition

On November 1, 2015, M&T completed the acquisition of Hudson City Bancorp, Inc. (“Hudson City”), headquartered in Paramus, New Jersey. On that date, Hudson City Savings Bank, the banking subsidiary of Hudson City, was merged into M&T Bank, a wholly owned banking subsidiary of M&T. Hudson City Savings Bank operated 135 banking offices in New Jersey, Connecticut and New York at the date of acquisition. The results of operations acquired in the Hudson City transaction have been included in the Company’s financial results since November 1, 2015. After application of the election, allocation and proration procedures contained in the merger agreement with Hudson City, M&T paid $2.1 billion in cash and issued 25,953,950 shares of M&T common stock in exchange for Hudson City shares outstanding at the time of the acquisition. The purchase price was approximately $5.2 billion based on the cash paid to Hudson City shareholders, the fair value of M&T stock exchanged and the estimated fair value of Hudson City stock awards converted into M&T stock awards. The acquisition of Hudson City expanded the Company’s presence in New Jersey, Connecticut and New York, and management expects that the Company will benefit from greater geographic diversity and the advantages of scale associated with a larger company.

The Hudson City transaction has been accounted for using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed and consideration exchanged were recorded at estimated fair value on the acquisition date. The consideration paid for Hudson City’s common equity and the amounts of identifiable assets acquired and liabilities assumed as of the acquisition date were as follows:


	(in thousands)
Identifiable assets:
Cash and due from banks	$	131,688
Interest-bearing deposits at banks		7,568,934
Investment securities		7,929,014
Loans		19,015,013
Goodwill		1,079,787
Core deposit intangible		131,665
Other assets		843,219

Total identifiable assets		36,699,320


Liabilities:
Deposits		17,879,589
Borrowings		13,211,598
Other liabilities		405,025

Total liabilities		31,496,212

Total consideration	$	5,203,108


Cash paid	$	2,064,284
Common stock issued (25,953,950 shares)		3,110,581
Common stock awards converted		28,243

Total consideration	$	5,203,108

In early November 2015, the Company sold $5.8 billion of investment securities obtained in the acquisition and repaid $10.6 billion of borrowings assumed in the transaction. In connection with the acquisition, the Company recorded approximately $1.1 billion of goodwill and $132 million of core deposit intangible. The core deposit intangible asset is being amortized over a period of 7 years using an accelerated method.

The following table presents certain pro forma information as if Hudson City had been included in the Company’s results of operations in the first quarter of 2015. These results combine the historical results of Hudson City into the Company’s consolidated statement of income and, while certain adjustments were made for the estimated impact of certain fair valuation adjustments and other acquisition-related activity, they are not indicative of what would have occurred had the acquisition taken place as indicated. In particular, no adjustments have been made to eliminate the impact of gains on securities transactions of $7 million during the three months ended March 31, 2015 that may not have been recognized had the investment securities been recorded at fair value. Additionally, the Company expects to achieve operating cost savings and other business synergies as a result of the acquisition which are not reflected in the pro forma amounts that follow.


	Pro forma Three months ended March 31, 2015
	(in thousands)

Total revenues(a)	$	1,253,445
Net income		285,237

(a)

Represents net interest income plus other income.

In connection with the Hudson City acquisition, the Company incurred merger-related expenses related to systems conversions and other costs of integrating and conforming acquired operations with and into the Company. Those expenses consisted largely of professional services and other temporary help fees associated with preparing for systems conversions and/or integration of operations; costs related to termination of existing contractual arrangements for various services; initial marketing and promotion expenses designed to introduce M&T Bank to its new customers; severance (for former Hudson City employees); travel costs; and other costs of completing the transaction and commencing operations in new markets and offices. The Company expects that there will be additional merger-related expenses in 2016.

A summary of merger-related expenses included in the consolidated statement of income follows:


	Three months ended March 31, 2016
	(in thousands)

Salaries and employee benefits	$	5,274
Equipment and net occupancy		939
Printing, postage and supplies		937
Other cost of operations		16,012

Total	$	23,162

There were no merger-related expenses during the first quarter of 2015.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

Investment securities

3 Months Ended

Mar. 31, 2016

Investments, Debt and Equity Securities [Abstract]

Investment securities

3.	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)
March 31, 2016
Investment securities available for sale:
U.S. Treasury and federal agencies	$	201,002		1,197		7	$	202,192
Obligations of states and political subdivisions		5,356		138		46		5,448
Mortgage-backed securities:
Government issued or guaranteed		11,490,181		265,879		5,998		11,750,062
Privately issued		65		2		2		65
Collateralized debt obligations		28,483		18,170		1,613		45,040
Other debt securities		136,968		1,407		25,667		112,708
Equity securities		75,271		10,225		364		85,132

		11,937,326		297,018		33,697		12,200,647


Investment securities held to maturity:
Obligations of states and political subdivisions		103,408		886		332		103,962
Mortgage-backed securities:
Government issued or guaranteed		2,445,563		78,448		2,070		2,521,941
Privately issued		175,467		1,848		40,048		137,267
Other debt securities		6,173		—		—		6,173

		2,730,611		81,182		42,450		2,769,343

Other securities		536,062		—		—		536,062

Total	$	15,203,999		378,200		76,147	$	15,506,052


	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
	(in thousands)
December 31, 2015
Investment securities available for sale:
U.S. Treasury and federal agencies	$	299,890		294		187	$	299,997
Obligations of states and political subdivisions		5,924		146		42		6,028
Mortgage-backed securities:
Government issued or guaranteed		11,592,959		142,370		48,701		11,686,628
Privately issued		74		2		2		74
Collateralized debt obligations		28,438		20,143		1,188		47,393
Other debt securities		137,556		1,514		20,190		118,880
Equity securities		73,795		10,230		354		83,671

		12,138,636		174,699		70,664		12,242,671

Investment securities held to maturity:
Obligations of states and political subdivisions		118,431		1,003		421		119,013
Mortgage-backed securities:
Government issued or guaranteed		2,553,612		50,936		7,817		2,596,731
Privately issued		181,091		2,104		41,367		141,828
Other debt securities		6,575		—		—		6,575

		2,859,709		54,043		49,605		2,864,147

Other securities		554,059		—		—		554,059

Total	$	15,552,404		228,742		120,269	$	15,660,877

There were no significant gross realized gains or losses from sales of investment securities for the quarters ended March 31, 2016 and 2015.

At March 31, 2016, 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	$	7,504		7,551
Due after one year through five years		201,714		203,128
Due after five years through ten years		2,728		2,926
Due after ten years		159,863		151,783

		371,809		365,388
Mortgage-backed securities available for sale		11,490,246		11,750,127

	$	11,862,055		12,115,515


Debt securities held to maturity:
Due in one year or less	$	32,387		32,542
Due after one year through five years		64,484		64,760
Due after five years through ten years		6,537		6,660
Due after ten years		6,173		6,173

		109,581		110,135
Mortgage-backed securities held to maturity		2,621,030		2,659,208

	$	2,730,611		2,769,343

A summary of investment securities that as of March 31, 2016 and December 31, 2015 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)
March 31, 2016
Investment securities available for sale:
U.S. Treasury and federal agencies	$	4,051		(7	)		—		—
Obligations of states and political subdivisions		—		—			1,706		(46	)
Mortgage-backed securities:
Government issued or guaranteed		337,672		(1,959	)		1,233,329		(4,039	)
Privately issued		—		—			34		(2	)
Collateralized debt obligations		10,326		(527	)		1,858		(1,086	)
Other debt securities		9,825		(1,203	)		88,715		(24,464	)
Equity securities		2,115		(210	)		146		(154	)

		363,989		(3,906	)		1,325,788		(29,791	)


Investment securities held to maturity:
Obligations of states and political subdivisions		28,707		(215	)		8,813		(117	)
Mortgage-backed securities:
Government issued or guaranteed		812		(12	)		232,432		(2,058	)
Privately issued		—		—			105,355		(40,048	)

		29,519		(227	)		346,600		(42,223	)

Total	$	393,508		(4,133	)		1,672,388		(72,014	)


December 31, 2015
Investment securities available for sale:
U.S. Treasury and federal agencies	$	147,508		(187	)		—		—
Obligations of states and political subdivisions		865		(2	)		1,335		(40	)
Mortgage-backed securities:
Government issued or guaranteed		4,061,899		(48,534	)		7,216		(167	)
Privately issued		—		—			43		(2	)
Collateralized debt obligations		5,711		(335	)		2,063		(853	)
Other debt securities		12,935		(462	)		93,344		(19,728	)
Equity securities		18,073		(207	)		153		(147	)

		4,246,991		(49,727	)		104,154		(20,937	)


Investment securities held to maturity:
Obligations of states and political subdivisions		42,913		(335	)		5,853		(86	)
Mortgage-backed securities:
Government issued or guaranteed		459,983		(1,801	)		228,867		(6,016	)
Privately issued		—		—			112,155		(41,367	)

		502,896		(2,136	)		346,875		(47,469	)

Total	$	4,749,887		(51,863	)		451,029		(68,406	)

The Company owned 538 individual investment securities with aggregate gross unrealized losses of $76 million at March 31, 2016. Based on a review of each of the securities in the investment securities portfolio at March 31, 2016, the Company concluded that it expected to recover the amortized cost basis of its investment. As of March 31, 2016, 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 March 31, 2016, the Company has not identified events or changes in circumstances which may have a significant adverse effect on the fair value of the $536 million of cost method investment securities.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Loans and leases and the allowance for credit losses

3 Months Ended

Mar. 31, 2016

Receivables [Abstract]

Loans and leases and the allowance for credit losses

4.	Loans and leases and the allowance for credit losses

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


	March 31, 2016		December 31, 2015
	(in thousands)

Outstanding principal balance	$	2,918,333		3,122,935
Carrying amount:
Commercial, financial, leasing, etc.		71,577		78,847
Commercial real estate		588,983		644,284
Residential real estate		964,893		1,016,129
Consumer		681,535		725,807

	$	2,306,988		2,465,067

Purchased impaired loans included in the table above totaled $716 million at March 31, 2016 and $768 million at December 31, 2015, 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-month periods ended March 31, 2016 and 2015 follows:


	Three months ended March 31, 2016
	Purchased impaired			Other acquired			Total
	(in thousands)

Balance at beginning of period	$	184,618			296,434			481,052
Interest income		(14,062	)		(37,862	)		(51,924	)
Reclassifications from nonaccretable balance, net		629			5,664			6,293
Other (a)		—			4,781			4,781

Balance at end of period	$	171,185			269,017			440,202


	Three months ended March 31, 2015
	Purchased impaired			Other acquired			Total
	(in thousands)

Balance at beginning of period	$	76,518			397,379			473,897
Interest income		(5,206	)		(41,277	)		(46,483	)
Reclassifications from nonaccretable balance, net		110			183			293
Other (a)		—			1,610			1,610

Balance at end of period	$	71,422			357,895			429,317

(a)

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

A summary of current, past due and nonaccrual loans as of March 31, 2016 and December 31, 2015 were as 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
March 31, 2016					(in thousands)
Commercial, financial, leasing, etc.	$	20,911,645		30,495		2,358		524		1,765		279,790		21,226,577
Real estate:
Commercial		23,740,729		149,108		41,776		6,818		39,840		171,256		24,149,527
Residential builder and developer		1,747,261		15,304		195		3,493		23,516		32,458		1,822,227
Other commercial construction		3,663,835		28,336		9,068		280		19,239		20,781		3,741,539
Residential		19,747,097		500,241		278,640		15,790		463,871		186,452		21,192,091
Residential-limited documentation		3,757,924		107,679		275		—		165,404		76,265		4,107,547
Consumer:
Home equity lines and loans		5,720,342		40,054		—		15,898		2,239		78,722		5,857,255
Automobile		2,580,241		33,439		—		2		—		14,817		2,628,499
Other		3,083,495		24,739		3,858		18,962		—		16,150		3,147,204

Total	$	84,952,569		929,395		336,170		61,767		715,874		876,691		87,872,466


	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
December 31, 2015					(in thousands)
Commercial, financial, leasing, etc.	$	20,122,648		52,868		2,310		693		1,902		241,917		20,422,338
Real estate:
Commercial		23,645,354		172,439		12,963		8,790		46,790		179,606		24,065,942
Residential builder and developer		1,507,856		7,969		5,760		6,925		28,734		28,429		1,585,673
Other commercial construction		3,428,939		65,932		7,936		2,001		24,525		16,363		3,545,696
Residential		20,507,551		560,312		284,451		16,079		488,599		153,281		22,010,273
Residential-limited documentation		3,885,073		137,289		—		—		175,518		61,950		4,259,830
Consumer:
Home equity lines and loans		5,805,222		45,604		—		15,222		2,261		84,467		5,952,776
Automobile		2,446,473		56,181		—		6		—		16,597		2,519,257
Other		3,051,435		36,702		4,021		18,757		—		16,799		3,127,714

Total	$	84,400,551		1,135,296		317,441		68,473		768,329		799,409		87,489,499

(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 that were impaired at acquisition date and were recorded at fair value.

One-to-four family residential mortgage loans held for sale were $269 million and $353 million at March 31, 2016 and December 31, 2015, respectively. Commercial mortgage loans held for sale were $128 million at March 31, 2016 and $39 million at December 31, 2015.

Changes in the allowance for credit losses for the three months ended March 31, 2016 were as follows:


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

Beginning balance	$	300,404			326,831			72,238			178,320			78,199			955,992
Provision for credit losses		24,364			4,013			1,218			19,893			(488	)		49,000
Net charge-offs
Charge-offs		(6,149	)		(1,272	)		(6,972	)		(44,319	)		—			(58,712	)
Recoveries		5,247			2,413			1,887			6,925			—			16,472

Net charge-offs		(902	)		1,141			(5,085	)		(37,394	)		—			(42,240	)

Ending balance	$	323,866			331,985			68,371			160,819			77,711			962,752

Changes in the allowance for credit losses for the three months ended March 31, 2015 were as follows:


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

Beginning balance	$	288,038			307,927			61,910			186,033			75,654		919,562
Provision for credit losses		1,442			15,542			960			19,574			482		38,000
Net charge-offs
Charge-offs		(12,350	)		(6,679	)		(3,118	)		(25,329	)		—		(47,476	)
Recoveries		3,939			585			989			5,774			—		11,287

Net charge-offs		(8,411	)		(6,094	)		(2,129	)		(19,555	)		—		(36,189	)

Ending balance	$	281,069			317,375			60,741			186,052			76,136		921,373

Despite the above allocation, 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 detailed or intensified 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 officers are responsible for continually assigning grades to these loans based on standards outlined in the Company’s Credit Policy. Internal loan grades are also monitored by the Company’s loan review department to ensure consistency and strict adherence to the prescribed standards. 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. As updated appraisals are obtained on individual loans or other events in the market place indicate that collateral values have significantly changed, individual loan grades are adjusted as appropriate. Changes in other factors cited may also lead to loan grade changes at any time. Except for consumer and residential real estate loans that are considered smaller balance homogenous loans and acquired loans that are evaluated on an aggregated basis, the Company considers a loan to be impaired for purposes of applying GAAP when, based on current information and events, it is probable that the Company will be unable to collect all amounts according to the contractual terms of the loan agreement or the loan is delinquent 90 days. Regardless of loan type, the Company considers a loan to be impaired if it qualifies as a troubled debt restructuring. Modified loans, including smaller balance homogenous loans, that are considered to be troubled debt restructurings 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.

The following tables provide information with respect to loans and leases that were considered impaired as of March 31, 2016 and December 31, 2015 and for the three month periods ended March 31, 2016 and 2015.


	March 31, 2016						December 31, 2015
	Recorded investment		Unpaid principal balance		Related allowance		Recorded investment		Unpaid principal balance		Related allowance
	(in thousands)
With an allowance recorded:
Commercial, financial, leasing, etc.	$	204,786		223,269		58,714		179,037		195,821		44,752
Real estate:
Commercial		86,612		97,912		19,600		85,974		95,855		18,764
Residential builder and developer		6,581		8,296		839		3,316		5,101		196
Other commercial construction		2,358		2,678		397		3,548		3,843		348
Residential		77,579		95,679		4,348		79,558		96,751		4,727
Residential-limited documentation		87,791		101,841		7,000		90,356		104,251		8,000
Consumer:
Home equity lines and loans		27,544		28,540		3,904		25,220		26,195		3,777
Automobile		21,289		21,289		4,867		22,525		22,525		4,709
Other		17,876		17,876		4,844		17,620		17,620		4,820

		532,416		597,380		104,513		507,154		567,962		90,093

With no related allowance recorded:
Commercial, financial, leasing, etc.		105,342		126,130		—		93,190		110,735		—
Real estate:
Commercial		92,733		106,710		—		101,340		116,230		—
Residential builder and developer		28,938		49,177		—		27,651		47,246		—
Other commercial construction		18,811		37,498		—		13,221		31,477		—
Residential		17,574		28,336		—		19,621		30,940		—
Residential-limited documentation		17,362		29,544		—		18,414		31,113		—

		280,760		377,395		—		273,437		367,741		—


Total:
Commercial, financial, leasing, etc.		310,128		349,399		58,714		272,227		306,556		44,752
Real estate:
Commercial		179,345		204,622		19,600		187,314		212,085		18,764
Residential builder and developer		35,519		57,473		839		30,967		52,347		196
Other commercial construction		21,169		40,176		397		16,769		35,320		348
Residential		95,153		124,015		4,348		99,179		127,691		4,727
Residential-limited documentation		105,153		131,385		7,000		108,770		135,364		8,000
Consumer:
Home equity lines and loans		27,544		28,540		3,904		25,220		26,195		3,777
Automobile		21,289		21,289		4,867		22,525		22,525		4,709
Other		17,876		17,876		4,844		17,620		17,620		4,820

Total	$	813,176		974,775		104,513		780,591		935,703		90,093


	Three months ended March 31, 2016						Three months ended March 31, 2015
			Interest income recognized						Interest income recognized
	Average recorded investment		Total		Cash basis		Average recorded investment		Total		Cash basis
	(in thousands)
Commercial, financial, leasing, etc.	$	296,584		611		611		214,618		604		604
Real estate:
Commercial		182,454		1,474		1,474		153,070		1,102		1,102
Residential builder and developer		33,750		42		42		73,151		63		63
Other commercial construction		16,868		38		38		25,540		55		55
Residential		96,788		1,372		882		104,490		1,446		910
Residential-limited documentation		107,473		1,472		630		125,654		1,610		647
Consumer:
Home equity lines and loans		26,019		246		85		19,683		201		48
Automobile		21,962		339		36		29,013		450		54
Other		17,717		178		27		18,861		174		33

Total	$	799,615		5,772		3,825		764,080		5,705		3,516

In accordance with the previously described policies, the Company utilizes a loan grading system that is applied to all commercial loans and commercial real estate loans. Loan grades are utilized to differentiate risk within the portfolio and consider the expectations of default for each loan. 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. All larger balance criticized commercial loans and commercial real estate loans are individually reviewed by centralized loan review personnel each quarter to determine the appropriateness of the assigned loan grade, including whether the loan should be reported as accruing or nonaccruing. Smaller balance criticized loans are analyzed by business line risk management areas to ensure proper loan grade classification. 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. 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, Financial, Leasing, etc.		Commercial		Residential Builder and Developer		Other Commercial Construction
	(in thousands)
March 31, 2016
Pass	$	20,155,277		23,138,987		1,700,088		3,631,947
Criticized accrual		791,510		839,284		89,681		88,811
Criticized nonaccrual		279,790		171,256		32,458		20,781

Total	$	21,226,577		24,149,527		1,822,227		3,741,539


December 31, 2015
Pass	$	19,442,183		23,098,856		1,497,465		3,432,679
Criticized accrual		738,238		787,480		59,779		96,654
Criticized nonaccrual		241,917		179,606		28,429		16,363

Total	$	20,422,338		24,065,942		1,585,673		3,545,696

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 aggregated $52 million and $24 million, respectively, at March 31, 2016 and $55 million and $21 million, respectively, at December 31, 2015. 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 totaled $20 million and $32 million, respectively, at March 31, 2016 and $20 million and $28 million, respectively, at December 31, 2015.

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.

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


	Commercial, Financial, Leasing, etc.		Real Estate
	Commercial, Financial, Leasing, etc.		Commercial		Residential		Consumer		Total
	(in thousands)
March 31, 2016
Individually evaluated for impairment	$	58,714		20,611		11,348		13,615	$	104,288
Collectively evaluated for impairment		264,652		308,897		55,970		145,841		775,360
Purchased impaired		500		2,477		1,053		1,363		5,393

Allocated	$	323,866		331,985		68,371		160,819		885,041

Unallocated										77,711


Total									$	962,752


December 31, 2015
Individually evaluated for impairment	$	44,752		19,175		12,727		13,306	$	89,960
Collectively evaluated for impairment		255,615		307,000		57,624		163,511		783,750
Purchased impaired		37		656		1,887		1,503		4,083

Allocated	$	300,404		326,831		72,238		178,320		877,793

Unallocated										78,199


Total									$	955,992

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


	Commercial, Financial, Leasing, etc.		Real Estate
	Commercial, Financial, Leasing, etc.		Commercial		Residential		Consumer		Total
	(in thousands)
March 31, 2016
Individually evaluated for impairment	$	310,128		235,039		200,306		66,709	$	812,182
Collectively evaluated for impairment		20,914,684		29,395,659		24,470,057		11,564,010		86,344,410
Purchased impaired		1,765		82,595		629,275		2,239		715,874


Total	$	21,226,577		29,713,293		25,299,638		11,632,958	$	87,872,466


December 31, 2015
Individually evaluated for impairment	$	272,227		234,132		207,949		65,365	$	779,673
Collectively evaluated for impairment		20,148,209		28,863,130		25,398,037		11,532,121		85,941,497
Purchased impaired		1,902		100,049		664,117		2,261		768,329


Total	$	20,422,338		29,197,311		26,270,103		11,599,747	$	87,489,499

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.

The tables below summarize the Company’s loan modification activities that were considered troubled debt restructurings for the three months ended March 31, 2016 and 2015:


			Recorded investment				Financial effects of modification
Three months ended March 31, 2016	Number		Pre- modification		Post- modification		Recorded investment (a)			Interest (b)
			(dollars in thousands)
Commercial, financial, leasing, etc.
Principal deferral		24	$	11,571	$	12,721	$	1,150		$	—
Combination of concession types		7		6,157		5,952		(205	)		—
Real estate:
Commercial
Principal deferral		16		3,483		3,448		(35	)		—
Combination of concession types		5		3,933		3,924		(9	)		(35	)
Residential
Principal deferral		17		1,981		2,191		210			—
Combination of concession types		10		2,321		2,369		48			—
Residential-limited documentation
Principal deferral		1		125		138		13			—
Combination of concession types		5		1,312		1,379		67			(339	)
Consumer:
Home equity lines and loans
Principal deferral		3		335		335		—			—
Combination of concession types		23		2,496		2,496		—			(283	)
Automobile
Principal deferral		48		521		521		—			—
Other		16		38		38		—			—
Combination of concession types		8		85		85		—			(3	)
Other
Principal deferral		26		374		374		—			—
Other		2		25		25		—			—
Combination of concession types		8		147		147		—			(27	)

Total		219	$	34,904	$	36,143	$	1,239		$	(687	)

(a)

Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages.

(b)

Represents the present value of interest rate concessions discounted at the effective rate of the original loan.


			Recorded investment				Financial effects of modification
Three months ended March 31, 2015	Number		Pre- modification		Post- modification		Recorded investment (a)			Interest (b)
			(dollars in thousands)
Commercial, financial, leasing, etc.
Principal deferral		21	$	1,572	$	1,557	$	(15	)	$	—
Interest rate reduction		1		99		99		—			(19	)
Combination of concession types		3		9,155		6,989		(2,166	)		—
Real estate:
Commercial
Principal deferral		7		3,792		3,776		(16	)		—
Combination of concession types		4		1,646		1,637		(9	)		(52	)
Residential builder and developer
Principal deferral		1		1,398		1,398		—			—
Residential
Principal deferral		7		721		742		21			—
Combination of concession types		3		294		349		55			(34	)
Residential-limited documentation
Combination of concession types		1		210		210		—			(4	)
Consumer:
Home equity lines and loans
Principal deferral		1		21		21		—			—
Combination of concession types		5		196		196		—			(13	)
Automobile
Principal deferral		35		303		303		—			—
Interest rate reduction		3		42		42		—			(3	)
Other		10		20		20		—			—
Combination of concession types		8		84		84		—			(7	)
Other
Principal deferral		22		296		296		—			—
Other		5		59		59		—			—
Combination of concession types		13		224		224		—			(25	)

Total		150	$	20,132	$	18,002	$	(2,130	)	$	(157	)

(a)

Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages.

(b)

Represents the present value of interest rate concessions discounted at the effective rate of the original loan.

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 March 31, 2016 and 2015 and for which there was a subsequent payment default during the three-month periods ended March 31, 2016 and 2015, respectively, were not material.

The amount of foreclosed residential real estate property held by the Company was $169 million and $172 million at March 31, 2016 and December 31, 2015, respectively. There were $309 million and $315 million at March 31, 2016 and December 31, 2015, respectively, of loans secured by residential real estate that were in the process of foreclosure.

Borrowings

3 Months Ended

Mar. 31, 2016

Debt Disclosure [Abstract]

Borrowings

5.	Borrowings

M&T had $515 million of fixed and variable rate junior subordinated deferrable interest debentures (“Junior Subordinated Debentures”) outstanding at March 31, 2016 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, beginning in 2016 none of the securities are includable in M&T’s Tier 1 regulatory capital, but do qualify for inclusion in 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. On April 15, 2015, M&T redeemed all of the issued and outstanding Capital Securities issued by M&T Capital Trust I, M&T Capital Trust II and M&T Capital Trust III, and the related Junior Subordinated Debentures held by those respective trusts. In the aggregate, $323 million of Junior Subordinated Debentures were redeemed.

Also included in long-term borrowings are agreements to repurchase securities of $1.9 billion at each of March 31, 2016 and December 31, 2015. 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 $2.1 billion and $2.0 billion at March 31, 2016 and December 31, 2015, respectively.

Shareholders' equity

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Shareholders' equity

6.	Shareholders’ equity

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

Issued and outstanding preferred stock of M&T as of March 31, 2016 and December 31, 2015 is presented below:


	Shares issued and outstanding		Carrying value
	(dollars in thousands)
Series A (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		230,000	$	230,000

Series C (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		151,500	$	151,500

Series D (b)
Fixed Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		50,000	$	500,000

Series E (c)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		350,000	$	350,000

(a)

Dividends, if declared, are paid at 6.375%. Warrants to purchase M&T common stock at $73.86 per share issued in connection with the Series A preferred stock expire in 2018 and totaled 719,175 at March 31, 2016 and December 31, 2015, respectively.

(b)

Dividends, if declared, are paid semi-annually at a rate of 6.875% per year. The shares are redeemable in whole or in part on or after June 15, 2016. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence.

(c)

Dividends, if declared, are paid semi-annually at a rate of 6.45% through February 14, 2024 and thereafter will be paid quarterly at a rate of the three-month LIBOR plus 361 basis points (hundredths of one percent). The shares are redeemable in whole or in part on or after February 15, 2024. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days following that occurrence.

In addition to the Series A warrants mentioned in (a) above, a warrant to purchase 95,383 shares of M&T common stock at $518.96 per share was outstanding at March 31, 2016 and December 31, 2015. The obligation under that warrant was assumed by M&T in an acquisition.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 5
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29-31)
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (SX 210.3-04)
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 505
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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

Pension plans and other postretirement benefits

3 Months Ended

Mar. 31, 2016

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 pension expense for defined benefit plans consisted of the following:


	Pension benefits						Other postretirement benefits
	Three months ended March 31
	2016			2015			2016			2015
	(in thousands)

Service cost	$	6,382			6,000			458			200
Interest cost on projected benefit obligation		20,883			17,775			1,205			650
Expected return on plan assets		(27,814	)		(23,575	)		—			—
Amortization of prior service credit		(825	)		(1,525	)		(350	)		(350	)
Amortization of net actuarial loss		8,300			11,175			—			25


Net periodic benefit cost	$	6,926			9,850			1,313			525

Expense incurred in connection with the Company’s defined contribution pension and retirement savings plans totaled $17,690,000 and $16,750,000 for the three months ended March 31, 2016 and 2015, respectively.

Earnings per common share

3 Months Ended

Mar. 31, 2016

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 March 31
	2016			2015
	(in thousands, except per share)
Income available to common shareholders:

Net income	$	298,528			241,613
Less: Preferred stock dividends (a)		(20,318	)		(20,318	)

Net income available to common equity		278,210			221,295
Less: Income attributable to unvested stock-based compensation awards		(2,466	)		(2,465	)


Net income available to common shareholders	$	275,744			218,830

Weighted-average shares outstanding:

Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		160,220			133,542
Less: Unvested stock-based compensation awards		(1,486	)		(1,493	)


Weighted-average shares outstanding		158,734			132,049

Basic earnings per common share	$	1.74			1.66

(a)

Including impact of not as yet declared cumulative dividends.

The computations of diluted earnings per common share follow:


	Three months ended March 31
	2016			2015
	(in thousands, except per share)

Net income available to common equity	$	278,210			221,295
Less: Income attributable to unvested stock-based compensation awards		(2,462	)		(2,458	)


Net income available to common shareholders	$	275,748			218,837

Adjusted weighted-average shares outstanding:

Common and unvested stock-based compensation awards		160,220			133,542
Less: Unvested stock-based compensation awards		(1,486	)		(1,493	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		447			720


Adjusted weighted-average shares outstanding		159,181			132,769

Diluted earnings per common share	$	1.73			1.65

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 approximately 2.8 million and 2.7 million common shares during the three-month periods ended March 31, 2016 and 2015, respectively, were not included in the computations of diluted earnings per common share because the effect on those periods would have been antidilutive.

Comprehensive income

3 Months Ended

Mar. 31, 2016

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 Securities
	With OTTI (a)			All other			Defined benefit plans			Other			Total amount before tax			Income tax			Net
	(in thousands)

Balance - January 1, 2016	$	16,359			62,849			(489,660	)		(4,093	)	$	(414,545	)		162,918		$	(251,627	)

Other comprehensive income before reclassifications:
Unrealized holding gains (losses), net		(370	)		159,660			—			—			159,290			(62,680	)		96,610
Foreign currency translation adjustment		—			—			—			(83	)		(83	)		30			(53	)

Total other comprehensive income(loss) before reclassifications		(370	)		159,660			—			(83	)		159,207			(62,650	)		96,557


Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:

Accretion of unrealized holding losses on held-to-maturity (“HTM”) securities		—			968			—			—			968	(b)		(381	)		587
Gains realized in net income		—			(4	)		—			—			(4	)(c)		1			(3	)
Accretion of net gain on terminated cash flow hedges		—			—			—			(39	)		(39	)(d)		15			(24	)
Amortization of prior service credit		—			—			(1,175	)		—			(1,175	)(e)		462			(713	)
Amortization of actuarial losses		—			—			8,300			—			8,300	(e)		(3,266	)		5,034

Total reclassifications		—			964			7,125			(39	)		8,050			(3,169	)		4,881


Total gain (loss) during the period		(370	)		160,624			7,125			(122	)		167,257			(65,819	)		101,438


Balance - March 31, 2016	$	15,989			223,473			(482,535	)		(4,215	)	$	(247,288	)		97,099		$	(150,189	)


	Investment Securities
	With OTTI (a)		All other		Defined benefit plans			Other			Total amount before tax			Income tax			Net
	(in thousands)

Balance - January 1, 2015	$	7,438		201,828		(503,027	)		(4,082	)	$	(297,843	)		116,849		$	(180,994	)

Other comprehensive income before reclassifications:
Unrealized holding gains, net		8,011		32,063		—			—			40,074			(15,247	)		24,827
Foreign currency translation adjustment		—		—		—			(3,732	)		(3,732	)		1,348			(2,384	)
Gains on cash flow hedges		—		—		—			1,453			1,453			(568	)		885

Total other comprehensive income(loss) before reclassifications		8,011		32,063		—			(2,279	)		37,795			(14,467	)		23,328


Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:

Amortization of unrealized holding losses on HTM securities		—		739		—			—			739	(b)		(289	)		450
Losses realized in net income		—		98		—			—			98	(c)		(36	)		62
Accretion of net gain on terminated cash flow hedges		—		—		—			(24	)		(24	)(d)		10			(14	)
Amortization of prior service credit		—		—		(1,875	)		—			(1,875	)(e)		934			(941	)
Amortization of actuarial losses		—		—		11,200			—			11,200	(e)		(5,582	)		5,618

Total reclassifications		—		837		9,325			(24	)		10,138			(4,963	)		5,175


Total gain (loss) during the period		8,011		32,900		9,325			(2,303	)		47,933			(19,430	)		28,503


Balance - March 31, 2015	$	15,449		234,728		(493,702	)		(6,385	)	$	(249,910	)		97,419		$	(152,491	)

(a)

Other-than-temporary impairment

(b)

Included in interest income

(c)

Included in gain (loss) on bank investment securities

(d)

Included in interest expense

(e)

Included in salaries and employee benefits expense

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


	Investment securities					Defined benefit plans
	With OTTI			All other		Defined benefit plans			Other			Total
	(in thousands)

Balance - December 31, 2015	$	9,921			38,166		(296,979	)		(2,735	)	$	(251,627	)

Net gain (loss) during period		(224	)		97,418		4,321			(77	)		101,438


Balance - March 31, 2016	$	9,697			135,584		(292,658	)		(2,812	)	$	(150,189	)

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 15
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6522872

+ Details

Derivative financial instruments

3 Months Ended

Mar. 31, 2016

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 and collateral provisions protecting the at-risk party. Based on adherence to the Company’s credit standards and the presence of the netting and collateral provisions, the Company believes that the credit risk inherent in these contracts was not significant as of March 31, 2016.

The net effect of interest rate swap agreements was to increase net interest income by $10 million and $11 million for the three-month periods ended March 31, 2016 and 2015, 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-
	Notional		Average		average rate
	amount		maturity		Fixed			Variable
	(in thousands)		(in years)
March 31, 2016
Fair value hedges:
Fixed rate long-term borrowings (a)	$	1,400,000		1.4		4.42	%		1.59	%


December 31, 2015
Fair value hedges:
Fixed rate long-term borrowings (a)	$	1,400,000		1.7		4.42	%		1.39	%

(a)

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

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 $18.9 billion and $18.4 billion at March 31, 2016 and December 31, 2015, respectively. The notional amounts of foreign currency and other option and futures contracts entered into for trading account purposes aggregated $2.8 billion and $1.6 billion at March 31, 2016 and December 31, 2015, 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
	March 31, 2016		December 31, 2015		March 31, 2016		December 31, 2015
	(in thousands)
Derivatives designated and qualifying as hedging instruments
Fair value hedges:
Interest rate swap agreements (a)	$	41,259		43,892	$	—		—
Commitments to sell real estate loans (a)		412		1,844		3,243		656

		41,671		45,736		3,243		656

Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		16,929		10,282		44		403
Commitments to sell real estate loans (a)		428		533		2,413		846
Trading:
Interest rate contracts (b)		329,739		203,517		278,981		153,723
Foreign exchange and other option and futures contracts (b)		17,807		8,569		16,888		7,022

		364,903		222,901		298,326		161,994


Total derivatives	$	406,574		268,637	$	301,569		162,650

(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.


	Amount of gain (loss) recognized
	Three months ended March 31, 2016					Three months ended March 31, 2015
	Derivative			Hedged item		Derivative			Hedged item
	(in thousands)
Derivatives in fair value hedging relationships

Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	(2,633	)		1,870	$	(396	)		161


Derivatives not designated as hedging instruments

Trading:
Interest rate contracts (b)	$	974				$	660
Foreign exchange and other option and futures contracts (b)		1,212					2,789


Total	$	2,186				$	3,449

(a)

Reported as other revenues from operations.

(b)

Reported as trading account and foreign exchange gains.

The Company 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 $22 million and $18 million at March 31, 2016 and December 31, 2015, 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 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.

The aggregate fair value of derivative financial instruments in a liability position, which are subject to enforceable master netting arrangements, was $98 million and $59 million at March 31, 2016 and December 31, 2015, respectively. After consideration of such netting arrangements, the net liability positions with counterparties aggregated $95 million and $55 million at March 31, 2016 and December 31, 2015, respectively. The Company was required to post collateral relating to those positions of $84 million and $52 million, at March 31, 2016 and December 31, 2015, 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 to the derivative financial instruments could demand immediate incremental collateralization on those instruments in a net liability position. The aggregate fair value of all derivative financial instruments with such credit risk-related contingent features in a net liability position on March 31, 2016 was $19 million, for which the Company had posted collateral of $13 million in the normal course of business. If the credit risk-related contingent features had been triggered on March 31, 2016, the maximum amount of additional collateral the Company would have been required to post with counterparties was $6 million.

The aggregate fair value of derivative financial instruments in an asset position, which are subject to enforceable master netting arrangements, was $24 million and $23 million at March 31, 2016 and December 31, 2015, respectively. After consideration of such netting arrangements, the net asset positions with counterparties aggregated $21 million and $19 million at March 31, 2016 and December 31, 2015, respectively. Counterparties posted collateral relating to those positions of $21 million and $22 million at March 31, 2016 and December 31, 2015, 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 additional collateral for contracts in a net liability position. The net fair values of derivative financial instruments cleared through clearinghouses at March 31, 2016 was a net liability position of $156 million and at December 31, 2015 was a net liability position of $50 million. Collateral posted with clearinghouses was $204 million and $99 million at March 31, 2016 and December 31, 2015, respectively.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6441202&loc=d3e80720-113993

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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Reference 7: http://www.xbrl.org/2003/role/presentationRef
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 815
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-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959

Reference 16: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 17: http://www.xbrl.org/2003/role/presentationRef
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Reference 18: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41638-113959

Reference 19: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Variable interest entities and asset securitizations

3 Months Ended

Mar. 31, 2016

Text Block [Abstract]

Variable interest entities and asset securitizations

11.

Variable interest entities and asset securitizations

In accordance with GAAP, at December 31, 2015 the Company determined that it was the primary beneficiary of a residential mortgage loan securitization trust considering its role as servicer and its retained subordinated interests in the trust. As a result, the Company had included the one-to-four family residential mortgage loans that were included in the trust in its consolidated financial statements. In the first quarter of 2016, the securitization trust was terminated as the Company exercised its right to purchase the underlying mortgage loans pursuant to the clean-up call provisions of the trust. At December 31, 2015, the carrying value of the loans in the securitization trust was $81 million. The outstanding principal amount of mortgage-backed securities issued by the qualified special purpose trust that was held by parties unrelated to the Company at December 31, 2015 was $13 million.

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 March 31, 2016 and December 31, 2015, the Company included the junior subordinated debentures as “long-term borrowings” in its consolidated balance sheet and recognized $24 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 $1.1 billion at each of March 31, 2016 and December 31, 2015. 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 $290 million, including $80 million of unfunded commitments, at March 31, 2016 and $295 million, including $78 million of unfunded commitments, at December 31, 2015. Contingent commitments to provide additional capital contributions to these partnerships were not material at March 31, 2016. 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 a 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 cost 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 $11 million and $10 million of its investments in qualified affordable housing projects to income tax expense during the three-month periods ended March 31, 2016 and 2015, respectively, and recognized $14 million of tax credits and other tax benefits during each of 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 management fees. Such waivers were not material during the three months ended March 31, 2016 and 2015.

Fair value measurements

3 Months Ended

Mar. 31, 2016

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 March 31, 2016.

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 swap agreements 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

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.

Included in collateralized debt obligations are securities backed by trust preferred securities issued by financial institutions and other entities. The Company could not obtain pricing indications for many of these securities from its two primary independent pricing sources. The Company, therefore, performed internal modeling to estimate the cash flows and fair value of its portfolio of securities backed by trust preferred securities at March 31, 2016 and December 31, 2015. The modeling techniques included estimating cash flows using bond-specific assumptions about future collateral defaults and related loss severities. The resulting cash flows were then discounted by reference to market yields observed in the single-name trust preferred securities market. In determining a market yield applicable to the estimated cash flows, a margin over LIBOR ranging from 4% to 10%, with a weighted-average of 8%, was used. Significant unobservable inputs used in the determination of estimated fair value of collateralized debt obligations are included in the accompanying table of significant unobservable inputs to Level 3 measurements. At March 31, 2016, the total amortized cost and fair value of securities backed by trust preferred securities issued by financial institutions and other entities were $28 million and $45 million, respectively, and at December 31, 2015 were $28 million and $47 million, respectively. Privately issued mortgage-backed securities and securities backed by trust preferred securities issued by financial institutions and other entities constituted all of the available-for-sale investment securities classified as Level 3 valuations.

The Company ensures an appropriate control framework is in place over the valuation processes and techniques used for significant Level 3 fair value measurements. Internal pricing models used for significant valuation measurements have generally been subjected to validation procedures including testing of mathematical constructs, review of valuation methodology and significant assumptions used.

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.

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.

The following tables present assets and liabilities at March 31, 2016 and December 31, 2015 measured at estimated fair value on a recurring basis:


	Fair value measurements at March 31, 2016		Level 1(a)		Level 2(a)		Level 3
	(in thousands)

Trading account assets	$	467,987		69,689		398,298		—
Investment securities available for sale:
U.S. Treasury and federal agencies		202,192		—		202,192		—
Obligations of states and political subdivisions		5,448		—		5,448		—
Mortgage-backed securities:
Government issued or guaranteed		11,750,062		—		11,750,062		—
Privately issued		65		—		—		65
Collateralized debt obligations		45,040		—		—		45,040
Other debt securities		112,708		—		112,708		—
Equity securities		85,132		67,150		17,982		—

		12,200,647		67,150		12,088,392		45,105


Real estate loans held for sale		396,764		—		396,764		—
Other assets (b)		59,028		—		42,099		16,929

Total assets	$	13,124,426		136,839		12,925,553		62,034


Trading account liabilities	$	295,869		—		295,869		—
Other liabilities (b)		5,700		—		5,656		44

Total liabilities	$	301,569		—		301,525		44


	Fair value measurements at December 31, 2015		Level 1(a)		Level 2(a)		Level 3
	(in thousands)

Trading account assets	$	273,783		56,763		217,020		—
Investment securities available for sale:
U.S. Treasury and federal agencies		299,997		—		299,997		—
Obligations of states and political subdivisions		6,028		—		6,028		—
Mortgage-backed securities:
Government issued or guaranteed		11,686,628		—		11,686,628		—
Privately issued		74		—		—		74
Collateralized debt obligations		47,393		—		—		47,393
Other debt securities		118,880		—		118,880		—
Equity securities		83,671		65,178		18,493		—

		12,242,671		65,178		12,130,026		47,467


Real estate loans held for sale		392,036		—		392,036		—
Other assets (b)		56,551		—		46,269		10,282

Total assets	$	12,965,041		121,941		12,785,351		57,749


Trading account liabilities	$	160,745		—		160,745		—
Other liabilities (b)		1,905		—		1,502		403

Total liabilities	$	162,650		—		162,247		403

(a)

There were no significant transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2016 and the year ended December 31, 2015.

(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).

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the three months ended March 31, 2016 were as follows:


	Investment securities available for sale
	Privately issued mortgage-backed securities			Collateralized debt obligations			Other assets and other liabilities
	(in thousands)
Balance – January 1, 2016	$	74		$	47,393		$	9,879

Total gains (losses) realized/unrealized:
Included in earnings		—			—			23,898	(b)
Included in other comprehensive income		—			(2,148	)(c)		—
Settlements		(9	)		(205	)		—
Transfers in and/or out of Level 3 (a)		—			—			(16,892	)(d)


Balance – March 31, 2016	$	65		$	45,040		$	16,885


Changes in unrealized gains included in earnings related to assets still held at March 31, 2016	$	—		$	—		$	14,539	(b)

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the three months ended March 31, 2015 were as follows:


	Investment securities available for sale
	Privately issued mortgage-backed securities			Collateralized debt obligations			Other assets and other liabilities
	(in thousands)
Balance – January 1, 2015	$	103		$	50,316		$	17,347

Total gains (losses) realized/unrealized:
Included in earnings		—			—			29,770	(b)
Included in other comprehensive income		—			(2,004	)(c)		—
Settlements		(8	)		(1,034	)		—
Transfers in and/or out of Level 3 (a)		—			—			(20,887	)(d)


Balance – March 31, 2015	$	95		$	47,278		$	26,230


Changes in unrealized gains included in earnings related to assets still held at March 31, 2015	$	—		$	—		$	22,636	(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)

Reported as net unrealized losses on investment securities in the consolidated statement of comprehensive income.

(d)

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

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 generally 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 generally in the range of 10% to 90% at March 31, 2016. 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 non-recurring 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 $226 million at March 31, 2016 ($127 million and $99 million of which were classified as Level 2 and Level 3, respectively), $210 million at December 31, 2015 ($106 million and $104 million of which were classified as Level 2 and Level 3, respectively) and $101 million at March 31, 2015 ($67 million and $34 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 March 31, 2016 and 2015 were decreases of $27 million and $8 million for the three-month periods ended March 31, 2016 and 2015, 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 $62 million and $11 million at March 31, 2016 and March 31, 2015, respectively. Changes in fair value recognized for those foreclosed assets held by the Company were not material during the three-month periods ended March 31, 2016 and 2015.

Significant unobservable inputs to Level 3 measurements

The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for Level 3 assets and liabilities at March 31, 2016 and December 31, 2015:


	Fair value at March 31, 2016		Valuation technique	Unobservable input/assumptions	Range (weighted- average)
	(in thousands)
Recurring fair value measurements

Privately issued mortgage–backed securities	$	65	Two independent pricing quotes	—	—

Collateralized debt obligations		45,040	Discounted cash flow	Probability of default	10%-56% (31%)
				Loss severity	100%

Net other assets (liabilities) (a)		16,885	Discounted cash flow	Commitment expirations	0%-66% (31%)

	Fair value at December 31, 2015		Valuation technique	Unobservable input/assumptions	Range (weighted- average)
	(in thousands)
Recurring fair value measurements

Privately issued mortgage–backed securities	$	74	Two independent pricing quotes	—	—

Collateralized debt obligations		47,393	Discounted cash flow	Probability of default	10%-56% (31%)
				Loss severity	100%

Net other assets (liabilities) (a)		9,879	Discounted cash flow	Commitment expirations	0%-60% (39%)

(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 probability of default and loss severity for collateralized debt securities would generally result in a lower (higher) fair value measurement.

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

Disclosures of fair value of financial instruments

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


	March 31, 2016
	Carrying amount			Estimated fair value			Level 1		Level 2			Level 3
				(in thousands)
Financial assets:
Cash and cash equivalents	$	1,178,175		$	1,178,175		$	1,112,933	$	65,242		$	—
Interest-bearing deposits at banks		9,545,181			9,545,181			—		9,545,181			—
Trading account assets		467,987			467,987			69,689		398,298			—
Investment securities		15,467,320			15,506,052			67,150		15,256,530			182,372
Loans and leases:
Commercial loans and leases		21,226,577			20,875,827			—		—			20,875,827
Commercial real estate loans		29,713,293			29,569,740			—		127,736			29,442,004
Residential real estate loans		25,299,638			25,386,240			—		4,590,667			20,795,573
Consumer loans		11,632,958			11,553,135			—		—			11,553,135
Allowance for credit losses		(962,752	)		—			—		—			—

Loans and leases, net		86,909,714			87,384,942			—		4,718,403			82,666,539
Accrued interest receivable		318,486			318,486			—		318,486			—

Financial liabilities:
Noninterest-bearing deposits	$	(29,709,218	)	$	(29,709,218	)		—	$	(29,709,218	)		—
Savings and interest-checking deposits		(51,497,240	)		(51,497,240	)		—		(51,497,240	)		—
Time deposits		(12,841,331	)		(12,879,619	)		—		(12,879,619	)		—
Deposits at Cayman Islands office		(166,787	)		(166,787	)		—		(166,787	)		—
Short-term borrowings		(1,766,826	)		(1,766,826	)		—		(1,766,826	)		—
Long-term borrowings		(10,341,035	)		(10,338,217	)		—		(10,338,217	)		—
Accrued interest payable		(80,605	)		(80,605	)		—		(80,605	)		—
Trading account liabilities		(295,869	)		(295,869	)		—		(295,869	)		—

Other financial instruments:
Commitments to originate real estate loans for sale	$	16,885		$	16,885			—	$	—		$	16,885
Commitments to sell real estate loans		(4,816	)		(4,816	)		—		(4,816	)		—
Other credit-related commitments		(118,521	)		(118,521	)		—		—			(118,521	)
Interest rate swap agreements used for interest rate risk management		41,259			41,259			—		41,259			—


	December 31, 2015
	Carrying amount			Estimated fair value			Level 1		Level 2			Level 3
				(in thousands)
Financial assets:
Cash and cash equivalents	$	1,368,040		$	1,368,040		$	1,276,678	$	91,362		$	—
Interest-bearing deposits at banks		7,594,350			7,594,350			—		7,594,350			—
Trading account assets		273,783			273,783			56,763		217,020			—
Investment securities		15,656,439			15,660,877			65,178		15,406,404			189,295
Loans and leases:
Commercial loans and leases		20,422,338			20,146,201			—		—			20,146,201
Commercial real estate loans		29,197,311			29,044,244			—		38,774			29,005,470
Residential real estate loans		26,270,103			26,267,771			—		4,727,816			21,539,955
Consumer loans		11,599,747			11,550,270			—		—			11,550,270
Allowance for credit losses		(955,992	)		—			—		—			—

Loans and leases, net		86,533,507			87,008,486			—		4,766,590			82,241,896
Accrued interest receivable		306,496			306,496			—		306,496			—

Financial liabilities:
Noninterest-bearing deposits	$	(29,110,635	)	$	(29,110,635	)		—	$	(29,110,635	)		—
Savings and interest-checking deposits		(49,566,644	)		(49,566,644	)		—		(49,566,644	)		—
Time deposits		(13,110,392	)		(13,135,042	)		—		(13,135,042	)		—
Deposits at Cayman Islands office		(170,170	)		(170,170	)		—		(170,170	)		—
Short-term borrowings		(2,132,182	)		(2,132,182	)		—		(2,132,182	)		—
Long-term borrowings		(10,653,858	)		(10,639,556	)		—		(10,639,556	)		—
Accrued interest payable		(85,145	)		(85,145	)		—		(85,145	)		—
Trading account liabilities		(160,745	)		(160,745	)		—		(160,745	)		—

Other financial instruments:
Commitments to originate real estate loans for sale	$	9,879		$	9,879			—	$	—		$	9,879
Commitments to sell real estate loans		875			875			—		875			—
Other credit-related commitments		(122,334	)		(122,334	)		—		—			(122,334	)
Interest rate swap agreements used for interest rate risk management		43,892			43,892			—		43,892			—

With the exception of marketable securities, certain off-balance sheet financial instruments and one-to-four family residential 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 following assumptions, methods and calculations were used in determining the estimated fair value of financial instruments not measured at fair value in the consolidated balance sheet.

Cash and cash equivalents, interest-bearing deposits at banks, deposits at Cayman Islands office, short-term borrowings, accrued interest receivable and accrued interest payable

Due to the nature of cash and cash equivalents and the near maturity of interest-bearing deposits at banks, deposits at Cayman Islands office, short-term borrowings, accrued interest receivable and accrued interest payable, the Company estimated that the carrying amount of such instruments approximated estimated fair value.

Investment securities

Estimated fair values of investments in readily marketable securities were generally based on quoted market prices. Investment securities that were not readily marketable were assigned amounts based on estimates provided by outside parties or modeling techniques that relied upon discounted calculations of projected cash flows or, in the case of other investment securities, which include capital stock of the Federal Reserve Bank of New York and the Federal Home Loan Bank of New York, at an amount equal to the carrying amount.

Loans and leases

In general, discount rates used to calculate values for loan products were based on the Company’s pricing at the respective period end. A higher discount rate was assumed with respect to estimated cash flows associated with nonaccrual loans. Projected loan cash flows were adjusted for estimated credit losses. However, such estimates made by the Company may not be indicative of assumptions and adjustments that a purchaser of the Company’s loans and leases would seek.

Deposits

Pursuant to GAAP, the estimated fair value ascribed to noninterest-bearing deposits, savings deposits and interest-checking deposits must be established at carrying value because of the customers’ ability to withdraw funds immediately. Time deposit accounts are required to be revalued based upon prevailing market interest rates for similar maturity instruments. As a result, amounts assigned to time deposits were based on discounted cash flow calculations using prevailing market interest rates based on the Company’s pricing at the respective date for deposits with comparable remaining terms to maturity.

The Company believes that deposit accounts have a value greater than that prescribed by GAAP. The Company feels, however, that the value associated with these deposits is greatly influenced by characteristics of the buyer, such as the ability to reduce the costs of servicing the deposits and deposit attrition which often occurs following an acquisition.

Long-term borrowings

The amounts assigned to long-term borrowings were based on quoted market prices, when available, or were based on discounted cash flow calculations using prevailing market interest rates for borrowings of similar terms and credit risk.

Other commitments and contingencies

As described in note 13, in the normal course of business, various commitments and contingent liabilities are outstanding, such as loan commitments, credit guarantees and letters of credit. The Company’s pricing of such financial instruments is based largely on credit quality and relationship, probability of funding and other requirements. Loan commitments often have fixed expiration dates and contain termination and other clauses which provide for relief from funding in the event of significant deterioration in the credit quality of the customer. The rates and terms of the Company’s loan commitments, credit guarantees and letters of credit are competitive with other financial institutions operating in markets served by the Company. The Company believes that the carrying amounts, which are included in other liabilities, are reasonable estimates of the fair value of these financial instruments.

The Company does not believe that the estimated information presented herein is representative of the earnings power or value of the Company. The preceding analysis, which is inherently limited in depicting fair value, also does not consider any value associated with existing customer relationships nor the ability of the Company to create value through loan origination, deposit gathering or fee generating activities.

Many of the estimates presented herein are based upon the use of highly subjective information and assumptions and, accordingly, the results may not be precise. Management believes that fair value estimates may not be comparable between financial institutions due to the wide range of permitted valuation techniques and numerous estimates which must be made. Furthermore, because the disclosed fair value amounts were estimated as of the balance sheet date, the amounts actually realized or paid upon maturity or settlement of the various financial instruments could be significantly different.

- Definition

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

+ References + Details

Commitments and contingencies

3 Months Ended

Mar. 31, 2016

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. The following table presents the Company’s significant commitments. Certain of these commitments are not included in the Company’s consolidated balance sheet.


	March 31, 2016		December 31, 2015
	(in thousands)
Commitments to extend credit
Home equity lines of credit	$	5,604,610		5,631,680
Commercial real estate loans to be sold		184,198		57,597
Other commercial real estate		5,727,946		5,949,933
Residential real estate loans to be sold		520,694		488,621
Other residential real estate		281,735		212,619
Commercial and other		12,077,612		11,802,850

Standby letters of credit		3,330,241		3,330,013

Commercial letters of credit		45,798		55,559

Financial guarantees and indemnification contracts		2,773,590		2,794,322

Commitments to sell real estate loans		958,337		782,885

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. 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 $2.6 billion and $2.5 billion at March 31, 2016 and December 31, 2015, 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.

The Company also has commitments under long-term operating leases.

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. Subject to the outcome of the matter discussed in the following paragraph, at March 31, 2016, management believes that any further liability arising out of the Company’s obligation to loan purchasers is not material to the Company’s consolidated financial position.

The Company is the subject of an investigation by government agencies relating to the origination of Federal Housing Administration (“FHA”) insured residential home loans and residential home loans sold to Freddie Mac and Fannie Mae. A number of other U.S. financial institutions have announced similar investigations. Regarding FHA loans, the U.S. Department of Housing and Urban Development (“HUD”) Office of Inspector General and the Department of Justice (collectively, the “Government”) are investigating whether the Company complied with underwriting guidelines concerning certain loans where HUD paid FHA insurance claims. The Company is fully cooperating with the investigation. The Government has advised the Company that based upon its review of a sample of loans for which an FHA insurance claim was paid by HUD, some of the loans do not meet underwriting guidelines. The Company, based on its own review of the sample, does not agree with the sampling methodology and loan analysis employed by the Government. Regarding loans originated by the Company and sold to Freddie Mac and Fannie Mae, the investigation concerns whether the mortgages sold to Freddie Mac and Fannie Mae comply with applicable underwriting guidelines. The Company is also cooperating with that portion of the investigation. The investigation could lead to claims by the Government under the False Claims Act and the Financial Institutions Reform, Recovery, and Enforcement Act of 1989, which allow treble and other special damages substantially in excess of actual losses. Remedies in these proceedings or settlements may include restitution, fines, penalties, or alterations in the Company’s business practices. The Company and the Government continue settlement discussions regarding the investigation and although progress has been made, the parties have not yet reached a definitive agreement. Based upon the current status of these negotiations, management expects that this potential settlement should not have a material impact on the Company’s consolidated financial condition or results of operations in future periods.

M&T and its subsidiaries are subject in the normal course of business to various pending and threatened legal proceedings and other 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. To the extent the pending or threatened litigation could result in exposure in excess of that 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 between $0 and $40 million. Although the Company does not believe that the outcome of pending litigations will be material to the Company’s consolidated financial position, it cannot rule out the possibility that such outcomes will be material to the consolidated results of operations for a particular reporting period in the future.

Segment information

3 Months Ended

Mar. 31, 2016

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 2015 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, reported segment results are 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. Effective July 1, 2015, the Company changed its internal profitability reporting to move a builder and developer lending unit from the Residential Mortgage Banking segment to the Commercial Real Estate segment. Accordingly, financial information presented herein for the three-month period ended March 31, 2015 has been reclassified to conform to the current presentation. As a result, total revenues and net income decreased in the Residential Mortgage Banking segment and increased in the Commercial Real Estate segment by $6 million and $3 million, respectively, for the three-month period ended March 31, 2015 from that which was previously reported.

As also described in note 22 in the 2015 Annual Report, neither goodwill nor core deposit and other intangible assets (and the amortization charges associated with such assets) resulting from acquisitions of financial institutions have been allocated to the Company’s reportable segments, but are included in the “All Other” category. The Company does, however, assign such intangible assets to business units for purposes of testing for impairment.

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


	Three months ended March 31
	2016								2015
	Total revenues(a)		Inter- segment revenues			Net income (loss)			Total revenues(a)		Inter- segment revenues			Net income (loss)
	(in thousands)
Business Banking	$	113,689		991			25,448		$	108,560		1,045			24,811
Commercial Banking		253,617		1,056			101,327			246,581		1,085			96,423
Commercial Real Estate		177,380		387			80,529			169,021		82			82,591
Discretionary Portfolio		86,835		(14,323	)		39,988			15,474		(5,443	)		5,954
Residential Mortgage Banking		96,935		19,660			17,077			105,757		11,387			29,460
Retail Banking		339,046		3,014			63,288			300,391		3,137			68,888
All Other		225,395		(10,785	)		(29,129	)		154,007		(11,293	)		(66,514	)

Total	$	1,292,897		—			298,528		$	1,099,791		—			241,613


	Average total assets
	Three months ended March 31					Year ended December 31
	2016		2015			2015
	(in millions)
Business Banking	$	5,424		5,300			5,339
Commercial Banking		24,838		23,683			24,143
Commercial Real Estate		19,839		18,334	(b)		18,827
Discretionary Portfolio		42,509		22,714			26,648
Residential Mortgage Banking		2,647		3,197	(b)		2,918
Retail Banking		11,568		10,788			11,035
All Other		16,427		11,876			12,870

Total	$	123,252		95,892			101,780

(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 pricing 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 $6,332,000 and $5,838,000 for the three-month periods ended March 31, 2016 and 2015, 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.

(b)

Average assets of the Commercial Real Estate and Residential Mortgage Banking segments for the three-month period ended March 31, 2015 differ by approximately $315 million from the previously reported balances reflecting the noted change in the Company’s internal profitability reporting to move a builder and developer lending unit from the Residential Mortgage Banking segment to the Commercial Real Estate segment.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8981-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e9038-108599

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8971-108599

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8595-108599

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8380-108599

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=51669610&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
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+ Details

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

3 Months Ended

Mar. 31, 2016

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. The carrying value of that investment was $20 million at March 31, 2016.

Bayview Financial Holdings, L.P. (together with its affiliates, “Bayview Financial”), a privately-held specialty mortgage 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 $4.0 billion and $4.1 billion at March 31, 2016 and December 31, 2015, respectively. Revenues from those servicing rights were $5 million and $6 million during the three-month periods ended March 31, 2016 and 2015, respectively. The Company sub-services residential real estate loans for Bayview Financial having outstanding principal balances totaling $36.3 billion and $37.7 billion at March 31, 2016 and December 31, 2015, respectively. Revenues earned for sub-servicing loans for Bayview Financial were $23 million and $35 million for the three-month periods ended March 31, 2016 and 2015, respectively. In addition, the Company held $175 million and $181 million of mortgage-backed securities in its held-to-maturity portfolio at March 31, 2016 and December 31, 2015, respectively, that were securitized by Bayview Financial.

Sale of trust accounts

3 Months Ended

Mar. 31, 2016

Discontinued Operations and Disposal Groups [Abstract]

Sale of trust accounts

16.

Sale of trust accounts

In April 2015, the Company sold the trade processing business within the retirement services division of its Institutional Client Services business. That sale resulted in an after-tax gain of $23 million ($45 million pre-tax) that reflected the allocation of approximately $11 million of previously recorded goodwill to the divested business. Revenues of the sold business had been included in “trust income” and were $9 million during the three months ended March 31, 2015. After considering related expenses, net income attributable to the business that was sold was not material to the consolidated results of operations of the Company during the first quarter of 2015.

- Definition

The entire disclosure related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Significant accounting policies (Policies)	3 Months Ended
Significant accounting policies (Policies)	Mar. 31, 2016
Accounting Policies [Abstract]
Basis of Accounting	The consolidated 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, 2015 (“2015 Annual Report”). In the opinion of management, all adjustments necessary for a fair presentation have been made and were all of a normal recurring nature.

Acquisition (Tables)

3 Months Ended

Mar. 31, 2016

Business Combinations [Abstract]

Schedule of Assets Acquired and Liabilities

The consideration paid for Hudson City’s common equity and the amounts of identifiable assets acquired and liabilities assumed as of the acquisition date were as follows:


	(in thousands)
Identifiable assets:
Cash and due from banks	$	131,688
Interest-bearing deposits at banks		7,568,934
Investment securities		7,929,014
Loans		19,015,013
Goodwill		1,079,787
Core deposit intangible		131,665
Other assets		843,219

Total identifiable assets		36,699,320


Liabilities:
Deposits		17,879,589
Borrowings		13,211,598
Other liabilities		405,025

Total liabilities		31,496,212

Total consideration	$	5,203,108


Cash paid	$	2,064,284
Common stock issued (25,953,950 shares)		3,110,581
Common stock awards converted		28,243

Total consideration	$	5,203,108

Pro Forma Information

Additionally, the Company expects to achieve operating cost savings and other business synergies as a result of the acquisition which are not reflected in the pro forma amounts that follow.


	Pro forma Three months ended March 31, 2015
	(in thousands)

Total revenues(a)	$	1,253,445
Net income		285,237

(a)

Represents net interest income plus other income.

Summary of Merger-Related Expenses

A summary of merger-related expenses included in the consolidated statement of income follows:


	Three months ended March 31, 2016
	(in thousands)

Salaries and employee benefits	$	5,274
Equipment and net occupancy		939
Printing, postage and supplies		937
Other cost of operations		16,012

Total	$	23,162

Investment securities (Tables)

3 Months Ended

Mar. 31, 2016

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)
March 31, 2016
Investment securities available for sale:
U.S. Treasury and federal agencies	$	201,002		1,197		7	$	202,192
Obligations of states and political subdivisions		5,356		138		46		5,448
Mortgage-backed securities:
Government issued or guaranteed		11,490,181		265,879		5,998		11,750,062
Privately issued		65		2		2		65
Collateralized debt obligations		28,483		18,170		1,613		45,040
Other debt securities		136,968		1,407		25,667		112,708
Equity securities		75,271		10,225		364		85,132

		11,937,326		297,018		33,697		12,200,647


Investment securities held to maturity:
Obligations of states and political subdivisions		103,408		886		332		103,962
Mortgage-backed securities:
Government issued or guaranteed		2,445,563		78,448		2,070		2,521,941
Privately issued		175,467		1,848		40,048		137,267
Other debt securities		6,173		—		—		6,173

		2,730,611		81,182		42,450		2,769,343

Other securities		536,062		—		—		536,062

Total	$	15,203,999		378,200		76,147	$	15,506,052


	Amortized cost		Gross unrealized gains		Gross unrealized losses		Estimated fair value
	(in thousands)
December 31, 2015
Investment securities available for sale:
U.S. Treasury and federal agencies	$	299,890		294		187	$	299,997
Obligations of states and political subdivisions		5,924		146		42		6,028
Mortgage-backed securities:
Government issued or guaranteed		11,592,959		142,370		48,701		11,686,628
Privately issued		74		2		2		74
Collateralized debt obligations		28,438		20,143		1,188		47,393
Other debt securities		137,556		1,514		20,190		118,880
Equity securities		73,795		10,230		354		83,671

		12,138,636		174,699		70,664		12,242,671

Investment securities held to maturity:
Obligations of states and political subdivisions		118,431		1,003		421		119,013
Mortgage-backed securities:
Government issued or guaranteed		2,553,612		50,936		7,817		2,596,731
Privately issued		181,091		2,104		41,367		141,828
Other debt securities		6,575		—		—		6,575

		2,859,709		54,043		49,605		2,864,147

Other securities		554,059		—		—		554,059

Total	$	15,552,404		228,742		120,269	$	15,660,877

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

At March 31, 2016, 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	$	7,504		7,551
Due after one year through five years		201,714		203,128
Due after five years through ten years		2,728		2,926
Due after ten years		159,863		151,783

		371,809		365,388
Mortgage-backed securities available for sale		11,490,246		11,750,127

	$	11,862,055		12,115,515


Debt securities held to maturity:
Due in one year or less	$	32,387		32,542
Due after one year through five years		64,484		64,760
Due after five years through ten years		6,537		6,660
Due after ten years		6,173		6,173

		109,581		110,135
Mortgage-backed securities held to maturity		2,621,030		2,659,208

	$	2,730,611		2,769,343

Investment Securities in Continuous Unrealized Loss Position


	Less than 12 months					12 months or more
	Fair value		Unrealized losses			Fair value		Unrealized losses
			(in thousands)
March 31, 2016
Investment securities available for sale:
U.S. Treasury and federal agencies	$	4,051		(7	)		—		—
Obligations of states and political subdivisions		—		—			1,706		(46	)
Mortgage-backed securities:
Government issued or guaranteed		337,672		(1,959	)		1,233,329		(4,039	)
Privately issued		—		—			34		(2	)
Collateralized debt obligations		10,326		(527	)		1,858		(1,086	)
Other debt securities		9,825		(1,203	)		88,715		(24,464	)
Equity securities		2,115		(210	)		146		(154	)

		363,989		(3,906	)		1,325,788		(29,791	)


Investment securities held to maturity:
Obligations of states and political subdivisions		28,707		(215	)		8,813		(117	)
Mortgage-backed securities:
Government issued or guaranteed		812		(12	)		232,432		(2,058	)
Privately issued		—		—			105,355		(40,048	)

		29,519		(227	)		346,600		(42,223	)

Total	$	393,508		(4,133	)		1,672,388		(72,014	)


December 31, 2015
Investment securities available for sale:
U.S. Treasury and federal agencies	$	147,508		(187	)		—		—
Obligations of states and political subdivisions		865		(2	)		1,335		(40	)
Mortgage-backed securities:
Government issued or guaranteed		4,061,899		(48,534	)		7,216		(167	)
Privately issued		—		—			43		(2	)
Collateralized debt obligations		5,711		(335	)		2,063		(853	)
Other debt securities		12,935		(462	)		93,344		(19,728	)
Equity securities		18,073		(207	)		153		(147	)

		4,246,991		(49,727	)		104,154		(20,937	)


Investment securities held to maturity:
Obligations of states and political subdivisions		42,913		(335	)		5,853		(86	)
Mortgage-backed securities:
Government issued or guaranteed		459,983		(1,801	)		228,867		(6,016	)
Privately issued		—		—			112,155		(41,367	)

		502,896		(2,136	)		346,875		(47,469	)

Total	$	4,749,887		(51,863	)		451,029		(68,406	)

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

3 Months Ended

Mar. 31, 2016

Receivables [Abstract]

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


	March 31, 2016		December 31, 2015
	(in thousands)

Outstanding principal balance	$	2,918,333		3,122,935
Carrying amount:
Commercial, financial, leasing, etc.		71,577		78,847
Commercial real estate		588,983		644,284
Residential real estate		964,893		1,016,129
Consumer		681,535		725,807

	$	2,306,988		2,465,067

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-month periods ended March 31, 2016 and 2015 follows:


	Three months ended March 31, 2016
	Purchased impaired			Other acquired			Total
	(in thousands)

Balance at beginning of period	$	184,618			296,434			481,052
Interest income		(14,062	)		(37,862	)		(51,924	)
Reclassifications from nonaccretable balance, net		629			5,664			6,293
Other (a)		—			4,781			4,781

Balance at end of period	$	171,185			269,017			440,202


	Three months ended March 31, 2015
	Purchased impaired			Other acquired			Total
	(in thousands)

Balance at beginning of period	$	76,518			397,379			473,897
Interest income		(5,206	)		(41,277	)		(46,483	)
Reclassifications from nonaccretable balance, net		110			183			293
Other (a)		—			1,610			1,610

Balance at end of period	$	71,422			357,895			429,317

(a)

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

Summary of Current, Past Due and Nonaccrual Loans

A summary of current, past due and nonaccrual loans as of March 31, 2016 and December 31, 2015 were as 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
March 31, 2016					(in thousands)
Commercial, financial, leasing, etc.	$	20,911,645		30,495		2,358		524		1,765		279,790		21,226,577
Real estate:
Commercial		23,740,729		149,108		41,776		6,818		39,840		171,256		24,149,527
Residential builder and developer		1,747,261		15,304		195		3,493		23,516		32,458		1,822,227
Other commercial construction		3,663,835		28,336		9,068		280		19,239		20,781		3,741,539
Residential		19,747,097		500,241		278,640		15,790		463,871		186,452		21,192,091
Residential-limited documentation		3,757,924		107,679		275		—		165,404		76,265		4,107,547
Consumer:
Home equity lines and loans		5,720,342		40,054		—		15,898		2,239		78,722		5,857,255
Automobile		2,580,241		33,439		—		2		—		14,817		2,628,499
Other		3,083,495		24,739		3,858		18,962		—		16,150		3,147,204

Total	$	84,952,569		929,395		336,170		61,767		715,874		876,691		87,872,466


	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
December 31, 2015					(in thousands)
Commercial, financial, leasing, etc.	$	20,122,648		52,868		2,310		693		1,902		241,917		20,422,338
Real estate:
Commercial		23,645,354		172,439		12,963		8,790		46,790		179,606		24,065,942
Residential builder and developer		1,507,856		7,969		5,760		6,925		28,734		28,429		1,585,673
Other commercial construction		3,428,939		65,932		7,936		2,001		24,525		16,363		3,545,696
Residential		20,507,551		560,312		284,451		16,079		488,599		153,281		22,010,273
Residential-limited documentation		3,885,073		137,289		—		—		175,518		61,950		4,259,830
Consumer:
Home equity lines and loans		5,805,222		45,604		—		15,222		2,261		84,467		5,952,776
Automobile		2,446,473		56,181		—		6		—		16,597		2,519,257
Other		3,051,435		36,702		4,021		18,757		—		16,799		3,127,714

Total	$	84,400,551		1,135,296		317,441		68,473		768,329		799,409		87,489,499

(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 that were impaired at acquisition date and were recorded at fair value.

Changes in Allowance for Credit Losses

Changes in the allowance for credit losses for the three months ended March 31, 2016 were as follows:


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

Beginning balance	$	300,404			326,831			72,238			178,320			78,199			955,992
Provision for credit losses		24,364			4,013			1,218			19,893			(488	)		49,000
Net charge-offs
Charge-offs		(6,149	)		(1,272	)		(6,972	)		(44,319	)		—			(58,712	)
Recoveries		5,247			2,413			1,887			6,925			—			16,472

Net charge-offs		(902	)		1,141			(5,085	)		(37,394	)		—			(42,240	)

Ending balance	$	323,866			331,985			68,371			160,819			77,711			962,752

Changes in the allowance for credit losses for the three months ended March 31, 2015 were as follows:


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

Beginning balance	$	288,038			307,927			61,910			186,033			75,654		919,562
Provision for credit losses		1,442			15,542			960			19,574			482		38,000
Net charge-offs
Charge-offs		(12,350	)		(6,679	)		(3,118	)		(25,329	)		—		(47,476	)
Recoveries		3,939			585			989			5,774			—		11,287

Net charge-offs		(8,411	)		(6,094	)		(2,129	)		(19,555	)		—		(36,189	)

Ending balance	$	281,069			317,375			60,741			186,052			76,136		921,373

Impaired Loans and Leases


	March 31, 2016						December 31, 2015
	Recorded investment		Unpaid principal balance		Related allowance		Recorded investment		Unpaid principal balance		Related allowance
	(in thousands)
With an allowance recorded:
Commercial, financial, leasing, etc.	$	204,786		223,269		58,714		179,037		195,821		44,752
Real estate:
Commercial		86,612		97,912		19,600		85,974		95,855		18,764
Residential builder and developer		6,581		8,296		839		3,316		5,101		196
Other commercial construction		2,358		2,678		397		3,548		3,843		348
Residential		77,579		95,679		4,348		79,558		96,751		4,727
Residential-limited documentation		87,791		101,841		7,000		90,356		104,251		8,000
Consumer:
Home equity lines and loans		27,544		28,540		3,904		25,220		26,195		3,777
Automobile		21,289		21,289		4,867		22,525		22,525		4,709
Other		17,876		17,876		4,844		17,620		17,620		4,820

		532,416		597,380		104,513		507,154		567,962		90,093

With no related allowance recorded:
Commercial, financial, leasing, etc.		105,342		126,130		—		93,190		110,735		—
Real estate:
Commercial		92,733		106,710		—		101,340		116,230		—
Residential builder and developer		28,938		49,177		—		27,651		47,246		—
Other commercial construction		18,811		37,498		—		13,221		31,477		—
Residential		17,574		28,336		—		19,621		30,940		—
Residential-limited documentation		17,362		29,544		—		18,414		31,113		—

		280,760		377,395		—		273,437		367,741		—


Total:
Commercial, financial, leasing, etc.		310,128		349,399		58,714		272,227		306,556		44,752
Real estate:
Commercial		179,345		204,622		19,600		187,314		212,085		18,764
Residential builder and developer		35,519		57,473		839		30,967		52,347		196
Other commercial construction		21,169		40,176		397		16,769		35,320		348
Residential		95,153		124,015		4,348		99,179		127,691		4,727
Residential-limited documentation		105,153		131,385		7,000		108,770		135,364		8,000
Consumer:
Home equity lines and loans		27,544		28,540		3,904		25,220		26,195		3,777
Automobile		21,289		21,289		4,867		22,525		22,525		4,709
Other		17,876		17,876		4,844		17,620		17,620		4,820

Total	$	813,176		974,775		104,513		780,591		935,703		90,093

Interest Income Recognized on Impaired Loans


	Three months ended March 31, 2016						Three months ended March 31, 2015
			Interest income recognized						Interest income recognized
	Average recorded investment		Total		Cash basis		Average recorded investment		Total		Cash basis
	(in thousands)
Commercial, financial, leasing, etc.	$	296,584		611		611		214,618		604		604
Real estate:
Commercial		182,454		1,474		1,474		153,070		1,102		1,102
Residential builder and developer		33,750		42		42		73,151		63		63
Other commercial construction		16,868		38		38		25,540		55		55
Residential		96,788		1,372		882		104,490		1,446		910
Residential-limited documentation		107,473		1,472		630		125,654		1,610		647
Consumer:
Home equity lines and loans		26,019		246		85		19,683		201		48
Automobile		21,962		339		36		29,013		450		54
Other		17,717		178		27		18,861		174		33

Total	$	799,615		5,772		3,825		764,080		5,705		3,516

Summary of Loan Grades

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, Financial, Leasing, etc.		Commercial		Residential Builder and Developer		Other Commercial Construction
	(in thousands)
March 31, 2016
Pass	$	20,155,277		23,138,987		1,700,088		3,631,947
Criticized accrual		791,510		839,284		89,681		88,811
Criticized nonaccrual		279,790		171,256		32,458		20,781

Total	$	21,226,577		24,149,527		1,822,227		3,741,539


December 31, 2015
Pass	$	19,442,183		23,098,856		1,497,465		3,432,679
Criticized accrual		738,238		787,480		59,779		96,654
Criticized nonaccrual		241,917		179,606		28,429		16,363

Total	$	20,422,338		24,065,942		1,585,673		3,545,696

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, Leasing, etc.		Real Estate
	Commercial, Financial, Leasing, etc.		Commercial		Residential		Consumer		Total
	(in thousands)
March 31, 2016
Individually evaluated for impairment	$	58,714		20,611		11,348		13,615	$	104,288
Collectively evaluated for impairment		264,652		308,897		55,970		145,841		775,360
Purchased impaired		500		2,477		1,053		1,363		5,393

Allocated	$	323,866		331,985		68,371		160,819		885,041

Unallocated										77,711


Total									$	962,752


December 31, 2015
Individually evaluated for impairment	$	44,752		19,175		12,727		13,306	$	89,960
Collectively evaluated for impairment		255,615		307,000		57,624		163,511		783,750
Purchased impaired		37		656		1,887		1,503		4,083

Allocated	$	300,404		326,831		72,238		178,320		877,793

Unallocated										78,199


Total									$	955,992

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, Leasing, etc.		Real Estate
	Commercial, Financial, Leasing, etc.		Commercial		Residential		Consumer		Total
	(in thousands)
March 31, 2016
Individually evaluated for impairment	$	310,128		235,039		200,306		66,709	$	812,182
Collectively evaluated for impairment		20,914,684		29,395,659		24,470,057		11,564,010		86,344,410
Purchased impaired		1,765		82,595		629,275		2,239		715,874


Total	$	21,226,577		29,713,293		25,299,638		11,632,958	$	87,872,466


December 31, 2015
Individually evaluated for impairment	$	272,227		234,132		207,949		65,365	$	779,673
Collectively evaluated for impairment		20,148,209		28,863,130		25,398,037		11,532,121		85,941,497
Purchased impaired		1,902		100,049		664,117		2,261		768,329


Total	$	20,422,338		29,197,311		26,270,103		11,599,747	$	87,489,499

Loan Modification Activities that were Considered Troubled Debt Restructurings

The tables below summarize the Company’s loan modification activities that were considered troubled debt restructurings for the three months ended March 31, 2016 and 2015:


			Recorded investment				Financial effects of modification
Three months ended March 31, 2016	Number		Pre- modification		Post- modification		Recorded investment (a)			Interest (b)
			(dollars in thousands)
Commercial, financial, leasing, etc.
Principal deferral		24	$	11,571	$	12,721	$	1,150		$	—
Combination of concession types		7		6,157		5,952		(205	)		—
Real estate:
Commercial
Principal deferral		16		3,483		3,448		(35	)		—
Combination of concession types		5		3,933		3,924		(9	)		(35	)
Residential
Principal deferral		17		1,981		2,191		210			—
Combination of concession types		10		2,321		2,369		48			—
Residential-limited documentation
Principal deferral		1		125		138		13			—
Combination of concession types		5		1,312		1,379		67			(339	)
Consumer:
Home equity lines and loans
Principal deferral		3		335		335		—			—
Combination of concession types		23		2,496		2,496		—			(283	)
Automobile
Principal deferral		48		521		521		—			—
Other		16		38		38		—			—
Combination of concession types		8		85		85		—			(3	)
Other
Principal deferral		26		374		374		—			—
Other		2		25		25		—			—
Combination of concession types		8		147		147		—			(27	)

Total		219	$	34,904	$	36,143	$	1,239		$	(687	)

(a)

Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages.

(b)

Represents the present value of interest rate concessions discounted at the effective rate of the original loan.


			Recorded investment				Financial effects of modification
Three months ended March 31, 2015	Number		Pre- modification		Post- modification		Recorded investment (a)			Interest (b)
			(dollars in thousands)
Commercial, financial, leasing, etc.
Principal deferral		21	$	1,572	$	1,557	$	(15	)	$	—
Interest rate reduction		1		99		99		—			(19	)
Combination of concession types		3		9,155		6,989		(2,166	)		—
Real estate:
Commercial
Principal deferral		7		3,792		3,776		(16	)		—
Combination of concession types		4		1,646		1,637		(9	)		(52	)
Residential builder and developer
Principal deferral		1		1,398		1,398		—			—
Residential
Principal deferral		7		721		742		21			—
Combination of concession types		3		294		349		55			(34	)
Residential-limited documentation
Combination of concession types		1		210		210		—			(4	)
Consumer:
Home equity lines and loans
Principal deferral		1		21		21		—			—
Combination of concession types		5		196		196		—			(13	)
Automobile
Principal deferral		35		303		303		—			—
Interest rate reduction		3		42		42		—			(3	)
Other		10		20		20		—			—
Combination of concession types		8		84		84		—			(7	)
Other
Principal deferral		22		296		296		—			—
Other		5		59		59		—			—
Combination of concession types		13		224		224		—			(25	)

Total		150	$	20,132	$	18,002	$	(2,130	)	$	(157	)

(a)

Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages.

(b)

Represents the present value of interest rate concessions discounted at the effective rate of the original loan.

Shareholders' equity (Tables)

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Issued and Outstanding Preferred Stock

Issued and outstanding preferred stock of M&T as of March 31, 2016 and December 31, 2015 is presented below:


	Shares issued and outstanding		Carrying value
	(dollars in thousands)
Series A (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		230,000	$	230,000

Series C (a)
Fixed Rate Cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		151,500	$	151,500

Series D (b)
Fixed Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share		50,000	$	500,000

Series E (c)
Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share		350,000	$	350,000

(a)

(b)

(c)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=27011957&loc=d3e177068-122764

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21553-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6403732&loc=d3e21300-112643

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.28,29)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 30
-Article 5

+ Details

Pension plans and other postretirement benefits (Tables)

3 Months Ended

Mar. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Net Periodic Pension Expense for Defined Benefit Plans

Net periodic pension expense for defined benefit plans consisted of the following:


	Pension benefits						Other postretirement benefits
	Three months ended March 31
	2016			2015			2016			2015
	(in thousands)

Service cost	$	6,382			6,000			458			200
Interest cost on projected benefit obligation		20,883			17,775			1,205			650
Expected return on plan assets		(27,814	)		(23,575	)		—			—
Amortization of prior service credit		(825	)		(1,525	)		(350	)		(350	)
Amortization of net actuarial loss		8,300			11,175			—			25


Net periodic benefit cost	$	6,926			9,850			1,313			525

Earnings per common share (Tables)

3 Months Ended

Mar. 31, 2016

Earnings Per Share [Abstract]

Computations of Basic Earnings Per Common Share

The computations of basic earnings per common share follow:


	Three months ended March 31
	2016			2015
	(in thousands, except per share)
Income available to common shareholders:

Net income	$	298,528			241,613
Less: Preferred stock dividends (a)		(20,318	)		(20,318	)

Net income available to common equity		278,210			221,295
Less: Income attributable to unvested stock-based compensation awards		(2,466	)		(2,465	)


Net income available to common shareholders	$	275,744			218,830

Weighted-average shares outstanding:

Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards		160,220			133,542
Less: Unvested stock-based compensation awards		(1,486	)		(1,493	)


Weighted-average shares outstanding		158,734			132,049

Basic earnings per common share	$	1.74			1.66

(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 March 31
	2016			2015
	(in thousands, except per share)

Net income available to common equity	$	278,210			221,295
Less: Income attributable to unvested stock-based compensation awards		(2,462	)		(2,458	)


Net income available to common shareholders	$	275,748			218,837

Adjusted weighted-average shares outstanding:

Common and unvested stock-based compensation awards		160,220			133,542
Less: Unvested stock-based compensation awards		(1,486	)		(1,493	)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock		447			720


Adjusted weighted-average shares outstanding		159,181			132,769

Diluted earnings per common share	$	1.73			1.65

Comprehensive income (Tables)

3 Months Ended

Mar. 31, 2016

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 Securities
	With OTTI (a)			All other			Defined benefit plans			Other			Total amount before tax			Income tax			Net
	(in thousands)

Balance - January 1, 2016	$	16,359			62,849			(489,660	)		(4,093	)	$	(414,545	)		162,918		$	(251,627	)

Other comprehensive income before reclassifications:
Unrealized holding gains (losses), net		(370	)		159,660			—			—			159,290			(62,680	)		96,610
Foreign currency translation adjustment		—			—			—			(83	)		(83	)		30			(53	)

Total other comprehensive income(loss) before reclassifications		(370	)		159,660			—			(83	)		159,207			(62,650	)		96,557


Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:

Accretion of unrealized holding losses on held-to-maturity (“HTM”) securities		—			968			—			—			968	(b)		(381	)		587
Gains realized in net income		—			(4	)		—			—			(4	)(c)		1			(3	)
Accretion of net gain on terminated cash flow hedges		—			—			—			(39	)		(39	)(d)		15			(24	)
Amortization of prior service credit		—			—			(1,175	)		—			(1,175	)(e)		462			(713	)
Amortization of actuarial losses		—			—			8,300			—			8,300	(e)		(3,266	)		5,034

Total reclassifications		—			964			7,125			(39	)		8,050			(3,169	)		4,881


Total gain (loss) during the period		(370	)		160,624			7,125			(122	)		167,257			(65,819	)		101,438


Balance - March 31, 2016	$	15,989			223,473			(482,535	)		(4,215	)	$	(247,288	)		97,099		$	(150,189	)


	Investment Securities
	With OTTI (a)		All other		Defined benefit plans			Other			Total amount before tax			Income tax			Net
	(in thousands)

Balance - January 1, 2015	$	7,438		201,828		(503,027	)		(4,082	)	$	(297,843	)		116,849		$	(180,994	)

Other comprehensive income before reclassifications:
Unrealized holding gains, net		8,011		32,063		—			—			40,074			(15,247	)		24,827
Foreign currency translation adjustment		—		—		—			(3,732	)		(3,732	)		1,348			(2,384	)
Gains on cash flow hedges		—		—		—			1,453			1,453			(568	)		885

Total other comprehensive income(loss) before reclassifications		8,011		32,063		—			(2,279	)		37,795			(14,467	)		23,328


Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income:

Amortization of unrealized holding losses on HTM securities		—		739		—			—			739	(b)		(289	)		450
Losses realized in net income		—		98		—			—			98	(c)		(36	)		62
Accretion of net gain on terminated cash flow hedges		—		—		—			(24	)		(24	)(d)		10			(14	)
Amortization of prior service credit		—		—		(1,875	)		—			(1,875	)(e)		934			(941	)
Amortization of actuarial losses		—		—		11,200			—			11,200	(e)		(5,582	)		5,618

Total reclassifications		—		837		9,325			(24	)		10,138			(4,963	)		5,175


Total gain (loss) during the period		8,011		32,900		9,325			(2,303	)		47,933			(19,430	)		28,503


Balance - March 31, 2015	$	15,449		234,728		(493,702	)		(6,385	)	$	(249,910	)		97,419		$	(152,491	)

(a)

Other-than-temporary impairment

(b)

Included in interest income

(c)

Included in gain (loss) on bank investment securities

(d)

Included in interest expense

(e)

Included in salaries and employee benefits expense

Accumulated Other Comprehensive Income (Loss), Net

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


	Investment securities					Defined benefit plans
	With OTTI			All other		Defined benefit plans			Other			Total
	(in thousands)

Balance - December 31, 2015	$	9,921			38,166		(296,979	)		(2,735	)	$	(251,627	)

Net gain (loss) during period		(224	)		97,418		4,321			(77	)		101,438


Balance - March 31, 2016	$	9,697			135,584		(292,658	)		(2,812	)	$	(150,189	)

Derivative financial instruments (Tables)

3 Months Ended

Mar. 31, 2016

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-
	Notional		Average		average rate
	amount		maturity		Fixed			Variable
	(in thousands)		(in years)
March 31, 2016
Fair value hedges:
Fixed rate long-term borrowings (a)	$	1,400,000		1.4		4.42	%		1.59	%


December 31, 2015
Fair value hedges:
Fixed rate long-term borrowings (a)	$	1,400,000		1.7		4.42	%		1.39	%

(a)

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

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
	March 31, 2016		December 31, 2015		March 31, 2016		December 31, 2015
	(in thousands)
Derivatives designated and qualifying as hedging instruments
Fair value hedges:
Interest rate swap agreements (a)	$	41,259		43,892	$	—		—
Commitments to sell real estate loans (a)		412		1,844		3,243		656

		41,671		45,736		3,243		656

Derivatives not designated and qualifying as hedging instruments
Mortgage-related commitments to originate real estate loans for sale (a)		16,929		10,282		44		403
Commitments to sell real estate loans (a)		428		533		2,413		846
Trading:
Interest rate contracts (b)		329,739		203,517		278,981		153,723
Foreign exchange and other option and futures contracts (b)		17,807		8,569		16,888		7,022

		364,903		222,901		298,326		161,994


Total derivatives	$	406,574		268,637	$	301,569		162,650

(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.

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


	Amount of gain (loss) recognized
	Three months ended March 31, 2016					Three months ended March 31, 2015
	Derivative			Hedged item		Derivative			Hedged item
	(in thousands)
Derivatives in fair value hedging relationships

Interest rate swap agreements:
Fixed rate long-term borrowings (a)	$	(2,633	)		1,870	$	(396	)		161


Derivatives not designated as hedging instruments

Trading:
Interest rate contracts (b)	$	974				$	660
Foreign exchange and other option and futures contracts (b)		1,212					2,789


Total	$	2,186				$	3,449

(a)

Reported as other revenues from operations.

(b)

Reported as trading account and foreign exchange gains.

Fair value measurements (Tables)

3 Months Ended

Mar. 31, 2016

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis

The following tables present assets and liabilities at March 31, 2016 and December 31, 2015 measured at estimated fair value on a recurring basis:


	Fair value measurements at March 31, 2016		Level 1(a)		Level 2(a)		Level 3
	(in thousands)

Trading account assets	$	467,987		69,689		398,298		—
Investment securities available for sale:
U.S. Treasury and federal agencies		202,192		—		202,192		—
Obligations of states and political subdivisions		5,448		—		5,448		—
Mortgage-backed securities:
Government issued or guaranteed		11,750,062		—		11,750,062		—
Privately issued		65		—		—		65
Collateralized debt obligations		45,040		—		—		45,040
Other debt securities		112,708		—		112,708		—
Equity securities		85,132		67,150		17,982		—

		12,200,647		67,150		12,088,392		45,105


Real estate loans held for sale		396,764		—		396,764		—
Other assets (b)		59,028		—		42,099		16,929

Total assets	$	13,124,426		136,839		12,925,553		62,034


Trading account liabilities	$	295,869		—		295,869		—
Other liabilities (b)		5,700		—		5,656		44

Total liabilities	$	301,569		—		301,525		44


	Fair value measurements at December 31, 2015		Level 1(a)		Level 2(a)		Level 3
	(in thousands)

Trading account assets	$	273,783		56,763		217,020		—
Investment securities available for sale:
U.S. Treasury and federal agencies		299,997		—		299,997		—
Obligations of states and political subdivisions		6,028		—		6,028		—
Mortgage-backed securities:
Government issued or guaranteed		11,686,628		—		11,686,628		—
Privately issued		74		—		—		74
Collateralized debt obligations		47,393		—		—		47,393
Other debt securities		118,880		—		118,880		—
Equity securities		83,671		65,178		18,493		—

		12,242,671		65,178		12,130,026		47,467


Real estate loans held for sale		392,036		—		392,036		—
Other assets (b)		56,551		—		46,269		10,282

Total assets	$	12,965,041		121,941		12,785,351		57,749


Trading account liabilities	$	160,745		—		160,745		—
Other liabilities (b)		1,905		—		1,502		403

Total liabilities	$	162,650		—		162,247		403

(a)

There were no significant transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2016 and the year ended December 31, 2015.

(b)

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 the three months ended March 31, 2016 were as follows:


	Investment securities available for sale
	Privately issued mortgage-backed securities			Collateralized debt obligations			Other assets and other liabilities
	(in thousands)
Balance – January 1, 2016	$	74		$	47,393		$	9,879

Total gains (losses) realized/unrealized:
Included in earnings		—			—			23,898	(b)
Included in other comprehensive income		—			(2,148	)(c)		—
Settlements		(9	)		(205	)		—
Transfers in and/or out of Level 3 (a)		—			—			(16,892	)(d)


Balance – March 31, 2016	$	65		$	45,040		$	16,885


Changes in unrealized gains included in earnings related to assets still held at March 31, 2016	$	—		$	—		$	14,539	(b)

The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the three months ended March 31, 2015 were as follows:


	Investment securities available for sale
	Privately issued mortgage-backed securities			Collateralized debt obligations			Other assets and other liabilities
	(in thousands)
Balance – January 1, 2015	$	103		$	50,316		$	17,347

Total gains (losses) realized/unrealized:
Included in earnings		—			—			29,770	(b)
Included in other comprehensive income		—			(2,004	)(c)		—
Settlements		(8	)		(1,034	)		—
Transfers in and/or out of Level 3 (a)		—			—			(20,887	)(d)


Balance – March 31, 2015	$	95		$	47,278		$	26,230


Changes in unrealized gains included in earnings related to assets still held at March 31, 2015	$	—		$	—		$	22,636	(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)

Reported as net unrealized losses on investment securities in the consolidated statement of comprehensive income.

(d)

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

Quantitative Information Related to Significant Unobservable Inputs


	Fair value at March 31, 2016		Valuation technique	Unobservable input/assumptions	Range (weighted- average)
	(in thousands)
Recurring fair value measurements

Privately issued mortgage–backed securities	$	65	Two independent pricing quotes	—	—

Collateralized debt obligations		45,040	Discounted cash flow	Probability of default	10%-56% (31%)
				Loss severity	100%

Net other assets (liabilities) (a)		16,885	Discounted cash flow	Commitment expirations	0%-66% (31%)

	Fair value at December 31, 2015		Valuation technique	Unobservable input/assumptions	Range (weighted- average)
	(in thousands)
Recurring fair value measurements

Privately issued mortgage–backed securities	$	74	Two independent pricing quotes	—	—

Collateralized debt obligations		47,393	Discounted cash flow	Probability of default	10%-56% (31%)
				Loss severity	100%

Net other assets (liabilities) (a)		9,879	Discounted cash flow	Commitment expirations	0%-60% (39%)

(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:


	March 31, 2016
	Carrying amount			Estimated fair value			Level 1		Level 2			Level 3
				(in thousands)
Financial assets:
Cash and cash equivalents	$	1,178,175		$	1,178,175		$	1,112,933	$	65,242		$	—
Interest-bearing deposits at banks		9,545,181			9,545,181			—		9,545,181			—
Trading account assets		467,987			467,987			69,689		398,298			—
Investment securities		15,467,320			15,506,052			67,150		15,256,530			182,372
Loans and leases:
Commercial loans and leases		21,226,577			20,875,827			—		—			20,875,827
Commercial real estate loans		29,713,293			29,569,740			—		127,736			29,442,004
Residential real estate loans		25,299,638			25,386,240			—		4,590,667			20,795,573
Consumer loans		11,632,958			11,553,135			—		—			11,553,135
Allowance for credit losses		(962,752	)		—			—		—			—

Loans and leases, net		86,909,714			87,384,942			—		4,718,403			82,666,539
Accrued interest receivable		318,486			318,486			—		318,486			—

Financial liabilities:
Noninterest-bearing deposits	$	(29,709,218	)	$	(29,709,218	)		—	$	(29,709,218	)		—
Savings and interest-checking deposits		(51,497,240	)		(51,497,240	)		—		(51,497,240	)		—
Time deposits		(12,841,331	)		(12,879,619	)		—		(12,879,619	)		—
Deposits at Cayman Islands office		(166,787	)		(166,787	)		—		(166,787	)		—
Short-term borrowings		(1,766,826	)		(1,766,826	)		—		(1,766,826	)		—
Long-term borrowings		(10,341,035	)		(10,338,217	)		—		(10,338,217	)		—
Accrued interest payable		(80,605	)		(80,605	)		—		(80,605	)		—
Trading account liabilities		(295,869	)		(295,869	)		—		(295,869	)		—

Other financial instruments:
Commitments to originate real estate loans for sale	$	16,885		$	16,885			—	$	—		$	16,885
Commitments to sell real estate loans		(4,816	)		(4,816	)		—		(4,816	)		—
Other credit-related commitments		(118,521	)		(118,521	)		—		—			(118,521	)
Interest rate swap agreements used for interest rate risk management		41,259			41,259			—		41,259			—


	December 31, 2015
	Carrying amount			Estimated fair value			Level 1		Level 2			Level 3
				(in thousands)
Financial assets:
Cash and cash equivalents	$	1,368,040		$	1,368,040		$	1,276,678	$	91,362		$	—
Interest-bearing deposits at banks		7,594,350			7,594,350			—		7,594,350			—
Trading account assets		273,783			273,783			56,763		217,020			—
Investment securities		15,656,439			15,660,877			65,178		15,406,404			189,295
Loans and leases:
Commercial loans and leases		20,422,338			20,146,201			—		—			20,146,201
Commercial real estate loans		29,197,311			29,044,244			—		38,774			29,005,470
Residential real estate loans		26,270,103			26,267,771			—		4,727,816			21,539,955
Consumer loans		11,599,747			11,550,270			—		—			11,550,270
Allowance for credit losses		(955,992	)		—			—		—			—

Loans and leases, net		86,533,507			87,008,486			—		4,766,590			82,241,896
Accrued interest receivable		306,496			306,496			—		306,496			—

Financial liabilities:
Noninterest-bearing deposits	$	(29,110,635	)	$	(29,110,635	)		—	$	(29,110,635	)		—
Savings and interest-checking deposits		(49,566,644	)		(49,566,644	)		—		(49,566,644	)		—
Time deposits		(13,110,392	)		(13,135,042	)		—		(13,135,042	)		—
Deposits at Cayman Islands office		(170,170	)		(170,170	)		—		(170,170	)		—
Short-term borrowings		(2,132,182	)		(2,132,182	)		—		(2,132,182	)		—
Long-term borrowings		(10,653,858	)		(10,639,556	)		—		(10,639,556	)		—
Accrued interest payable		(85,145	)		(85,145	)		—		(85,145	)		—
Trading account liabilities		(160,745	)		(160,745	)		—		(160,745	)		—

Other financial instruments:
Commitments to originate real estate loans for sale	$	9,879		$	9,879			—	$	—		$	9,879
Commitments to sell real estate loans		875			875			—		875			—
Other credit-related commitments		(122,334	)		(122,334	)		—		—			(122,334	)
Interest rate swap agreements used for interest rate risk management		43,892			43,892			—		43,892			—

Commitments and contingencies (Tables)

3 Months Ended

Mar. 31, 2016

Commitments and Contingencies Disclosure [Abstract]

Company's Significant Commitments

The following table presents the Company’s significant commitments. Certain of these commitments are not included in the Company’s consolidated balance sheet.


	March 31, 2016		December 31, 2015
	(in thousands)
Commitments to extend credit
Home equity lines of credit	$	5,604,610		5,631,680
Commercial real estate loans to be sold		184,198		57,597
Other commercial real estate		5,727,946		5,949,933
Residential real estate loans to be sold		520,694		488,621
Other residential real estate		281,735		212,619
Commercial and other		12,077,612		11,802,850

Standby letters of credit		3,330,241		3,330,013

Commercial letters of credit		45,798		55,559

Financial guarantees and indemnification contracts		2,773,590		2,794,322

Commitments to sell real estate loans		958,337		782,885

Segment information (Tables)

3 Months Ended

Mar. 31, 2016

Segment Reporting [Abstract]

Information about Company's Segments

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


	Three months ended March 31
	2016								2015
	Total revenues(a)		Inter- segment revenues			Net income (loss)			Total revenues(a)		Inter- segment revenues			Net income (loss)
	(in thousands)
Business Banking	$	113,689		991			25,448		$	108,560		1,045			24,811
Commercial Banking		253,617		1,056			101,327			246,581		1,085			96,423
Commercial Real Estate		177,380		387			80,529			169,021		82			82,591
Discretionary Portfolio		86,835		(14,323	)		39,988			15,474		(5,443	)		5,954
Residential Mortgage Banking		96,935		19,660			17,077			105,757		11,387			29,460
Retail Banking		339,046		3,014			63,288			300,391		3,137			68,888
All Other		225,395		(10,785	)		(29,129	)		154,007		(11,293	)		(66,514	)

Total	$	1,292,897		—			298,528		$	1,099,791		—			241,613


	Average total assets
	Three months ended March 31					Year ended December 31
	2016		2015			2015
	(in millions)
Business Banking	$	5,424		5,300			5,339
Commercial Banking		24,838		23,683			24,143
Commercial Real Estate		19,839		18,334	(b)		18,827
Discretionary Portfolio		42,509		22,714			26,648
Residential Mortgage Banking		2,647		3,197	(b)		2,918
Retail Banking		11,568		10,788			11,035
All Other		16,427		11,876			12,870

Total	$	123,252		95,892			101,780

(a)

(b)

Acquisition - Additional Information (Detail)		1 Months Ended	3 Months Ended
Acquisition - Additional Information (Detail)	Nov. 01, 2015 USD ($) Office shares	Nov. 30, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Proceeds from sales of investment securities			$ 518,000	$ 693,000
Goodwill			4,593,112,000		$ 4,593,112,000
Hudson City [Member]
Business Acquisition [Line Items]
Gross amount of cash paid in the acquisition	$ 2,064,284,000
Total purchase consideration	$ 5,203,108,000
Number of banking offices acquired in New Jersey, Connecticut and New York \| Office	135
Proceeds from sales of investment securities		$ 5,800,000,000
Repayments of borrowings assumed in acquisition		$ 10,600,000,000
Goodwill	$ 1,079,787,000
Core deposit intangible assets			$ 132,000,000
Amortization period of core deposit intangible assets			7 years
Other- than-temporary impairment				7,000,000
Merger-related expenses			$ 23,162,000	$ 0
Hudson City [Member] \| Common Stock [Member]
Business Acquisition [Line Items]
Shares issued upon acquisition \| shares	25,953,950

Acquisition - Schedule of Assets Acquired and Liabilities (Detail) - USD ($) $ in Thousands	Nov. 01, 2015	Mar. 31, 2016	Dec. 31, 2015
Identifiable assets:
Goodwill		$ 4,593,112	$ 4,593,112
Hudson City [Member]
Identifiable assets:
Cash and due from banks	$ 131,688
Interest-bearing deposits at banks	7,568,934
Investment securities	7,929,014
Loans	19,015,013
Goodwill	1,079,787
Core deposit intangible	131,665
Other assets	843,219
Total identifiable assets	36,699,320
Liabilities:
Deposits	17,879,589
Borrowings	13,211,598
Other liabilities	405,025
Total liabilities	31,496,212
Total consideration	5,203,108
Cash paid	2,064,284
Common stock awards converted	28,243
Total consideration	5,203,108
Hudson City [Member] \| Common Stock [Member]
Liabilities:
Common stock issued (25,953,950 shares)	$ 3,110,581

Acquisition - Schedule of Assets Acquired and Liabilities (Parenthetical) (Detail)	Nov. 01, 2015 shares
Common Stock [Member] \| Hudson City [Member]
Business Acquisition [Line Items]
Common stock issued	25,953,950

Acquisition - Pro Forma Information (Detail) $ in Thousands	3 Months Ended
Acquisition - Pro Forma Information (Detail) $ in Thousands	Mar. 31, 2015 USD ($)
Business Acquisition, Pro Forma Information [Abstract]
Total revenues pro forma	$ 1,253,445
Net income pro forma	$ 285,237

Acquisition - Summary of Merger-Related Expenses (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Summary of merger-related expenses
Salaries and employee benefits	$ 431,785,000	$ 389,893,000
Equipment and net occupancy	74,178,000	66,470,000
Printing, postage and supplies	11,986,000	9,590,000
Other cost of operations	220,602,000	202,969,000
Hudson City [Member]
Summary of merger-related expenses
Salaries and employee benefits	5,274,000
Equipment and net occupancy	939,000
Printing, postage and supplies	937,000
Other cost of operations	16,012,000
Total merger-related expenses	$ 23,162,000	$ 0

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Other securities, Amortized cost	$ 536,062	$ 554,059
Other securities, Gross unrealized gains	0	0
Other securities, Gross unrealized losses	0	0
Other securities, Estimated fair value	536,062	554,059
Investment securities available for sale, amortized cost	11,937,326	12,138,636
Investment securities available for sale, gross unrealized gains	297,018	174,699
Investment securities available for sale, gross unrealized losses	33,697	70,664
Investment securities available for sale, estimated fair value	12,200,647	12,242,671
Amortized cost for held to maturity	2,730,611	2,859,709
Gross unrealized gains for held to maturity	81,182	54,043
Gross unrealized losses for held to maturity	42,450	49,605
Estimated fair value for held to maturity	2,769,343	2,864,147
Total Amortized cost	15,203,999	15,552,404
Total for Gross unrealized gains	378,200	228,742
Total for Gross unrealized losses	76,147	120,269
Total for Estimated fair value	15,506,052	15,660,877
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	5,356	5,924
Investment securities available for sale, gross unrealized gains	138	146
Investment securities available for sale, gross unrealized losses	46	42
Investment securities available for sale, estimated fair value	5,448	6,028
Amortized cost for held to maturity	103,408	118,431
Gross unrealized gains for held to maturity	886	1,003
Gross unrealized losses for held to maturity	332	421
Estimated fair value for held to maturity	103,962	119,013
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	11,490,181	11,592,959
Investment securities available for sale, gross unrealized gains	265,879	142,370
Investment securities available for sale, gross unrealized losses	5,998	48,701
Investment securities available for sale, estimated fair value	11,750,062	11,686,628
Amortized cost for held to maturity	2,445,563	2,553,612
Gross unrealized gains for held to maturity	78,448	50,936
Gross unrealized losses for held to maturity	2,070	7,817
Estimated fair value for held to maturity	2,521,941	2,596,731
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	65	74
Investment securities available for sale, gross unrealized gains	2	2
Investment securities available for sale, gross unrealized losses	2	2
Investment securities available for sale, estimated fair value	65	74
Amortized cost for held to maturity	175,467	181,091
Gross unrealized gains for held to maturity	1,848	2,104
Gross unrealized losses for held to maturity	40,048	41,367
Estimated fair value for held to maturity	137,267	141,828
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	136,968	137,556
Investment securities available for sale, gross unrealized gains	1,407	1,514
Investment securities available for sale, gross unrealized losses	25,667	20,190
Investment securities available for sale, estimated fair value	112,708	118,880
Amortized cost for held to maturity	6,173	6,575
Estimated fair value for held to maturity	6,173	6,575
U.S. Treasury and Federal Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	201,002	299,890
Investment securities available for sale, gross unrealized gains	1,197	294
Investment securities available for sale, gross unrealized losses	7	187
Investment securities available for sale, estimated fair value	202,192	299,997
Collateralized Debt Obligations [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	28,483	28,438
Investment securities available for sale, gross unrealized gains	18,170	20,143
Investment securities available for sale, gross unrealized losses	1,613	1,188
Investment securities available for sale, estimated fair value	45,040	47,393
Equity Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Investment securities available for sale, amortized cost	75,271	73,795
Investment securities available for sale, gross unrealized gains	10,225	10,230
Investment securities available for sale, gross unrealized losses	364	354
Investment securities available for sale, estimated fair value	$ 85,132	$ 83,671

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Debt securities available for sale:
Due in one year or less	$ 7,504
Due after one year through five years	201,714
Due after five years through ten years	2,728
Due after ten years	159,863
Total available for sale (amortized cost)	371,809
Mortgage-backed securities available for sale	11,490,246
Total	11,862,055
Debt securities held to maturity:
Due in one year or less	32,387
Due after one year through five years	64,484
Due after five years through ten years	6,537
Due after ten years	6,173
Total available for held to maturity (amortized cost)	109,581
Mortgage-backed securities held to maturity	2,621,030
Amortized cost for held to maturity	2,730,611	$ 2,859,709
Debt securities available for sale:
Due in one year or less	7,551
Due after one year through five years	203,128
Due after five years through ten years	2,926
Due after ten years	151,783
Total available for sale (fair value)	365,388
Mortgage-backed securities available for sale	11,750,127
Total	12,115,515
Debt securities held to maturity:
Due in one year or less	32,542
Due after one year through five years	64,760
Due after five years through ten years	6,660
Due after ten years	6,173
Total available for held to maturity (fair value)	110,135
Mortgage-backed securities held to maturity	2,659,208
Total	$ 2,769,343	$ 2,864,147

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 363,989	$ 4,246,991
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(3,906)	(49,727)
Estimated fair value, 12 months or more	1,325,788	104,154
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(29,791)	(20,937)
Held to maturity, Estimated fair value, Less than 12 months	29,519	502,896
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(227)	(2,136)
Held to maturity, Estimated fair value, 12 months or more	346,600	346,875
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(42,223)	(47,469)
Total investment securities, fair value less than 12 months	393,508	4,749,887
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(4,133)	(51,863)
Total of investment securities, fair value, 12 Months or More	1,672,388	451,029
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(72,014)	(68,406)
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		865
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses		(2)
Estimated fair value, 12 months or more	1,706	1,335
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(46)	(40)
Held to maturity, Estimated fair value, Less than 12 months	28,707	42,913
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(215)	(335)
Held to maturity, Estimated fair value, 12 months or more	8,813	5,853
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(117)	(86)
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	337,672	4,061,899
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(1,959)	(48,534)
Estimated fair value, 12 months or more	1,233,329	7,216
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(4,039)	(167)
Held to maturity, Estimated fair value, Less than 12 months	812	459,983
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(12)	(1,801)
Held to maturity, Estimated fair value, 12 months or more	232,432	228,867
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(2,058)	(6,016)
Privately Issued Mortgage-Backed Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, 12 months or more	34	43
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(2)	(2)
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	4,051	147,508
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(7)	(187)
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Held to maturity, Estimated fair value, 12 months or more	105,355	112,155
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(40,048)	(41,367)
Collateralized Debt Obligations [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	10,326	5,711
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(527)	(335)
Estimated fair value, 12 months or more	1,858	2,063
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(1,086)	(853)
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	9,825	12,935
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(1,203)	(462)
Estimated fair value, 12 months or more	88,715	93,344
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(24,464)	(19,728)
Equity Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	2,115	18,073
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(210)	(207)
Estimated fair value, 12 months or more	146	153
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	$ (154)	$ (147)

Investment Securities - Additional Information (Detail) $ in Thousands	Mar. 31, 2016 USD ($) Investment	Dec. 31, 2015 USD ($)
Amortized Cost and Fair Value Debt Securities [Abstract]
Number of investment securities with aggregate gross unrealized losses \| Investment	538
Unrealized losses on individual investment securities	$ 76,147	$ 120,269
Cost method investment securities	$ 536,000

Loans and Leases and the Allowance for Credit Losses - Outstanding Principal Balance and Carrying Amount of Loans that is Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 2,918,333	$ 3,122,935
Carrying amount	2,306,988	2,465,067
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	71,577	78,847
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	588,983	644,284
Residential Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	964,893	1,016,129
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 681,535	$ 725,807

Loans and Leases and the Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Loans And Leases Receivable [Line Items]
Contractual principal and interest payments	$ 716	$ 768
Commercial real estate loans held for sale	$ 128	39
Loan delinquent period	90 days
Minimum delinquency period for loan level collectability analysis consumer mortgage	150 days
Amount of foreclosed residential real estate property held	$ 169	172
Loans secured by residential real estate that were in the process of foreclosure	$ 309	$ 315
Maximum [Member]
Loans And Leases Receivable [Line Items]
Purchased impaired loans as a percentage of total assets	1.00%	1.00%
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	$ 269	$ 353
Carrying value of loans for which partial charge-off has been recognized	52	55
Mortgage loans, customer balance outstanding	20	20
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	24	21
Mortgage loans, customer balance outstanding	$ 32	$ 28

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
	Mar. 31, 2016	Mar. 31, 2015
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 481,052	$ 473,897
Interest income	(51,924)	(46,483)
Reclassifications from nonaccretable balance, net	6,293	293
Other	4,781	1,610
Balance at end of period	440,202	429,317
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	184,618	76,518
Interest income	(14,062)	(5,206)
Reclassifications from nonaccretable balance, net	629	110
Balance at end of period	171,185	71,422
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	296,434	397,379
Interest income	(37,862)	(41,277)
Reclassifications from nonaccretable balance, net	5,664	183
Other	4,781	1,610
Balance at end of period	$ 269,017	$ 357,895

Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 84,952,569	$ 84,400,551
30-89 Days past due	929,395	1,135,296
Accruing loans past due 90 days or more	336,170	317,441
Purchased impaired	715,874	768,329
Nonaccrual	876,691	799,409
Loans and leases, net of unearned discount	87,872,466	87,489,499
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	20,911,645	20,122,648
30-89 Days past due	30,495	52,868
Accruing loans past due 90 days or more	2,358	2,310
Purchased impaired	1,765	1,902
Nonaccrual	279,790	241,917
Loans and leases, net of unearned discount	21,226,577	20,422,338
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	23,740,729	23,645,354
30-89 Days past due	149,108	172,439
Accruing loans past due 90 days or more	41,776	12,963
Purchased impaired	39,840	46,790
Nonaccrual	171,256	179,606
Loans and leases, net of unearned discount	24,149,527	24,065,942
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,747,261	1,507,856
30-89 Days past due	15,304	7,969
Accruing loans past due 90 days or more	195	5,760
Purchased impaired	23,516	28,734
Nonaccrual	32,458	28,429
Loans and leases, net of unearned discount	1,822,227	1,585,673
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,663,835	3,428,939
30-89 Days past due	28,336	65,932
Accruing loans past due 90 days or more	9,068	7,936
Purchased impaired	19,239	24,525
Nonaccrual	20,781	16,363
Loans and leases, net of unearned discount	3,741,539	3,545,696
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	19,747,097	20,507,551
30-89 Days past due	500,241	560,312
Accruing loans past due 90 days or more	278,640	284,451
Purchased impaired	463,871	488,599
Nonaccrual	186,452	153,281
Loans and leases, net of unearned discount	21,192,091	22,010,273
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,757,924	3,885,073
30-89 Days past due	107,679	137,289
Accruing loans past due 90 days or more	275
Purchased impaired	165,404	175,518
Nonaccrual	76,265	61,950
Loans and leases, net of unearned discount	4,107,547	4,259,830
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	5,720,342	5,805,222
30-89 Days past due	40,054	45,604
Purchased impaired	2,239	2,261
Nonaccrual	78,722	84,467
Loans and leases, net of unearned discount	5,857,255	5,952,776
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	2,580,241	2,446,473
30-89 Days past due	33,439	56,181
Nonaccrual	14,817	16,597
Loans and leases, net of unearned discount	2,628,499	2,519,257
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,083,495	3,051,435
30-89 Days past due	24,739	36,702
Accruing loans past due 90 days or more	3,858	4,021
Nonaccrual	16,150	16,799
Loans and leases, net of unearned discount	3,147,204	3,127,714
Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	61,767	68,473
Accruing Loans Acquired at Discount [Member] \| Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	524	693
Accruing Loans Acquired at Discount [Member] \| Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	6,818	8,790
Accruing Loans Acquired at Discount [Member] \| Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	3,493	6,925
Accruing Loans Acquired at Discount [Member] \| Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	280	2,001
Accruing Loans Acquired at Discount [Member] \| Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	15,790	16,079
Accruing Loans Acquired at Discount [Member] \| Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	15,898	15,222
Accruing Loans Acquired at Discount [Member] \| Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	2	6
Accruing Loans Acquired at Discount [Member] \| Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past due 90 days or more	$ 18,962	$ 18,757

Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 955,992	$ 919,562
Provision for credit losses	49,000	38,000
Net charge-offs
Charge-offs	(58,712)	(47,476)
Recoveries	16,472	11,287
Net charge-offs	(42,240)	(36,189)
Ending balance	962,752	921,373
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	300,404	288,038
Provision for credit losses	24,364	1,442
Net charge-offs
Charge-offs	(6,149)	(12,350)
Recoveries	5,247	3,939
Net charge-offs	(902)	(8,411)
Ending balance	323,866	281,069
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	326,831	307,927
Provision for credit losses	4,013	15,542
Net charge-offs
Charge-offs	(1,272)	(6,679)
Recoveries	2,413	585
Net charge-offs	1,141	(6,094)
Ending balance	331,985	317,375
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	72,238	61,910
Provision for credit losses	1,218	960
Net charge-offs
Charge-offs	(6,972)	(3,118)
Recoveries	1,887	989
Net charge-offs	(5,085)	(2,129)
Ending balance	68,371	60,741
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	178,320	186,033
Provision for credit losses	19,893	19,574
Net charge-offs
Charge-offs	(44,319)	(25,329)
Recoveries	6,925	5,774
Net charge-offs	(37,394)	(19,555)
Ending balance	160,819	186,052
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	78,199	75,654
Provision for credit losses	(488)	482
Net charge-offs
Ending balance	$ 77,711	$ 76,136

Loans and Leases and the Allowance for Credit Losses - Impaired Loans and Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	$ 532,416	$ 507,154
Unpaid principal balance with related allowance	597,380	567,962
Related allowance	104,513	90,093
Recorded investment with no related allowance	280,760	273,437
Unpaid principal balance with no related allowance	377,395	367,741
Recorded investment	813,176	780,591
Unpaid principal balance	974,775	935,703
Related allowance	104,513	90,093
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	86,612	85,974
Unpaid principal balance with related allowance	97,912	95,855
Related allowance	19,600	18,764
Recorded investment with no related allowance	92,733	101,340
Unpaid principal balance with no related allowance	106,710	116,230
Recorded investment	179,345	187,314
Unpaid principal balance	204,622	212,085
Related allowance	19,600	18,764
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	21,289	22,525
Unpaid principal balance with related allowance	21,289	22,525
Related allowance	4,867	4,709
Recorded investment	21,289	22,525
Unpaid principal balance	21,289	22,525
Related allowance	4,867	4,709
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	204,786	179,037
Unpaid principal balance with related allowance	223,269	195,821
Related allowance	58,714	44,752
Recorded investment with no related allowance	105,342	93,190
Unpaid principal balance with no related allowance	126,130	110,735
Recorded investment	310,128	272,227
Unpaid principal balance	349,399	306,556
Related allowance	58,714	44,752
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	6,581	3,316
Unpaid principal balance with related allowance	8,296	5,101
Related allowance	839	196
Recorded investment with no related allowance	28,938	27,651
Unpaid principal balance with no related allowance	49,177	47,246
Recorded investment	35,519	30,967
Unpaid principal balance	57,473	52,347
Related allowance	839	196
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	2,358	3,548
Unpaid principal balance with related allowance	2,678	3,843
Related allowance	397	348
Recorded investment with no related allowance	18,811	13,221
Unpaid principal balance with no related allowance	37,498	31,477
Recorded investment	21,169	16,769
Unpaid principal balance	40,176	35,320
Related allowance	397	348
Residential [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	77,579	79,558
Unpaid principal balance with related allowance	95,679	96,751
Related allowance	4,348	4,727
Recorded investment with no related allowance	17,574	19,621
Unpaid principal balance with no related allowance	28,336	30,940
Recorded investment	95,153	99,179
Unpaid principal balance	124,015	127,691
Related allowance	4,348	4,727
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	87,791	90,356
Unpaid principal balance with related allowance	101,841	104,251
Related allowance	7,000	8,000
Recorded investment with no related allowance	17,362	18,414
Unpaid principal balance with no related allowance	29,544	31,113
Recorded investment	105,153	108,770
Unpaid principal balance	131,385	135,364
Related allowance	7,000	8,000
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	27,544	25,220
Unpaid principal balance with related allowance	28,540	26,195
Related allowance	3,904	3,777
Recorded investment	27,544	25,220
Unpaid principal balance	28,540	26,195
Related allowance	3,904	3,777
Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	17,876	17,620
Unpaid principal balance with related allowance	17,876	17,620
Related allowance	4,844	4,820
Recorded investment	17,876	17,620
Unpaid principal balance	17,876	17,620
Related allowance	$ 4,844	$ 4,820

Loans and Leases and the Allowance for Credit Losses - Interest Income Recognized on Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	$ 799,615	$ 764,080
Interest income recognized, Total	5,772	5,705
Interest income recognized, Cash basis	3,825	3,516
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	182,454	153,070
Interest income recognized, Total	1,474	1,102
Interest income recognized, Cash basis	1,474	1,102
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	296,584	214,618
Interest income recognized, Total	611	604
Interest income recognized, Cash basis	611	604
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	33,750	73,151
Interest income recognized, Total	42	63
Interest income recognized, Cash basis	42	63
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	16,868	25,540
Interest income recognized, Total	38	55
Interest income recognized, Cash basis	38	55
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	96,788	104,490
Interest income recognized, Total	1,372	1,446
Interest income recognized, Cash basis	882	910
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	107,473	125,654
Interest income recognized, Total	1,472	1,610
Interest income recognized, Cash basis	630	647
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	26,019	19,683
Interest income recognized, Total	246	201
Interest income recognized, Cash basis	85	48
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	21,962	29,013
Interest income recognized, Total	339	450
Interest income recognized, Cash basis	36	54
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	17,717	18,861
Interest income recognized, Total	178	174
Interest income recognized, Cash basis	$ 27	$ 33

Loans and Leases and the Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 87,872,466	$ 87,489,499
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	21,226,577	20,422,338
Commercial, Financial, Leasing, etc. [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	20,155,277	19,442,183
Commercial, Financial, Leasing, etc. [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	791,510	738,238
Commercial, Financial, Leasing, etc. [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	279,790	241,917
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	24,149,527	24,065,942
Commercial [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,138,987	23,098,856
Commercial [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	839,284	787,480
Commercial [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	171,256	179,606
Residential Builder and Developer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,822,227	1,585,673
Residential Builder and Developer [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,700,088	1,497,465
Residential Builder and Developer [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	89,681	59,779
Residential Builder and Developer [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	32,458	28,429
Other Commercial Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,741,539	3,545,696
Other Commercial Construction [Member] \| Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,631,947	3,432,679
Other Commercial Construction [Member] \| Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	88,811	96,654
Other Commercial Construction [Member] \| Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 20,781	$ 16,363

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	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 104,288	$ 89,960
Allowance for credit losses	775,360	783,750
Allowance for credit losses	962,752	955,992	$ 921,373	$ 919,562
Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	5,393	4,083
Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	885,041	877,793
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	77,711	78,199	$ 76,136	$ 75,654
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	58,714	44,752
Allowance for credit losses	264,652	255,615
Commercial, Financial, Leasing, etc. [Member] \| Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	500	37
Commercial, Financial, Leasing, etc. [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	323,866	300,404
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	20,611	19,175
Allowance for credit losses	308,897	307,000
Commercial 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	2,477	656
Commercial Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	331,985	326,831
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	11,348	12,727
Allowance for credit losses	55,970	57,624
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	1,053	1,887
Residential Real Estate [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	68,371	72,238
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	13,615	13,306
Allowance for credit losses	145,841	163,511
Consumer Loans [Member] \| Purchased Impaired [Member] \| Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	1,363	1,503
Consumer Loans [Member] \| Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 160,819	$ 178,320

Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) Modification	Mar. 31, 2015 USD ($) Modification
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	219	150
Pre-modification, Recorded investment	$ 34,904	$ 20,132
Post-modification, Recorded investment	36,143	18,002
Financial effects of modification, Recorded investment	1,239	(2,130)
Financial effects of modification, Interest	$ (687)	$ (157)
Principal Deferral [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	16	7
Pre-modification, Recorded investment	$ 3,483	$ 3,792
Post-modification, Recorded investment	3,448	3,776
Financial effects of modification, Recorded investment	$ (35)	$ (16)
Principal Deferral [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	24	21
Pre-modification, Recorded investment	$ 11,571	$ 1,572
Post-modification, Recorded investment	12,721	1,557
Financial effects of modification, Recorded investment	$ 1,150	$ (15)
Principal Deferral [Member] \| Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification		1
Pre-modification, Recorded investment		$ 1,398
Post-modification, Recorded investment		$ 1,398
Principal Deferral [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	17	7
Pre-modification, Recorded investment	$ 1,981	$ 721
Post-modification, Recorded investment	2,191	742
Financial effects of modification, Recorded investment	$ 210	$ 21
Principal Deferral [Member] \| Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	1
Pre-modification, Recorded investment	$ 125
Post-modification, Recorded investment	138
Financial effects of modification, Recorded investment	$ 13
Principal Deferral [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	3	1
Pre-modification, Recorded investment	$ 335	$ 21
Post-modification, Recorded investment	$ 335	$ 21
Principal Deferral [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	48	35
Pre-modification, Recorded investment	$ 521	$ 303
Post-modification, Recorded investment	$ 521	$ 303
Principal Deferral [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	26	22
Pre-modification, Recorded investment	$ 374	$ 296
Post-modification, Recorded investment	$ 374	$ 296
Interest Rate Reduction [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification		1
Pre-modification, Recorded investment		$ 99
Post-modification, Recorded investment		99
Financial effects of modification, Interest		$ (19)
Interest Rate Reduction [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification		3
Pre-modification, Recorded investment		$ 42
Post-modification, Recorded investment		42
Financial effects of modification, Interest		$ (3)
Combination of Concession Types [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	5	4
Pre-modification, Recorded investment	$ 3,933	$ 1,646
Post-modification, Recorded investment	3,924	1,637
Financial effects of modification, Recorded investment	(9)	(9)
Financial effects of modification, Interest	$ (35)	$ (52)
Combination of Concession Types [Member] \| Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	7	3
Pre-modification, Recorded investment	$ 6,157	$ 9,155
Post-modification, Recorded investment	5,952	6,989
Financial effects of modification, Recorded investment	$ (205)	$ (2,166)
Combination of Concession Types [Member] \| Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	10	3
Pre-modification, Recorded investment	$ 2,321	$ 294
Post-modification, Recorded investment	2,369	349
Financial effects of modification, Recorded investment	$ 48	55
Financial effects of modification, Interest		$ (34)
Combination of Concession Types [Member] \| Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	5	1
Pre-modification, Recorded investment	$ 1,312	$ 210
Post-modification, Recorded investment	1,379	210
Financial effects of modification, Recorded investment	67
Financial effects of modification, Interest	$ (339)	$ (4)
Combination of Concession Types [Member] \| Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	23	5
Pre-modification, Recorded investment	$ 2,496	$ 196
Post-modification, Recorded investment	2,496	196
Financial effects of modification, Interest	$ (283)	$ (13)
Combination of Concession Types [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	8	8
Pre-modification, Recorded investment	$ 85	$ 84
Post-modification, Recorded investment	85	84
Financial effects of modification, Interest	$ (3)	$ (7)
Combination of Concession Types [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	8	13
Pre-modification, Recorded investment	$ 147	$ 224
Post-modification, Recorded investment	147	224
Financial effects of modification, Interest	$ (27)	$ (25)
Other [Member] \| Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	16	10
Pre-modification, Recorded investment	$ 38	$ 20
Post-modification, Recorded investment	$ 38	$ 20
Other [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications \| Modification	2	5
Pre-modification, Recorded investment	$ 25	$ 59
Post-modification, Recorded investment	$ 25	$ 59

Borrowings - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Schedule Of Borrowings [Line Items]
Junior subordinated debentures	$ 515
Trust preferred capital securities	0.00%
Debt Maturity, Start Year	Jan. 01, 2027
Debt Maturity, End Year	Dec. 31, 2033
Agreements to repurchase securities	$ 1,900	$ 1,900
Collateral posted	$ 2,100	2,000
Latest year of repurchase for securities sold under agreements to repurchase	2020
Junior Subordinated Debt [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures redeemed		$ 323

Shareholders' Equity - Additional Information (Detail) - $ / shares	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Preferred stock, shares authorized	1,000,000	1,000,000	1,000,000
Preferred stock, par value	$ 1.00	$ 1.00	$ 1.00
Warrant [Member] \| Assumed In Acquisition [Member]
Class of Stock [Line Items]
Exercise price of each class of warrants or rights outstanding	$ 518.96	$ 518.96
Warrant to purchase common stock	95,383	95,383

Shareholders' Equity - Issued and Outstanding Preferred Stock (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Carrying value	$ 1,231,500	$ 1,231,500
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	230,000	230,000
Preferred stock, shares outstanding	230,000	230,000
Carrying value	$ 230,000	$ 230,000
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	151,500	151,500
Preferred stock, shares outstanding	151,500	151,500
Carrying value	$ 151,500	$ 151,500
Series D Fixed Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	50,000	50,000
Preferred stock, shares outstanding	50,000	50,000
Carrying value	$ 500,000	$ 500,000
Series E Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	350,000	350,000
Preferred stock, shares outstanding	350,000	350,000
Carrying value	$ 350,000	$ 350,000

Shareholders' Equity - Issued and Outstanding Preferred Stock (Parenthetical) (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Series A Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Preferred stock dividend rate	6.375%
Exercise price of each class of warrants or rights outstanding	$ 73.86
Warrants and rights outstanding	719,175	719,175
Warrants, year of expiration	2018
Series C Fixed Rate Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series D Fixed Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	10,000
Preferred stock dividend rate	6.875%
Preferred Stock, Redemption Feature, Redemption Term	90 days
Preferred shares redemption date	Jun. 15, 2016
Series E Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Preferred stock dividend rate	6.45%
Preferred Stock, Redemption Feature, Redemption Term	90 days
Preferred shares redemption date	Feb. 15, 2024
Date of change in the dividend rate	Feb. 14, 2024
London Interbank offered rate plus basis points	3.61%

Pension Plans and Other Postretirement Benefits - Net Periodic Pension Expense for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6,382	$ 6,000
Interest cost on projected benefit obligation	20,883	17,775
Expected return on plan assets	(27,814)	(23,575)
Amortization of prior service credit	(825)	(1,525)
Amortization of net actuarial loss	8,300	11,175
Net periodic benefit cost	6,926	9,850
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	458	200
Interest cost on projected benefit obligation	1,205	650
Amortization of prior service credit	(350)	(350)
Amortization of net actuarial loss		25
Net periodic benefit cost	$ 1,313	$ 525

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Defined contribution pension and retirement savings plans total expense	$ 17,690,000	$ 16,750,000

Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income available to common shareholders:
Net income	$ 298,528	$ 241,613
Less: Preferred stock dividends	(20,318)	(20,318)
Net income available to common equity	278,210	221,295
Less: Income attributable to unvested stock-based compensation awards	(2,466)	(2,465)
Net income available to common shareholders	$ 275,744	$ 218,830
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	160,220	133,542
Less: Unvested stock-based compensation awards	(1,486)	(1,493)
Weighted-average shares outstanding	158,734	132,049
Basic earnings per common share	$ 1.74	$ 1.66

Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income available to common equity	$ 278,210	$ 221,295
Less: Income attributable to unvested stock-based compensation awards	(2,462)	(2,458)
Net income available to common shareholders	$ 275,748	$ 218,837
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	160,220	133,542
Less: Unvested stock-based compensation awards	(1,486)	(1,493)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	447	720
Adjusted weighted-average shares outstanding	159,181	132,769
Diluted earnings per common share	$ 1.73	$ 1.65

Earnings Per Common Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	2.8	2.7

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
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (414,545)	$ (297,843)
Unrealized holding gains (losses), before tax	159,290	40,074
Foreign currency translation adjustment, before tax	(83)	(3,732)
Gains on cash flow hedges, before tax		1,453
Total other comprehensive income(loss) before reclassifications, before tax	159,207	37,795
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities, before tax	968	739
Gains realized in net income, before tax	(4)	98
Accretion of net gain on terminated cash flow hedges, before tax	(39)	(24)
Amortization of prior service credit, before tax	(1,175)	(1,875)
Amortization of actuarial losses, before tax	8,300	11,200
Total reclassifications, before tax	8,050	10,138
Total gain (loss) during the period, before tax	167,257	47,933
Ending balance, before tax	(247,288)	(249,910)
Beginning balance, tax	162,918	116,849
Unrealized holding gains (losses), net of tax	(62,680)	(15,247)
Foreign currency translation adjustment, tax	30	1,348
Gains on cash flow hedges, tax		(568)
Total other comprehensive income(loss) before reclassifications, tax	(62,650)	(14,467)
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities, tax	(381)	(289)
Gains realized in net income, tax	1	(36)
Accretion of net gain on terminated cash flow hedges, tax	15	10
Amortization of prior service credit, tax	462	934
Amortization of actuarial losses, tax	(3,266)	(5,582)
Total reclassifications, tax	(3,169)	(4,963)
Total gain (loss) during the period, tax	(65,819)	(19,430)
Ending balance, tax	97,099	97,419
Beginning balance	(251,627)	(180,994)
Unrealized holding gains (losses), net of tax	96,610	24,827
Foreign currency translation adjustment, net of tax	(53)	(2,384)
Gains on cash flow hedges, net of tax		885
Total other comprehensive income(loss) before reclassifications, net of tax	96,557	23,328
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities, net of tax	587	450
Gains realized in net income, net of tax	(3)	62
Accretion of net gain on terminated cash flow hedges, net of tax	(24)	(14)
Amortization of prior service credit, net of tax	(713)	(941)
Amortization of actuarial losses, net of tax	5,034	5,618
Total reclassifications, net of tax	4,881	5,175
Total other comprehensive income	101,438	28,503
Ending balance	(150,189)	(152,491)
Investment Securities With OTTI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	16,359	7,438
Unrealized holding gains (losses), before tax	(370)	8,011
Total other comprehensive income(loss) before reclassifications, before tax	(370)	8,011
Total gain (loss) during the period, before tax	(370)	8,011
Ending balance, before tax	15,989	15,449
Investment Securities All Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	62,849	201,828
Unrealized holding gains (losses), before tax	159,660	32,063
Total other comprehensive income(loss) before reclassifications, before tax	159,660	32,063
Accretion of unrealized holding losses on held-to-maturity ("HTM") securities, before tax	968	739
Gains realized in net income, before tax	(4)	98
Total reclassifications, before tax	964	837
Total gain (loss) during the period, before tax	160,624	32,900
Ending balance, before tax	223,473	234,728
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(489,660)	(503,027)
Amortization of prior service credit, before tax	(1,175)	(1,875)
Amortization of actuarial losses, before tax	8,300	11,200
Total reclassifications, before tax	7,125	9,325
Total gain (loss) during the period, before tax	7,125	9,325
Ending balance, before tax	(482,535)	(493,702)
Beginning balance	(296,979)
Total other comprehensive income	4,321
Ending balance	(292,658)
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(4,093)	(4,082)
Foreign currency translation adjustment, before tax	(83)	(3,732)
Gains on cash flow hedges, before tax		1,453
Total other comprehensive income(loss) before reclassifications, before tax	(83)	(2,279)
Accretion of net gain on terminated cash flow hedges, before tax	(39)	(24)
Total reclassifications, before tax	(39)	(24)
Total gain (loss) during the period, before tax	(122)	(2,303)
Ending balance, before tax	$ (4,215)	$ (6,385)

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (251,627)	$ (180,994)
Net gain (loss) during period	101,438	28,503
Ending balance	(150,189)	$ (152,491)
Investment Securities With OTTI [Member] \| Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	9,921
Net gain (loss) during period	(224)
Ending balance	9,697
Investment Securities All Other [Member] \| Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	38,166
Net gain (loss) during period	97,418
Ending balance	135,584
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(296,979)
Net gain (loss) during period	4,321
Ending balance	(292,658)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(2,735)
Net gain (loss) during period	(77)
Ending balance	$ (2,812)

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References + Details

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Derivative [Line Items]
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	$ 22,000,000		$ 18,000,000
Aggregate fair value of derivative financial instruments in a liability position	98,000,000		59,000,000
Net liability positions with counterparties	95,000,000		55,000,000
Post collateral requirements relating to positions	84,000,000		52,000,000
Aggregate fair value of derivative financial instruments in asset position	24,000,000		23,000,000
Net asset positions with counterparties	21,000,000		19,000,000
Counterparties posted collateral relating to positions	21,000,000		22,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	204,000,000		99,000,000
Aggregate fair value of derivative financial instruments in a net liability position	156,000,000		50,000,000
Credit Risk Derivative [Member]
Derivative [Line Items]
Aggregate fair value of derivative financial instruments in a net liability position	19,000,000
Fair value of collateral already posted for derivative financial instruments	13,000,000
Fair value of additional collateral to be posted for derivative financial instruments	6,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase in net interest income due to interest rate swap agreements	10,000,000	$ 11,000,000
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	18,900,000,000		18,400,000,000
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 2,800,000,000		$ 1,600,000,000

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - Fixed Rate Long-Term Borrowings [Member] - Fair Value Hedges [Member] - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Notional Amount	$ 1,400,000,000	$ 1,400,000,000
Average Maturity (in years)	1 year 4 months 24 days	1 year 8 months 12 days
Weighted-Average Rate, Fixed	4.42%	4.42%
Weighted-Average Rate, Variable	1.59%	1.39%

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	$ 406,574	$ 268,637
Liability derivatives, Fair value	301,569	162,650
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	364,903	222,901
Liability derivatives, Fair value	298,326	161,994
Fair Value Hedges [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	41,671	45,736
Liability derivatives, Fair value	3,243	656
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	41,259	43,892
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	428	533
Liability derivatives, Fair value	2,413	846
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	412	1,844
Liability derivatives, Fair value	3,243	656
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	16,929	10,282
Liability derivatives, Fair value	44	403
Interest Rate Contracts [Member] \| Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives, Fair value	329,739	203,517
Liability derivatives, Fair value	278,981	153,723
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	17,807	8,569
Liability derivatives, Fair value	$ 16,888	$ 7,022

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 2,186	$ 3,449
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	974	660
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	1,212	2,789
Interest Rate Swap Agreements [Member] \| Fixed Rate Long-Term Borrowings [Member] \| Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, Derivatives	(2,633)	(396)
Derivatives in fair value hedging relationships, Hedged item	$ 1,870	$ 161

Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Variable Interest Entity Disclosure [Abstract]
Carrying value of loans in the Securitization trusts			$ 81,000,000
Combined outstanding principal amount of mortgage-backed securities issued by qualified special purpose trust held by unrelated parties			13,000,000
Other assets for its "investment" in the common securities recognized by the company of various trusts	$ 24,000,000		24,000,000
Total assets of partnerships in which the company invested	1,100,000,000		1,100,000,000
Maximum exposure to loss of investments in real estate partnerships	290,000,000		295,000,000
Unfunded commitments included in company's maximum exposure to loss of investments in real estate partnerships	80,000,000		$ 78,000,000
Investments amortized to income tax expense	11,000,000	$ 10,000,000
Federal tax credits and other federal tax benefits recognized	$ 14,000,000	$ 14,000,000

Fair Value Measurements - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) Source	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of independent pricing sources used to value privately issued mortgage-backed securities valued with internal modeling \| Source	2
Securities issued by financial institutions and other entities backed by trust preferred securities at cost	$ 28		$ 28
Fair value of securities issued by financial institutions and other entities backed by trust preferred securities	45		47
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	27	$ 8
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	226	101	210
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	62	11
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	127	67	106
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	$ 99	$ 34	$ 104
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount margin over LIBOR	4.00%
Discount rates for fair value estimations	10.00%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount margin over LIBOR	10.00%
Discount rates for fair value estimations	90.00%
Weighted Average [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount margin over LIBOR	8.00%

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	$ 467,987	$ 273,783
Investment securities	12,200,647	12,242,671
Real estate loans held for sale	396,764	392,036
Other assets	59,028	56,551
Total assets	13,124,426	12,965,041
Trading account liabilities	295,869	160,745
Other liabilities	5,700	1,905
Total liabilities	301,569	162,650
U.S. Treasury and Federal Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	202,192	299,997
Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	5,448	6,028
Government Issued or Guaranteed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	11,750,062	11,686,628
Privately Issued Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	65	74
Collateralized Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	45,040	47,393
Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	112,708	118,880
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	85,132	83,671
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	69,689	56,763
Investment securities	67,150	65,178
Total assets	136,839	121,941
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	67,150	65,178
Significant Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	398,298	217,020
Investment securities	12,088,392	12,130,026
Real estate loans held for sale	396,764	392,036
Other assets	42,099	46,269
Total assets	12,925,553	12,785,351
Trading account liabilities	295,869	160,745
Other liabilities	5,656	1,502
Total liabilities	301,525	162,247
Significant Observable Inputs (Level 2) [Member] \| U.S. Treasury and Federal Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	202,192	299,997
Significant Observable Inputs (Level 2) [Member] \| Obligations of States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	5,448	6,028
Significant Observable Inputs (Level 2) [Member] \| Government Issued or Guaranteed [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	11,750,062	11,686,628
Significant Observable Inputs (Level 2) [Member] \| Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	112,708	118,880
Significant Observable Inputs (Level 2) [Member] \| Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	17,982	18,493
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	45,105	47,467
Other assets	16,929	10,282
Total assets	62,034	57,749
Other liabilities	44	403
Total liabilities	44	403
Significant Unobservable Inputs (Level 3) [Member] \| Privately Issued Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	65	74
Significant Unobservable Inputs (Level 3) [Member] \| Collateralized Debt Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities	$ 45,040	$ 47,393

Fair Value Measurements - Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Other Assets and Other Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 9,879	$ 17,347
Total gains (losses) realized/unrealized:
Included in earnings	23,898	29,770
Transfers in and/or out of Level 3	(16,892)	(20,887)
Ending Balance	16,885	26,230
Changes in unrealized gains (losses) included in earnings related to assets still held at end of period	14,539	22,636
Privately Issued [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	74	103
Total gains (losses) realized/unrealized:
Settlements	(9)	(8)
Ending Balance	65	95
Collateralized Debt Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	47,393	50,316
Total gains (losses) realized/unrealized:
Included in other comprehensive income	(2,148)	(2,004)
Settlements	(205)	(1,034)
Ending Balance	$ 45,040	$ 47,278

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Privately Issued [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value	$ 65	$ 74	$ 95	$ 103
Collateralized Debt Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value	45,040	47,393	47,278	50,316
Other Assets and Other Liabilities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value	16,885	9,879	$ 26,230	$ 17,347
Discounted Cash Flows [Member] \| Collateralized Debt Obligations [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value	$ 45,040	$ 47,393
Loss severity	100.00%	100.00%
Discounted Cash Flows [Member] \| Collateralized Debt Obligations [Member] \| Weighted Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probability of default	31.00%	31.00%
Discounted Cash Flows [Member] \| Collateralized Debt Obligations [Member] \| Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probability of default	10.00%	10.00%
Discounted Cash Flows [Member] \| Collateralized Debt Obligations [Member] \| Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Probability of default	56.00%	56.00%
Discounted Cash Flows [Member] \| Other Assets and Other Liabilities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value	$ 16,885	$ 9,879
Discounted Cash Flows [Member] \| Other Assets and Other Liabilities [Member] \| Weighted Average [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Commitment expirations	31.00%	39.00%
Discounted Cash Flows [Member] \| Other Assets and Other Liabilities [Member] \| Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Discounted Cash Flows [Member] \| Other Assets and Other Liabilities [Member] \| Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Commitment expirations	66.00%	60.00%
Two Independent Pricing Quotes [Member] \| Privately Issued [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value	$ 65	$ 74

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Financial assets:
Cash and cash equivalents	$ 1,178,175	$ 1,368,040	$ 1,366,853	$ 1,373,357
Interest-bearing deposits at banks	9,545,181	7,594,350
Trading account assets	467,987	273,783
Investment securities	15,467,320	15,656,439
Loans and leases:
Allowance for credit losses	(962,752)	(955,992)	$ (921,373)	$ (919,562)
Loans and leases, net	86,909,714	86,533,507
Financial liabilities:
Noninterest-bearing deposits	(29,709,218)	(29,110,635)
Time deposits	(12,841,331)	(13,110,392)
Deposits at Cayman Islands office	(166,787)	(170,170)
Short-term borrowings	(206,709)	(150,546)
Long-term borrowings	(10,341,035)	(10,653,858)
Trading account liabilities	(295,869)	(160,745)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,112,933	1,276,678
Trading account assets	69,689	56,763
Investment securities	67,150	65,178
Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	65,242	91,362
Interest-bearing deposits at banks	9,545,181	7,594,350
Trading account assets	398,298	217,020
Investment securities	15,256,530	15,406,404
Loans and leases:
Commercial real estate loans	127,736	38,774
Residential real estate loans	4,590,667	4,727,816
Loans and leases, net	4,718,403	4,766,590
Accrued interest receivable	318,486	306,496
Financial liabilities:
Noninterest-bearing deposits	(29,709,218)	(29,110,635)
Savings and interest-checking deposits	(51,497,240)	(49,566,644)
Time deposits	(12,879,619)	(13,135,042)
Deposits at Cayman Islands office	(166,787)	(170,170)
Short-term borrowings	(1,766,826)	(2,132,182)
Long-term borrowings	(10,338,217)	(10,639,556)
Accrued interest payable	(80,605)	(85,145)
Trading account liabilities	(295,869)	(160,745)
Other financial instruments:
Commitments to sell real estate loans	4,816	875
Interest rate swap agreements used for interest rate risk management	41,259	43,892
Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	182,372	189,295
Loans and leases:
Commercial loans and leases	20,875,827	20,146,201
Commercial real estate loans	29,442,004	29,005,470
Residential real estate loans	20,795,573	21,539,955
Consumer loans	11,553,135	11,550,270
Loans and leases, net	82,666,539	82,241,896
Other financial instruments:
Commitments to originate real estate loans for sale	16,885	9,879
Other credit-related commitments	(118,521)	(122,334)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,178,175	1,368,040
Interest-bearing deposits at banks	9,545,181	7,594,350
Trading account assets	467,987	273,783
Investment securities	15,467,320	15,656,439
Loans and leases:
Commercial loans and leases	21,226,577	20,422,338
Commercial real estate loans	29,713,293	29,197,311
Residential real estate loans	25,299,638	26,270,103
Consumer loans	11,632,958	11,599,747
Allowance for credit losses	(962,752)	(955,992)
Loans and leases, net	86,909,714	86,533,507
Accrued interest receivable	318,486	306,496
Financial liabilities:
Noninterest-bearing deposits	(29,709,218)	(29,110,635)
Savings and interest-checking deposits	(51,497,240)	(49,566,644)
Time deposits	(12,841,331)	(13,110,392)
Deposits at Cayman Islands office	(166,787)	(170,170)
Short-term borrowings	(1,766,826)	(2,132,182)
Long-term borrowings	(10,341,035)	(10,653,858)
Accrued interest payable	(80,605)	(85,145)
Trading account liabilities	(295,869)	(160,745)
Other financial instruments:
Commitments to originate real estate loans for sale	16,885	9,879
Commitments to sell real estate loans	4,816	875
Other credit-related commitments	(118,521)	(122,334)
Interest rate swap agreements used for interest rate risk management	41,259	43,892
Estimate Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,178,175	1,368,040
Interest-bearing deposits at banks	9,545,181	7,594,350
Trading account assets	467,987	273,783
Investment securities	15,506,052	15,660,877
Loans and leases:
Commercial loans and leases	20,875,827	20,146,201
Commercial real estate loans	29,569,740	29,044,244
Residential real estate loans	25,386,240	26,267,771
Consumer loans	11,553,135	11,550,270
Loans and leases, net	87,384,942	87,008,486
Accrued interest receivable	318,486	306,496
Financial liabilities:
Noninterest-bearing deposits	(29,709,218)	(29,110,635)
Savings and interest-checking deposits	(51,497,240)	(49,566,644)
Time deposits	(12,879,619)	(13,135,042)
Deposits at Cayman Islands office	(166,787)	(170,170)
Short-term borrowings	(1,766,826)	(2,132,182)
Long-term borrowings	(10,338,217)	(10,639,556)
Accrued interest payable	(80,605)	(85,145)
Trading account liabilities	(295,869)	(160,745)
Other financial instruments:
Commitments to originate real estate loans for sale	16,885	9,879
Commitments to sell real estate loans	4,816	875
Other credit-related commitments	(118,521)	(122,334)
Interest rate swap agreements used for interest rate risk management	$ 41,259	$ 43,892

Commitments and Contingencies - Company's Significant Commitments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Commitments to extend credit
Home equity lines of credit	$ 5,604,610	$ 5,631,680
Commercial real estate loans to be sold	184,198	57,597
Other commercial real estate	5,727,946	5,949,933
Residential real estate loans to be sold	520,694	488,621
Other residential real estate	281,735	212,619
Commercial and other	12,077,612	11,802,850
Standby letters of credit	3,330,241	3,330,013
Commercial letters of credit	45,798	55,559
Financial guarantees and indemnification contracts	2,773,590	2,794,322
Commitments to sell real estate loans	$ 958,337	$ 782,885

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program	$ 2,600,000,000	$ 2,500,000,000
Range of reasonably possible losses, minimum	0
Range of reasonably possible losses, maximum	$ 40,000,000

Segment Information - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2015 USD ($)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Decrease in revenues	$ 6
Decrease in net income	3
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Increase in revenues	6
Increase in net income	$ 3

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Net income (loss)	$ 298,528	$ 241,613
Business Banking [Member]
Segment Reporting Information [Line Items]
Net income (loss)	25,448	24,811
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net income (loss)	101,327	96,423
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Net income (loss)	80,529	82,591
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Net income (loss)	39,988	5,954
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Net income (loss)	17,077	29,460
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net income (loss)	63,288	68,888
All Other [Member]
Segment Reporting Information [Line Items]
Net income (loss)	(29,129)	(66,514)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	1,292,897	1,099,791
Operating Segments [Member] \| Business Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	113,689	108,560
Operating Segments [Member] \| Commercial Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	253,617	246,581
Operating Segments [Member] \| Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Total revenues	177,380	169,021
Operating Segments [Member] \| Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Total revenues	86,835	15,474
Operating Segments [Member] \| Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	96,935	105,757
Operating Segments [Member] \| Retail Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	339,046	300,391
Operating Segments [Member] \| All Other [Member]
Segment Reporting Information [Line Items]
Total revenues	225,395	154,007
Intersegment Activity Eliminated in Consolidated Totals [Member] \| Business Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	991	1,045
Intersegment Activity Eliminated in Consolidated Totals [Member] \| Commercial Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	1,056	1,085
Intersegment Activity Eliminated in Consolidated Totals [Member] \| Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Total revenues	387	82
Intersegment Activity Eliminated in Consolidated Totals [Member] \| Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Total revenues	(14,323)	(5,443)
Intersegment Activity Eliminated in Consolidated Totals [Member] \| Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	19,660	11,387
Intersegment Activity Eliminated in Consolidated Totals [Member] \| Retail Banking [Member]
Segment Reporting Information [Line Items]
Total revenues	3,014	3,137
Intersegment Activity Eliminated in Consolidated Totals [Member] \| All Other [Member]
Segment Reporting Information [Line Items]
Total revenues	$ (10,785)	$ (11,293)

Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Segment Reporting Information [Line Items]
Average Assets	$ 123,252	$ 101,780	$ 95,892
Business Banking [Member]
Segment Reporting Information [Line Items]
Average Assets	5,424	5,339	5,300
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Average Assets	24,838	24,143	23,683
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average Assets	19,839	18,827	18,334
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Average Assets	42,509	26,648	22,714
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average Assets	2,647	2,918	3,197
Retail Banking [Member]
Segment Reporting Information [Line Items]
Average Assets	11,568	11,035	10,788
All Other [Member]
Segment Reporting Information [Line Items]
Average Assets	$ 16,427	$ 12,870	$ 11,876

Segment Information - Summary of Segment Information (Parenthetical) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Taxable-equivalent adjustment	$ 6,332,000	$ 5,838,000
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average assets		315,000,000
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average assets		$ 315,000,000

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	$ 4,000		$ 4,100
Revenues from servicing	$ 5	$ 6
Bayview Lending Group [Member]
Schedule of Equity Method Investments [Line Items]
Minority interest in Bayview Lending Group LLC	20.00%
Carrying value of minority interest investment in Bayview Lending Group LLC	$ 20
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	36,300		37,700
Revenues from sub-servicing	23	$ 35
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	$ 175		$ 181

Sale of Trust Accounts - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2015	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Gain on sale of business net of tax	$ 23
Gain on sale of business before tax	45
Goodwill recorded	$ 11
Revenue on sale of business		$ 9