M&T Bank (MTB) 10-K 20 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	MTB
Entity Registrant Name	M&T BANK CORP
Entity Central Index Key	36,270
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		138,526,278
Entity Public Float			$ 23,892,660,033

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 1,605,439	$ 1,420,888
Interest-bearing deposits at banks	8,105,197	5,078,903
Trading account	185,584	132,909
Investment securities (includes pledged securities that can be sold or repledged of $487,365 at December 31, 2018; $487,151 at December 31, 2017)
Available for sale (cost: $8,869,423 at December 31, 2018; $10,938,796 at December 31, 2017)	8,682,509	10,896,284
Held to maturity (fair value: $3,255,483 at December 31, 2018; $3,341,762 at December 31, 2017)	3,316,640	3,353,213
Equity and other securities (cost: $677,187 at December 31, 2018; $415,028 at December 31, 2017)	693,664	415,028
Total investment securities	12,692,813	14,664,525
Loans and leases	88,733,492	88,242,886
Unearned discount	(267,015)	(253,903)
Loans and leases, net of unearned discount	88,466,477	87,988,983
Allowance for credit losses	(1,019,444)	(1,017,198)
Loans and leases, net	87,447,033	86,971,785
Premises and equipment	647,408	646,451
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	47,067	71,589
Accrued interest and other assets	4,773,750	5,013,325
Total assets	120,097,403	118,593,487
Liabilities
Noninterest-bearing deposits	32,256,668	33,975,180
Savings and interest-checking deposits	50,963,744	51,698,008
Time deposits	6,124,254	6,580,962
Deposits at Cayman Islands office	811,906	177,996
Total deposits	90,156,572	92,432,146
Short-term borrowings	4,398,378	175,099
Accrued interest and other liabilities	1,637,348	1,593,993
Long-term borrowings	8,444,914	8,141,430
Total liabilities	104,637,212	102,342,668
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 December 31, 2018 and December 31, 2017; Liquidation preference of $10,000 per share: 50,000 shares at December 31, 2018 and December 31, 2017	1,231,500	1,231,500
Common stock, $.50 par, 250,000,000 shares authorized, 159,765,044 shares issued at December 31, 2018; 159,817,518 shares issued at December 31, 2017	79,883	79,909
Common stock issuable, 24,563 shares at December 31, 2018; 27,138 shares at December 31, 2017	1,726	1,847
Additional paid-in capital	6,579,342	6,590,855
Retained earnings	11,516,672	10,164,804
Accumulated other comprehensive income (loss), net	(420,081)	(363,814)
Treasury stock — common, at cost — 21,255,275 shares at December 31, 2018; 9,733,115 shares at December 31, 2017	(3,528,851)	(1,454,282)
Total shareholders’ equity	15,460,191	16,250,819
Total liabilities and shareholders’ equity	$ 120,097,403	$ 118,593,487

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Pledged securities that can be sold or repledged	$ 487,365,000	$ 487,151,000
Investment securities, available for sale, amortized cost	8,869,423,000	10,938,796,000
Investment securities, held to maturity, fair value	3,255,483,000	3,341,762,000
Equity and other securities, cost	$ 677,187,000	$ 415,028,000
Preferred stock, par value	$ 1	$ 1
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	159,765,044	159,817,518
Common stock issuable, shares	24,563	27,138
Treasury stock, common shares	21,255,275	9,733,115
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 Incom

Consolidated Statement of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest income
Loans and leases, including fees	$ 4,164,561	$ 3,742,867	$ 3,485,050
Investment securities
Fully taxable	323,912	361,157	361,494
Exempt from federal taxes	665	1,431	2,606
Deposits at banks	108,182	61,326	45,516
Other	1,391	1,014	1,205
Total interest income	4,598,711	4,167,795	3,895,871
Interest expense
Savings and interest-checking deposits	215,411	133,177	87,704
Time deposits	51,423	61,505	102,841
Deposits at Cayman Islands office	5,633	1,186	797
Short-term borrowings	5,386	1,511	3,625
Long-term borrowings	248,556	189,372	231,017
Total interest expense	526,409	386,751	425,984
Net interest income	4,072,302	3,781,044	3,469,887
Provision for credit losses	132,000	168,000	190,000
Net interest income after provision for credit losses	3,940,302	3,613,044	3,279,887
Other income
Brokerage services income	51,069	61,445	63,423
Trading account and foreign exchange gains	32,547	35,301	41,126
Gain (loss) on bank investment securities	(6,301)	21,279	30,314
Other revenues from operations	451,321	440,538	426,150
Total other income	1,856,000	1,851,143	1,825,996
Other expense
Salaries and employee benefits	1,752,264	1,648,794	1,618,074
Equipment and net occupancy	298,828	295,084	295,141
Outside data processing and software	199,025	184,670	172,389
FDIC assessments	68,526	101,871	105,045
Advertising and marketing	85,710	69,203	87,137
Printing, postage and supplies	35,658	35,960	39,546
Amortization of core deposit and other intangible assets	24,522	31,366	42,613
Other costs of operations	823,529	773,377	687,540
Total other expense	3,288,062	3,140,325	3,047,485
Income before taxes	2,508,240	2,323,862	2,058,398
Income taxes	590,160	915,556	743,284
Net income	1,918,080	1,408,306	1,315,114
Net income available to common shareholders
Basic	1,836,028	1,327,503	1,223,459
Diluted	$ 1,836,035	$ 1,327,517	$ 1,223,481
Net income per common share
Basic	$ 12.75	$ 8.72	$ 7.80
Diluted	$ 12.74	$ 8.70	$ 7.78
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 360,442	$ 363,827	$ 373,697
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	429,337	427,372	419,102
Trust Income [Member]
Other income
Revenue from contract with customer	$ 537,585	$ 501,381	$ 472,184

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Partners Capital [Abstract]
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized losses on investment securities	(86,523)	(19,766)	(64,406)
Cash flow hedges adjustments	6,091	(9,912)	(94)
Foreign currency translation adjustment	(2,225)	2,241	(2,614)
Defined benefit plans liability adjustments	43,243	22,288	24,105
Total other comprehensive loss	(39,414)	(5,149)	(43,009)
Total comprehensive income	$ 1,878,666	$ 1,403,157	$ 1,272,105

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	132,000	168,000	190,000
Depreciation and amortization of premises and equipment	104,864	109,587	106,996
Amortization of capitalized servicing rights	49,619	56,172	50,982
Amortization of core deposit and other intangible assets	24,522	31,366	42,613
Provision for deferred income taxes	15,857	400,790	174,013
Asset write-downs	24,774	15,429	21,036
Net gain on sales of assets	(23,503)	(53,467)	(63,222)
Net change in accrued interest receivable, payable	(7,162)	(17,896)	(12,282)
Net change in other accrued income and expense	13,436	(201,981)	60,263
Net change in loans originated for sale	(150,695)	711,657	(665,649)
Net change in trading account assets and liabilities	(11,940)	153,972	(36,453)
Net cash provided by operating activities	2,089,852	2,781,935	1,183,411
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale	418	534,160	63,513
Proceeds from sales of investment securities equity and other	650,858	178,468	94,749
Proceeds from maturities of investment securities Available for sale	1,997,263	2,131,118	2,309,208
Proceeds from maturities of investment securities Held to maturity	478,172	528,585	609,080
Purchases of investment securities Available for sale	(12,494)	(251,185)	(3,562,711)
Purchases of investment securities Held to maturity	(444,703)	(1,425,690)	(214,791)
Purchases of investment securities equity and other	(834,856)	(132,378)	(1,808)
Net (increase) decrease in loans and leases	(475,895)	1,931,492	(2,952,129)
Net (increase) decrease in interest-bearing deposits at banks	(3,026,294)	(78,265)	2,593,712
Capital expenditures, net	(97,676)	(78,966)	(107,693)
Net decrease in loan servicing advances	307,252	37,761	170,141
Other, net	47,904	19,825	277,961
Net cash provided (used) by investing activities	(1,410,051)	3,394,925	(720,768)
Cash flows from financing activities
Net increase (decrease) in deposits	(2,272,505)	(3,075,322)	3,554,673
Net increase (decrease) in short-term borrowings	4,223,279	11,657	(1,937,105)
Proceeds from long-term borrowings	1,773,189	2,145,950
Payments on long-term borrowings	(1,459,081)	(3,433,440)	(1,119,898)
Purchases of treasury stock	(2,194,396)	(1,205,905)	(641,334)
Dividends paid — common	(510,382)	(457,402)	(441,891)
Dividends paid — preferred	(72,521)	(72,734)	(81,270)
Redemption of Series D preferred stock			(500,000)
Other, net	17,167	10,675	161,691
Net cash used by financing activities	(495,250)	(6,076,521)	(510,134)
Net increase (decrease) in cash, cash equivalents and restricted cash	184,551	100,339	(47,491)
Cash, cash equivalents and restricted cash at beginning of period	1,420,888	1,320,549	1,368,040
Cash, cash equivalents and restricted cash at end of period	1,605,439	1,420,888	1,320,549
Supplemental disclosure of cash flow information
Interest received during the period	4,568,991	4,155,723	3,903,374
Interest paid during the period	516,230	405,290	498,951
Income taxes paid during the period	375,116	494,205	276,866
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	72,408	121,292	124,033
Securitization of residential mortgage loans allocated to Available-for-sale investment securities	22,448	36,747	24,233
Securitization of residential mortgage loans allocated to capitalized servicing rights	$ 365	$ 422	248
Series F Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series F preferred stock			$ 495,000

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Series D Preferred Stock [Member]	Series F Preferred Stock [Member]	Series A Warrants [Member]	Preferred Stock [Member]	Preferred Stock [Member]Series D Preferred Stock [Member]	Preferred Stock [Member]Series F Preferred Stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Series F Preferred Stock [Member]	Additional Paid-in Capital [Member]Series A Warrants [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]	Treasury Stock [Member]Series A Warrants [Member]
Beginning balance at Dec. 31, 2015	$ 16,173,289				$ 1,231,500			$ 79,782	$ 2,364	$ 6,680,768			$ 8,430,502	$ (251,627)
Total comprehensive income	1,272,105												1,315,114	(43,009)
Preferred stock cash dividends	(81,270)												(81,270)
Redemption of Series D Preferred Stock		$ (500,000)				$ (500,000)
Issuance of preferred stock			$ 495,000				$ 500,000				$ (5,000)
Exercise of stock warrants into common stock				$ (2)								$ (4,750)				$ 4,748
Purchases of treasury stock	(641,334)														$ (641,334)
Stock-based compensation plans:
Compensation expense, net	27,290							169		16,132					10,989
Exercises of stock options, net	169,617							18		(12,190)					181,789
Stock purchase plan	10,594									275					10,319
Directors’ stock plan	2,080							2		535					1,543
Deferred compensation plans, net, including dividend equivalents	3							2	(219)	163			(93)		150
Other	1,015									1,015
Common stock cash dividends	(441,765)												(441,765)
Ending balance at Dec. 31, 2016	16,486,622				1,231,500			79,973	2,145	6,676,948			9,222,488	(294,636)	(431,796)
Total comprehensive income	1,403,157												1,408,306	(5,149)
Reclassification of income tax effects to retained earnings	64,029												64,029	(64,029)
Preferred stock cash dividends	(72,734)												(72,734)
Exercise of stock warrants into common stock												(28,746)				28,746
Purchases of treasury stock	(1,205,905)														(1,205,905)
Stock-based compensation plans:
Compensation expense, net	12,004							(64)		(47,670)					59,738
Exercises of stock options, net	72,274									(12,142)					84,416
Stock purchase plan	10,831									2,563					8,268
Directors’ stock plan	1,926									270					1,656
Deferred compensation plans, net, including dividend equivalents	(156)								(298)	(368)			(85)		595
Common stock cash dividends	(457,200)												(457,200)
Ending balance at Dec. 31, 2017	16,250,819				1,231,500			79,909	1,847	6,590,855			10,164,804	(363,814)	(1,454,282)
Cumulative effect of change in accounting principle — equity securities	(16,853)												16,853	(16,853)
Total comprehensive income	1,878,666												1,918,080	(39,414)
Preferred stock cash dividends	(72,521)												(72,521)
Exercise of stock warrants into common stock												$ (22,394)				$ 22,394
Purchases of treasury stock	(2,194,396)														(2,194,396)
Stock-based compensation plans:
Compensation expense, net	34,908							(26)		12,421					22,513
Exercises of stock options, net	59,766									(3,793)					63,559
Stock purchase plan	11,124									2,358					8,766
Directors’ stock plan	2,337									162					2,175
Deferred compensation plans, net, including dividend equivalents	(54)								(121)	(267)			(86)		420
Common stock cash dividends	(510,458)												(510,458)
Ending balance at Dec. 31, 2018	$ 15,460,191				$ 1,231,500			$ 79,883	$ 1,726	$ 6,579,342			$ 11,516,672	$ (420,081)	$ (3,528,851)

Consolidated Statement of Cha_2

Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retained Earnings [Member]
Common stock per share dividend amount	$ 3.55	$ 3	$ 2.80
Series A Warrants [Member]
Exercise of warrants into shares of common stock	136,676	204,133
Series A Warrants [Member] | Treasury Stock [Member]
Exercise of warrants into shares of common stock	257,630	374,786	87,381
Exercise of warrants into shares of common stock	136,676	204,133	41,439

Significant accounting policies

Significant accounting policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant accounting policies	1. Significant accounting policies M&T Bank Corporation (“M&T”) is a bank holding company headquartered in Buffalo, New York. Through subsidiaries, M&T provides individuals, corporations and other businesses, and institutions with commercial and retail banking services, including loans and deposits, trust, mortgage banking, asset management, insurance and other financial services. Banking activities are largely focused on consumers residing in New York State, Maryland, New Jersey, Pennsylvania, Delaware, Connecticut, Virginia, West Virginia and the District of Columbia and on small and medium-size businesses based in those areas. Certain subsidiaries also conduct activities in other areas. The accounting and reporting policies of M&T and subsidiaries (“the Company”) are in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and general practices within the banking industry. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The significant accounting policies are as follows: Consolidation The consolidated financial statements include M&T and all of its subsidiaries. All significant intercompany accounts and transactions of consolidated subsidiaries have been eliminated in consolidation. The financial statements of M&T included in note 25 report investments in subsidiaries under the equity method. Information about some limited purpose entities that are affiliates of the Company but are not included in the consolidated financial statements appears in note 19. Consolidated Statement of Cash Flows For purposes of this statement, cash and due from banks and federal funds sold are considered cash and cash equivalents. Securities purchased under agreements to resell and securities sold under agreements to repurchase Securities purchased under agreements to resell and securities sold under agreements to repurchase are treated as collateralized financing transactions and are recorded at amounts equal to the cash or other consideration exchanged. It is generally the Company’s policy to take possession of collateral pledged to secure agreements to resell. Trading account Financial instruments used for trading purposes are stated at fair value. Realized gains and losses and unrealized changes in fair value of financial instruments utilized in trading activities are included in “trading account and foreign exchange gains” in the consolidated statement of income. Investment securities Investments in debt securities are classified as held to maturity and stated at amortized cost when management has the positive intent and ability to hold such securities to maturity. Investments in other debt securities are classified as available for sale and stated at estimated fair value with unrealized changes in fair value included in “accumulated other comprehensive income (loss), net.” Investments in equity securities having readily determinable fair values are stated at fair value and, beginning in 2018, unrealized changes in fair value are included in earnings. Investments in equity securities that do not have readily determinable fair values are stated at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Prior to 2018, equity securities with readily determinable fair values were classified as available for sale. Amortization of premiums and accretion of discounts for investment securities available for sale and held to maturity are included in interest income. Other securities are stated at cost and include stock of the Federal Reserve Bank of New York and the Federal Home Loan Bank (“FHLB”) of New York. Individual debt securities are written down through a charge to earnings when declines in value below the cost basis of a security are considered to be other than temporary. In cases where fair value is less than amortized cost and the Company intends to sell a debt security, it is more likely than not to be required to sell a debt security before recovery of its amortized cost basis, or the Company does not expect to recover the entire amortized cost basis of a debt security, an other-than-temporary impairment is considered to have occurred. If the Company intends to sell the debt security or more likely than not will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is recognized in earnings equal to the entire difference between the debt security’s amortized cost basis and its fair value. If the Company does not expect to recover the entire amortized cost basis of the security, the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the other-than-temporary impairment related to the credit loss is recognized in earnings while the amount related to other factors is recognized in other comprehensive income, net of applicable taxes. Subsequently, the Company accounts for the other-than-temporarily impaired debt security as if the security had been purchased on the measurement date of the other-than-temporary impairment at an amortized cost basis equal to the previous amortized cost basis less the other-than-temporary impairment recognized in earnings. Realized gains and losses on the sales of investment securities are determined using the specific identification method. Loans and leases The Company’s accounting methods for loans depends on whether the loans were originated by the Company or were acquired in a business combination. Originated loans and leases Interest income on loans is accrued on a level yield method. Loans are placed on nonaccrual status and previously accrued interest thereon is charged against income when principal or interest is delinquent 90 days, unless management determines that the loan status clearly warrants other treatment. Nonaccrual commercial loans and commercial real estate loans are returned to accrual status when borrowers have demonstrated an ability to repay their loans and there are no delinquent principal and interest payments. Consumer loans not secured by residential real estate are returned to accrual status when all past due principal and interest payments have been paid by the borrower. Loans secured by residential real estate are returned to accrual status when they are deemed to have an insignificant delay in payments of 90 days or less. Loan balances are charged off when it becomes evident that such balances are not fully collectible. For commercial loans and commercial real estate loans, charge-offs are recognized after an assessment by credit personnel of the capacity and willingness of the borrower to repay, the estimated value of any collateral, and any other potential sources of repayment. A charge-off is recognized when, after such assessment, it becomes evident that the loan balance is not fully collectible. For loans secured by residential real estate, the excess of the loan balances over the net realizable value of the property collateralizing the loan is charged-off when the loan becomes 150 days delinquent. Consumer loans are generally charged-off when the loans are 91 to 180 days past due, depending on whether the loan is collateralized and the status of repossession activities with respect to such collateral. Loan fees and certain direct loan origination costs are deferred and recognized as an interest yield adjustment over the life of the loan. Net deferred fees have been included in unearned discount as a reduction of loans outstanding. Commitments to sell real estate loans are utilized by the Company 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 recorded in the consolidated balance sheet includes changes in estimated fair market value during the hedge period, typically from the date of close through the sale date. Valuation adjustments made on these loans and commitments are included in “mortgage banking revenues.” Except for consumer and residential mortgage loans that are considered smaller balance homogenous loans and are evaluated collectively, 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. Impaired loans are classified as either nonaccrual or as loans renegotiated at below market rates which continue to accrue interest, provided that a credit assessment of the borrower’s financial condition results in an expectation of full repayment under the modified contractual terms. Certain loans greater than 90 days delinquent are not considered impaired if they are well-secured and in the process of collection. Loans less than 90 days delinquent are deemed to have an insignificant delay in payment and are generally not considered impaired. Impairment of a loan is measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s observable market price, or the fair value of collateral if the loan is collateral-dependent. Interest received on impaired loans placed on nonaccrual status is generally applied to reduce the carrying value of the loan or, if principal is considered fully collectible, recognized as interest income. Residual value estimates for commercial leases are generally determined through internal or external reviews of the leased property. The Company reviews commercial lease residual values at least annually and recognizes residual value impairments deemed to be other than temporary. Loans and leases acquired in a business combination Loans acquired in a business combination subsequent to December 31, 2008 are initially recorded at fair value with no carry-over of an acquired entity’s previously established allowance for credit losses. Purchased impaired loans represent specifically identified loans with evidence of credit deterioration for which it was probable at acquisition that the Company would be unable to collect all contractual principal and interest payments. For purchased impaired loans and other loans acquired at a discount that was, in part, attributable to credit quality, the excess of cash flows expected at acquisition over the estimated fair value of acquired loans is recognized as interest income over the remaining lives of the loans. Subsequent decreases in the expected principal cash flows require the Company to evaluate the need for additions to the Company’s allowance for credit losses. Subsequent improvements in expected cash flows result first in the recovery of any related allowance for credit losses and then in recognition of additional interest income over the then-remaining lives of the loans. For all other acquired loans, the difference between the fair value and outstanding principal balance of the loans is recognized as an adjustment to interest income over the lives of those loans. Those loans are then accounted for in a manner that is similar to originated loans. Allowance for credit losses The allowance for credit losses represents, in management’s judgment, the amount of losses inherent in the loan and lease portfolio as of the balance sheet date. The allowance is determined by management’s evaluation of the loan and lease portfolio based on such factors as the differing economic risks associated with each loan category, the current financial condition of specific borrowers, the economic environment in which borrowers operate, the level of delinquent loans, the value of any collateral and, where applicable, the existence of any guarantees or indemnifications. The effects of probable decreases in expected principal cash flows on loans acquired at a discount are also considered in the establishment of the allowance for credit losses. 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 included in “other assets” in the consolidated balance sheet. An in-substance repossession or foreclosure occurs and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Upon acquisition of assets taken in satisfaction of a defaulted loan, the excess of the remaining loan balance over the asset’s estimated fair value less costs to sell is charged-off against the allowance for credit losses. Subsequent declines in value of the assets are recognized as “other costs of operations” in the consolidated statement of income. Premises and equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation expense is computed principally using the straight-line method over the estimated useful lives of the assets. Capitalized servicing rights Capitalized servicing assets are included in “other assets” in the consolidated balance sheet. Separately recognized servicing assets are initially measured at fair value. The Company uses the amortization method to subsequently measure servicing assets. Under that method, capitalized servicing assets are charged to expense in proportion to and over the period of estimated net servicing income. To estimate the fair value of servicing rights, the Company considers market prices for similar assets and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate, and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceeds estimated fair value. Impairment is recognized through a valuation allowance. Sales and securitizations of financial assets Transfers of financial assets for which the Company has surrendered control of the financial assets are accounted for as sales. Interests in a sale of financial assets that continue to be held by the Company, including servicing rights, are measured at fair value. The fair values of retained debt securities are generally determined through reference to independent pricing information. The fair values of retained servicing rights and any other retained interests are determined based on the present value of expected future cash flows associated with those interests and by reference to market prices for similar assets. Securitization structures typically require the use of special-purpose trusts that are considered variable interest entities. A variable interest entity is included in the consolidated financial statements if the Company has the power to direct the activities that most significantly impact the variable interest entity’s economic performance and has the obligation to absorb losses or the right to receive benefits of the variable interest entity that could potentially be significant to that entity. Goodwill and core deposit and other intangible assets Goodwill represents the excess of the cost of an acquired entity over the fair value of the identifiable net assets acquired. Goodwill is not amortized, but rather is tested for impairment at least annually at the reporting unit level, which is either at the same level or one level below an operating segment. Other acquired intangible assets with finite lives, such as core deposit intangibles, are initially recorded at estimated fair value and are amortized over their estimated lives. Core deposit and other intangible assets are generally amortized using accelerated methods over estimated useful lives of five to ten years. The Company periodically assesses whether events or changes in circumstances indicate that the carrying amounts of core deposit and other intangible assets may be impaired. Derivative financial instruments The Company accounts for derivative financial instruments at fair value. If certain conditions are met, a derivative may be specifically designated as (a) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, (b) a hedge of the exposure to variable cash flows of a forecasted transaction or (c) a hedge of the foreign currency exposure of a net investment in a foreign operation, an unrecognized firm commitment, an available-for-sale security, or a foreign currency denominated forecasted transaction. 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. For such agreements, amounts receivable or payable are recognized as accrued under the terms of the agreement and the net differential is recorded as an adjustment to interest income or expense of the related asset or liability. Interest rate swap agreements may be designated as either fair value hedges or cash flow hedges. In a fair value hedge, the fair values of the interest rate swap agreements and changes in the fair values of the hedged items are recorded in the Company’s consolidated balance sheet with the corresponding gain or loss recognized in current earnings. The difference between changes in the fair values of interest rate swap agreements and the hedged items represents hedge ineffectiveness and, beginning in 2018, is recorded in the same income statement line item that is used to present the earnings effect of the hedged item in the consolidated statement of income. In a cash flow hedge, the derivative’s unrealized gain or loss is initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affects earnings. Prior to 2018, hedge ineffectiveness for fair value and cash flow hedges was recorded in “other revenues from operations” in the consolidated statement of income. In addition, for cash flow hedges, the effective portion of the derivative’s unrealized gain or loss was initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affected earnings. The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in the fair value of real estate loans held for sale. Commitments to originate real estate loans to be held for sale and commitments to sell real estate loans are generally recorded in the consolidated balance sheet at estimated fair value. Derivative instruments not related to mortgage banking activities, including financial futures commitments and interest rate swap agreements, that do not satisfy the hedge accounting requirements are recorded at fair value and are generally classified as trading account assets or liabilities with resultant changes in fair value being recognized in “trading account and foreign exchange gains” in the consolidated statement of income. Stock-based compensation Stock-based compensation expense is recognized over the vesting period of the stock-based grant based on the estimated grant date value of the stock-based compensation, except that the recognition of compensation costs is accelerated for stock-based awards granted to retirement-eligible employees and employees who will become retirement-eligible prior to full vesting of the award because the Company’s incentive compensation plan allows for vesting at the time an employee retires. Effective January 2017, the Company adopted amended accounting guidance which requires excess tax benefits or deficiencies associated with stock-based compensation be recognized in income tax expense. Previously, tax effects resulting from changes in M&T’s share price were recorded through shareholders’ equity. Income taxes Deferred tax assets and liabilities are recognized for the future tax effects attributable to differences between the financial statement value of existing assets and liabilities and their respective tax bases and carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates and laws. The Company evaluates uncertain tax positions using the two-step process required by GAAP. The first step requires a determination of whether it is more likely than not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Under the second step, a tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company accounts for its investments in qualified affordable housing projects using the proportional amortization method. Under that method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense. Basic earnings per common share exclude dilution and are computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding (exclusive of shares represented by the unvested portion of restricted stock and restricted stock unit grants) and common shares issuable under deferred compensation arrangements during the period. Diluted earnings per common share reflect shares represented by the unvested portion of restricted stock and restricted stock unit grants and the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in earnings. Proceeds assumed to have been received on such exercise or conversion are assumed to be used to purchase shares of M&T common stock at the average market price during the period, as required by the “treasury stock method” of accounting. GAAP requires that unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) shall be considered participating securities and 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 that contain such rights and, accordingly, the Company’s earnings per common share are calculated using the two-class method. Treasury stock Repurchases of shares of M&T common stock are recorded at cost as a reduction of shareholders’ equity. Reissuances of shares of treasury stock are recorded at average cost.

Investment securities

Investment securities	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Investment securities	2. Investment securities On January 1, 2018, the Company adopted amended guidance requiring equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in the consolidated statement of income. This amended guidance excludes equity method investments, investments in consolidated subsidiaries, exchange membership ownership interests, and Federal Home Loan Bank of New York and Federal Reserve Bank of New York capital stock. Upon adoption the Company reclassified $17 million, after-tax effect, from accumulated other comprehensive income to retained earnings, representing the difference between fair value and the cost basis of equity investments with readily determinable fair values at January 1, 2018. Net unrealized losses recorded as gain (loss) on bank investment securities in the consolidated statement of income during the year ended December 31, 2018 were $6 million. 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) December 31, 2018 Investment securities available for sale: U.S. Treasury and federal agencies $ 1,346,782 $ — $ 9,851 $ 1,336,931 Obligations of states and political subdivisions 1,660 4 5 1,659 Mortgage-backed securities: Government issued or guaranteed 7,383,340 15,754 182,103 7,216,991 Privately issued 24 — 2 22 Other debt securities 137,617 770 11,481 126,906 8,869,423 16,528 203,442 8,682,509 Investment securities held to maturity: U.S. Treasury and federal agencies 446,542 — 239 446,303 Obligations of states and political subdivisions 7,494 22 12 7,504 Mortgage-backed securities: Government issued or guaranteed 2,745,776 4,165 55,111 2,694,830 Privately issued 113,160 12,345 22,327 103,178 Other debt securities 3,668 — — 3,668 3,316,640 16,532 77,689 3,255,483 Total debt securities $ 12,186,063 $ 33,060 $ 281,131 $ 11,937,992 Equity and other securities: Readily marketable equity — at fair value $ 77,440 $ 17,295 $ 818 $ 93,917 Other — at cost 599,747 — — 599,747 Total equity and other securities $ 677,187 $ 17,295 $ 818 $ 693,664 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In thousands) December 31, 2017 Investment securities available for sale: U.S. Treasury and federal agencies $ 1,965,665 $ — $ 18,178 $ 1,947,487 Obligations of states and political subdivisions 2,555 36 2 2,589 Mortgage-backed securities: Government issued or guaranteed 8,755,482 59,497 98,587 8,716,392 Privately issued 28 — — 28 Other debt securities 136,905 2,402 10,475 128,832 Equity securities 78,161 23,219 424 100,956 10,938,796 85,154 127,666 10,896,284 Investment securities held to maturity: Obligations of states and political subdivisions 24,562 109 49 24,622 Mortgage-backed securities: Government issued or guaranteed 3,187,953 27,236 13,746 3,201,443 Privately issued 135,688 2,574 27,575 110,687 Other debt securities 5,010 — — 5,010 3,353,213 29,919 41,370 3,341,762 Other securities — at cost 415,028 — — 415,028 Total $ 14,707,037 $ 115,073 $ 169,036 $ 14,653,074 No investment in securities of a single non-U.S. Government, government agency or government guaranteed issuer exceeded ten percent of shareholders’ equity at December 31, 2018. As of December 31, 2018, the latest available investment ratings of all obligations of states and political subdivisions, privately issued mortgage-backed securities and other debt securities were: Average Credit Rating of Fair Value Amount Amortized Cost Estimated Fair Value A or Better BBB BB B or Less Not Rated (In thousands) Obligations of states and political subdivisions $ 9,154 $ 9,163 $ 8,637 $ 526 $ — $ — $ — Privately issued mortgage-backed securities 113,184 103,200 17,055 16 — 34,180 51,949 Other debt securities 141,285 130,574 4,818 59,814 31,053 — 34,889 Total $ 263,623 $ 242,937 $ 30,510 $ 60,356 $ 31,053 $ 34,180 $ 86,838 The amortized cost and estimated fair value of collateralized mortgage obligations included in mortgage-backed securities were as follows: December 31 2018 2017 (In thousands) Collateralized mortgage obligations: Amortized cost $ 115,171 $ 138,527 Estimated fair value 105,155 113,516 Gross realized gains on investment securities were $23,251,000 in 2017 and $30,545,000 in 2016. During 2017, the Company sold a portion of its Fannie Mae and Freddie Mac preferred stock holdings held in the available-for-sale investment securities portfolio for a gain of $18 million. During 2016, the Company sold its collateralized debt obligations held in the available-for-sale portfolio for a gain of $30 million. There were no significant gross realized gains or losses from sales of investment securities in 2018. There were no significant gross realized losses from sales of investment securities in 2017 or 2016. At December 31, 2018, 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 $ 1,344,408 1,334,695 Due after one year through five years 9,555 9,319 Due after five years through ten years 102,081 95,653 Due after ten years 30,015 25,829 1,486,059 1,465,496 Mortgage-backed securities available for sale 7,383,364 7,217,013 $ 8,869,423 8,682,509 Debt securities held to maturity: Due in one year or less $ 449,468 449,237 Due after one year through five years 4,568 4,570 Due after ten years 3,668 3,668 457,704 457,475 Mortgage-backed securities held to maturity 2,858,936 2,798,008 $ 3,316,640 3,255,483 A summary of investment securities that as of December 31, 2018 and 2017 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) December 31, 2018 Investment securities available for sale: U.S. Treasury and federal agencies $ 273 (2 ) 1,335,559 (9,849 ) Obligations of states and political subdivisions 629 (5 ) — — Mortgage-backed securities: Government issued or guaranteed 405,558 (2,892 ) 5,646,773 (179,211 ) Privately issued 22 (2 ) — — Other debt securities 53,478 (2,187 ) 66,014 (9,294 ) 459,960 (5,088 ) 7,048,346 (198,354 ) Investment securities held to maturity: U.S. Treasury and federal agencies 446,303 (239 ) — — Obligations of states and political subdivisions — — 3,126 (12 ) Mortgage-backed securities: Government issued or guaranteed 179,354 (989 ) 2,082,723 (54,122 ) Privately issued — — 51,943 (22,327 ) 625,657 (1,228 ) 2,137,792 (76,461 ) Total $ 1,085,617 (6,316 ) 9,186,138 (274,815 ) December 31, 2017 Investment securities available for sale: U.S. Treasury and federal agencies $ 278,132 (1,761 ) 1,669,355 (16,417 ) Obligations of states and political subdivisions — — 474 (2 ) Mortgage-backed securities: Government issued or guaranteed 2,106,142 (13,695 ) 3,138,841 (84,892 ) Other debt securities 3,067 (26 ) 61,159 (10,449 ) Equity securities (a) — — 18,162 (424 ) 2,387,341 (15,482 ) 4,887,991 (112,184 ) Investment securities held to maturity: Obligations of states and political subdivisions 2,954 (4 ) 6,110 (45 ) Mortgage-backed securities: Government issued or guaranteed 1,331,759 (7,036 ) 265,695 (6,710 ) Privately issued 5,061 (1,216 ) 55,255 (26,359 ) 1,339,774 (8,256 ) 327,060 (33,114 ) Total $ 3,727,115 (23,738 ) 5,215,051 (145,298 ) (a) Beginning January 1, 2018, equity securities with readily determinable fair values are required to be measured at fair value with changes in fair value recognized in the consolidated statement of income. As a result, subsequent to December 31, 2017 disclosing the time period for which these equity securities had been in a continuous unrealized loss position is no longer relevant. The Company owned 1,402 individual investment securities with aggregate gross unrealized losses of $281 million at December 31, 2018. Based on a review of each of the securities in the investment securities portfolio at December 31, 2018, the Company concluded that it expected to recover the amortized cost basis of its investment. As of December 31, 2018, 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 December 31, 2018, the Company has not identified events or changes in circumstances which may have a significant adverse effect on the fair value of the $600 million of cost method investment securities. At December 31, 2018, investment securities with a carrying value of $2,605,034,000, including $2,040,362,000 of investment securities available for sale, were pledged to secure borrowings from various FHLBs, repurchase agreements, governmental deposits, interest rate swap agreements and available lines of credit as described in note 8. Investment securities pledged by the Company to secure obligations whereby the secured party is permitted by contract or custom to sell or repledge such collateral totaled $487,365,000 at December 31, 2018. The pledged securities included securities of the U.S. Treasury and federal agencies and mortgage-backed securities.

Loans and leases

Loans and leases	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Loans and leases	3. Loans and leases Total loans and leases outstanding were comprised of the following: December 31 2018 2017 (In thousands) Loans Commercial, financial, etc. $ 21,730,012 $ 20,474,696 Real estate: Residential 17,150,658 19,619,259 Commercial 25,666,200 25,345,779 Construction 8,823,635 8,125,925 Consumer 13,956,086 13,251,665 Total loans 87,326,591 86,817,324 Leases Commercial 1,406,901 1,425,562 Total loans and leases 88,733,492 88,242,886 Less: unearned discount (267,015 ) (253,903 ) Total loans and leases, net of unearned discount $ 88,466,477 $ 87,988,983 One-to-four family residential mortgage loans held for sale were $205 million at December 31, 2018 and $356 million at December 31, 2017. Commercial real estate loans held for sale were $347 million at December 31, 2018 and $22 million at December 31, 2017. As of December 31, 2018, approximately $3.4 billion of commercial real estate loan balances serviced for others had been sold with recourse in conjunction with the Company’s participation in the Fannie Mae Delegated Underwriting and Servicing (“DUS”) program. At December 31, 2018, the Company estimated that the recourse obligations described above were not material to the Company’s consolidated financial position. There have been no material losses incurred as a result of those credit recourse arrangements. In addition to recourse obligations, as described in note 21, 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. Charges incurred for such obligation were not material in 2018, 2017 or 2016. A summary of current, past due and nonaccrual loans as of December 31, 2018 and 2017 follows: Current 30-89 Days Past Due Accruing Loans Due 90 Days or More (a) Accruing Loans Acquired a Discount Past Due 90 days or More (b) Purchased Impaired (c) Nonaccrual Total (In thousands) December 31, 2018 Commercial, financial, leasing, etc. $ 22,701,020 39,798 2,567 168 — 234,423 $ 22,977,976 Real estate: Commercial 25,250,983 134,474 11,457 10 9,769 203,672 25,610,365 Residential builder and developer 1,665,178 20,333 — — — 4,798 1,690,309 Other commercial construction 6,982,077 43,615 14,344 — 641 22,205 7,062,882 Residential 13,591,790 404,808 189,682 6,650 203,044 233,352 14,629,326 Residential — limited documentation 2,278,040 72,544 — — 89,851 84,685 2,525,120 Consumer: Home equity lines and loans 4,758,513 25,416 — 5,033 — 71,292 4,860,254 Recreational finance 4,085,781 29,947 — 235 — 11,199 4,127,162 Automobile 3,555,757 79,804 — — — 23,359 3,658,920 Other 1,271,811 15,598 4,477 27,654 — 4,623 1,324,163 Total $ 86,140,950 866,337 222,527 39,750 303,305 893,608 $ 88,466,477 December 31, 2017 Commercial, financial, leasing, etc. $ 21,332,234 167,756 1,322 327 21 240,991 $ 21,742,651 Real estate: Commercial 24,910,381 166,305 4,444 6,016 16,815 184,982 25,288,943 Residential builder and developer 1,618,973 5,159 — — 1,135 6,451 1,631,718 Other commercial construction 6,407,451 23,467 — — 4,706 10,088 6,445,712 Residential 15,376,759 474,372 233,437 7,582 282,102 235,834 16,610,086 Residential — limited documentation 2,718,019 83,898 — — 105,236 96,105 3,003,258 Consumer: Home equity lines and loans 5,171,345 38,546 — 9,391 — 74,500 5,293,782 Recreational finance 3,229,570 23,802 — 546 — 6,509 3,260,427 Automobile 3,441,371 78,511 — — — 23,781 3,543,663 Other 1,119,501 17,127 5,202 23,556 — 3,357 1,168,743 Total $ 85,325,604 1,078,943 244,405 47,418 410,015 882,598 $ 87,988,983 (a) (b) (c) If nonaccrual and renegotiated loans had been accruing interest at their originally contracted terms, interest income on such loans would have amounted to $68,745,000 in 2018, $63,872,000 in 2017 and $68,371,000 in 2016. The actual amounts included in interest income during 2018, 2017 and 2016 on such loans were $32,983,000, $31,425,000 and $33,941,000, respectively. The outstanding principal balance and the carrying amount of loans acquired at a discount that were recorded at fair value at the acquisition date and included in the consolidated balance sheet were as follows: December 31 2018 2017 (In thousands) Outstanding principal balance $ 1,016,785 $ 1,394,188 Carrying amount: Commercial, financial, leasing, etc. 27,073 31,105 Commercial real estate 135,047 228,054 Residential real estate 473,511 620,827 Consumer 91,860 123,413 $ 727,491 $ 1,003,399 Purchased impaired loans included in the table above totaled $303 million at December 31, 2018 and $410 million at December 31, 2017, 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 years ended December 31, 2018, 2017 and 2016 follows: For the Year Ended December 31, 2018 2017 2016 Purchased Impaired Other Acquired Purchased Impaired Other Acquired Purchased Impaired Other Acquired (In thousands) Balance at beginning of period $ 157,918 $ 133,162 $ 154,233 $ 201,153 $ 184,618 $ 296,434 Interest income (37,819 ) (63,856 ) (47,452 ) (82,605 ) (52,769 ) (123,044 ) Reclassifications from nonaccretable balance 27,111 22,849 51,137 16,437 22,384 22,677 Other (a) — 4,752 — (1,823 ) — 5,086 Balance at end of period $ 147,210 $ 96,907 $ 157,918 $ 133,162 $ 154,233 $ 201,153 (a) Other changes in expected cash flows including changes in interest rates and prepayment assumptions. 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 that follow summarize the Company’s loan modification activities that were considered troubled debt restructurings for the years ended December 31, 2018, 2017 and 2016: Post-modification (a) Year Ended December 31, 2018 Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total (Dollars in thousands) Commercial, financial, leasing, etc. 203 $ 102,445 $ 50,490 $ 803 $ 6,210 $ 45,411 $ 102,914 Real estate: Commercial 83 30,217 16,870 175 4,686 9,000 30,731 Other commercial construction 1 752 746 — — — 746 Residential 134 34,798 19,962 — — 18,110 38,072 Residential — limited documentation 9 1,887 827 — — 1,423 2,250 Consumer: Home equity lines and loans 47 3,952 224 — — 3,755 3,979 Recreational finance 7 202 202 — — — 202 Automobile 73 1,330 1,318 — — 12 1,330 Total 557 $ 175,583 $ 90,639 $ 978 $ 10,896 $ 77,711 $ 180,224 Year Ended December 31, 2017 Commercial, financial, leasing, etc. 217 $ 111,036 $ 25,051 $ — $ 6,459 $ 57,153 $ 88,663 Real estate: Commercial 83 44,924 17,039 — 868 22,975 40,882 Residential builder and developer 3 12,291 — — — 10,879 10,879 Other commercial construction 2 168 168 — — — 168 Residential 141 31,827 16,633 — — 17,974 34,607 Residential — limited documentation 20 4,230 911 — — 3,661 4,572 Consumer: Home equity lines and loans 110 10,049 1,137 — 491 8,585 10,213 Recreational finance 9 160 160 — — — 160 Automobile 69 1,378 1,203 — — 175 1,378 Total 654 $ 216,063 $ 62,302 $ — $ 7,818 $ 121,402 $ 191,522 Post-modification (a) Year Ended December 31, 2016 Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total (Dollars in thousands) Commercial, financial, leasing, etc. 164 $ 154,093 $ 102,446 $ — $ — $ 41,673 $ 144,119 Real estate: Commercial 81 44,870 23,558 — 4,576 15,603 43,737 Residential builder and developer 6 39,660 22,958 — — 15,123 38,081 Other commercial construction 3 3,113 250 — — 2,782 3,032 Residential 119 20,057 11,771 — — 9,367 21,138 Residential — limited documentation 21 3,560 1,047 — — 2,917 3,964 Consumer: Home equity lines and loans 103 11,870 761 — — 11,110 11,871 Recreational finance 10 318 270 — 20 28 318 Automobile 163 1,264 1,124 — 55 85 1,264 Other 69 891 698 — 25 168 891 Total 739 $ 279,696 $ 164,883 $ — $ 4,676 $ 98,856 $ 268,415 (a) 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 December 31, 2018, 2017 and 2016 and for which there was a subsequent payment default during the respective year were not material. Borrowings by directors and certain officers of M&T and its banking subsidiaries, and by associates of such persons, exclusive of loans aggregating less than $60,000, amounted to $77,414,000 and $93,103,000 at December 31, 2018 and 2017, respectively. During 2018, new borrowings by such persons amounted to $1,900,000 (including any borrowings of new directors or officers that were outstanding at the time of their election) and repayments and other reductions (including reductions resulting from individuals ceasing to be directors or officers) were $17,589,000. At December 31, 2018, approximately $11.6 billion of commercial loans and leases, $13.2 billion of commercial real estate loans, $12.8 billion of one-to-four family residential real estate loans, $2.4 billion of home equity loans and lines of credit and $6.1 billion of other consumer loans were pledged to secure outstanding borrowings from the FHLB of New York and available lines of credit as described in note 8. The Company’s loan and lease portfolio includes commercial lease financing receivables consisting of direct financing and leveraged leases for machinery and equipment, railroad equipment, commercial trucks and trailers, and aircraft. A summary of lease financing receivables follows: December 31 2018 2017 (In thousands) Commercial leases: Direct financings: Lease payments receivable $ 1,155,464 $ 1,159,584 Estimated residual value of leased assets 85,169 89,666 Unearned income (110,458 ) (110,261 ) Investment in direct financings 1,130,175 1,138,989 Leveraged leases: Lease payments receivable 85,007 87,821 Estimated residual value of leased assets 81,261 88,491 Unearned income (33,717 ) (35,792 ) Investment in leveraged leases 132,551 140,520 Total investment in leases $ 1,262,726 $ 1,279,509 Deferred taxes payable arising from leveraged leases $ 74,995 $ 81,359 Included within the estimated residual value of leased assets at December 31, 2018 and 2017 were $39 million and $37 million, respectively, in residual value associated with direct financing leases that are guaranteed by the lessees or others. At December 31, 2018, the minimum future lease payments to be received from lease financings were as follows: (In thousands) Year ending December 31: 2019 $ 326,898 2020 310,255 2021 224,150 2022 141,244 2023 88,182 Later years 149,742 $ 1,240,471 The amount of foreclosed residential real estate property held by the Company was $77 million and $108 million at December 31, 2018 and 2017, respectively. There were $391 million and $497 million at December 31, 2018 and 2017, respectively, in loans secured by residential real estate that were in the process of foreclosure. Of all loans in the process of foreclosure at December 31, 2018, approximately 39% were classified as purchased impaired and 21% were government guaranteed.

Allowance for credit losses

Allowance for credit losses	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Allowance for credit losses	4. Allowance for credit losses Changes in the allowance for credit losses for the years ended December 31, 2018, 2017 and 2016 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) 2018 Beginning balance $ 328,599 374,085 65,405 170,809 78,300 $ 1,017,198 Provision for credit losses 33,967 (41,181 ) 12,401 127,068 (255 ) 132,000 Net charge-offs Charge-offs (60,414 ) (12,286 ) (15,345 ) (143,196 ) — (231,241 ) Recoveries 27,903 21,037 6,664 45,883 — 101,487 Net (charge-offs) recoveries (32,511 ) 8,751 (8,681 ) (97,313 ) — (129,754 ) Ending balance $ 330,055 341,655 69,125 200,564 78,045 $ 1,019,444 2017 Beginning balance $ 330,833 362,719 61,127 156,288 78,030 $ 988,997 Provision for credit losses 41,511 6,715 16,094 103,410 270 168,000 Net charge-offs Charge-offs (64,941 ) (7,931 ) (20,799 ) (130,927 ) — (224,598 ) Recoveries 21,196 12,582 8,983 42,038 — 84,799 Net (charge-offs) recoveries (43,745 ) 4,651 (11,816 ) (88,889 ) — (139,799 ) Ending balance $ 328,599 374,085 65,405 170,809 78,300 $ 1,017,198 2016 Beginning balance $ 300,404 326,831 72,238 178,320 78,199 $ 955,992 Provision for credit losses 59,506 33,627 6,902 90,134 (169 ) 190,000 Net charge-offs Charge-offs (59,244 ) (4,805 ) (26,133 ) (141,073 ) — (231,255 ) Recoveries 30,167 7,066 8,120 28,907 — 74,260 Net (charge-offs) recoveries (29,077 ) 2,261 (18,013 ) (112,166 ) — (156,995 ) Ending balance $ 330,833 362,719 61,127 156,288 78,030 $ 988,997 Despite the allocations in the preceding tables, the allowance for credit losses is general in nature and is available to absorb losses from any loan or lease type. In establishing the allowance for credit losses, the Company estimates losses attributable to specific troubled credits identified through both normal and targeted credit review processes and also estimates losses inherent in other loans and leases on a collective basis. For purposes of determining the level of the allowance for credit losses, the Company evaluates its loan and lease portfolio by loan type. The amounts of loss components in the Company’s loan and lease portfolios are determined through a loan-by-loan analysis of larger balance commercial loans and commercial real estate loans that are in nonaccrual status and by applying loss factors to groups of loan balances based on loan type and management’s classification of such loans under the Company’s loan grading system. Measurement of the specific loss components is typically based on expected future cash flows, collateral values and other factors that may impact the borrower’s ability to pay. In determining the allowance for credit losses, the Company utilizes a loan grading system that is applied to commercial and commercial real estate credits on an individual loan basis. Loan grades are assigned loss component factors that reflect the Company’s loss estimate for each group of loans and leases. Factors considered in assigning loan grades and loss component factors include borrower-specific information related to expected future cash flows and operating results, collateral values, geographic location, financial condition and performance, payment status, and other information; levels of and trends in portfolio charge-offs and recoveries; levels of and trends in portfolio delinquencies and impaired loans; changes in the risk profile of specific portfolios; trends in volume and terms of loans; effects of changes in credit concentrations; and observed trends and practices in the banking industry. The following tables provide information with respect to loans and leases that were considered impaired as of December 31, 2018 and 2017 and for the years ended December 31, 2018, 2017 and 2016. December 31, 2018 December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance (In thousands) With an allowance recorded: Commercial, financial, leasing, etc. $ 153,478 175,549 46,034 177,250 194,257 45,488 Real estate: Commercial 110,253 125,117 11,937 67,199 75,084 9,140 Residential builder and developer 5,981 6,557 462 5,320 5,641 308 Other commercial construction 10,563 11,113 640 4,817 20,357 647 Residential 124,974 147,817 5,402 101,724 122,602 4,000 Residential — limited documentation 74,156 90,066 3,000 77,277 92,439 3,900 Consumer: Home equity lines and loans 47,982 53,248 9,135 48,847 53,914 8,812 Recreational finance 6,138 9,163 1,261 1,496 3,680 299 Automobile 3,527 3,599 729 13,498 15,737 2,811 Other 5,203 8,380 1,046 1,724 2,192 357 542,255 630,609 79,646 499,152 585,903 75,762 With no related allowance recorded: Commercial, financial, leasing, etc. 105,507 136,128 — 89,126 115,327 — Real estate: Commercial 113,376 124,657 — 138,356 149,716 — Residential builder and developer 2,593 2,602 — 5,057 5,296 — Other commercial construction 11,710 11,880 — 5,456 9,130 — Residential 15,379 20,496 — 13,574 18,980 — Residential — limited documentation 5,631 9,796 — 9,588 16,138 — 254,196 305,559 — 261,157 314,587 — Total: Commercial, financial, leasing, etc. 258,985 311,677 46,034 266,376 309,584 45,488 Real estate: Commercial 223,629 249,774 11,937 205,555 224,800 9,140 Residential builder and developer 8,574 9,159 462 10,377 10,937 308 Other commercial construction 22,273 22,993 640 10,273 29,487 647 Residential 140,353 168,313 5,402 115,298 141,582 4,000 Residential — limited documentation 79,787 99,862 3,000 86,865 108,577 3,900 Consumer: Home equity lines and loans 47,982 53,248 9,135 48,847 53,914 8,812 Recreational finance 6,138 9,163 1,261 1,496 3,680 299 Automobile 3,527 3,599 729 13,498 15,737 2,811 Other 5,203 8,380 1,046 1,724 2,192 357 Total $ 796,451 936,168 79,646 760,309 900,490 75,762 Year Ended December 31, 2018 Year Ended December 31, 2017 Interest Income Recognized Interest Income Recognized Average Recorded Investment Total Cash Basis Average Recorded Investment Total Cash Basis (In thousands) Commercial, financial, leasing, etc. $ 263,018 7,873 7,873 240,157 3,894 3,894 Real estate: Commercial 194,451 10,880 10,880 207,616 4,497 4,497 Residential builder and developer 8,699 1,779 1,779 16,209 6,419 6,419 Other commercial construction 11,467 3,474 3,474 15,142 1,001 1,001 Residential 129,593 8,386 3,456 110,646 7,177 3,406 Residential — limited documentation 82,854 6,118 1,723 93,097 5,981 1,607 Consumer: Home equity lines and loans 48,591 1,698 289 47,323 1,681 400 Recreational finance 1,849 333 9 1,041 212 9 Automobile 9,262 690 69 15,045 1,025 81 Other 4,413 230 13 2,322 96 2 Total $ 754,197 41,461 29,565 748,598 31,983 21,316 Year Ended December 31, 2016 Interest Income Recognized Average Recorded Investment Total Cash Basis (In thousands) Commercial, financial, leasing, etc. $ 277,647 8,342 8,342 Real estate: Commercial 175,877 4,878 4,878 Residential builder and developer 29,237 2,300 2,300 Other commercial construction 19,697 644 644 Residential 98,394 6,227 3,154 Residential — 103,060 5,999 1,975 Consumer: Home equity lines and loans 36,493 1,325 410 Recreational finance 2,549 147 49 Automobile 19,636 1,242 99 Other 6,669 293 34 Total $ 769,259 31,397 21,885 Commercial loans and commercial real estate loans with a lower expectation of default are assigned one of ten possible “pass” loan grades and are generally ascribed lower loss factors when determining the allowance for credit losses. Loans with an elevated level of credit risk are classified as “criticized” and are ascribed a higher loss factor when determining the allowance for credit losses. Criticized loans may be classified as “nonaccrual” if the Company no longer expects to collect all amounts according to the contractual terms of the loan agreement or the loan is delinquent 90 days or more. Furthermore, criticized nonaccrual commercial loans and commercial real estate loans are considered impaired and, as a result, specific loss allowances on such loans are established within the allowance for credit losses to the extent appropriate in each individual instance. The following table summarizes the loan grades applied to the various classes of the Company’s commercial loans and commercial real estate loans. Real Estate Commercial, Residential Other Financial, Builder and Commercial Leasing, etc. Commercial Developer Construction (In thousands) December 31, 2018 Pass $ 21,693,705 24,539,706 1,546,002 6,890,562 Criticized accrual 1,049,848 866,987 139,509 150,115 Criticized nonaccrual 234,423 203,672 4,798 22,205 Total $ 22,977,976 25,610,365 1,690,309 7,062,882 December 31, 2017 Pass $ 20,490,486 24,380,184 1,485,148 6,270,812 Criticized accrual 1,011,174 723,777 140,119 164,812 Criticized nonaccrual 240,991 184,982 6,451 10,088 Total $ 21,742,651 25,288,943 1,631,718 6,445,712 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 by giving consideration to estimated collateral values. The carrying value of residential real estate loans and home equity loans and lines of credit for which a partial charge-off has been recognized totaled $29 million and $23 million, respectively, at December 31, 2018 and $34 million and $25 million, respectively, at December 31, 2017. Residential real estate loans and home equity loans and lines of credit that were more than 150 days past due but did not require a partial charge-off because the net realizable value of the collateral exceeded the outstanding customer balance were $21 million and $31 million, respectively, at December 31, 2018 and $20 million and $32 million, respectively, at December 31, 2017. 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, Real Estate Leasing, etc. Commercial Residential Consumer Total (In thousands) December 31, 2018 Individually evaluated for impairment $ 46,034 13,039 8,402 12,171 $ 79,646 Collectively evaluated for impairment 284,021 328,616 48,326 188,393 849,356 Purchased impaired — — 12,397 — 12,397 Allocated $ 330,055 341,655 69,125 200,564 $ 941,399 Unallocated 78,045 Total $ 1,019,444 December 31, 2017 Individually evaluated for impairment $ 45,488 10,095 7,900 12,279 $ 75,762 Collectively evaluated for impairment 283,111 363,990 47,645 158,530 853,276 Purchased impaired — — 9,860 — 9,860 Allocated $ 328,599 374,085 65,405 170,809 938,898 Unallocated 78,300 Total $ 1,017,198 The recorded investment in loans and leases summarized on the basis of the Company’s impairment methodology was as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Total (In thousands) December 31, 2018 Individually evaluated for impairment $ 258,985 254,476 220,140 62,850 $ 796,451 Collectively evaluated for impairment 22,718,991 34,098,670 16,641,411 13,907,649 87,366,721 Purchased impaired — 10,410 292,895 — 303,305 Total $ 22,977,976 34,363,556 17,154,446 13,970,499 $ 88,466,477 December 31, 2017 Individually evaluated for impairment $ 266,376 226,205 202,163 65,565 $ 760,309 Collectively evaluated for impairment 21,476,254 33,117,512 19,023,843 13,201,050 86,818,659 Purchased impaired 21 22,656 387,338 — 410,015 Total $ 21,742,651 33,366,373 19,613,344 13,266,615 $ 87,988,983

Premises and equipment

Premises and equipment	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Premises and equipment	5. Premises and equipment The detail of premises and equipment was as follows: December 31 2018 2017 (In thousands) Land $ 97,082 $ 98,077 Buildings 465,482 454,610 Leasehold improvements 240,731 239,956 Furniture and equipment — owned 669,782 676,665 Furniture and equipment — capital leases 18,582 18,039 1,491,659 1,487,347 Less: accumulated depreciation and amortization Owned assets 835,218 830,832 Capital leases 9,033 10,064 844,251 840,896 Premises and equipment, net $ 647,408 $ 646,451 Net lease expense for all operating leases totaled $110,703,000 in 2018, $114,362,000 in 2017 and $113,663,000 in 2016. Minimum lease payments under noncancelable operating leases are presented in note 21. Minimum lease payments required under capital leases are not material.

Capitalized servicing assets

Capitalized servicing assets	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Capitalized servicing assets	6. Capitalized servicing assets Changes in capitalized servicing assets were as follows: Residential Mortgage Loans Commercial Mortgage Loans For the Year Ended December 31, 2018 2017 2016 2018 2017 2016 (In thousands) Beginning balance $ 114,978 $ 117,351 $ 118,303 $ 114,076 $ 103,764 $ 83,692 Originations 28,985 28,792 28,618 26,298 34,620 40,117 Purchases 454 699 638 — — — Amortization (23,908 ) (31,864 ) (30,208 ) (25,711 ) (24,308 ) (20,045 ) 120,509 114,978 117,351 114,663 114,076 103,764 Valuation allowance — — — — — — Ending balance, net $ 120,509 $ 114,978 $ 117,351 $ 114,663 $ 114,076 $ 103,764 Residential mortgage loans serviced for others were $22.2 billion at December 31, 2018, $22.6 billion at December 31, 2017 and $22.8 billion at December 31, 2016. Excluded from residential mortgage loans serviced for others were loans sub-serviced for others of $56.8 billion, $56.6 billion and $30.4 billion at December 31, 2018, 2017, and 2016, respectively. On January 31, 2019, the Company purchased servicing rights for residential real estate loans that had outstanding principal balances at that date of approximately $13.3 billion. The purchase price of such servicing rights was approximately $146 million, subject to certain final adjustments. Transfer of the loans to the Company’s loan servicing system is expected to occur in the second quarter of 2019. Commercial mortgage loans serviced for others were $15.5 billion at December 31, 2018, $13.6 billion at December 31, 2017 and $11.8 billion at December 31, 2016. Excluded from commercial mortgage loans serviced for others were loans sub-serviced for others of $2.7 billion at December 31, 2018 and $2.6 billion at December 31, 2017. The estimated fair value of capitalized residential mortgage loan servicing assets was approximately $240 million at December 31, 2018 and $234 million at December 31, 2017. The fair value of capitalized residential mortgage loan servicing assets was estimated using weighted-average discount rates of 11.4% and 12.2% at December 31, 2018 and 2017, respectively, and contemporaneous prepayment assumptions that vary by loan type. At December 31, 2018 and 2017, the discount rate represented a weighted-average option-adjusted spread (“OAS”) of 963 basis points (hundredths of one percent) and 1,067 basis points, respectively, over market implied forward London Interbank Offered Rates (“LIBOR”). The estimated fair value of capitalized residential mortgage loan servicing rights may vary significantly in subsequent periods due to changing interest rates and the effect thereof on prepayment speeds. The estimated fair value of capitalized commercial mortgage loan servicing assets was approximately $135 million and $132 million at December 31, 2018 and 2017, respectively. An 18% discount rate was used to estimate the fair value of capitalized commercial mortgage loan servicing rights at December 31, 2018 and 2017 with no prepayment assumptions because, in general, the servicing agreements allow the Company to share in customer loan prepayment fees and thereby recover the remaining carrying value of the capitalized servicing rights associated with such loan. The Company’s ability to realize the carrying value of capitalized commercial mortgage servicing rights is more dependent on the borrowers’ abilities to repay the underlying loans than on prepayments or changes in interest rates. The key economic assumptions used to determine the fair value of significant portfolios of capitalized servicing rights at December 31, 2018 and the sensitivity of such value to changes in those assumptions are summarized in the table that follows. Those calculated sensitivities are hypothetical and actual changes in the fair value of capitalized servicing rights may differ significantly from the amounts presented herein. The effect of a variation in a particular assumption on the fair value of the servicing rights is calculated without changing any other assumption. In reality, changes in one factor may result in changes in another which may magnify or counteract the sensitivities. The changes in assumptions are presumed to be instantaneous. Residential Commercial (Dollars in thousands) Weighted-average prepayment speeds 10.99 % Impact on fair value of 10% adverse change $ (9,327 ) Impact on fair value of 20% adverse change (17,925 ) Weighted-average OAS 9.63 % Impact on fair value of 10% adverse change $ (6,758 ) Impact on fair value of 20% adverse change (13,135 ) Weighted-average discount rate 18.00 % Impact on fair value of 10% adverse change $ (6,029 ) Impact on fair value of 20% adverse change (11,626 )

Goodwill and other intangible a

Goodwill and other intangible assets	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	7. Goodwill and other intangible assets The Company does not amortize goodwill, however, core deposit and other intangible assets are amortized over the estimated life of each respective asset. Total amortizing intangible assets were comprised of the following: Gross Carrying Amount Accumulated Amortization Net Carrying Amount (In thousands) December 31, 2018 Core deposit $ 887,459 $ 843,572 $ 43,887 Other 182,568 179,388 3,180 Total $ 1,070,027 $ 1,022,960 $ 47,067 December 31, 2017 Core deposit $ 887,459 $ 820,110 $ 67,349 Other 182,568 178,328 4,240 Total $ 1,070,027 $ 998,438 $ 71,589 Amortization of core deposit and other intangible assets was generally computed using accelerated methods over original amortization periods of five to ten years. The weighted-average original amortization period was approximately eight years. Amortization expense for core deposit and other intangible assets was $24,522,000, $31,366,000 and $42,613,000 for the years ended December 31, 2018, 2017 and 2016, respectively. Estimated amortization expense in future years for such intangible assets is as follows: (In thousands) Year ending December 31: 2019 $ 19,086 2020 14,383 2021 9,681 2022 3,917 $ 47,067 The Company completed annual goodwill impairment tests as of October 1, 2018, 2017 and 2016. For purposes of testing for impairment, the Company assigned all recorded goodwill to the reporting units originally intended to benefit from past business combinations, which has historically been the Company’s core relationship business reporting units. Goodwill was generally assigned based on the implied fair value of the acquired goodwill applicable to the benefited reporting units at the time of each respective acquisition. The implied fair value of the goodwill was determined as the difference between the estimated incremental overall fair value of the reporting unit and the estimated fair value of the net assets assigned to the reporting unit as of each respective acquisition date. To test for goodwill impairment at each evaluation date, the Company compared the estimated fair value of each of its reporting units to their respective carrying amounts and certain other assets and liabilities assigned to the reporting unit, including goodwill and core deposit and other intangible assets. The methodologies used to estimate fair values of reporting units as of the acquisition dates and as of the evaluation dates were similar. For the Company’s core customer relationship business reporting units, fair value was estimated as the present value of the expected future cash flows of the reporting unit. Based on the results of the goodwill impairment tests, the Company concluded that the amount of recorded goodwill was not impaired at the respective testing dates. A summary of goodwill assigned to each of the Company’s reportable segments as of December 31, 2018 and 2017 for purposes of testing for impairment is as follows: (In thousands) Business Banking $ 864,366 Commercial Banking 1,401,873 Commercial Real Estate 654,389 Discretionary Portfolio — Residential Mortgage Banking — Retail Banking 1,309,191 All Other 363,293 Total $ 4,593,112

Borrowings

Borrowings	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Borrowings	8. Borrowings The amounts and interest rates of short-term borrowings were as follows: Federal Funds Purchased and Repurchase Agreements Other Short-term Borrowings Total (Dollars in thousands) At December 31, 2018 Amount outstanding $ 198,378 $ 4,200,000 $ 4,398,378 Weighted-average interest rate 1.68 % 2.63 % 2.58 % For the year ended December 31, 2018 Highest amount at a month-end $ 2,654,416 $ 4,200,000 Daily-average amount outstanding 261,200 69,465 $ 330,665 Weighted-average interest rate 1.49 % 2.16 % 1.63 % At December 31, 2017 Amount outstanding $ 175,099 $ — $ 175,099 Weighted-average interest rate 0.92 % — 0.92 % For the year ended December 31, 2017 Highest amount at a month-end $ 204,977 $ 1,500,000 Daily-average amount outstanding 188,459 16,164 $ 204,623 Weighted-average interest rate 0.69 % 1.27 % 0.74 % At December 31, 2016 Amount outstanding $ 163,442 $ — $ 163,442 Weighted-average interest rate 0.32 % — 0.32 % For the year ended December 31, 2016 Highest amount at a month-end $ 225,940 $ 1,974,013 Daily-average amount outstanding 203,853 689,969 $ 893,822 Weighted-average interest rate 0.28 % 0.44 % 0.41 % Short-term borrowings have a stated maturity of one year or less at the date the Company enters into the obligation. In general, federal funds purchased and short-term repurchase agreements outstanding at December 31, 2018 matured on the next business day following year-end. In addition, of the short-term borrowings with the FHLB of New York at December 31, 2018, $3.0 billion matured on the next business day and $1.2 billion matured on February 1, 2019. At December 31, 2018, M&T Bank had lines of credit under formal agreements as follows: (In thousands) Outstanding borrowings $ 4,776,510 Unused 27,637,030 At December 31, 2018, M&T Bank had borrowing facilities available with the FHLBs whereby M&T Bank could borrow up to approximately $18.8 billion. Additionally, M&T Bank had an available line of credit with the Federal Reserve Bank of New York totaling approximately $13.7 billion at December 31, 2018. M&T Bank is required to pledge loans and investment securities as collateral for these borrowing facilities. Long-term borrowings were as follows: December 31, 2018 2017 (In thousands) Senior notes of M&T Bank Corporation: Variable rate due 2023 $ 249,688 $ — 3.55% due 2023 506,021 — Senior notes of M&T Bank: Variable rate due 2021 349,794 — Variable rate due 2022 249,658 249,558 1.45% due 2018 — 499,907 2.25% due 2019 645,801 644,977 2.30% due 2019 — 746,919 2.05% due 2020 737,793 739,961 2.10% due 2020 741,965 743,788 2.625% due 2021 646,301 — 2.50% due 2022 634,525 638,872 2.90% due 2025 749,488 749,404 Advances from FHLB: Fixed rates 576,446 576,876 Agreements to repurchase securities 409,154 421,771 Subordinated notes of Wilmington Trust Corporation (a wholly owned subsidiary of M&T): 8.50% due 2018 — 200,000 Subordinated notes of M&T Bank: Variable rate due 2020 409,361 409,361 Variable rate due 2021 500,000 500,000 3.40% due 2027 481,692 491,176 Junior subordinated debentures of M&T associated with preferred capital securities: Fixed rates: BSB Capital Trust I — 8.125%, due 2028 15,705 15,682 Provident Trust I — 8.29%, due 2028 27,489 26,847 Southern Financial Statutory Trust I — 10.60%, due 2030 6,713 6,664 Variable rates: First Maryland Capital I — due 2027 147,333 146,794 First Maryland Capital II — due 2027 149,280 148,617 Allfirst Asset Trust — due 2029 96,785 96,640 BSB Capital Trust III — due 2033 15,464 15,464 Provident Statutory Trust III — due 2033 55,143 54,466 Southern Financial Capital Trust III — due 2033 8,141 8,051 Other 35,174 9,635 $ 8,444,914 $ 8,141,430 The senior notes of M&T were issued in July 2018. The variable rate notes pay interest quarterly at a rate that is indexed to the three-month LIBOR. The contractual interest rate for those notes was 2.51% at December 31, 2018. The variable rate senior notes of M&T Bank pay interest quarterly at rates that are indexed to the three-month LIBOR. The contractual interest rates for those notes ranged from 2.76% to 3.25% at December 31, 2018 and were 2.05% at December 31, 2017. The weighted-average contractual interest rate was Long-term fixed rate advances from the FHLB had contractual interest rates ranging from 1.97% to 5.98%. The weighted-average contractual interest rate was 2.06%. Advances from the FHLB mature at various dates through 2035 and are secured by residential real estate loans, commercial real estate loans and investment securities. Long-term agreements to repurchase securities had contractual interest rates that ranged from 4.09% to 4.58% at each of December 31, 2018 and 2017. The weighted-average contractual interest rates payable were 4.31% at December 31, 2018 December 31, 2017 The subordinated notes of M&T Bank are unsecured and are subordinate to the claims of its other creditors. The notes that mature in 2020 pay interest monthly at a rate that is indexed to the one-month LIBOR. The contractual interest rate was 3.72% and 2.78% at December 31, 2018 and 2017, respectively. The notes that mature in 2021 pay interest quarterly at a rate that is indexed to the three-month LIBOR. The contractual interest rate was 3.38% at December 31, 2018 and 2.12% at December 31, 2017. The subordinated notes of Wilmington Trust Corporation matured in April 2018. The fixed and variable rate junior subordinated deferrable interest debentures of M&T (“Junior Subordinated Debentures”) are held by various trusts and were issued in connection with the issuance by those trusts of preferred capital securities (“Capital Securities”) and common securities (“Common Securities”). The proceeds from the issuances of the Capital Securities and the Common Securities were used by the trusts to purchase the Junior Subordinated Debentures. The Common Securities of each of those trusts are wholly owned by M&T and are the only class of each trust’s securities possessing general voting powers. The Capital Securities represent preferred undivided interests in the assets of the corresponding trust. Under the Federal Reserve Board’s risk-based capital guidelines, the Capital Securities qualify for inclusion in Tier 2 regulatory capital. The variable rate Junior Subordinated Debentures pay interest quarterly at rates that are indexed to the three-month LIBOR. Those rates ranged from 3.39% to 5.69% at December 31, 2018 and from 2.23% to 4.71% at December 31, 2017. The weighted-average variable rates payable on those Junior Subordinated Debentures were 3.94% at December 31, 2018 and 2.83% at December 31, 2017. 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. Long-term borrowings at December 31, 2018 mature as follows: (In thousands) Year ending December 31: 2019 $ 1,525,057 2020 1,994,450 2021 1,522,796 2022 891,731 2023 755,710 Later years 1,755,170 $ 8,444,914

Shareholders_ equity

Shareholders’ equity	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Shareholders’ equity	9. 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 December 31, 2018 and 2017 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 E (b) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share 350,000 $ 350,000 Series F (c) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share 50,000 $ 500,000 (a) (b) (c)

Revenue from contracts with cus

Revenue from contracts with customers	12 Months Ended
	Dec. 31, 2018
Revenue From Contract With Customer [Abstract]
Revenue from contracts with customers	10. Revenue from contracts with customers Effective January 1, 2018 the Company adopted amended accounting and disclosure guidance for revenue from contracts with customers under the modified retrospective approach. A significant amount of the Company’s revenues are derived from net interest income on financial assets and liabilities, mortgage banking revenues, trading account and foreign exchange gains, investment securities gains, loan and letter of credit fees, operating lease income, income from bank-owned life insurance, and certain other revenues that are generally excluded from the scope of the amended guidance. As a result of the adoption, the Company began reporting credit card interchange revenue net of $14 million of rewards in other revenues from operations for the year ended December 31, 2018. Credit card rewards expense of $13 million and $6 million for the years ended December 31, 2017 and 2016, respectively, was included in other costs of operations. The adjustment to beginning retained earnings as well as the impact of any changes in timing of revenue recognition of noninterest income items within the scope of the guidance was not material to the Company’s consolidated financial position at December 31, 2017 or its consolidated results of operations for the year ended December 31, 2018. For noninterest income revenue streams within the scope of the amended guidance, the Company recognizes the expected amount of consideration as revenue when the performance obligations related to the services under the terms of a contract are satisfied. The Company’s contracts generally do not contain terms that necessitate significant judgment to determine the amount of revenue to recognize. Year Ended December 31, 2018 Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 62,323 96,407 9,870 — 10 254,590 6,137 $ 429,337 Trust income 9 917 — — — — 536,659 537,585 Brokerage services income — — — — — — 51,069 51,069 Other revenues from operations: Merchant discount and credit card fees 34,557 52,051 2,213 — — 14,924 2,208 105,953 Other — 8,796 7,259 1,738 3,814 38,529 30,233 90,369 $ 96,889 158,171 19,342 1,738 3,824 308,043 626,306 $ 1,214,313 Service charges on deposit accounts include fees deducted directly from customer account balances, such as account maintenance, insufficient funds and other transactional service charges, and also include debit card interchange revenue resulting from customer initiated transactions. Account maintenance charges are generally recognized as revenue on a monthly basis, whereas other fees are recognized after the respective service is provided. Trust income includes fees related to the Institutional Client Services (“ICS”) business and the Wealth Advisory Services (“WAS”) business. Revenues from the ICS business are largely derived from a variety of trustee, agency, investment, cash management and administrative services, whereas revenues from the WAS business are mainly derived from asset management, fiduciary services, and family office services. Trust fees may be billed in arrears or in advance and are recognized as revenues as the Company’s performance obligations are satisfied. Certain fees are based on a percentage of assets invested or under management and are recognized as the service is performed and constraints regarding the uncertainty of the amount of fees are resolved. Brokerage services income includes revenues from the sale of mutual funds and annuities and securities brokerage fees. Such revenues are generally recognized at the time of transaction execution. Mutual fund and other distribution fees are recognized upon initial placement of customer funds as well as in future periods as such customers continue to hold amounts in those mutual funds. Other revenues from operations include merchant discount and credit card fees such as interchange fees and merchant discount fees that are generally recognized when the cardholder’s transaction is approved and settled. Beginning in 2018, credit card rewards accrued to cardholders are recognized as a reduction of interchange revenue. Also included in other revenues from operations are insurance commissions, ATM surcharge fees, and advisory fees. Insurance commissions are recognized at the time the insurance policy is executed with the customer. Insurance renewal commissions are recognized upon subsequent renewal of the policy. ATM surcharge fees are included in revenue at the time of the respective ATM transaction. Advisory fees are generally recognized at the conclusion of the advisory engagement when the Company has satisfied its service obligation.

Stock-based compensation plans

Stock-based compensation plans	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based compensation plans	11. Stock-based compensation plans Stock-based compensation expense was $66 million in 2018, $61 million in 2017 and $65 million in 2016. The Company recognized income tax benefits related to stock-based compensation of $24 million in 2018, $35 million in 2017 and $31 million in The Company’s equity incentive compensation plan allows for the issuance of various forms of stock-based compensation, including stock options, restricted stock, restricted stock units and performance-based awards. At December 31, 2018 and 2017, respectively, there were 2,833,428 and 3,278,036 shares available for future grant under the Company’s equity incentive compensation plan. Restricted stock awards Restricted stock awards are comprised of restricted stock and restricted stock units. Restricted stock awards granted since 2014 vest over three years. Restricted stock awards granted prior to 2014 vested over four years. A portion of restricted stock awards granted after 2013 require a performance condition to be met before such awards vest. Unrecognized compensation expense associated with restricted stock was $5 million as of December 31, 2018 and is expected to be recognized over a weighted-average period of approximately one year. The Company may issue restricted shares from treasury stock to the extent available or issue new shares. The number of restricted shares issued was 181,939 in 2017 and 218,341 in 2016, with a weighted-average grant date fair value of $29,557,000 in 2017 and $24,085,000 in 2016. There were no restricted shares issues in 2018. Unrecognized compensation expense associated with restricted stock units was $18 million as of December 31, 2018 and is expected to be recognized over a weighted-average period of approximately one year. The number of restricted stock units issued was 348,512 in 2018, 235,983 in 2017 and 348,297 in 2016, with a weighted-average grant date fair value of $66,050,000, $38,364,000 and $38,795,000, respectively. A summary of restricted stock and restricted stock unit activity follows: Restricted Stock Units Outstanding Weighted- Average Grant Price Restricted Stock Outstanding Weighted- Average Grant Price Unvested at January 1, 2018 482,557 $ 133.05 373,744 $ 135.41 Granted 348,512 189.52 — — Vested (265,027 ) 127.39 (182,905 ) 126.60 Cancelled (9,167 ) 194.45 (11,400 ) 138.52 Unvested at December 31, 2018 556,875 $ 170.07 179,439 $ 144.18 Stock option awards Stock options issued generally vest over three years and are exercisable over terms not exceeding ten years and one day. Stock options issued prior to 2018 generally vested over four years. The Company used an option pricing model to estimate the grant date present value of stock options granted. The Company granted 116,852 stock options in 2018. Stock options granted in 2017 and 2016 were not significant. A summary of stock option activity follows: Weighted-Average Stock Options Outstanding Exercise Price Life (In Years) Aggregate Intrinsic Value (In thousands) Outstanding at January 1, 2018 665,412 $ 152.23 Granted 116,852 190.78 Exercised (535,724 ) 154.91 Expired (25,949 ) 221.81 Outstanding at December 31, 2018 220,591 $ 157.98 5.3 $ 2,739 Exercisable at December 31, 2018 103,725 $ 121.11 5.3 $ 2,737 For 2018, 2017 and 2016, M&T received $60 million, $72 million and $172 million, respectively, in cash and realized tax benefits from the exercise of stock options of $3 million, $10 million and $15 million, respectively. The intrinsic value of stock options exercised during those periods was $16 million, $31 million and $42 million, respectively. As of December 31, 2018, the amount of unrecognized compensation cost related to non-vested stock options was not material. The total grant date fair value of stock options vested during 2018, 2017 and 2016 was not material. Upon the exercise of stock options, the Company may issue shares from treasury stock to the extent available or issue new shares. Stock purchase plan The stock purchase plan provides eligible employees of the Company with the right to purchase shares of M&T common stock at a discount through accumulated payroll deductions. In connection with the employee stock purchase plan, 2,500,000 shares of M&T common stock were authorized for issuance under a plan adopted in 2013. There were 58,167 shares issued in 2018, 66,504 shares issued in 2017 and 97,880 shares issued in 2016. For 2018, 2017 and 2016, M&T received $9,987,000, $9,730,000 and $9,528,000, respectively, in cash for shares purchased through the employee stock purchase plan. Compensation expense recognized for the stock purchase plan was not significant in 2018, 2017 or 2016. Deferred bonus plan The Company provided a deferred bonus plan pursuant to which eligible employees could elect to defer all or a portion of their annual incentive compensation awards and allocate such awards to several investment options, including M&T common stock. Participants could elect the timing of distributions from the plan. Such distributions are payable in cash with the exception of balances allocated to M&T common stock which are distributable in the form of M&T common stock. Shares of M&T common stock distributable pursuant to the terms of the deferred bonus plan were 18,292 and 19,633 at December 31, 2018 and 2017, respectively. The obligation to issue shares is included in “common stock issuable” in the consolidated balance sheet. Directors’ stock plan The Company maintains a compensation plan for non-employee members of the Company’s boards of directors and directors advisory councils that allows such members to receive all or a portion of their compensation in shares of M&T common stock. Through December 31, 2018, 269,373 shares had been issued in connection with the directors’ stock plan. Through acquisitions, the Company assumed obligations to issue shares of M&T common stock related to deferred directors compensation plans. Shares of common stock issuable under such plans were 6,271 and 7,505 at December 31, 2018 and 2017, respectively. The obligation to issue shares is included in “common stock issuable” in the consolidated balance sheet.

Pension plans and other postret

Pension plans and other postretirement benefits	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Pension plans and other postretirement benefits	12. 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. The Company uses a December 31 measurement date for all of its plans. Net periodic pension expense for defined benefit plans consisted of the following: Year Ended December 31 2018 2017 2016 (In thousands) Service cost $ 20,346 $ 20,193 $ 25,037 Interest cost on benefit obligation 74,704 79,270 83,410 Expected return on plan assets (123,127 ) (108,524 ) (108,473 ) Amortization of prior service cost (credit) 557 557 (3,228 ) Recognized net actuarial loss 43,793 29,263 30,145 Net periodic pension expense $ 16,273 $ 20,759 $ 26,891 Net other postretirement benefits expense for defined benefit plans consisted of the following: Year Ended December 31 2018 2017 2016 (In thousands) Service cost $ 938 $ 1,172 $ 1,595 Interest cost on benefit obligation 2,293 3,716 4,971 Amortization of prior service credit (4,729 ) (1,359 ) (1,359 ) Recognized net actuarial (gain) loss (826 ) (988 ) 60 Net other postretirement benefits expense $ (2,324 ) $ 2,541 $ 5,267 Service cost is reflected in salaries and employee benefits expense. The other components of net periodic benefit expense are reflected in other costs of operations. Data relating to the funding position of the defined benefit plans were as follows: Pension Benefits Other Postretirement Benefits 2018 2017 2018 2017 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 2,188,736 $ 2,007,158 $ 68,637 $ 109,922 Service cost 20,346 20,193 938 1,172 Interest cost 74,704 79,270 2,293 3,716 Plan participants’ contributions — — 2,974 2,929 Amendments and curtailments — — — (30,088 ) Actuarial (gain) loss (228,897 ) 172,180 (4,758 ) (8,511 ) Medicare Part D reimbursement — — 508 630 Benefits paid (105,276 ) (90,065 ) (10,601 ) (11,133 ) Benefit obligation at end of year 1,949,613 2,188,736 59,991 68,637 Change in plan assets: Fair value of plan assets at beginning of year 2,014,891 1,642,131 — — Actual return on plan assets (90,657 ) 251,381 — — Employer contributions 14,875 211,444 7,119 7,574 Plan participants’ contributions — — 2,974 2,929 Medicare Part D reimbursement — — 508 630 Benefits paid (105,276 ) (90,065 ) (10,601 ) (11,133 ) Fair value of plan assets at end of year 1,833,833 2,014,891 — — Funded status $ (115,780 ) $ (173,845 ) $ (59,991 ) $ (68,637 ) Accrued liabilities recognized in the consolidated balance sheet $ (115,780 ) $ (173,845 ) $ (59,991 ) $ (68,637 ) Amounts recognized in accumulated other comprehensive income (“AOCI”) were: Net loss (gain) $ 401,716 $ 460,622 $ (17,868 ) $ (13,936 ) Net prior service cost (credit) 2,391 2,948 (31,737 ) (36,466 ) Pre-tax adjustment to AOCI 404,107 463,570 (49,605 ) (50,402 ) Taxes (106,240 ) (121,873 ) 13,041 13,251 Net adjustment to AOCI $ 297,867 $ 341,697 $ (36,564 ) $ (37,151 ) The Company has an unfunded supplemental pension plan for certain key executives and others. The projected benefit obligation and accumulated benefit obligation included in the preceding data related to such plan were $143,406,000 as of December 31, 2018 and $165,210,000 as of December 31, 2017. The accumulated benefit obligation for all defined benefit pension plans was $1,925,741,000 and $2,158,601,000 at December 31, 2018 and 2017, respectively. GAAP requires an employer to recognize in its balance sheet as an asset or liability the overfunded or underfunded status of a defined benefit postretirement plan, measured as the difference between the fair value of plan assets and the benefit obligation. For a pension plan, the benefit obligation is the projected benefit obligation; for any other postretirement benefit plan, such as a retiree health care plan, the benefit obligation is the accumulated postretirement benefit obligation. Gains or losses and prior service costs or credits that arise during the period, but are not included as components of net periodic benefit expense, are recognized as a component of other comprehensive income. Amortization of net gains and losses is included in annual net periodic benefit expense if, as of the beginning of the year, the net gain or loss exceeds 10% of the greater of the benefit obligation or the fair value of the plan assets. As indicated in the preceding table, as of December 31, 2018 the Company recorded a minimum liability adjustment of $354,502,000 ($404,107,000 related to pension plans and $(49,605,000) related to other postretirement benefits) with a corresponding reduction of shareholders’ equity, net of applicable deferred taxes, of $261,303,000. In aggregate, the benefit plans realized a net gain during 2018 that resulted in a decrease to the minimum liability adjustment from that which was recorded at December 31, 2017 of $58,666,000. The net gain was mainly the result of raising the discount rate used to measure the benefit obligation of all plans to 4.25% at December 31, 2018 from 3.50% used at the prior year-end and the amortization of actuarial losses during 2018, offset, in part, by losses on plan assets in 2018. Pension Plans Other Postretirement Benefit Plans Total (In thousands) 2018 Net loss (gain) $ (15,113 ) $ (4,758 ) $ (19,871 ) Amortization of prior service (cost) credit (557 ) 4,729 4,172 Amortization of actuarial (loss) gain (43,793 ) 826 (42,967 ) Total recognized in other comprehensive income, pre-tax $ (59,463 ) $ 797 $ (58,666 ) 2017 Net loss (gain) $ 29,323 $ (8,511 ) $ 20,812 Amendments and curtailments — (30,088 ) (30,088 ) Amortization of prior service (cost) credit (557 ) 1,359 802 Amortization of actuarial (loss) gain (29,263 ) 988 (28,275 ) Total recognized in other comprehensive income, pre-tax $ (497 ) $ (36,252 ) $ (36,749 ) The following table reflects the amortization of amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit expense during 2019: Pension Plans Other Postretirement Benefit Plans (In thousands) Amortization of net prior service cost (credit) $ 557 $ (4,730 ) Amortization of net loss (gain) 17,755 1,168 The Company also provides a qualified defined contribution pension plan to eligible employees who were not participants in the defined benefit pension plan as of December 31, 2005 and to other employees who have elected to participate in the defined contribution plan. The Company makes contributions to the defined contribution plan each year in an amount that is based on an individual participant’s total compensation (generally defined as total wages, incentive compensation, commissions and bonuses) and years of service. Participants do not contribute to the defined contribution pension plan. Pension expense recorded in 2018, 2017 and 2016 associated with the defined contribution pension plan was approximately $29 million, $30 million and $25 million, respectively. Assumptions The assumed weighted-average rates used to determine benefit obligations at December 31 were: Pension Benefits Other Postretirement Benefits 2018 2017 2018 2017 Discount rate 4.25 % 3.50 % 4.25 % 3.50 % Rate of increase in future compensation levels 4.31 % 4.33 % — — The assumed weighted-average rates used to determine net benefit expense for the years ended December 31 were: Pension Benefits Other Postretirement Benefits 2018 2017 2016 2018 2017 2016 Discount rate 3.50 % 4.00 % 4.25 % 3.50 % 4.00 % 4.25 % Long-term rate of return on plan assets 6.50 % 6.50 % 6.50 % — — — Rate of increase in future compensation levels 4.33 % 4.39 % 4.37 % — — — The discount rate used by the Company to determine the present value of the Company’s future benefit obligations reflects specific market yields for a hypothetical portfolio of highly rated corporate bonds that would produce cash flows similar to the Company’s benefit plan obligations and the level of market interest rates in general as of the year-end. The expected long-term rate of return assumption as of each measurement date was developed through analysis of historical market returns, current market conditions, anticipated future asset allocations, the funds’ past experience, and expectations on potential future market returns. The expected rate of return assumption represents a long-term average view of the performance of the plan assets, a return that may or may not be achieved during any one calendar year. The Company’s defined benefit pension plan is sensitive to the long-term rate of return on plan assets and the discount rate. To demonstrate the sensitivity of pension expense to changes in these assumptions, with all other assumptions held constant, 25 basis point increases in: the rate of return on plan assets would have resulted in a decrease in pension expense of approximately $5 million; and the discount rate would have resulted in a decrease in pension expense of approximately $7 million. Decreases of 25 basis points in those assumptions would have resulted in similar changes in amount, but in the opposite direction from the changes presented in the preceding sentence. Additionally, an increase of 25 basis points in the discount rate would have decreased the benefit obligation by $62 million and a decrease of 25 basis points in the discount rate would have increased the benefit obligation by $65 million at December 31, 2018. For measurement of other postretirement benefits, a 6.25% annual rate of increase in the per capita cost of covered health care benefits was assumed for 2019. The rate was assumed to decrease to 5.00% over ten years. A one-percentage point change in assumed health care cost trend rates would have had the following effects: +1% -1% (In thousands) Increase (decrease) in: Service and interest cost $ 55 $ (50 ) Accumulated postretirement benefit obligation 1,204 (1,094 ) Plan assets The Company’s policy is to invest the pension plan assets in a prudent manner for the purpose of providing benefit payments to participants and mitigating reasonable expenses of administration. The Company’s investment strategy is designed to provide a total return that, over the long-term, places an emphasis on the preservation of capital. The strategy attempts to maximize investment returns on assets at a level of risk deemed appropriate by the Company while complying with applicable regulations and laws. The investment strategy utilizes asset diversification as a principal determinant for establishing an appropriate risk profile while emphasizing total return realized from capital appreciation, dividends and interest income. The target allocations for plan assets are generally 25 to 60 percent equity securities, 10 to 65 percent debt securities, and 10 to 85 percent money-market investments/cash equivalents and other investments, although holdings could be more or less than these general guidelines based on market conditions at the time and actions taken or recommended by the investment managers providing advice to the Company. Assets are managed by a combination of internal and external investment managers. Equity securities may include investments in domestic and international equities, through individual securities, mutual funds and exchange-traded funds. Debt securities may include investments in corporate bonds of companies from diversified industries, mortgage-backed securities guaranteed by government agencies and U.S. Treasury securities, through individual securities and mutual funds. Additionally, the Company’s defined benefit pension plan held $361,178,000 (20% of total assets) of real estate funds, private investments, hedge funds and other investments at December 31, 2018. Returns on invested assets are periodically compared with target market indices for each asset type to aid management in evaluating such returns. Furthermore, management regularly reviews the investment policy and may, if deemed appropriate, make changes to the target allocations noted above. The fair values of the Company’s pension plan assets at December 31, 2018 and 2017, by asset category, were as follows: Fair Value Measurement of Plan Assets At December 31, 2018 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (In thousands) Asset category: Money-market investments $ 23,049 $ 10,794 $ 12,255 $ — Equity securities: M&T 125,299 125,299 — — Domestic(a) 191,640 191,640 — — International(b) 7,752 7,752 — — Mutual funds: Domestic(a) 216,523 216,523 — — International(b) 316,923 316,923 — — 858,137 858,137 — — Debt securities: Corporate(c) 103,672 — 103,672 — Government 182,034 — 182,034 — International 2,140 — 2,140 — Mutual funds: Domestic(d) 280,902 280,902 — — International 20,661 20,661 — — 589,409 301,563 287,846 — Other: Diversified mutual fund 74,446 74,446 — — Real estate partnerships 11,807 2,791 — 9,016 Private equity 63,699 — — 63,699 Hedge funds 200,811 125,309 — 75,502 Guaranteed deposit fund 10,415 — — 10,415 361,178 202,546 — 158,632 Total(e) $ 1,831,773 $ 1,373,040 $ 300,101 $ 158,632 Fair Value Measurement of Plan Assets At December 31, 2017 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (In thousands) Asset category: Money-market investments $ 117,648 $ 62,706 $ 54,942 $ — Equity securities: M&T 154,818 154,818 — — Domestic(a) 240,763 240,763 — — International(b) 13,349 13,349 — — Mutual funds: Domestic(a) 205,509 205,509 — — International(b) 405,200 405,200 — — 1,019,639 1,019,639 — — Debt securities: Corporate(c) 89,751 — 89,751 — Government 235,984 — 235,984 — International 2,176 — 2,176 — Mutual funds: Domestic(d) 243,456 243,456 — — 571,367 243,456 327,911 — Other: Diversified mutual fund 80,227 80,227 — — Real estate partnerships 3,747 842 — 2,905 Private equity 31,484 — — 31,484 Hedge funds 178,080 125,966 — 52,114 Guaranteed deposit fund 10,925 — — 10,925 304,463 207,035 — 97,428 Total(e) $ 2,013,117 $ 1,532,836 $ 382,853 $ 97,428 (a) (b) (c) (d) (e) Pension plan assets included common stock of M&T with a fair value of $125,299,000 (7% of total plan assets) at December 31, 2018 and $154,818,000 (8% of total plan assets) at December 31, 2017. No investment in securities of a non-U.S. Government or government agency issuer exceeded ten percent of plan assets at December 31, 2018. The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2018 were as follows: Balance – January 1, 2018 Purchases (Sales) Total Realized/ Unrealized Gains (Losses) Balance – December 31, 2018 (In thousands) Other Real estate partnerships $ 2,905 $ 4,717 $ 1,394 $ 9,016 Private equity 31,484 30,396 1,819 63,699 Hedge funds 52,114 19,971 3,417 75,502 Guaranteed deposit fund 10,925 — (510 ) 10,415 Total $ 97,428 $ 55,084 $ 6,120 $ 158,632 The Company makes contributions to its funded qualified defined benefit pension plan as required by government regulation or as deemed appropriate by management after considering factors such as the fair value of plan assets, expected returns on such assets, and the present value of benefit obligations of the plan. The Company made voluntary contributions of $200 million to the qualified defined benefit pension plan in 2017. Estimated benefits expected to be paid in future years related to the Company’s defined benefit pension and other postretirement benefits plans are as follows: Pension Benefits Other Postretirement Benefits (In thousands) Year ending December 31: 2019 $ 94,427 $ 7,108 2020 99,361 6,975 2021 103,502 4,284 2022 106,270 4,196 2023 110,753 4,108 2024 through 2028 600,961 19,065 The Company has a retirement savings plan (“RSP”) that is a defined contribution plan in which eligible employees of the Company may defer up to 50% of qualified compensation via contributions to the plan. The Company makes an employer matching contribution in an amount equal to 75% of an employee’s contribution, up to 4.5% of the employee’s qualified compensation. Employees’ accounts, including employee contributions, employer matching contributions and accumulated earnings thereon, are at all times fully vested and nonforfeitable. Employee benefits expense resulting from the Company’s contributions to the RSP totaled $42,897,000, $38,229,000 and $36,776,000 in 2018, 2017 and 2016, respectively.

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income taxes	13. Income taxes The components of income tax expense were as follows: Year Ended December 31 2018 2017 2016 (In thousands) Current Federal $ 408,428 $ 363,043 $ 428,750 State and local 113,706 94,714 95,426 Total current 522,134 457,757 524,176 Deferred Federal (12,780 ) 367,308 147,662 State and local 28,637 33,482 26,351 Total deferred 15,857 400,790 174,013 Amortization of investments in qualified affordable housing projects 52,169 57,009 45,095 Total income taxes applicable to pre-tax income $ 590,160 $ 915,556 $ 743,284 The Company files a consolidated federal income tax return reflecting taxable income earned by all domestic subsidiaries. In prior years, applicable federal tax law allowed certain financial institutions the option of deducting as bad debt expense for tax purposes amounts in excess of actual losses. In accordance with GAAP, such financial institutions were not required to provide deferred income taxes on such excess. Recapture of the excess tax bad debt reserve established under the previously allowed method will result in taxable income if M&T Bank fails to maintain bank status as defined in the Internal Revenue Code or charges are made to the reserve for other than bad debt losses. At December 31, 2018, M&T Bank’s tax bad debt reserve for which no federal income taxes have been provided was $137,121,000. No actions are planned that would cause this reserve to become wholly or partially taxable. Income taxes attributable to gains or losses on bank investment securities were a benefit of $1,628,000 in 2018, and an expense of $7,195,000 in 2017 and $11,925,000 in 2016. No alternative minimum tax expense was recognized in 2017 or 2016. The Tax Cuts and Jobs Act (“Tax Act”) was signed into law on December 22, 2017, reducing the corporate federal income tax rate from 35% to 21% effective January 1, 2018 and making other changes to U.S. corporate income tax laws, including eliminating the alternative minimum tax as of January 1, 2018. GAAP requires that the impact of the provisions of the Tax Act be accounted for in the period of enactment. Accordingly, the incremental income tax expense recorded by the Company in the fourth quarter of 2017 related to the Tax Act was $85 million. That additional expense was largely attributable to the reduction in carrying value of net deferred tax assets reflecting lower future tax benefits resulting from the lower corporate income tax rate. During 2018 the Company received approval from the Internal Revenue Service to change the timing of recognition of certain loan fees retroactive to 2017. Given the reduction of the federal income tax rate, the change resulted in a $15 million reduction of income tax expense in 2018. The Company also adopted new accounting guidance for share-based transactions during the first quarter of 2017. That guidance requires that all excess tax benefits and tax deficiencies associated with share-based compensation be recognized as a component of income tax expense in the income statement. Previously, tax effects resulting from changes in M&T’s share price subsequent to the grant date were recorded through shareholders’ equity at the time of vesting or exercise. The adoption of the amended accounting guidance resulted in a $9 million and $22 million reduction of income tax expense in 2018 and 2017, respectively. Total income taxes differed from the amount computed by applying the statutory federal income tax rate to pre-tax income as follows: Year Ended December 31 2018 2017 2016 (In thousands) Income taxes at statutory federal income tax rate $ 526,730 $ 813,352 $ 720,439 Increase (decrease) in taxes: Tax-exempt income (26,186 ) (40,778 ) (35,364 ) State and local income taxes, net of federal income tax effect 112,451 83,327 79,155 Qualified affordable housing project federal tax credits, net (12,240 ) (16,015 ) (15,091 ) Initial impact of enactment of Tax Act — 85,431 — Other (10,595 ) (9,761 ) (5,855 ) $ 590,160 $ 915,556 $ 743,284 Deferred tax assets (liabilities) were comprised of the following at December 31: 2018 2017 2016 (In thousands) Losses on loans and other assets $ 322,818 $ 345,609 $ 590,288 Retirement benefits 30,057 45,322 143,067 Postretirement and other employee benefits 23,563 26,009 52,512 Incentive and other compensation plans 24,796 25,050 36,616 Interest on loans — 37,900 61,266 Stock-based compensation 26,759 26,676 52,181 Unrealized losses 52,580 — 10,741 Other 43,880 66,247 106,876 Gross deferred tax assets 524,453 572,813 1,053,547 Leasing transactions (186,787 ) (181,159 ) (266,268 ) Unrealized gains — (94,285 ) — Capitalized servicing rights (54,894 ) (51,781 ) (71,108 ) Depreciation and amortization (61,881 ) (52,733 ) (63,959 ) Interest on loans (18,920 ) — — Other (28,350 ) (21,599 ) (87,200 ) Gross deferred tax liabilities (350,832 ) (401,557 ) (488,535 ) Net deferred tax asset $ 173,621 $ 171,256 $ 565,012 The Company believes that it is more likely than not that the deferred tax assets will be realized through taxable earnings or alternative tax strategies. The income tax credits shown in the statement of income of M&T in note 25 arise principally from operating losses before dividends from subsidiaries. A reconciliation of the beginning and ending amount of unrecognized tax benefits follows: Federal, State and Local Tax Accrued Interest Unrecognized Income Tax Benefits (In thousands) Gross unrecognized tax benefits at January 1, 2016 $ 24,537 $ 7,969 $ 32,506 Increases as a result of tax positions taken during 2016 12,237 — 12,237 Increases as a result of tax positions taken in prior years — 656 656 Decreases as a result of tax positions taken in prior years (885 ) (710 ) (1,595 ) Gross unrecognized tax benefits at December 31, 2016 35,889 7,915 43,804 Increases as a result of tax positions taken during 2017 13,019 — 13,019 Increases as a result of tax positions taken in prior years — 1,379 1,379 Decreases as a result of settlements with taxing authorities (332 ) (168 ) (500 ) Decreases as a result of tax positions taken in prior years (3,144 ) (3,475 ) (6,619 ) Gross unrecognized tax benefits at December 31, 2017 45,432 5,651 51,083 Increases as a result of tax positions taken during 2018 13,426 — 13,426 Increases as a result of tax positions taken in prior years — 1,969 1,969 Decreases as a result of settlements with taxing authorities (664 ) (289 ) (953 ) Decreases as a result of tax positions taken in prior years (1,920 ) (702 ) (2,622 ) Gross unrecognized tax benefits at December 31, 2018 $ 56,274 $ 6,629 62,903 Less: Federal, state and local income tax benefits (13,209 ) Net unrecognized tax benefits at December 31, 2018 that, if recognized, would impact the effective income tax rate $ 49,694 The Company’s policy is to recognize interest and penalties, if any, related to unrecognized tax benefits in income taxes in the consolidated statement of income. The balance of accrued interest at December 31, 2018 is included in the table above. The Company’s federal, state and local income tax returns are routinely subject to examinations from various governmental taxing authorities. Such examinations may result in challenges to the tax return treatment applied by the Company to specific transactions. Management believes that the assumptions and judgment used to record tax-related assets or liabilities have been appropriate. Should determinations rendered by tax authorities ultimately indicate that management’s assumptions were inappropriate, the result and adjustments required could have a material effect on the Company’s results of operations. Examinations by the Internal Revenue Service of the Company’s federal income tax returns have been largely concluded through 2017, although under statute the income tax returns from 2015 through 2017 could be adjusted. The Company also files income tax returns in over forty states and numerous local jurisdictions. Substantially all material state and local matters have been concluded for years through 2013. It is not reasonably possible to estimate when examinations for any subsequent years will be completed.

Earnings per common share

Earnings per common share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings per common share	14. Earnings per common share The computations of basic earnings per common share follow: Year Ended December 31 2018 2017 2016 (In thousands, except per share) Income available to common shareholders: Net income $ 1,918,080 $ 1,408,306 $ 1,315,114 Less: Preferred stock dividends(a) (72,521 ) (72,734 ) (81,270 ) Net income available to common equity 1,845,559 1,335,572 1,233,844 Less: Income attributable to unvested stock-based compensation awards (9,531 ) (8,069 ) (10,385 ) Net income available to common shareholders $ 1,836,028 $ 1,327,503 $ 1,223,459 Weighted-average shares outstanding: Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards 144,740 153,092 158,121 Less: Unvested stock-based compensation awards (748 ) (933 ) (1,341 ) Weighted-average shares outstanding 143,992 152,159 156,780 Basic earnings per common share $ 12.75 $ 8.72 $ 7.80 (a) The computations of diluted earnings per common share follow: Year Ended December 31 2018 2017 2016 (In thousands, except per share) Net income available to common equity $ 1,845,559 $ 1,335,572 $ 1,233,844 Less: Income attributable to unvested stock-based compensation awards (9,524 ) (8,055 ) (10,363 ) Net income available to common shareholders $ 1,836,035 $ 1,327,517 $ 1,223,481 Adjusted weighted-average shares outstanding: Common and unvested stock-based compensation awards 144,740 153,092 158,121 Less: Unvested stock-based compensation awards (748 ) (933 ) (1,341 ) Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock 159 392 524 Adjusted weighted-average shares outstanding 144,151 152,551 157,304 Diluted earnings per common share $ 12.74 $ 8.70 $ 7.78 GAAP defines unvested share-based awards that contain nonforfeitable rights to dividends or dividend equivalents (whether Stock-based compensation awards and warrants to purchase common stock of M&T representing common shares of

Comprehensive income

Comprehensive income	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Comprehensive income	15. Comprehensive income In February 2018, the Financial Accounting Standards Board issued accounting guidance related to reclassification of certain tax effects from AOCI so that following enactment of the Tax Act the tax effects of items within AOCI reflect the appropriate tax. The guidance provided for a reclassification from AOCI to retained earnings for the effect of remeasuring deferred tax assets and liabilities related to items within AOCI at the 21 percent corporate tax rate established by the Tax Act. The impact of that reclassification was an increase in retained earnings as of December 31, 2017 resulting from items remaining in AOCI as of that date as follows: (In thousands) Net unrealized losses on investment securities $ 8,065 Defined benefit plans liability adjustments 53,960 Cash flow hedges and other 2,004 Increase to retained earnings $ 64,029 The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other Investment Defined Benefit Total Amount Income Securities (a) Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2018 $ (59,957 ) (413,168 ) (20,165 ) $ (493,290 ) 129,476 $ (363,814 ) Cumulative effect of change in accounting principle — equity securities (22,795 ) — — (22,795 ) 5,942 (16,853 ) Other comprehensive income before reclassifications: Unrealized holding losses, net (121,589 ) — — (121,589 ) 31,946 (89,643 ) Foreign currency translation adjustment — — (2,817 ) (2,817 ) 592 (2,225 ) Unrealized losses on cash flow hedges — — (4,965 ) (4,965 ) 1,306 (3,659 ) Current year benefit plans gains — 19,871 — 19,871 (5,224 ) 14,647 Total other comprehensive income (loss) before reclassifications (121,589 ) 19,871 (7,782 ) (109,500 ) 28,620 (80,880 ) Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities 4,252 — — 4,252 (c) (1,118 ) 3,134 Gains realized in net income (18 ) — — (18 ) (d) 4 (14 ) Accretion of net gain on terminated cash flow hedges — — (111 ) (111 ) (e) 29 (82 ) Net yield adjustment from cash flow hedges currently in effect — — 13,339 13,339 (c) (3,507 ) 9,832 Amortization of prior service credit — (4,172 ) — (4,172 ) (f) 1,097 (3,075 ) Amortization of actuarial losses — 42,967 — 42,967 (f) (11,296 ) 31,671 Total other comprehensive income (loss) (117,355 ) 58,666 5,446 (53,243 ) 13,829 (39,414 ) Balance — December 31, 2018 $ (200,107 ) (354,502 ) (14,719 ) $ (569,328 ) 149,247 $ (420,081 ) Investment Securities Defined Benefit Total Amount Income With OTTI (b) All Other Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2017 $ 46,725 (73,785 ) (449,917 ) (8,268 ) $ (485,245 ) 190,609 $ (294,636 ) Other comprehensive income before reclassifications: Unrealized holding gains (losses), net (8,746 ) (6,259 ) — — (15,005 ) 7,269 (7,736 ) Foreign currency translation adjustment — — — 4,447 4,447 (2,206 ) 2,241 Unrealized losses on cash flow hedges — — — (12,291 ) (12,291 ) 4,837 (7,454 ) Current year benefit plans gains — — 9,276 — 9,276 (3,650 ) 5,626 Total other comprehensive income (loss) before reclassifications (8,746 ) (6,259 ) 9,276 (7,844 ) (13,573 ) 6,250 (7,323 ) Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities — 3,387 — — 3,387 (c) (1,333 ) 2,054 Gains realized in net income (18,351 ) (2,928 ) — — (21,279 ) (d) 7,195 (14,084 ) Accretion of net gain on terminated cash flow hedges — — — (137 ) (137 ) (e) 54 (83 ) Net yield adjustment from cash flow hedges currently in effect — — — (3,916 ) (3,916 ) (c) 1,541 (2,375 ) Amortization of prior service credit — — (802 ) — (802 ) (f) 315 (487 ) Amortization of actuarial losses — — 28,275 — 28,275 (f) (11,126 ) 17,149 Total other comprehensive income (loss) (27,097 ) (5,800 ) 36,749 (11,897 ) (8,045 ) 2,896 (5,149 ) Reclassification of income tax effects to retained earnings — — — — — (64,029 ) (64,029 ) Balance — December 31, 2017 $ 19,628 (79,585 ) (413,168 ) (20,165 ) $ (493,290 ) 129,476 $ (363,814 ) 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 30,366 (110,316 ) — — (79,950 ) 31,509 (48,441 ) Foreign currency translation adjustment — — — (4,020 ) (4,020 ) 1,406 (2,614 ) Current year benefit plans gains — — 14,125 — 14,125 (5,557 ) 8,568 Total other comprehensive income (loss) before reclassifications 30,366 (110,316 ) 14,125 (4,020 ) (69,845 ) 27,358 (42,487 ) Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities — 3,996 — — 3,996 (c) (1,572 ) 2,424 Gains realized in net income — (30,314 ) — — (30,314 ) (d) 11,925 (18,389 ) Accretion of net gain on terminated cash flow hedges — — — (155 ) (155 ) (e) 61 (94 ) Amortization of prior service credit — — (4,587 ) — (4,587 ) (f) 1,805 (2,782 ) Amortization of actuarial losses — — 30,205 — 30,205 (f) (11,886 ) 18,319 Total other comprehensive income (loss) 30,366 (136,634 ) 39,743 (4,175 ) (70,700 ) 27,691 (43,009 ) Balance — December 31, 2016 $ 46,725 (73,785 ) (449,917 ) (8,268 ) $ (485,245 ) 190,609 $ (294,636 ) (a) Beginning January 1, 2018, equity securities with readily determinable market values are required to be measured at fair value with changes in fair value recognized in the income statement. Separate presentation of investment securities with an other-than-temporary impairment change is no longer required. (b) Other-than-temporary impairment. (c) Included in interest income. (d) Included in gain (loss) on bank investment securities. (e) Included in interest expense. (f) Included in other costs of operations. Accumulated other comprehensive income (loss), net consisted of the following: Defined Investment Securities Benefit Plans Other Total (In thousands) Balance at January 1, 2016 $ 48,087 $ (296,979 ) $ (2,735 ) $ (251,627 ) Net gain (loss) during 2016 (64,406 ) 24,105 (2,708 ) (43,009 ) Balance at December 31, 2016 (16,319 ) (272,874 ) (5,443 ) (294,636 ) Net gain (loss) during 2017 (19,766 ) 22,288 (7,671 ) (5,149 ) Reclassification of income tax effects to retained earnings (8,065 ) (53,960 ) (2,004 ) (64,029 ) Balance at December 31, 2017 (44,150 ) (304,546 ) (15,118 ) (363,814 ) Cumulative effect of change in accounting principle — equity securities (16,853 ) — — (16,853 ) Net gain (loss) during 2018 (86,523 ) 43,243 3,866 (39,414 ) Balance at December 31, 2018 $ (147,526 ) $ (261,303 ) $ (11,252 ) $ (420,081 )

Other income and other expense

Other income and other expense	12 Months Ended
	Dec. 31, 2018
Other Income And Expenses [Abstract]
Other income and other expense	16. Other income and other expense The following items, which exceeded 1% of total interest income and other income in the respective period, were included in either “other revenues from operations” or “other costs of operations” in the consolidated statement of income: Year Ended December 31 2018 2017 2016 (In thousands) Other income: Credit-related fee income $ 82,614 $ 77,580 $ 70,424 Other expense: Professional services 312,998 289,862 268,060 Accrual for Wilmington Trust Corporation legal-related matters 135,000

International activities

International activities	12 Months Ended
	Dec. 31, 2018
International Activities [Abstract]
International Activities	17. International activities The Company engages in limited international activities including certain trust-related services in Europe, collecting Eurodollar deposits, engaging in foreign currency transactions associated with customer activity, providing credit to support the international activities of domestic companies and holding certain loans to foreign borrowers. Assets and revenues associated with international activities represent less than 1% of the Company’s consolidated assets and revenues. International assets included $172 million and $159 million of loans to foreign borrowers at December 31, 2018 and 2017, respectively. Deposits at M&T Bank’s Cayman Islands office were $812 million and $178 million at December 31, 2018 and 2017, respectively. The Company uses such deposits to facilitate customer demand and as an alternative to short-term borrowings when the costs of such deposits seem reasonable. Deposits at M&T Bank’s office in Ontario, Canada were $22 million at December 31, 2018 and $45 million at December 31, 2017. Revenues from providing international trust-related services were approximately $29 million in 2018, $24 million in 2017 and $25 million in 2016.

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative financial instruments	18. Derivative financial instruments As part of managing interest rate risk, the Company enters into interest rate swap agreements to modify the repricing characteristics of certain portions of the Company’s portfolios of earning assets and interest-bearing liabilities. The Company designates interest rate swap agreements utilized in the management of interest rate risk as either fair value hedges or cash flow hedges. Interest rate swap agreements are generally entered into with counterparties that meet established credit standards and most contain master netting, collateral and/or settlement provisions protecting the at-risk party. Based on adherence to the Company’s credit standards and the presence of the netting, collateral or settlement provisions, the Company believes that the credit risk inherent in these contracts was not material as of December 31, 2018. The net effect of interest rate swap agreements was to decrease net interest income by $25 million in 2018 and to increase net interest income by $25 million in 2017 and $37 million in 2016. Information about interest rate swap agreements entered into for interest rate risk management purposes summarized by type of financial instrument the swap agreements were intended to hedge follows: Weighted- Average Rate Estimated Notional Average Fair Value Amount Maturity Fixed Variable Gain (a) (In thousands) (In years) (In December 31, 2018 Fair value hedges: Fixed rate long-term borrowings (b) $ 4,450,000 2.8 2.47 % 3.02 % $ 4,219 Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(c) 15,400,000 1.3 1.52 % 2.35 % 1,311 Total $ 19,850,000 1.7 $ 5,530 December 31, 2017 Fair value hedges: Fixed rate long-term borrowings (b) $ 4,550,000 2.9 2.27 % 2.09 % $ 573 Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(d) 4,850,000 2.0 1.52 % 1.36 % 66 Total $ 9,400,000 2.5 $ 639 (a) C ertain clearinghouse exchange rules provide that required payments by counterparties for variation margin are treated as settlements of those positions. The impact of such settlements at December 31, 2018 and December 31, 2017 was a reduction of the estimated fair value losses on interest rate swap agreements designated as fair value hedges of $54.7 million and $41.1 million, respectively, and on interest rate swap agreements designated as cash flow hedges of $9.1 million and $16.3 million, respectively. (b) Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate. (c) Includes notional amount and terms of $12.6 billion of forward-starting interest rate swap agreements that will become effective in 2019 and 2020. (d) Includes notional amount and terms of $2.0 billion of forward-starting interest rate swap agreements that will become effective in 2019. The notional amount of interest rate swap agreements entered into for risk management purposes that were outstanding at December 31, 2018 mature as follows: (In thousands) Year ending December 31: 2019 $ 3,500,000 2020 11,200,000 2021 3,500,000 2022 650,000 2023 500,000 2027 500,000 $ 19,850,000 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 $42.9 billion and $29.9 billion at December 31, 2018 and 2017, respectively. The notional amounts of foreign currency and other option and futures contracts entered into for trading account purposes aggregated $763 million and $530 million at December 31, 2018 and 2017, 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 December 31 December 31 2018 2017 2018 2017 (In thousands) Derivatives designated and qualifying as hedging instruments Interest rate swap agreements (a) $ 5,530 $ 639 $ — $ — Commitments to sell real estate loans (a) 1,090 734 6,434 283 6,620 1,373 6,434 283 Derivatives not designated and qualifying as hedging instruments Mortgage-related commitments to originate real estate loans for sale (a) 9,304 8,797 1,592 494 Commitments to sell real estate loans (a) 3,702 2,526 4,535 1,019 Trading: Interest rate contracts (b) 118,687 74,164 169,255 132,104 Foreign exchange and other option and futures contracts (b) 10,549 5,657 8,870 5,286 142,242 91,144 184,252 138,903 Total derivatives $ 148,862 $ 92,517 $ 190,686 $ 139,186 (a) (b) Amount of Gain (Loss) Recognized Year Ended December 31, 2018 Year Ended December 31, 2017 Year Ended December 31, 2016 Derivative Hedged Item Derivative Hedged Item Derivative Hedged Item (In thousands) Derivatives in fair value hedging relationships Interest rate swap agreements: Fixed rate long-term borrowings (a) $ (10,006 ) 10,969 $ (52,392 ) 51,628 $ (32,000 ) 30,906 Derivatives not designated as hedging Trading: Interest rate contracts (b) $ 4,506 $ 5,398 $ 14,042 Foreign exchange and other option and futures contracts (b) 9,416 6,821 7,665 Total $ 13,922 $ 12,219 $ 21,707 (a) (b) Carrying Amount of the Hedged Item Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item December 31 December 31 2018 2017 2018 2017 (In thousands) Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges Long-term debt $ 4,394,109 $ 4,504,029 $ (51,102 ) $ (40,133 ) The amount of gain (loss) recognized in the consolidated statement of income associated with derivatives designated as cash flow hedges was not material. The Company also has commitments to sell and commitments to originate residential and commercial real estate loans that are considered derivatives. The Company designates certain of the commitments to sell real estate loans as fair value hedges of real estate loans held for sale. The Company also utilizes commitments to sell real estate loans to offset the exposure to changes in the fair value of certain commitments to originate real estate loans for sale. As a result of these activities, net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans were approximately $18 million and $16 million at December 31, 2018 and 2017, respectively. Changes in unrealized gains and losses are included in mortgage banking revenues and, in general, are realized in subsequent periods as the related loans are sold and commitments satisfied. The Company does not offset derivative asset and liability positions in its consolidated financial statements. The Company’s exposure to credit risk by entering into derivative contracts is mitigated through master netting agreements and collateral posting or settlement requirements. Master netting agreements covering interest rate and foreign exchange contracts with the same party include a right to set-off that becomes enforceable in the event of default, early termination or under other specific conditions. The aggregate fair value of derivative financial instruments in a liability position, which are subject to enforceable master netting arrangements, was $21 million and $13 million at December 31, 2018 and 2017, respectively, for which the Company was required to post collateral relating to those positions of $18 million and $12 million at December 31, 2018 and 2017, 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 ratings were to fall below specified ratings, the counterparties of the derivative financial instruments could demand immediate incremental collateralization on those instruments in a net liability position. The aggregate fair value of all derivative financial instruments with such credit risk-related contingent features in a net liability position on December 31, 2018 was not significant. If the credit risk-related contingent features had been triggered on December 31, 2018, the Company would not have been required to post any additional collateral with counterparties. The aggregate fair value of derivative financial instruments in an asset position, which are subject to enforceable master netting arrangements, was $18 million and $13 million at December 31, 2018 and 2017, respectively. Counterparties posted collateral relating to those positions of $16 million and $12 million at December 31, 2018 and 2017, respectively. Trading account interest rate swap agreements entered into with customers are subject to the Company’s credit risk standards and often contain collateral provisions. In addition to the derivative contracts noted above, the Company clears certain derivative transactions through a clearinghouse, rather than directly with counterparties. Those transactions cleared through a clearinghouse require initial margin collateral and variation margin payments depending on the contracts being in a net asset or liability position. The amount of initial margin collateral posted by the Company was $65 million and $52 million at December 31, 2018 and 2017, respectively. The fair value asset and liability amounts of derivative contracts have been reduced by variation margin payments treated as settlements as described herein. Variation margin on derivative contracts not treated as settlements continues to represent collateral posted or received by the Company.

Variable interest entities

Variable interest entities	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Variable interest entities	19. Variable interest entities The Company’s securitization activity has consisted of securitizing loans originated for sale into government issued or guaranteed mortgage-backed securities. The amounts of those securitizations in 2018, 2017 and 2016 are presented in the Company’s consolidated statement of cash flows. The Company has not recognized any losses as a result of having securitized assets. As described in note 8, 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 December 31, 2018 and 2017, the Company included the junior subordinated debentures as “long-term borrowings” in its consolidated balance sheet and recognized $23 million in other assets for its “investment” in the common securities of the trusts that will be concomitantly repaid to M&T by the respective trust from the proceeds of M&T’s repayment of the junior subordinated debentures associated with preferred capital securities described in note 8. The Company has invested as a limited partner in various partnerships that collectively had total assets of approximately $1.1 billion at of December 31, 2018 and $1.0 billion at December 31, 2017. 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 $523 million, including $280 million of unfunded commitments, at December 31, 2018 and $420 million, including $201 million of unfunded commitments, at December 31, 2017. Contingent commitments to provide additional capital contributions to these partnerships were not material at December 31, 2018. The Company has not provided financial or other support to the partnerships that was not contractually required. Management currently estimates that no material losses are probable as a result of the Company’s involvement with such entities. The Company, in its position as limited partner, does not direct the activities that most significantly impact the economic performance of the partnerships and, therefore, in accordance with the accounting provisions for variable interest entities, the partnership entities are not included in the Company’s consolidated financial statements. The Company’s investment cost in qualified affordable housing projects is amortized to income taxes in the consolidated statement of income as tax credits and other tax benefits resulting from deductible losses associated with the projects are received. The Company serves as investment advisor for certain registered money-market funds. The Company has no explicit arrangement to provide support to those funds, but may waive portions of its allowable management fees as a result of market conditions.

Fair value measurements

Fair value measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair value measurements	20. 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 December 31, 2018. 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 include interest rate contracts and foreign exchange contracts with customers who require such services with offsetting positions with third parties to minimize the Company’s risk with respect to such transactions. The Company generally determines the fair value of its derivative trading account assets and liabilities using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2. Mutual funds held in connection with deferred compensation and other arrangements have been classified as Level 1 valuations. Valuations of investments in municipal and other bonds can generally be obtained through reference to quoted prices in less active markets for the same or similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2. Investment securities available for sale and equity securities The majority of the Company’s available-for-sale investment securities have been valued by reference to prices for similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2. Certain investments in mutual funds and equity securities are actively traded and, therefore, have been classified as Level 1 valuations. Real estate loans held for sale The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in fair value of real estate loans held for sale. The carrying value of hedged real estate loans held for sale includes changes in estimated fair value during the hedge period. Typically, the Company attempts to hedge real estate loans held for sale from the date of close through the sale date. The fair value of hedged real estate loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans with similar characteristics and, accordingly, such loans have been classified as a Level 2 valuation. 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 is 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 December 31, 2018 and 2017 measured at estimated fair value on a recurring basis: Fair Value Measurements Level 1 (a) Level 2 (a) Level 3 (In thousands) December 31, 2018 Trading account assets $ 185,584 $ 46,018 $ 139,566 $ — Investment securities available for sale: U.S. Treasury and federal agencies 1,336,931 — 1,336,931 — Obligations of states and political subdivisions 1,659 — 1,659 — Mortgage-backed securities: Government issued or guaranteed 7,216,991 — 7,216,991 — Privately issued 22 — — 22 Other debt securities 126,906 — 126,906 — 8,682,509 — 8,682,487 22 Equity securities 93,917 71,989 21,928 — Real estate loans held for sale 551,697 — 551,697 — Other assets (b) 19,626 — 10,322 9,304 Total assets $ 9,533,333 $ 118,007 $ 9,406,000 $ 9,326 Trading account liabilities $ 178,125 $ — $ 178,125 $ — Other liabilities (b) 12,561 — 10,969 1,592 Total liabilities $ 190,686 $ — $ 189,094 $ 1,592 December 31, 2017 Trading account assets $ 132,909 $ 47,873 $ 85,036 $ — Investment securities available for sale: U.S. Treasury and federal agencies 1,947,487 — 1,947,487 — Obligations of states and political subdivisions 2,589 — 2,589 — Mortgage-backed securities: Government issued or guaranteed 8,716,392 — 8,716,392 — Privately issued 28 — — 28 Other debt securities 128,832 — 128,832 — Equity securities 100,956 73,232 27,724 — 10,896,284 73,232 10,823,024 28 Real estate loans held for sale 378,047 — 378,047 — Other assets (b) 12,696 — 3,899 8,797 Total assets $ 11,419,936 $ 121,105 $ 11,290,006 $ 8,825 Trading account liabilities $ 137,390 $ — $ 137,390 $ — Other liabilities (b) 1,796 — 1,302 494 Total liabilities $ 139,186 $ — $ 138,692 $ 494 (a) (b) The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the years ended December 31, 2018, 2017 and 2016 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets (In thousands) 2018 Balance — January 1, 2018 $ 28 $ 8,303 Total gains realized/unrealized: Included in earnings — 58,740 (b) Settlements (6 ) — Transfers out of Level 3 (a) — (59,331 ) (e) Balance — December 31, 2018 $ 22 7,712 Changes in unrealized gains included in earnings related to assets still held at December 31, 2018 $ — 7,386 (b) 2017 Balance — January 1, 2017 $ 44 7,325 Total gains realized/unrealized: Included in earnings — 77,832 (b) Settlements (16 ) — Transfers out of Level 3 (a) — (76,854 ) (e) Balance — December 31, 2017 $ 28 8,303 Changes in unrealized gains included in earnings related to assets still held at December 31, 2017 $ — 7,978 (b) Investment Securities Available for Sale Privately Issued Mortgage-Backed Collateralized Other Assets (In thousands) 2016 Balance — January 1, 2016 $ 74 47,393 9,879 Total gains (losses) realized/unrealized: Included in earnings — 30,041 (c) 110,937 (b) Included in other comprehensive income — (18,268 ) (d) — Sales — (58,296 ) — Settlements (30 ) (870 ) — Transfers out of Level 3 (a) — — (113,491 ) (e) Balance — December 31, 2016 $ 44 — 7,325 Changes in unrealized gains included in earnings related to assets still held at December 31, 2016 $ — — 7,256 (b) (a) (b) (c) (d) (e) 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 85% at December 31, 2018. 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 $268 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 $28 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 December 31, 2018 and 2017: Fair Value Valuation Technique Unobservable Inputs/Assumptions Range (Weighted- Average) (In December 31, 2018 Recurring fair value measurements Privately issued mortgage-backed securities $ 22 Two independent pricing quotes — — Net other assets (liabilities) (a) 7,712 Discounted cash flow Commitment expirations 0%-95% (13%) December 31, 2017 Recurring fair value measurements Privately issued mortgage-backed securities $ 28 Two independent pricing quotes — — Net other assets (liabilities) (a) 8,303 Discounted cash flow Commitment expirations 0%-78% (22%) (a) Sensitivity of fair value measurements to changes in unobservable inputs An increase (decrease) in the estimate of expirations for commitments to originate real estate loans would generally result in a lower (higher) fair value measurement. Estimated commitment expirations are derived considering loan type, changes in interest rates and remaining length of time until closing. Disclosures of fair value of financial instruments The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following tables: December 31, 2018 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,605,439 1,605,439 1,528,302 77,137 — Interest-bearing deposits at banks 8,105,197 8,105,197 — 8,105,197 — Trading account assets 185,584 185,584 46,018 139,566 — Investment securities 12,692,813 12,631,656 71,989 12,456,467 103,200 Loans and leases: Commercial loans and leases 22,977,976 22,587,387 — — 22,587,387 Commercial real estate loans 34,363,556 33,832,558 — 346,775 33,485,783 Residential real estate loans 17,154,446 16,974,545 — 3,920,447 13,054,098 Consumer loans 13,970,499 13,819,545 — — 13,819,545 Allowance for credit losses (1,019,444 ) — — — — Loans and leases, net 87,447,033 87,214,035 — 4,267,222 82,946,813 Accrued interest receivable 353,965 353,965 — 353,965 — Financial liabilities: Noninterest-bearing deposits $ (32,256,668 ) (32,256,668 ) — (32,256,668 ) — Savings and interest-checking deposits (50,963,744 ) (50,963,744 ) — (50,963,744 ) — Time deposits (6,124,254 ) (6,201,957 ) — (6,201,957 ) — Deposits at Cayman Islands office (811,906 ) (811,906 ) — (811,906 ) — Short-term borrowings (4,398,378 ) (4,398,378 ) — (4,398,378 ) — Long-term borrowings (8,444,914 ) (8,385,289 ) — (8,385,289 ) — Accrued interest payable (95,274 ) (95,274 ) — (95,274 ) — Trading account liabilities (178,125 ) (178,125 ) — (178,125 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 7,712 7,712 — — 7,712 Commitments to sell real estate loans (6,177 ) (6,177 ) — (6,177 ) — Other credit-related commitments (131,688 ) (131,688 ) — — (131,688 ) Interest rate swap agreements used for interest rate risk management 5,530 5,530 — 5,530 — December 31, 2017 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,420,888 1,420,888 1,352,035 68,853 — Interest-bearing deposits at banks 5,078,903 5,078,903 — 5,078,903 — Trading account assets 132,909 132,909 47,873 85,036 — Investment securities 14,664,525 14,653,074 73,232 14,469,127 110,715 Loans and leases: Commercial loans and leases 21,742,651 21,321,282 — — 21,321,282 Commercial real estate loans 33,366,373 32,950,724 — 22,130 32,928,594 Residential real estate loans 19,613,344 19,596,826 — 4,440,645 15,156,181 Consumer loans 13,266,615 13,161,517 — — 13,161,517 Allowance for credit losses (1,017,198 ) — — — — Loans and leases, net 86,971,785 87,030,349 — 4,462,775 82,567,574 Accrued interest receivable 327,170 327,170 — 327,170 — Financial liabilities: Noninterest-bearing deposits $ (33,975,180 ) (33,975,180 ) — (33,975,180 ) — Savings and interest-checking deposits (51,698,008 ) (51,698,008 ) — (51,698,008 ) — Time deposits (6,580,962 ) (6,635,048 ) — (6,635,048 ) — Deposits at Cayman Islands office (177,996 ) (177,996 ) — (177,996 ) — Short-term borrowings (175,099 ) (175,099 ) — (175,099 ) — Long-term borrowings (8,141,430 ) (8,193,783 ) — (8,193,783 ) — Accrued interest payable (75,641 ) (75,641 ) — (75,641 ) — Trading account liabilities (137,390 ) (137,390 ) — (137,390 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 8,303 8,303 — — 8,303 Commitments to sell real estate loans 1,958 1,958 — 1,958 — Other credit-related commitments (125,281 ) (125,281 ) — — (125,281 ) Interest rate swap agreements used for interest rate risk management 639 639 — 639 — With the exception of marketable securities, certain off-balance sheet financial instruments and mortgage loans originated for sale, the Company’s financial instruments are not readily marketable and market prices do not exist. The Company, in attempting to comply with the provisions of GAAP that require disclosures of fair value of financial instruments, has not attempted to market its financial instruments to potential buyers, if any exist. Since negotiated prices in illiquid markets depend greatly upon the then present motivations of the buyer and seller, it is reasonable to assume that actual sales prices could vary widely from any estimate of fair value made without the benefit of negotiations. Additionally, changes in market interest rates can dramatically impact the value of financial instruments in a short period of time. The Company does not believe that the estimated information presented herein is representative of the earnings power or value of the Company. The preceding analysis, which is inherently limited in depicting fair value, also does not consider any value associated with existing customer relationships nor the ability of the Company to create value through loan origination, deposit gathering or fee generating activities. Many of the estimates presented herein are based upon the use of highly subjective information and assumptions and, accordingly, the results may not be precise. Management believes that fair value estimates may not be comparable between financial institutions due to the wide range of permitted valuation techniques and numerous estimates which must be made. Furthermore, because the disclosed fair value amounts were estimated as of the balance sheet date, the amounts actually realized or paid upon maturity or settlement of the various financial instruments could be significantly different.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and contingencies	21. 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. December 31 2018 2017 (In thousands) Commitments to extend credit Home equity lines of credit $ 5,484,197 5,482,622 Commercial real estate loans to be sold 229,401 194,763 Other commercial real estate 7,556,722 6,050,569 Residential real estate loans to be sold 245,211 347,113 Other residential real estate 219,351 201,426 Commercial and other 14,363,803 12,733,815 Standby letters of credit 2,326,991 2,497,844 Commercial letters of credit 55,808 46,739 Financial guarantees and indemnification contracts 3,529,136 3,434,381 Commitments to sell real estate loans 940,692 812,217 Commitments to extend credit are agreements to lend to customers, generally having fixed expiration dates or other termination clauses that may require payment of a fee. In addition to the amounts presented in the preceding table, the Company had discretionary funding commitments to commercial customers of $8.6 billion and $8.1 billion at December 31, 2018 and 2017, respectively, that the Company had the unconditional right to cancel prior to funding. Standby and commercial letters of credit are conditional commitments issued to guarantee the performance of a customer to a third party. Standby letters of credit generally are contingent upon the failure of the customer to perform according to the terms of the underlying contract with the third party, whereas commercial letters of credit are issued to facilitate commerce and typically result in the commitment being funded when the underlying transaction is consummated between the customer and a third party. The credit risk associated with commitments to extend credit and standby and commercial letters of credit is essentially the same as that involved with extending loans to customers and is subject to normal credit policies. Collateral may be obtained based on management’s assessment of the customer’s creditworthiness. Financial guarantees and indemnification contracts are oftentimes similar to standby letters of credit and include mandatory purchase agreements issued to ensure that customer obligations are fulfilled, recourse obligations associated with sold loans, and other guarantees of customer performance or compliance with designated rules and regulations. Included in financial guarantees and indemnification contracts are loan principal amounts sold with recourse in conjunction with the Company’s involvement in the Fannie Mae DUS program. The Company’s maximum credit risk for recourse associated with loans sold under this program totaled approximately $3.4 billion and $3.3 billion at December 31, 2018 and 2017, 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 recorded in the consolidated balance sheet at estimated fair market value. The Company occupies certain banking offices and uses certain equipment under noncancelable operating lease agreements expiring at various dates over the next 23 years. Minimum lease payments under noncancelable operating leases are summarized in the following table: (In thousands) Year ending December 31: 2019 $ 89,547 2020 82,536 2021 67,985 2022 54,504 2023 39,578 Later years 104,280 $ 438,430 The Company is contractually obligated to repurchase previously sold residential real estate loans that do not ultimately meet investor sale criteria related to underwriting procedures or loan documentation. When required to do so, the Company may reimburse loan purchasers for losses incurred or may repurchase certain loans. The Company reduces residential mortgage banking revenues by an estimate for losses related to its obligations to loan purchasers. The amount of those charges is based on the volume of loans sold, the level of reimbursement requests received from loan purchasers and estimates of losses that may be associated with previously sold loans. At December 31, 2018, the Company believes that its obligation to loan purchasers was not material to the Company’s consolidated financial position. As previously disclosed, Wilmington Trust Corporation, a wholly-owned subsidiary of M&T, was the subject of a class action lawsuit alleging that its financial reporting and securities filings prior to its acquisition by M&T in 2011 were in violation of securities laws. In April 2018, the parties reached an agreement in principle and a formal settlement was executed and filed with the court later in the second quarter of 2018. The proposed settlement was preliminarily approved by the court in July 2018. In the first quarter of 2018, the Company increased its reserve for litigation matters by $135 million in anticipation of the settlement. The settlement amount of $200 million was paid, pursuant to the settlement agreement, during the third quarter of 2018. The settlement agreement was approved by the court in the fourth quarter of 2018. 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 $50 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

Segment information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment information	22. 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 1 with certain exceptions. The more significant of these exceptions are described herein. The Company allocates interest income or interest expense using a methodology that charges users of funds (assets) interest expense and credits providers of funds (liabilities) with income based on the maturity, prepayment and/or repricing characteristics of the assets and liabilities. A provision for credit losses is allocated to segments in an amount based largely on actual net charge-offs incurred by the segment during the period plus or minus an amount necessary to adjust the segment’s allowance for credit losses due to changes in loan balances. In contrast, the level of the consolidated provision for credit losses is determined using the methodologies described in notes 1 and 4. The net effects of these allocations are recorded in the “All Other” category. Indirect fixed and variable expenses incurred by certain centralized support areas are allocated to segments based on actual usage (for example, volume measurements) and other criteria. Certain types of administrative expenses and bankwide expense accruals (including amortization of core deposit and other intangible assets associated with acquisitions of financial institutions) are generally not allocated to segments. Income taxes are allocated to segments based on the Company’s marginal statutory tax rate adjusted for any tax-exempt income or non-deductible expenses. Equity is allocated to the segments based on regulatory capital requirements and in proportion to an assessment of the inherent risks associated with the business of the segment (including interest, credit and operating risk). 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. Information about the Company’s segments is presented in the accompanying table. Income statement amounts are in thousands of dollars. Balance sheet amounts are in millions of dollars. For the Years Ended December 31, 2018, 2017 and 2016 Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio 2018 2017 2016 2018 2017 2016 2018 2017 2016 2018 2017 2016 Net interest income(a) $ 434,579 $ 393,948 $ 371,889 $ 821,812 $ 809,301 $ 785,339 $ 665,220 $ 649,378 $ 608,385 $ 228,051 $ 277,095 $ 345,926 Noninterest income 111,600 112,512 108,783 288,908 283,447 274,923 183,955 169,966 179,706 (9,690 ) 23,851 26,075 546,179 506,460 480,672 1,110,720 1,092,748 1,060,262 849,175 819,344 788,091 218,361 300,946 372,001 Provision for credit losses 10,916 15,598 12,709 8,976 11,876 34,903 3,159 (7,524 ) (3,447 ) 6,683 31,119 32,925 Amortization of core deposit and other intangible assets — — — — — — 1,060 1,060 — — — — Depreciation and other amortization 382 393 404 496 509 520 25,852 24,410 20,120 187 279 472 Other noninterest expense 305,340 294,493 292,124 364,102 339,936 327,616 217,387 207,493 204,965 65,393 76,021 95,300 Income (loss) before taxes 229,541 195,976 175,435 737,146 740,427 697,223 601,717 593,905 566,453 146,098 193,527 243,304 Income tax expense (benefit) 61,279 80,043 71,677 198,229 303,556 285,844 148,807 229,770 216,095 29,872 58,559 79,766 Net income (loss) $ 168,262 $ 115,933 $ 103,758 $ 538,917 $ 436,871 $ 411,379 $ 452,910 $ 364,135 $ 350,358 $ 116,226 $ 134,968 $ 163,538 Average total assets (in millions) $ 5,631 $ 5,602 $ 5,456 $ 26,626 $ 26,573 $ 25,592 $ 22,885 $ 22,741 $ 21,131 $ 32,123 $ 37,203 $ 40,867 Capital expenditures (in millions) $ — $ — $ — $ — $ — $ — $ — $ 1 $ — $ 1 $ — $ — For the Years Ended December 31, 2018, 2017 and 2016 Residential Mortgage Banking Retail Banking All Other Total 2018 2017 2016 2018 2017 2016 2018 2017 2016 2018 2017 2016 Net interest income(a) $ 13,933 $ 30,328 $ 29,809 $ 1,351,165 $ 1,210,066 $ 1,107,388 $ 557,542 $ 410,928 $ 221,151 $ 4,072,302 $ 3,781,044 $ 3,469,887 Noninterest income 305,560 321,589 342,858 324,228 329,833 323,176 651,439 609,945 570,475 1,856,000 1,851,143 1,825,996 319,493 351,917 372,667 1,675,393 1,539,899 1,430,564 1,208,981 1,020,873 791,626 5,928,302 5,632,187 5,295,883 Provision for credit losses (2,178 ) 1,254 (3,617 ) 112,572 107,412 120,437 (8,128 ) 8,265 (3,910 ) 132,000 168,000 190,000 Amortization of core deposit and other intangible assets — — — — — — 23,462 30,306 42,613 24,522 31,366 42,613 Depreciation and other amortization 24,288 32,011 30,264 35,274 38,234 37,657 68,004 69,923 68,541 154,483 165,759 157,978 Other noninterest expense 241,624 247,639 258,141 789,783 758,153 776,123 1,125,428 1,019,465 892,625 3,109,057 2,943,200 2,846,894 Income (loss) before taxes 55,759 71,013 87,879 737,764 636,100 496,347 215 (107,086 ) (208,243 ) 2,508,240 2,323,862 2,058,398 Income tax expense (benefit) 10,272 25,446 32,426 196,467 258,934 201,974 (54,766 ) (40,752 ) (144,498 ) 590,160 915,556 743,284 Net income (loss) $ 45,487 $ 45,567 $ 55,453 $ 541,297 $ 377,166 $ 294,373 $ 54,981 $ (66,334 ) $ (63,745 ) $ 1,918,080 $ 1,408,306 $ 1,315,114 Average total assets (in millions) $ 2,161 $ 2,355 $ 2,569 $ 13,656 $ 12,702 $ 11,840 $ 13,877 $ 13,684 $ 16,885 $ 116,959 $ 120,860 $ 124,340 Capital expenditures (in millions) $ 1 $ — $ — $ 31 $ 34 $ 46 $ 65 $ 44 $ 62 $ 98 $ 79 $ 108 (a) The Business Banking segment provides deposit, lending, cash management and other financial services to small businesses and professionals through the Company’s banking office network and several other delivery channels, including business banking centers, telephone banking, Internet banking and automated teller machines. The Commercial Banking segment provides a wide range of credit products and banking services to middle-market and large commercial customers, mainly within the markets the Company serves. Among the services provided by this segment are commercial lending and leasing, letters of credit, deposit products and cash management services. The Commercial Real Estate segment provides credit services which are secured by various types of multifamily residential and commercial real estate and deposit services to its customers. Activities of this segment include the origination, sales and servicing of commercial real estate loans. Commercial real estate loans held for sale are included in the Commercial Real Estate Segment. The Discretionary Portfolio segment includes securities; residential real estate loans and other assets; short-term and long-term borrowed funds; brokered deposits; and Cayman Islands branch deposits. This segment also provides foreign exchange services to customers. The Residential Mortgage Banking segment originates and services residential real estate loans for consumers and sells substantially all originated loans in the secondary market to investors or to the Discretionary Portfolio segment. The segment periodically purchases servicing rights to loans that have been originated by other entities. Residential real estate loans held for sale are included in the Residential Mortgage Banking segment. The Retail Banking segment offers a variety of services to consumers through several delivery channels that include banking offices, automated teller machines, and telephone, mobile and Internet banking. The “All Other” category includes other operating activities of the Company that are not directly attributable to the reported segments; the difference between the provision for credit losses and the calculated provision allocated to the reportable segments; goodwill and core deposit and other intangible assets resulting from acquisitions of financial institutions; merger-related gains and expenses resulting from acquisitions; the net impact of the Company’s internal funds transfer pricing methodology; eliminations of transactions between reportable segments; certain nonrecurring transactions; the residual effects of unallocated support systems and general and administrative expenses; and the impact of interest rate risk management strategies. The amount of intersegment activity eliminated in arriving at consolidated totals was included in the “All Other” category as follows: Year Ended December 31 2018 2017 2016 (In thousands) Revenues $ (41,285 ) $ (43,941 ) $ (48,625 ) Expenses (24,660 ) (32,623 ) (40,422 ) Income taxes (benefit) (4,371 ) (4,606 ) (3,338 ) Net income (loss) (12,254 ) (6,712 ) (4,865 ) The Company conducts substantially all of its operations in the United States. There are no transactions with a single customer that in the aggregate result in revenues that exceed ten percent of consolidated total revenues.

Regulatory matters

Regulatory matters	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Regulatory matters	23. Regulatory matters Payment of dividends by M&T’s banking subsidiaries is restricted by various legal and regulatory limitations. Dividends from any banking subsidiary to M&T are limited by the amount of earnings of the banking subsidiary in the current year and the preceding two years. For purposes of this test, at December 31, 2018, approximately $669 million was available for payment of dividends to M&T from banking subsidiaries. M&T may pay dividends and repurchase stock only in accordance with a capital plan that the Federal Reserve Board has not objected to. Banking regulations prohibit extensions of credit by the subsidiary banks to M&T unless appropriately secured by assets. Securities of affiliates are not eligible as collateral for this purpose. The bank subsidiaries are required to maintain reserves against certain deposit liabilities. During the maintenance periods that included December 31, 2018 and 2017, cash and due from banks and interest-earning deposits at banks included a daily average of $683,740,000 and $679,401,000, respectively, for such purpose. M&T and its subsidiary banks are required to comply with applicable capital adequacy regulations established by the federal banking agencies. Failure to meet minimum capital requirements can result in certain mandatory, and possibly additional discretionary, actions by regulators that, if undertaken, could have a material effect on the Company’s financial statements. Pursuant to the rules in effect as of December 31, 2018, the required minimum and well capitalized capital ratios are as follows: Well Minimum Capitalized ● Common equity Tier 1 ("CET1") to risk-weighted assets 4.5 % 6.5 % ● Tier 1 capital to risk-weighted assets 6.0 % 8.0 % ● Total capital to risk-weighted assets 8.0 % 10.0 % ● Leverage — Tier 1 capital to average total assets, as defined 4.0 % 5.0 % In addition, capital regulations provide for the phase-in of a “capital conservation buffer” composed entirely of CET1 on top of these minimum risk-weighted asset ratios. The fully phased-in capital conservation buffer as of January 1, 2019 is 2.5%. For 2018 and 2017, the phase-in transition portion of that buffer was 1.875% and 1.25%, respectively. The capital ratios and amounts of the Company and its banking subsidiaries as of December 31, 2018 and 2017 are presented below: M&T (Consolidated) M&T Bank Wilmington Trust, N.A. (Dollars in thousands) December 31, 2018: Common equity Tier 1 capital Amount $ 9,960,811 $ 10,636,136 $ 585,767 Ratio(a) 10.13 % 10.84 % 60.69 % Tier 1 capital Amount 11,193,770 10,636,136 585,767 Ratio(a) 11.38 % 10.84 % 60.69 % Total capital Amount 13,454,137 12,475,296 589,671 Ratio(a) 13.68 % 12.72 % 61.10 % Leverage Amount 11,193,770 10,636,136 585,767 Ratio(b) 9.88 % 9.42 % 12.51 % December 31, 2017: Common equity Tier 1 capital Amount $ 10,675,735 $ 9,978,163 $ 529,988 Ratio(a) 10.99 % 10.30 % 48.16 % Tier 1 capital Amount 11,908,166 9,978,163 529,988 Ratio(a) 12.26 % 10.30 % 48.16 % Total capital Amount 14,328,467 12,012,171 534,235 Ratio(a) 14.75 % 12.40 % 48.54 % Leverage Amount 11,908,166 9,978,163 529,988 Ratio(b) 10.31 % 8.68 % 13.03 % (a) (b)

Relationship with Bayview Lendi

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.	12 Months Ended
	Dec. 31, 2018
Text Block [Abstract]
Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.	24. Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. M&T holds a 20% minority interest in Bayview Lending Group LLC (“BLG”), a privately-held commercial mortgage company. M&T recognizes income or loss from BLG using the equity method of accounting. That investment had no remaining carrying value at December 31, 2018 as a result of cumulative losses recognized and cash distributions received in prior years. Income or losses recognized by M&T are included in other revenues from operations and totaled $24 million of income in 2018, compared with losses of $11 million in 2016. Income recognized in 2017 was not significant. Bayview Financial Holdings, L.P. (together with its affiliates, “Bayview Financial”), a privately-held specialty financial company, is BLG’s majority investor. In addition to their common investment in BLG, the Company and Bayview Financial conduct other business activities with each other. The Company has obtained loan servicing rights for mortgage loans from BLG and Bayview Financial having outstanding principal balances of $2.5 billion and $3.0 billion at December 31, 2018 and 2017, respectively. Revenues from those servicing rights were $14 million, $17 million and $19 million during 2018, 2017 and 2016, respectively. The Company sub-services residential mortgage loans for Bayview Financial having outstanding principal balances of $56.8 billion and $56.6 billion at December 31, 2018 and 2017, respectively. Revenues earned for sub-servicing loans for Bayview Financial were $114 million, $103 million and $98 million in 2018, 2017 and 2016, respectively. In addition, the Company held $113 million and $136 million of mortgage-backed securities in its held-to-maturity portfolio at December 31, 2018 and 2017, respectively, that were securitized by Bayview Financial. At December 31, 2018, the Company held $127 million of Bayview Financial’s $900 million syndicated loan facility.

Parent company financial statem

Parent company financial statements	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent company financial statements	25. Parent company financial statements Condensed Balance Sheet December 31 2018 2017 (In thousands) Assets Cash in subsidiary bank $ 40,609 $ 13,379 Due from consolidated bank subsidiaries Money-market savings 856,881 1,616,147 Current income tax receivable 1,117 4,437 Total due from consolidated bank subsidiaries 857,998 1,620,584 Investments in consolidated subsidiaries Banks 15,491,277 14,841,794 Other 324,360 253,904 Investments in trust preferred entities (note 19) 23,241 23,453 Other assets 64,187 66,023 Total assets $ 16,801,672 $ 16,819,137 Liabilities Accrued expenses and other liabilities $ 63,719 $ 49,093 Long-term borrowings 1,277,762 519,225 Total liabilities 1,341,481 568,318 Shareholders’ equity 15,460,191 16,250,819 Total liabilities and shareholders’ equity $ 16,801,672 $ 16,819,137 Condensed Statement of Income Year Ended December 31 2018 2017 2016 (In thousands, except per share) Income Dividends from consolidated bank subsidiaries $ 1,250,000 $ 1,540,000 $ 1,930,000 Equity in earnings of Bayview Lending Group LLC 23,500 352 (10,752 ) Other income 2,417 9,493 5,530 Total income 1,275,917 1,549,845 1,924,778 Expense Interest on long-term borrowings 36,354 21,591 18,963 Other expense 23,894 19,636 21,361 Total expense 60,248 41,227 40,324 Income before income taxes and equity in undistributed income of subsidiaries 1,215,669 1,508,618 1,884,454 Income tax credits 8,446 26,453 17,247 Income before equity in undistributed income of subsidiaries 1,224,115 1,535,071 1,901,701 Equity in undistributed income of subsidiaries Net income of subsidiaries 1,943,965 1,413,235 1,343,413 Less: dividends received (1,250,000 ) (1,540,000 ) (1,930,000 ) Equity in undistributed income of subsidiaries 693,965 (126,765 ) (586,587 ) Net income $ 1,918,080 $ 1,408,306 $ 1,315,114 Net income per common share Basic $ 12.75 $ 8.72 $ 7.80 Diluted 12.74 8.70 7.78 Condensed Statement of Cash Flows Year Ended December 31 2018 2017 2016 (In thousands) Cash flows from operating activities Net income $ 1,918,080 $ 1,408,306 $ 1,315,114 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed income of subsidiaries (693,965 ) 126,765 586,587 Benefit (provision) for deferred income taxes 4,949 4,543 (3,157 ) Net change in accrued income and expense (8,242 ) (170 ) 12,898 Gain on sale of assets — (2,995 ) (2,342 ) Net cash provided by operating activities 1,220,822 1,536,449 1,909,100 Cash flows from investing activities Proceeds from sales or maturities of investment securities — — 51 Other, net 29,933 12,407 13,619 Net cash provided by investing activities 29,933 12,407 13,670 Cash flows from financing activities Purchases of treasury stock (2,194,396 ) (1,205,905 ) (641,334 ) Dividends paid — common (510,382 ) (457,402 ) (441,891 ) Dividends paid — preferred (72,521 ) (72,734 ) (81,270 ) Proceeds from long-term borrowings 748,595 — — Redemption of Series D preferred stock — — (500,000 ) Proceeds from issuance of Series F preferred stock — — 495,000 Other, net 45,913 34,524 143,764 Net cash used by financing activities (1,982,791 ) (1,701,517 ) (1,025,731 ) Net increase (decrease) in cash and cash equivalents (732,036 ) (152,661 ) 897,039 Cash and cash equivalents at beginning of year 1,629,526 1,782,187 885,148 Cash and cash equivalents at end of year $ 897,490 $ 1,629,526 $ 1,782,187 Supplemental disclosure of cash flow information Interest received during the year $ 2,219 $ 2,313 $ 1,931 Interest paid during the year 17,482 18,498 15,918 Income taxes received during the year 6,362 21,740 8,877

Recent accounting developments

Recent accounting developments	12 Months Ended
	Dec. 31, 2018
Accounting Changes And Error Corrections [Abstract]
Recent accounting developments	26. Recent accounting developments The following table provides a description of accounting standards that were adopted by the Company in 2018 as well as standards that are not effective that could have an impact to M&T’s consolidated financial statements upon adoption. Standard Description Required date of adoption Effect on consolidated financial statements Standards Adopted in 2018 Revenue from Contracts with Customers The core principle of the accounting guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. January 1, 2018 As described in note 10 the Company adopted the revenue recognition guidance effective January 1, 2018 and applied the modified retrospective approach for reporting purposes. The adjustment to beginning retained earnings as well as the impact of any changes in the timing of revenue recognition of noninterest income items within the scope of this guidance did not have a material effect on the Company’s financial position or results of operations. Recognition and Measurement of Financial Assets and Financial Liabilities The amended guidance requires equity investments (excluding those accounted for under the equity method of accounting or those that result in consolidation of the investee) be measured at fair value with changes in fair value recognized in net income, public entities to use the exit price when measuring the fair value of financial instruments for disclosure purposes, and an entity to present separately in other comprehensive income a change in the instrument-specific credit risk when the entity has elected to measure a liability at fair value in accordance with the fair value option. January 1, 2018 At January 1, 2018 the Company reclassified marketable equity securities from investment securities available for sale. Upon adoption, $17 million of fair value changes in those equity securities, net of tax, were reclassified from accumulated other comprehensive income to retained earnings. See note 2 for information on amounts recognized in gain (loss) on bank investment securities in the consolidated statement of income. Improvements to Accounting for Hedging Activities The amended guidance expands and clarifies hedge accounting for nonfinancial and financial risk components, aligns the recognition and presentation of the effects of the hedging instrument and hedged item in the financial statements, and simplifies the requirements for assessing effectiveness in a hedging relationship. In October 2018, amended guidance was issued permitting the use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes in addition to the US Treasury, the LIBOR swap rate, the OIS rate based on Fed Funds Effective Rate, and the SIFMA Municipal Swap Rate. January 1, 2019 Early adoption permitted The Company early adopted the amended guidance on January 1, 2018 and such adoption did not have a material impact on its consolidated financial statements. Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost The amended guidance requires the service cost component of the net periodic pension cost and net periodic postretirement benefit cost to be reported in the same line item in the income statement as other compensation costs arising from services rendered by the pertinent employees during the period. The amendments also require that the other components of net benefit costs be presented separately from the service cost component. January 1, 2018 The Company adopted the new reporting requirements effective January 1, 2018. The Company previously reported all of its net periodic pension and postretirement benefit costs in salaries and employee benefits expense within the consolidated statement of income. Information about net periodic pension and postretirement benefit costs that were not service cost-related is included in note 12. The impact of adopting the amended guidance was not material. Standard Description Required date of adoption Effect on consolidated financial statements Standards Adopted in 2018 Scope of Modification Accounting for Share-Based Payment Awards The amended guidance addresses which changes to the terms and conditions of a share-based payment award require an entity to apply modification accounting. January 1, 2018 The Company adopted the amended guidance on January 1, 2018. The guidance is being applied on a prospective basis for awards modified on or after the adoption date. Restricted Cash The amended guidance requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. In addition, when cash, cash equivalents, and restricted cash or restricted cash equivalents are presented in more than one line item within the statement of financial position, the line items and amounts must be presented on the face of the statement of cash flows or disclosed in the notes to the financial statements. Information about the nature of restrictions on an entity’s cash and cash equivalents must also be disclosed. January 1, 2018 The guidance was adopted on January 1, 2018 and did not have a material impact on the Company’s consolidated financial statements. Classification of Certain Cash Receipts and Cash Payments This amendment provides clarifying guidance for classifying cash inflows or outflows on the statement of cash flows where current guidance is unclear or silent. January 1, 2018 The guidance was Clarifying the Definition of a Business The amended guidance clarifies the definition of a business for purposes of evaluating whether transactions would be accounted for as acquisitions (or disposals) of assets or businesses. January 1, 2018 The guidance was adopted January 1, 2018 and will be future transactions Standards Not Yet Adopted as of December 31, 2018 Leases The new guidance requires lessees to record a right-of-use asset and a lease liability for all leases with a term greater than 12 months. While the guidance requires all leases to be recognized in the balance sheet, there continues to be a differentiation between finance leases and operating leases for purposes of income statement recognition and cash flow statement presentation. For finance leases, interest on the lease liability and amortization of the right-of-use asset will be recognized separately in the statement of income. Repayments of principal on those lease liabilities will be classified within financing activities and payments of interest on the lease liability will be classified within operating activities in the statement of cash flows. For operating leases, a single lease cost is recognized in the statement of income and allocated over the lease term, generally on a straight-line basis. All cash payments are presented within operating activities in the statement of cash flows. The accounting applied by lessors is largely unchanged from existing GAAP, however, the guidance eliminates the accounting model for leveraged leases for leases that commence after the effective date of the guidance. January 1, 2019 Early adoption permitted The Company occupies certain banking offices and uses certain equipment under noncancelable operating lease agreements which prior to the adoption of the guidance are not reflected in its consolidated balance sheet at December 31, 2018 and 2017. The Company adopted the guidance effective January 1, 2019 and recognized a right of use asset of $394 million and increased liabilities by $399 million as a result of recognizing lease liabilities on its consolidated balance sheet. The Company does not expect the new guidance will have a material impact on its consolidated statement of income. Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of December 31, 2018 Premium Amortization on Purchased Callable Debt Securities The amended guidance requires the premium on callable debt securities to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. January 1, 2019 Early adoption permitted The Company adopted the amended guidance effective January 1, 2019 and applied the modified retrospective approach for reporting purposes. The adoption did not have a material effect on the Company’s financial position and will not have a material effect on its results of operations. Measurement of Credit Losses on Financial Instruments The amended guidance replaces the current incurred loss model for determining the allowance for credit losses. The guidance requires financial assets measured at amortized cost to be presented at the net amount expected to be collected. The allowance for credit losses will represent a valuation account that is deducted from the amortized cost basis of the financial assets to present their net carrying value at the amount expected to be collected. The income statement will reflect the measurement of credit losses for newly recognized financial assets as well as expected increases or decreases of expected credit losses that have taken place during the period. When determining the allowance, expected credit losses over the contractual term of the financial asset(s) (taking into account prepayments) will be estimated considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The amended guidance also requires recording an allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination. The initial allowance for these assets will be added to the purchase price at acquisition rather than being reported as an expense. Subsequent changes in the allowance will be recorded through the income statement as an expense adjustment. In addition, the amended guidance requires credit losses relating to available-for-sale debt securities to be recorded through an allowance for credit losses. The calculation of credit losses for available-for-sale securities will be similar to how it is determined under existing guidance. January 1, 2020 Early adoption permitted as of January 1, 2019 The Company is developing its approach for determining expected credit losses under the new guidance. The Company has a cross-functional implementation team working on model development, model validation, and development of a qualitative framework, data sourcing, and technology enhancements. The Company expects that the new guidance will result in an increase in its allowance for credit losses as a result of considering credit losses over the expected life of its loan portfolios. Increases in the level of allowances will reflect new requirements to include the nonaccretable principal difference on purchased credit impaired loans and estimated credit losses on investment securities classified as held-to-maturity, if any. The expected increase to the allowance for credit losses and the impact to the Company’s financial statements are still being determined. Simplifying the Test for Goodwill Impairment The amended guidance eliminates step 2 from the goodwill impairment test. January 1, 2020 Early adoption permitted The amendments should be applied using a prospective transition method. The Company does not expect the guidance will have a material impact on its consolidated financial statements, unless at some point in the future one of its reporting units were to fail step 1 of the goodwill impairment test. Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of December 31, 2018 Changes to the Disclosure Requirements for Fair Value Measurements The amended guidance modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurements. The amendments are a result of the disclosure framework project that focuses on improvements to the effectiveness of disclosures in the notes to financial statements. The amendments remove, modify, and add certain disclosure requirements. The disclosure requirements being removed relating to public companies are (1) the amount and reason for transfers between Level 1 and Level 2 of the fair value hierarchy, (2) the policy for timing of transfers between levels, and (3) the valuation process for Level 3 fair value measurements. The disclosure requirements being modified relating to public companies are (1) for investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s asset and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly, and (2) the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as a result of the use of unobservable inputs. The disclosure requirements being added relating to public companies are (1) to disclose the changes in unrealized gains and losses for the period for recurring Level 3 fair value measurements, and (2) to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. January 1, 2020 Early adoption permitted The amendments relating to changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurements uncertainty should be applied prospectively. All other amendments should be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements. Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract The amended guidance requires a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which implementation costs to capitalize and which costs to expense. January 1, 2020 Early adoption permitted The amendments should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The Company is evaluating the impact that the guidance will have on its consolidated financial statements. Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of December 31, 2018 Improvements to Related Party Guidance for VIEs The amended guidance requires that indirect interests held through related parties in common control arrangements should be considered on a proportional basis for determining whether fees paid to decision makers and service providers are variable interests. January 1, 2020 Early adoption permitted The amendments should be applied retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Company does not expect the guidance to have a material impact on its consolidated financial statements. Changes to the Disclosure Requirements for Defined Benefit Plans The amended guidance modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The amendments are a result of the disclosure framework project that focuses on improvements to the effectiveness of disclosures in the notes to financial statements. The amendments remove and add certain disclosure requirements. The disclosure requirements being removed relating to public companies are (1) the amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit cost over the next fiscal year, (2) the amount and timing of plan assets expected to be returned to the employer, (3) the 2001 disclosure requirement relating to Japanese Welfare Pension Insurance Law, (4) related party disclosures about the amount of future annual benefits covered by insurance, and (5) the effects of a one-percentage-point change in assumed health care cost trends on the benefit cost and obligation. The disclosure requirements being added relating to public companies are (1) the weighted-average interest crediting rates for cash balance plans , and (2) an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. January 1, 2021 Early adoption permitted The amendments should be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements.

Significant accounting polici_2

Significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Consolidation	Consolidation The consolidated financial statements include M&T and all of its subsidiaries. All significant intercompany accounts and transactions of consolidated subsidiaries have been eliminated in consolidation. The financial statements of M&T included in note 25 report investments in subsidiaries under the equity method. Information about some limited purpose entities that are affiliates of the Company but are not included in the consolidated financial statements appears in note 19.
Consolidated Statement of Cash Flows	Consolidated Statement of Cash Flows For purposes of this statement, cash and due from banks and federal funds sold are considered cash and cash equivalents.
Securities purchased under agreements to resell and securities sold under agreements to repurchase	Securities purchased under agreements to resell and securities sold under agreements to repurchase Securities purchased under agreements to resell and securities sold under agreements to repurchase are treated as collateralized financing transactions and are recorded at amounts equal to the cash or other consideration exchanged. It is generally the Company’s policy to take possession of collateral pledged to secure agreements to resell.
Trading account	Trading account Financial instruments used for trading purposes are stated at fair value. Realized gains and losses and unrealized changes in fair value of financial instruments utilized in trading activities are included in “trading account and foreign exchange gains” in the consolidated statement of income.
Investment securities	Investment securities Investments in debt securities are classified as held to maturity and stated at amortized cost when management has the positive intent and ability to hold such securities to maturity. Investments in other debt securities are classified as available for sale and stated at estimated fair value with unrealized changes in fair value included in “accumulated other comprehensive income (loss), net.” Investments in equity securities having readily determinable fair values are stated at fair value and, beginning in 2018, unrealized changes in fair value are included in earnings. Investments in equity securities that do not have readily determinable fair values are stated at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Prior to 2018, equity securities with readily determinable fair values were classified as available for sale. Amortization of premiums and accretion of discounts for investment securities available for sale and held to maturity are included in interest income. Other securities are stated at cost and include stock of the Federal Reserve Bank of New York and the Federal Home Loan Bank (“FHLB”) of New York. Individual debt securities are written down through a charge to earnings when declines in value below the cost basis of a security are considered to be other than temporary. In cases where fair value is less than amortized cost and the Company intends to sell a debt security, it is more likely than not to be required to sell a debt security before recovery of its amortized cost basis, or the Company does not expect to recover the entire amortized cost basis of a debt security, an other-than-temporary impairment is considered to have occurred. If the Company intends to sell the debt security or more likely than not will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is recognized in earnings equal to the entire difference between the debt security’s amortized cost basis and its fair value. If the Company does not expect to recover the entire amortized cost basis of the security, the Company does not intend to sell the security and it is not more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis, the other-than-temporary impairment is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the other-than-temporary impairment related to the credit loss is recognized in earnings while the amount related to other factors is recognized in other comprehensive income, net of applicable taxes. Subsequently, the Company accounts for the other-than-temporarily impaired debt security as if the security had been purchased on the measurement date of the other-than-temporary impairment at an amortized cost basis equal to the previous amortized cost basis less the other-than-temporary impairment recognized in earnings. Realized gains and losses on the sales of investment securities are determined using the specific identification method.
Loans and leases	Loans and leases The Company’s accounting methods for loans depends on whether the loans were originated by the Company or were acquired in a business combination. Originated loans and leases Interest income on loans is accrued on a level yield method. Loans are placed on nonaccrual status and previously accrued interest thereon is charged against income when principal or interest is delinquent 90 days, unless management determines that the loan status clearly warrants other treatment. Nonaccrual commercial loans and commercial real estate loans are returned to accrual status when borrowers have demonstrated an ability to repay their loans and there are no delinquent principal and interest payments. Consumer loans not secured by residential real estate are returned to accrual status when all past due principal and interest payments have been paid by the borrower. Loans secured by residential real estate are returned to accrual status when they are deemed to have an insignificant delay in payments of 90 days or less. Loan balances are charged off when it becomes evident that such balances are not fully collectible. For commercial loans and commercial real estate loans, charge-offs are recognized after an assessment by credit personnel of the capacity and willingness of the borrower to repay, the estimated value of any collateral, and any other potential sources of repayment. A charge-off is recognized when, after such assessment, it becomes evident that the loan balance is not fully collectible. For loans secured by residential real estate, the excess of the loan balances over the net realizable value of the property collateralizing the loan is charged-off when the loan becomes 150 days delinquent. Consumer loans are generally charged-off when the loans are 91 to 180 days past due, depending on whether the loan is collateralized and the status of repossession activities with respect to such collateral. Loan fees and certain direct loan origination costs are deferred and recognized as an interest yield adjustment over the life of the loan. Net deferred fees have been included in unearned discount as a reduction of loans outstanding. Commitments to sell real estate loans are utilized by the Company 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 recorded in the consolidated balance sheet includes changes in estimated fair market value during the hedge period, typically from the date of close through the sale date. Valuation adjustments made on these loans and commitments are included in “mortgage banking revenues.” Except for consumer and residential mortgage loans that are considered smaller balance homogenous loans and are evaluated collectively, 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. Impaired loans are classified as either nonaccrual or as loans renegotiated at below market rates which continue to accrue interest, provided that a credit assessment of the borrower’s financial condition results in an expectation of full repayment under the modified contractual terms. Certain loans greater than 90 days delinquent are not considered impaired if they are well-secured and in the process of collection. Loans less than 90 days delinquent are deemed to have an insignificant delay in payment and are generally not considered impaired. Impairment of a loan is measured based on the present value of expected future cash flows discounted at the loan’s effective interest rate, the loan’s observable market price, or the fair value of collateral if the loan is collateral-dependent. Interest received on impaired loans placed on nonaccrual status is generally applied to reduce the carrying value of the loan or, if principal is considered fully collectible, recognized as interest income. Residual value estimates for commercial leases are generally determined through internal or external reviews of the leased property. The Company reviews commercial lease residual values at least annually and recognizes residual value impairments deemed to be other than temporary. Loans and leases acquired in a business combination Loans acquired in a business combination subsequent to December 31, 2008 are initially recorded at fair value with no carry-over of an acquired entity’s previously established allowance for credit losses. Purchased impaired loans represent specifically identified loans with evidence of credit deterioration for which it was probable at acquisition that the Company would be unable to collect all contractual principal and interest payments. For purchased impaired loans and other loans acquired at a discount that was, in part, attributable to credit quality, the excess of cash flows expected at acquisition over the estimated fair value of acquired loans is recognized as interest income over the remaining lives of the loans. Subsequent decreases in the expected principal cash flows require the Company to evaluate the need for additions to the Company’s allowance for credit losses. Subsequent improvements in expected cash flows result first in the recovery of any related allowance for credit losses and then in recognition of additional interest income over the then-remaining lives of the loans. For all other acquired loans, the difference between the fair value and outstanding principal balance of the loans is recognized as an adjustment to interest income over the lives of those loans. Those loans are then accounted for in a manner that is similar to originated loans.
Allowance for credit losses	Allowance for credit losses The allowance for credit losses represents, in management’s judgment, the amount of losses inherent in the loan and lease portfolio as of the balance sheet date. The allowance is determined by management’s evaluation of the loan and lease portfolio based on such factors as the differing economic risks associated with each loan category, the current financial condition of specific borrowers, the economic environment in which borrowers operate, the level of delinquent loans, the value of any collateral and, where applicable, the existence of any guarantees or indemnifications. The effects of probable decreases in expected principal cash flows on loans acquired at a discount are also considered in the establishment of the allowance for credit losses.
Assets taken in foreclosure of defaulted loans	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 included in “other assets” in the consolidated balance sheet. An in-substance repossession or foreclosure occurs and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. Upon acquisition of assets taken in satisfaction of a defaulted loan, the excess of the remaining loan balance over the asset’s estimated fair value less costs to sell is charged-off against the allowance for credit losses. Subsequent declines in value of the assets are recognized as “other costs of operations” in the consolidated statement of income.
Premises and equipment	Premises and equipment Premises and equipment are stated at cost less accumulated depreciation. Depreciation expense is computed principally using the straight-line method over the estimated useful lives of the assets.
Capitalized servicing rights	Capitalized servicing rights Capitalized servicing assets are included in “other assets” in the consolidated balance sheet. Separately recognized servicing assets are initially measured at fair value. The Company uses the amortization method to subsequently measure servicing assets. Under that method, capitalized servicing assets are charged to expense in proportion to and over the period of estimated net servicing income. To estimate the fair value of servicing rights, the Company considers market prices for similar assets and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate, and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceeds estimated fair value. Impairment is recognized through a valuation allowance.
Sales and securitizations of financial assets	Sales and securitizations of financial assets Transfers of financial assets for which the Company has surrendered control of the financial assets are accounted for as sales. Interests in a sale of financial assets that continue to be held by the Company, including servicing rights, are measured at fair value. The fair values of retained debt securities are generally determined through reference to independent pricing information. The fair values of retained servicing rights and any other retained interests are determined based on the present value of expected future cash flows associated with those interests and by reference to market prices for similar assets. Securitization structures typically require the use of special-purpose trusts that are considered variable interest entities. A variable interest entity is included in the consolidated financial statements if the Company has the power to direct the activities that most significantly impact the variable interest entity’s economic performance and has the obligation to absorb losses or the right to receive benefits of the variable interest entity that could potentially be significant to that entity.
Goodwill and core deposit and other intangible assets	Goodwill and core deposit and other intangible assets Goodwill represents the excess of the cost of an acquired entity over the fair value of the identifiable net assets acquired. Goodwill is not amortized, but rather is tested for impairment at least annually at the reporting unit level, which is either at the same level or one level below an operating segment. Other acquired intangible assets with finite lives, such as core deposit intangibles, are initially recorded at estimated fair value and are amortized over their estimated lives. Core deposit and other intangible assets are generally amortized using accelerated methods over estimated useful lives of five to ten years. The Company periodically assesses whether events or changes in circumstances indicate that the carrying amounts of core deposit and other intangible assets may be impaired.
Derivative financial instruments	Derivative financial instruments The Company accounts for derivative financial instruments at fair value. If certain conditions are met, a derivative may be specifically designated as (a) a hedge of the exposure to changes in the fair value of a recognized asset or liability or an unrecognized firm commitment, (b) a hedge of the exposure to variable cash flows of a forecasted transaction or (c) a hedge of the foreign currency exposure of a net investment in a foreign operation, an unrecognized firm commitment, an available-for-sale security, or a foreign currency denominated forecasted transaction. 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. For such agreements, amounts receivable or payable are recognized as accrued under the terms of the agreement and the net differential is recorded as an adjustment to interest income or expense of the related asset or liability. Interest rate swap agreements may be designated as either fair value hedges or cash flow hedges. In a fair value hedge, the fair values of the interest rate swap agreements and changes in the fair values of the hedged items are recorded in the Company’s consolidated balance sheet with the corresponding gain or loss recognized in current earnings. The difference between changes in the fair values of interest rate swap agreements and the hedged items represents hedge ineffectiveness and, beginning in 2018, is recorded in the same income statement line item that is used to present the earnings effect of the hedged item in the consolidated statement of income. In a cash flow hedge, the derivative’s unrealized gain or loss is initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affects earnings. Prior to 2018, hedge ineffectiveness for fair value and cash flow hedges was recorded in “other revenues from operations” in the consolidated statement of income. In addition, for cash flow hedges, the effective portion of the derivative’s unrealized gain or loss was initially recorded as a component of other comprehensive income and subsequently reclassified into earnings when the forecasted transaction affected earnings. The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in the fair value of real estate loans held for sale. Commitments to originate real estate loans to be held for sale and commitments to sell real estate loans are generally recorded in the consolidated balance sheet at estimated fair value. Derivative instruments not related to mortgage banking activities, including financial futures commitments and interest rate swap agreements, that do not satisfy the hedge accounting requirements are recorded at fair value and are generally classified as trading account assets or liabilities with resultant changes in fair value being recognized in “trading account and foreign exchange gains” in the consolidated statement of income.
Stock-based compensation	Stock-based compensation Stock-based compensation expense is recognized over the vesting period of the stock-based grant based on the estimated grant date value of the stock-based compensation, except that the recognition of compensation costs is accelerated for stock-based awards granted to retirement-eligible employees and employees who will become retirement-eligible prior to full vesting of the award because the Company’s incentive compensation plan allows for vesting at the time an employee retires. Effective January 2017, the Company adopted amended accounting guidance which requires excess tax benefits or deficiencies associated with stock-based compensation be recognized in income tax expense. Previously, tax effects resulting from changes in M&T’s share price were recorded through shareholders’ equity.
Income taxes	Income taxes Deferred tax assets and liabilities are recognized for the future tax effects attributable to differences between the financial statement value of existing assets and liabilities and their respective tax bases and carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates and laws. The Company evaluates uncertain tax positions using the two-step process required by GAAP. The first step requires a determination of whether it is more likely than not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. Under the second step, a tax position that meets the more-likely-than-not recognition threshold is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company accounts for its investments in qualified affordable housing projects using the proportional amortization method. Under that method, the Company amortizes the initial cost of the investment in proportion to the tax credits and other tax benefits received and recognizes the net investment performance in the income statement as a component of income tax expense.
Earnings per common share	Basic earnings per common share exclude dilution and are computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding (exclusive of shares represented by the unvested portion of restricted stock and restricted stock unit grants) and common shares issuable under deferred compensation arrangements during the period. Diluted earnings per common share reflect shares represented by the unvested portion of restricted stock and restricted stock unit grants and the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in earnings. Proceeds assumed to have been received on such exercise or conversion are assumed to be used to purchase shares of M&T common stock at the average market price during the period, as required by the “treasury stock method” of accounting. GAAP requires that unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) shall be considered participating securities and 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 that contain such rights and, accordingly, the Company’s earnings per common share are calculated using the two-class method.
Treasury stock	Treasury stock Repurchases of shares of M&T common stock are recorded at cost as a reduction of shareholders’ equity. Reissuances of shares of treasury stock are recorded at average cost.

Investment securities (Tables)

Investment securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Amortized Cost and Estimated Fair Value of Investment Securities	On January 1, 2018, the Company adopted amended guidance requiring equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in the consolidated statement of income. This amended guidance excludes equity method investments, investments in consolidated subsidiaries, exchange membership ownership interests, and Federal Home Loan Bank of New York and Federal Reserve Bank of New York capital stock. Upon adoption the Company reclassified $17 million, after-tax effect, from accumulated other comprehensive income to retained earnings, representing the difference between fair value and the cost basis of equity investments with readily determinable fair values at January 1, 2018. Net unrealized losses recorded as gain (loss) on bank investment securities in the consolidated statement of income during the year ended December 31, 2018 were $6 million. 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) December 31, 2018 Investment securities available for sale: U.S. Treasury and federal agencies $ 1,346,782 $ — $ 9,851 $ 1,336,931 Obligations of states and political subdivisions 1,660 4 5 1,659 Mortgage-backed securities: Government issued or guaranteed 7,383,340 15,754 182,103 7,216,991 Privately issued 24 — 2 22 Other debt securities 137,617 770 11,481 126,906 8,869,423 16,528 203,442 8,682,509 Investment securities held to maturity: U.S. Treasury and federal agencies 446,542 — 239 446,303 Obligations of states and political subdivisions 7,494 22 12 7,504 Mortgage-backed securities: Government issued or guaranteed 2,745,776 4,165 55,111 2,694,830 Privately issued 113,160 12,345 22,327 103,178 Other debt securities 3,668 — — 3,668 3,316,640 16,532 77,689 3,255,483 Total debt securities $ 12,186,063 $ 33,060 $ 281,131 $ 11,937,992 Equity and other securities: Readily marketable equity — at fair value $ 77,440 $ 17,295 $ 818 $ 93,917 Other — at cost 599,747 — — 599,747 Total equity and other securities $ 677,187 $ 17,295 $ 818 $ 693,664 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In thousands) December 31, 2017 Investment securities available for sale: U.S. Treasury and federal agencies $ 1,965,665 $ — $ 18,178 $ 1,947,487 Obligations of states and political subdivisions 2,555 36 2 2,589 Mortgage-backed securities: Government issued or guaranteed 8,755,482 59,497 98,587 8,716,392 Privately issued 28 — — 28 Other debt securities 136,905 2,402 10,475 128,832 Equity securities 78,161 23,219 424 100,956 10,938,796 85,154 127,666 10,896,284 Investment securities held to maturity: Obligations of states and political subdivisions 24,562 109 49 24,622 Mortgage-backed securities: Government issued or guaranteed 3,187,953 27,236 13,746 3,201,443 Privately issued 135,688 2,574 27,575 110,687 Other debt securities 5,010 — — 5,010 3,353,213 29,919 41,370 3,341,762 Other securities — at cost 415,028 — — 415,028 Total $ 14,707,037 $ 115,073 $ 169,036 $ 14,653,074
Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities	As of December 31, 2018, the latest available investment ratings of all obligations of states and political subdivisions, privately issued mortgage-backed securities and other debt securities were: Average Credit Rating of Fair Value Amount Amortized Cost Estimated Fair Value A or Better BBB BB B or Less Not Rated (In thousands) Obligations of states and political subdivisions $ 9,154 $ 9,163 $ 8,637 $ 526 $ — $ — $ — Privately issued mortgage-backed securities 113,184 103,200 17,055 16 — 34,180 51,949 Other debt securities 141,285 130,574 4,818 59,814 31,053 — 34,889 Total $ 263,623 $ 242,937 $ 30,510 $ 60,356 $ 31,053 $ 34,180 $ 86,838
Amortized Cost and Estimated Fair Value of Collateralized Mortgage Obligations	The amortized cost and estimated fair value of collateralized mortgage obligations included in mortgage-backed securities were as follows: December 31 2018 2017 (In thousands) Collateralized mortgage obligations: Amortized cost $ 115,171 $ 138,527 Estimated fair value 105,155 113,516
Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity	At December 31, 2018, 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 $ 1,344,408 1,334,695 Due after one year through five years 9,555 9,319 Due after five years through ten years 102,081 95,653 Due after ten years 30,015 25,829 1,486,059 1,465,496 Mortgage-backed securities available for sale 7,383,364 7,217,013 $ 8,869,423 8,682,509 Debt securities held to maturity: Due in one year or less $ 449,468 449,237 Due after one year through five years 4,568 4,570 Due after ten years 3,668 3,668 457,704 457,475 Mortgage-backed securities held to maturity 2,858,936 2,798,008 $ 3,316,640 3,255,483
Investment Securities in Continuous Unrealized Loss Position	A summary of investment securities that as of December 31, 2018 and 2017 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) December 31, 2018 Investment securities available for sale: U.S. Treasury and federal agencies $ 273 (2 ) 1,335,559 (9,849 ) Obligations of states and political subdivisions 629 (5 ) — — Mortgage-backed securities: Government issued or guaranteed 405,558 (2,892 ) 5,646,773 (179,211 ) Privately issued 22 (2 ) — — Other debt securities 53,478 (2,187 ) 66,014 (9,294 ) 459,960 (5,088 ) 7,048,346 (198,354 ) Investment securities held to maturity: U.S. Treasury and federal agencies 446,303 (239 ) — — Obligations of states and political subdivisions — — 3,126 (12 ) Mortgage-backed securities: Government issued or guaranteed 179,354 (989 ) 2,082,723 (54,122 ) Privately issued — — 51,943 (22,327 ) 625,657 (1,228 ) 2,137,792 (76,461 ) Total $ 1,085,617 (6,316 ) 9,186,138 (274,815 ) December 31, 2017 Investment securities available for sale: U.S. Treasury and federal agencies $ 278,132 (1,761 ) 1,669,355 (16,417 ) Obligations of states and political subdivisions — — 474 (2 ) Mortgage-backed securities: Government issued or guaranteed 2,106,142 (13,695 ) 3,138,841 (84,892 ) Other debt securities 3,067 (26 ) 61,159 (10,449 ) Equity securities (a) — — 18,162 (424 ) 2,387,341 (15,482 ) 4,887,991 (112,184 ) Investment securities held to maturity: Obligations of states and political subdivisions 2,954 (4 ) 6,110 (45 ) Mortgage-backed securities: Government issued or guaranteed 1,331,759 (7,036 ) 265,695 (6,710 ) Privately issued 5,061 (1,216 ) 55,255 (26,359 ) 1,339,774 (8,256 ) 327,060 (33,114 ) Total $ 3,727,115 (23,738 ) 5,215,051 (145,298 ) (a) Beginning January 1, 2018, equity securities with readily determinable fair values are required to be measured at fair value with changes in fair value recognized in the consolidated statement of income. As a result, subsequent to December 31, 2017 disclosing the time period for which these equity securities had been in a continuous unrealized loss position is no longer relevant.

Loans and leases (Tables)

Loans and leases (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Total Loans and Leases Outstanding	Total loans and leases outstanding were comprised of the following: December 31 2018 2017 (In thousands) Loans Commercial, financial, etc. $ 21,730,012 $ 20,474,696 Real estate: Residential 17,150,658 19,619,259 Commercial 25,666,200 25,345,779 Construction 8,823,635 8,125,925 Consumer 13,956,086 13,251,665 Total loans 87,326,591 86,817,324 Leases Commercial 1,406,901 1,425,562 Total loans and leases 88,733,492 88,242,886 Less: unearned discount (267,015 ) (253,903 ) Total loans and leases, net of unearned discount $ 88,466,477 $ 87,988,983
Summary of Current, Past Due and Nonaccrual Loans	A summary of current, past due and nonaccrual loans as of December 31, 2018 and 2017 follows: Current 30-89 Days Past Due Accruing Loans Due 90 Days or More (a) Accruing Loans Acquired a Discount Past Due 90 days or More (b) Purchased Impaired (c) Nonaccrual Total (In thousands) December 31, 2018 Commercial, financial, leasing, etc. $ 22,701,020 39,798 2,567 168 — 234,423 $ 22,977,976 Real estate: Commercial 25,250,983 134,474 11,457 10 9,769 203,672 25,610,365 Residential builder and developer 1,665,178 20,333 — — — 4,798 1,690,309 Other commercial construction 6,982,077 43,615 14,344 — 641 22,205 7,062,882 Residential 13,591,790 404,808 189,682 6,650 203,044 233,352 14,629,326 Residential — limited documentation 2,278,040 72,544 — — 89,851 84,685 2,525,120 Consumer: Home equity lines and loans 4,758,513 25,416 — 5,033 — 71,292 4,860,254 Recreational finance 4,085,781 29,947 — 235 — 11,199 4,127,162 Automobile 3,555,757 79,804 — — — 23,359 3,658,920 Other 1,271,811 15,598 4,477 27,654 — 4,623 1,324,163 Total $ 86,140,950 866,337 222,527 39,750 303,305 893,608 $ 88,466,477 December 31, 2017 Commercial, financial, leasing, etc. $ 21,332,234 167,756 1,322 327 21 240,991 $ 21,742,651 Real estate: Commercial 24,910,381 166,305 4,444 6,016 16,815 184,982 25,288,943 Residential builder and developer 1,618,973 5,159 — — 1,135 6,451 1,631,718 Other commercial construction 6,407,451 23,467 — — 4,706 10,088 6,445,712 Residential 15,376,759 474,372 233,437 7,582 282,102 235,834 16,610,086 Residential — limited documentation 2,718,019 83,898 — — 105,236 96,105 3,003,258 Consumer: Home equity lines and loans 5,171,345 38,546 — 9,391 — 74,500 5,293,782 Recreational finance 3,229,570 23,802 — 546 — 6,509 3,260,427 Automobile 3,441,371 78,511 — — — 23,781 3,543,663 Other 1,119,501 17,127 5,202 23,556 — 3,357 1,168,743 Total $ 85,325,604 1,078,943 244,405 47,418 410,015 882,598 $ 87,988,983 (a) (b) (c)
Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet	The outstanding principal balance and the carrying amount of loans acquired at a discount that were recorded at fair value at the acquisition date and included in the consolidated balance sheet were as follows: December 31 2018 2017 (In thousands) Outstanding principal balance $ 1,016,785 $ 1,394,188 Carrying amount: Commercial, financial, leasing, etc. 27,073 31,105 Commercial real estate 135,047 228,054 Residential real estate 473,511 620,827 Consumer 91,860 123,413 $ 727,491 $ 1,003,399
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 years ended December 31, 2018, 2017 and 2016 follows: For the Year Ended December 31, 2018 2017 2016 Purchased Impaired Other Acquired Purchased Impaired Other Acquired Purchased Impaired Other Acquired (In thousands) Balance at beginning of period $ 157,918 $ 133,162 $ 154,233 $ 201,153 $ 184,618 $ 296,434 Interest income (37,819 ) (63,856 ) (47,452 ) (82,605 ) (52,769 ) (123,044 ) Reclassifications from nonaccretable balance 27,111 22,849 51,137 16,437 22,384 22,677 Other (a) — 4,752 — (1,823 ) — 5,086 Balance at end of period $ 147,210 $ 96,907 $ 157,918 $ 133,162 $ 154,233 $ 201,153 (a) Other changes in expected cash flows including changes in interest rates and prepayment assumptions.
Loan Modification Activities that were Considered Troubled Debt Restructurings	The tables that follow summarize the Company’s loan modification activities that were considered troubled debt restructurings for the years ended December 31, 2018, 2017 and 2016: Post-modification (a) Year Ended December 31, 2018 Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total (Dollars in thousands) Commercial, financial, leasing, etc. 203 $ 102,445 $ 50,490 $ 803 $ 6,210 $ 45,411 $ 102,914 Real estate: Commercial 83 30,217 16,870 175 4,686 9,000 30,731 Other commercial construction 1 752 746 — — — 746 Residential 134 34,798 19,962 — — 18,110 38,072 Residential — limited documentation 9 1,887 827 — — 1,423 2,250 Consumer: Home equity lines and loans 47 3,952 224 — — 3,755 3,979 Recreational finance 7 202 202 — — — 202 Automobile 73 1,330 1,318 — — 12 1,330 Total 557 $ 175,583 $ 90,639 $ 978 $ 10,896 $ 77,711 $ 180,224 Year Ended December 31, 2017 Commercial, financial, leasing, etc. 217 $ 111,036 $ 25,051 $ — $ 6,459 $ 57,153 $ 88,663 Real estate: Commercial 83 44,924 17,039 — 868 22,975 40,882 Residential builder and developer 3 12,291 — — — 10,879 10,879 Other commercial construction 2 168 168 — — — 168 Residential 141 31,827 16,633 — — 17,974 34,607 Residential — limited documentation 20 4,230 911 — — 3,661 4,572 Consumer: Home equity lines and loans 110 10,049 1,137 — 491 8,585 10,213 Recreational finance 9 160 160 — — — 160 Automobile 69 1,378 1,203 — — 175 1,378 Total 654 $ 216,063 $ 62,302 $ — $ 7,818 $ 121,402 $ 191,522 Post-modification (a) Year Ended December 31, 2016 Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total (Dollars in thousands) Commercial, financial, leasing, etc. 164 $ 154,093 $ 102,446 $ — $ — $ 41,673 $ 144,119 Real estate: Commercial 81 44,870 23,558 — 4,576 15,603 43,737 Residential builder and developer 6 39,660 22,958 — — 15,123 38,081 Other commercial construction 3 3,113 250 — — 2,782 3,032 Residential 119 20,057 11,771 — — 9,367 21,138 Residential — limited documentation 21 3,560 1,047 — — 2,917 3,964 Consumer: Home equity lines and loans 103 11,870 761 — — 11,110 11,871 Recreational finance 10 318 270 — 20 28 318 Automobile 163 1,264 1,124 — 55 85 1,264 Other 69 891 698 — 25 168 891 Total 739 $ 279,696 $ 164,883 $ — $ 4,676 $ 98,856 $ 268,415 (a)
Summary of Lease Financing Receivables	A summary of lease financing receivables follows: December 31 2018 2017 (In thousands) Commercial leases: Direct financings: Lease payments receivable $ 1,155,464 $ 1,159,584 Estimated residual value of leased assets 85,169 89,666 Unearned income (110,458 ) (110,261 ) Investment in direct financings 1,130,175 1,138,989 Leveraged leases: Lease payments receivable 85,007 87,821 Estimated residual value of leased assets 81,261 88,491 Unearned income (33,717 ) (35,792 ) Investment in leveraged leases 132,551 140,520 Total investment in leases $ 1,262,726 $ 1,279,509 Deferred taxes payable arising from leveraged leases $ 74,995 $ 81,359
Minimum Future Lease Payments to be Received from Lease Financings	At December 31, 2018, the minimum future lease payments to be received from lease financings were as follows: (In thousands) Year ending December 31: 2019 $ 326,898 2020 310,255 2021 224,150 2022 141,244 2023 88,182 Later years 149,742 $ 1,240,471

Allowance for credit losses (Ta

Allowance for credit losses (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Changes in Allowance for Credit Losses	Changes in the allowance for credit losses for the years ended December 31, 2018, 2017 and 2016 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) 2018 Beginning balance $ 328,599 374,085 65,405 170,809 78,300 $ 1,017,198 Provision for credit losses 33,967 (41,181 ) 12,401 127,068 (255 ) 132,000 Net charge-offs Charge-offs (60,414 ) (12,286 ) (15,345 ) (143,196 ) — (231,241 ) Recoveries 27,903 21,037 6,664 45,883 — 101,487 Net (charge-offs) recoveries (32,511 ) 8,751 (8,681 ) (97,313 ) — (129,754 ) Ending balance $ 330,055 341,655 69,125 200,564 78,045 $ 1,019,444 2017 Beginning balance $ 330,833 362,719 61,127 156,288 78,030 $ 988,997 Provision for credit losses 41,511 6,715 16,094 103,410 270 168,000 Net charge-offs Charge-offs (64,941 ) (7,931 ) (20,799 ) (130,927 ) — (224,598 ) Recoveries 21,196 12,582 8,983 42,038 — 84,799 Net (charge-offs) recoveries (43,745 ) 4,651 (11,816 ) (88,889 ) — (139,799 ) Ending balance $ 328,599 374,085 65,405 170,809 78,300 $ 1,017,198 2016 Beginning balance $ 300,404 326,831 72,238 178,320 78,199 $ 955,992 Provision for credit losses 59,506 33,627 6,902 90,134 (169 ) 190,000 Net charge-offs Charge-offs (59,244 ) (4,805 ) (26,133 ) (141,073 ) — (231,255 ) Recoveries 30,167 7,066 8,120 28,907 — 74,260 Net (charge-offs) recoveries (29,077 ) 2,261 (18,013 ) (112,166 ) — (156,995 ) Ending balance $ 330,833 362,719 61,127 156,288 78,030 $ 988,997
Impaired Loans and Leases	The following tables provide information with respect to loans and leases that were considered impaired as of December 31, 2018 and 2017 and for the years ended December 31, 2018, 2017 and 2016. December 31, 2018 December 31, 2017 Recorded Investment Unpaid Principal Balance Related Allowance Recorded Investment Unpaid Principal Balance Related Allowance (In thousands) With an allowance recorded: Commercial, financial, leasing, etc. $ 153,478 175,549 46,034 177,250 194,257 45,488 Real estate: Commercial 110,253 125,117 11,937 67,199 75,084 9,140 Residential builder and developer 5,981 6,557 462 5,320 5,641 308 Other commercial construction 10,563 11,113 640 4,817 20,357 647 Residential 124,974 147,817 5,402 101,724 122,602 4,000 Residential — limited documentation 74,156 90,066 3,000 77,277 92,439 3,900 Consumer: Home equity lines and loans 47,982 53,248 9,135 48,847 53,914 8,812 Recreational finance 6,138 9,163 1,261 1,496 3,680 299 Automobile 3,527 3,599 729 13,498 15,737 2,811 Other 5,203 8,380 1,046 1,724 2,192 357 542,255 630,609 79,646 499,152 585,903 75,762 With no related allowance recorded: Commercial, financial, leasing, etc. 105,507 136,128 — 89,126 115,327 — Real estate: Commercial 113,376 124,657 — 138,356 149,716 — Residential builder and developer 2,593 2,602 — 5,057 5,296 — Other commercial construction 11,710 11,880 — 5,456 9,130 — Residential 15,379 20,496 — 13,574 18,980 — Residential — limited documentation 5,631 9,796 — 9,588 16,138 — 254,196 305,559 — 261,157 314,587 — Total: Commercial, financial, leasing, etc. 258,985 311,677 46,034 266,376 309,584 45,488 Real estate: Commercial 223,629 249,774 11,937 205,555 224,800 9,140 Residential builder and developer 8,574 9,159 462 10,377 10,937 308 Other commercial construction 22,273 22,993 640 10,273 29,487 647 Residential 140,353 168,313 5,402 115,298 141,582 4,000 Residential — limited documentation 79,787 99,862 3,000 86,865 108,577 3,900 Consumer: Home equity lines and loans 47,982 53,248 9,135 48,847 53,914 8,812 Recreational finance 6,138 9,163 1,261 1,496 3,680 299 Automobile 3,527 3,599 729 13,498 15,737 2,811 Other 5,203 8,380 1,046 1,724 2,192 357 Total $ 796,451 936,168 79,646 760,309 900,490 75,762
Interest Income Recognized on Impaired Loans	Year Ended December 31, 2018 Year Ended December 31, 2017 Interest Income Recognized Interest Income Recognized Average Recorded Investment Total Cash Basis Average Recorded Investment Total Cash Basis (In thousands) Commercial, financial, leasing, etc. $ 263,018 7,873 7,873 240,157 3,894 3,894 Real estate: Commercial 194,451 10,880 10,880 207,616 4,497 4,497 Residential builder and developer 8,699 1,779 1,779 16,209 6,419 6,419 Other commercial construction 11,467 3,474 3,474 15,142 1,001 1,001 Residential 129,593 8,386 3,456 110,646 7,177 3,406 Residential — limited documentation 82,854 6,118 1,723 93,097 5,981 1,607 Consumer: Home equity lines and loans 48,591 1,698 289 47,323 1,681 400 Recreational finance 1,849 333 9 1,041 212 9 Automobile 9,262 690 69 15,045 1,025 81 Other 4,413 230 13 2,322 96 2 Total $ 754,197 41,461 29,565 748,598 31,983 21,316 Year Ended December 31, 2016 Interest Income Recognized Average Recorded Investment Total Cash Basis (In thousands) Commercial, financial, leasing, etc. $ 277,647 8,342 8,342 Real estate: Commercial 175,877 4,878 4,878 Residential builder and developer 29,237 2,300 2,300 Other commercial construction 19,697 644 644 Residential 98,394 6,227 3,154 Residential — 103,060 5,999 1,975 Consumer: Home equity lines and loans 36,493 1,325 410 Recreational finance 2,549 147 49 Automobile 19,636 1,242 99 Other 6,669 293 34 Total $ 769,259 31,397 21,885
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, Residential Other Financial, Builder and Commercial Leasing, etc. Commercial Developer Construction (In thousands) December 31, 2018 Pass $ 21,693,705 24,539,706 1,546,002 6,890,562 Criticized accrual 1,049,848 866,987 139,509 150,115 Criticized nonaccrual 234,423 203,672 4,798 22,205 Total $ 22,977,976 25,610,365 1,690,309 7,062,882 December 31, 2017 Pass $ 20,490,486 24,380,184 1,485,148 6,270,812 Criticized accrual 1,011,174 723,777 140,119 164,812 Criticized nonaccrual 240,991 184,982 6,451 10,088 Total $ 21,742,651 25,288,943 1,631,718 6,445,712
Allocation of Allowance for Credit Losses on Basis of Company's Impairment Methodology	The allocation of the allowance for credit losses summarized on the basis of the Company’s impairment methodology was as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Total (In thousands) December 31, 2018 Individually evaluated for impairment $ 46,034 13,039 8,402 12,171 $ 79,646 Collectively evaluated for impairment 284,021 328,616 48,326 188,393 849,356 Purchased impaired — — 12,397 — 12,397 Allocated $ 330,055 341,655 69,125 200,564 $ 941,399 Unallocated 78,045 Total $ 1,019,444 December 31, 2017 Individually evaluated for impairment $ 45,488 10,095 7,900 12,279 $ 75,762 Collectively evaluated for impairment 283,111 363,990 47,645 158,530 853,276 Purchased impaired — — 9,860 — 9,860 Allocated $ 328,599 374,085 65,405 170,809 938,898 Unallocated 78,300 Total $ 1,017,198
Recorded Investment in Loans and Leases on Basis of Company's Impairment Methodology	The recorded investment in loans and leases summarized on the basis of the Company’s impairment methodology was as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Total (In thousands) December 31, 2018 Individually evaluated for impairment $ 258,985 254,476 220,140 62,850 $ 796,451 Collectively evaluated for impairment 22,718,991 34,098,670 16,641,411 13,907,649 87,366,721 Purchased impaired — 10,410 292,895 — 303,305 Total $ 22,977,976 34,363,556 17,154,446 13,970,499 $ 88,466,477 December 31, 2017 Individually evaluated for impairment $ 266,376 226,205 202,163 65,565 $ 760,309 Collectively evaluated for impairment 21,476,254 33,117,512 19,023,843 13,201,050 86,818,659 Purchased impaired 21 22,656 387,338 — 410,015 Total $ 21,742,651 33,366,373 19,613,344 13,266,615 $ 87,988,983

Premises and equipment (Tables)

Premises and equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Summary of Premises and Equipment	The detail of premises and equipment was as follows: December 31 2018 2017 (In thousands) Land $ 97,082 $ 98,077 Buildings 465,482 454,610 Leasehold improvements 240,731 239,956 Furniture and equipment — owned 669,782 676,665 Furniture and equipment — capital leases 18,582 18,039 1,491,659 1,487,347 Less: accumulated depreciation and amortization Owned assets 835,218 830,832 Capital leases 9,033 10,064 844,251 840,896 Premises and equipment, net $ 647,408 $ 646,451

Capitalized servicing assets (T

Capitalized servicing assets (Tables)	12 Months Ended
	Dec. 31, 2018
Transfers And Servicing [Abstract]
Servicing Asset at Amortized Cost	Changes in capitalized servicing assets were as follows: Residential Mortgage Loans Commercial Mortgage Loans For the Year Ended December 31, 2018 2017 2016 2018 2017 2016 (In thousands) Beginning balance $ 114,978 $ 117,351 $ 118,303 $ 114,076 $ 103,764 $ 83,692 Originations 28,985 28,792 28,618 26,298 34,620 40,117 Purchases 454 699 638 — — — Amortization (23,908 ) (31,864 ) (30,208 ) (25,711 ) (24,308 ) (20,045 ) 120,509 114,978 117,351 114,663 114,076 103,764 Valuation allowance — — — — — — Ending balance, net $ 120,509 $ 114,978 $ 117,351 $ 114,663 $ 114,076 $ 103,764
Economic Assumptions Used to Determine Fair Value of Capitalized Servicing Rights and Sensitivity of Value to Changes in Assumptions	Residential Commercial (Dollars in thousands) Weighted-average prepayment speeds 10.99 % Impact on fair value of 10% adverse change $ (9,327 ) Impact on fair value of 20% adverse change (17,925 ) Weighted-average OAS 9.63 % Impact on fair value of 10% adverse change $ (6,758 ) Impact on fair value of 20% adverse change (13,135 ) Weighted-average discount rate 18.00 % Impact on fair value of 10% adverse change $ (6,029 ) Impact on fair value of 20% adverse change (11,626 )

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	Total amortizing intangible assets were comprised of the following: Gross Carrying Amount Accumulated Amortization Net Carrying Amount (In thousands) December 31, 2018 Core deposit $ 887,459 $ 843,572 $ 43,887 Other 182,568 179,388 3,180 Total $ 1,070,027 $ 1,022,960 $ 47,067 December 31, 2017 Core deposit $ 887,459 $ 820,110 $ 67,349 Other 182,568 178,328 4,240 Total $ 1,070,027 $ 998,438 $ 71,589
Estimated Amortization Expense in Future Years	Estimated amortization expense in future years for such intangible assets is as follows: (In thousands) Year ending December 31: 2019 $ 19,086 2020 14,383 2021 9,681 2022 3,917 $ 47,067
Summary of Goodwill Assigned to Reportable Segments for Purposes of Testing for Impairment	A summary of goodwill assigned to each of the Company’s reportable segments as of December 31, 2018 and 2017 for purposes of testing for impairment is as follows: (In thousands) Business Banking $ 864,366 Commercial Banking 1,401,873 Commercial Real Estate 654,389 Discretionary Portfolio — Residential Mortgage Banking — Retail Banking 1,309,191 All Other 363,293 Total $ 4,593,112

Borrowings (Tables)

Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Amounts and Interest Rates of Short-term Borrowings	The amounts and interest rates of short-term borrowings were as follows: Federal Funds Purchased and Repurchase Agreements Other Short-term Borrowings Total (Dollars in thousands) At December 31, 2018 Amount outstanding $ 198,378 $ 4,200,000 $ 4,398,378 Weighted-average interest rate 1.68 % 2.63 % 2.58 % For the year ended December 31, 2018 Highest amount at a month-end $ 2,654,416 $ 4,200,000 Daily-average amount outstanding 261,200 69,465 $ 330,665 Weighted-average interest rate 1.49 % 2.16 % 1.63 % At December 31, 2017 Amount outstanding $ 175,099 $ — $ 175,099 Weighted-average interest rate 0.92 % — 0.92 % For the year ended December 31, 2017 Highest amount at a month-end $ 204,977 $ 1,500,000 Daily-average amount outstanding 188,459 16,164 $ 204,623 Weighted-average interest rate 0.69 % 1.27 % 0.74 % At December 31, 2016 Amount outstanding $ 163,442 $ — $ 163,442 Weighted-average interest rate 0.32 % — 0.32 % For the year ended December 31, 2016 Highest amount at a month-end $ 225,940 $ 1,974,013 Daily-average amount outstanding 203,853 689,969 $ 893,822 Weighted-average interest rate 0.28 % 0.44 % 0.41 %
Lines of Credit Under Formal Agreements	At December 31, 2018, M&T Bank had lines of credit under formal agreements as follows: (In thousands) Outstanding borrowings $ 4,776,510 Unused 27,637,030
Long-term Borrowings	Long-term borrowings were as follows: December 31, 2018 2017 (In thousands) Senior notes of M&T Bank Corporation: Variable rate due 2023 $ 249,688 $ — 3.55% due 2023 506,021 — Senior notes of M&T Bank: Variable rate due 2021 349,794 — Variable rate due 2022 249,658 249,558 1.45% due 2018 — 499,907 2.25% due 2019 645,801 644,977 2.30% due 2019 — 746,919 2.05% due 2020 737,793 739,961 2.10% due 2020 741,965 743,788 2.625% due 2021 646,301 — 2.50% due 2022 634,525 638,872 2.90% due 2025 749,488 749,404 Advances from FHLB: Fixed rates 576,446 576,876 Agreements to repurchase securities 409,154 421,771 Subordinated notes of Wilmington Trust Corporation (a wholly owned subsidiary of M&T): 8.50% due 2018 — 200,000 Subordinated notes of M&T Bank: Variable rate due 2020 409,361 409,361 Variable rate due 2021 500,000 500,000 3.40% due 2027 481,692 491,176 Junior subordinated debentures of M&T associated with preferred capital securities: Fixed rates: BSB Capital Trust I — 8.125%, due 2028 15,705 15,682 Provident Trust I — 8.29%, due 2028 27,489 26,847 Southern Financial Statutory Trust I — 10.60%, due 2030 6,713 6,664 Variable rates: First Maryland Capital I — due 2027 147,333 146,794 First Maryland Capital II — due 2027 149,280 148,617 Allfirst Asset Trust — due 2029 96,785 96,640 BSB Capital Trust III — due 2033 15,464 15,464 Provident Statutory Trust III — due 2033 55,143 54,466 Southern Financial Capital Trust III — due 2033 8,141 8,051 Other 35,174 9,635 $ 8,444,914 $ 8,141,430
Maturity of Long-term Borrowings	Long-term borrowings at December 31, 2018 mature as follows: (In thousands) Year ending December 31: 2019 $ 1,525,057 2020 1,994,450 2021 1,522,796 2022 891,731 2023 755,710 Later years 1,755,170 $ 8,444,914

Shareholders_ equity (Tables)

Shareholders’ equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Issued and Outstanding Preferred Stock	Issued and outstanding preferred stock of M&T as of December 31, 2018 and 2017 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 E (b) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share 350,000 $ 350,000 Series F (c) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share 50,000 $ 500,000 (a) (b) (c)

Revenue from contracts with c_2

Revenue from contracts with customers (Tables)	12 Months Ended
	Dec. 31, 2018
ASU 2014-09 [Member]
Summary of Sources of Company’s Noninterest Income that are Subject to the Amended Guidance	The following table summarizes sources of the Company’s noninterest income during 2018 that are subject to the amended guidance. Year Ended December 31, 2018 Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 62,323 96,407 9,870 — 10 254,590 6,137 $ 429,337 Trust income 9 917 — — — — 536,659 537,585 Brokerage services income — — — — — — 51,069 51,069 Other revenues from operations: Merchant discount and credit card fees 34,557 52,051 2,213 — — 14,924 2,208 105,953 Other — 8,796 7,259 1,738 3,814 38,529 30,233 90,369 $ 96,889 158,171 19,342 1,738 3,824 308,043 626,306 $ 1,214,313

Stock-based compensation plans

Stock-based compensation plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Restricted Stock and Restricted Stock Unit Activity	A summary of restricted stock and restricted stock unit activity follows: Restricted Stock Units Outstanding Weighted- Average Grant Price Restricted Stock Outstanding Weighted- Average Grant Price Unvested at January 1, 2018 482,557 $ 133.05 373,744 $ 135.41 Granted 348,512 189.52 — — Vested (265,027 ) 127.39 (182,905 ) 126.60 Cancelled (9,167 ) 194.45 (11,400 ) 138.52 Unvested at December 31, 2018 556,875 $ 170.07 179,439 $ 144.18
Summary of Stock Option Activity	A summary of stock option activity follows: Weighted-Average Stock Options Outstanding Exercise Price Life (In Years) Aggregate Intrinsic Value (In thousands) Outstanding at January 1, 2018 665,412 $ 152.23 Granted 116,852 190.78 Exercised (535,724 ) 154.91 Expired (25,949 ) 221.81 Outstanding at December 31, 2018 220,591 $ 157.98 5.3 $ 2,739 Exercisable at December 31, 2018 103,725 $ 121.11 5.3 $ 2,737

Pension plans and other postr_2

Pension plans and other postretirement benefits (Tables)	12 Months Ended
	Dec. 31, 2018
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: Year Ended December 31 2018 2017 2016 (In thousands) Service cost $ 20,346 $ 20,193 $ 25,037 Interest cost on benefit obligation 74,704 79,270 83,410 Expected return on plan assets (123,127 ) (108,524 ) (108,473 ) Amortization of prior service cost (credit) 557 557 (3,228 ) Recognized net actuarial loss 43,793 29,263 30,145 Net periodic pension expense $ 16,273 $ 20,759 $ 26,891 Net other postretirement benefits expense for defined benefit plans consisted of the following: Year Ended December 31 2018 2017 2016 (In thousands) Service cost $ 938 $ 1,172 $ 1,595 Interest cost on benefit obligation 2,293 3,716 4,971 Amortization of prior service credit (4,729 ) (1,359 ) (1,359 ) Recognized net actuarial (gain) loss (826 ) (988 ) 60 Net other postretirement benefits expense $ (2,324 ) $ 2,541 $ 5,267
Data Relating to Funding Position of Defined Benefit Plans	Data relating to the funding position of the defined benefit plans were as follows: Pension Benefits Other Postretirement Benefits 2018 2017 2018 2017 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 2,188,736 $ 2,007,158 $ 68,637 $ 109,922 Service cost 20,346 20,193 938 1,172 Interest cost 74,704 79,270 2,293 3,716 Plan participants’ contributions — — 2,974 2,929 Amendments and curtailments — — — (30,088 ) Actuarial (gain) loss (228,897 ) 172,180 (4,758 ) (8,511 ) Medicare Part D reimbursement — — 508 630 Benefits paid (105,276 ) (90,065 ) (10,601 ) (11,133 ) Benefit obligation at end of year 1,949,613 2,188,736 59,991 68,637 Change in plan assets: Fair value of plan assets at beginning of year 2,014,891 1,642,131 — — Actual return on plan assets (90,657 ) 251,381 — — Employer contributions 14,875 211,444 7,119 7,574 Plan participants’ contributions — — 2,974 2,929 Medicare Part D reimbursement — — 508 630 Benefits paid (105,276 ) (90,065 ) (10,601 ) (11,133 ) Fair value of plan assets at end of year 1,833,833 2,014,891 — — Funded status $ (115,780 ) $ (173,845 ) $ (59,991 ) $ (68,637 ) Accrued liabilities recognized in the consolidated balance sheet $ (115,780 ) $ (173,845 ) $ (59,991 ) $ (68,637 ) Amounts recognized in accumulated other comprehensive income (“AOCI”) were: Net loss (gain) $ 401,716 $ 460,622 $ (17,868 ) $ (13,936 ) Net prior service cost (credit) 2,391 2,948 (31,737 ) (36,466 ) Pre-tax adjustment to AOCI 404,107 463,570 (49,605 ) (50,402 ) Taxes (106,240 ) (121,873 ) 13,041 13,251 Net adjustment to AOCI $ 297,867 $ 341,697 $ (36,564 ) $ (37,151 )
Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income	The table below reflects the changes in plan assets and benefit obligations recognized in other comprehensive income related to the Company’s postretirement benefit plans. Pension Plans Other Postretirement Benefit Plans Total (In thousands) 2018 Net loss (gain) $ (15,113 ) $ (4,758 ) $ (19,871 ) Amortization of prior service (cost) credit (557 ) 4,729 4,172 Amortization of actuarial (loss) gain (43,793 ) 826 (42,967 ) Total recognized in other comprehensive income, pre-tax $ (59,463 ) $ 797 $ (58,666 ) 2017 Net loss (gain) $ 29,323 $ (8,511 ) $ 20,812 Amendments and curtailments — (30,088 ) (30,088 ) Amortization of prior service (cost) credit (557 ) 1,359 802 Amortization of actuarial (loss) gain (29,263 ) 988 (28,275 ) Total recognized in other comprehensive income, pre-tax $ (497 ) $ (36,252 ) $ (36,749 )
Amortization of Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Expense	The following table reflects the amortization of amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit expense during 2019: Pension Plans Other Postretirement Benefit Plans (In thousands) Amortization of net prior service cost (credit) $ 557 $ (4,730 ) Amortization of net loss (gain) 17,755 1,168
Assumed Weighted-Average Rates Used to Determine Benefit Obligations	The assumed weighted-average rates used to determine benefit obligations at December 31 were: Pension Benefits Other Postretirement Benefits 2018 2017 2018 2017 Discount rate 4.25 % 3.50 % 4.25 % 3.50 % Rate of increase in future compensation levels 4.31 % 4.33 % — —
Assumed Weighted-Average Rates Used to Determine Net Benefit Expense	The assumed weighted-average rates used to determine net benefit expense for the years ended December 31 were: Pension Benefits Other Postretirement Benefits 2018 2017 2016 2018 2017 2016 Discount rate 3.50 % 4.00 % 4.25 % 3.50 % 4.00 % 4.25 % Long-term rate of return on plan assets 6.50 % 6.50 % 6.50 % — — — Rate of increase in future compensation levels 4.33 % 4.39 % 4.37 % — — —
Effects on One-Percentage Point Change in Assumed Health Care Cost Trend Rates	A one-percentage point change in assumed health care cost trend rates would have had the following effects: +1% -1% (In thousands) Increase (decrease) in: Service and interest cost $ 55 $ (50 ) Accumulated postretirement benefit obligation 1,204 (1,094 )
Fair Values of Company's Pension Plan Assets by Asset Category	The fair values of the Company’s pension plan assets at December 31, 2018 and 2017, by asset category, were as follows: Fair Value Measurement of Plan Assets At December 31, 2018 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (In thousands) Asset category: Money-market investments $ 23,049 $ 10,794 $ 12,255 $ — Equity securities: M&T 125,299 125,299 — — Domestic(a) 191,640 191,640 — — International(b) 7,752 7,752 — — Mutual funds: Domestic(a) 216,523 216,523 — — International(b) 316,923 316,923 — — 858,137 858,137 — — Debt securities: Corporate(c) 103,672 — 103,672 — Government 182,034 — 182,034 — International 2,140 — 2,140 — Mutual funds: Domestic(d) 280,902 280,902 — — International 20,661 20,661 — — 589,409 301,563 287,846 — Other: Diversified mutual fund 74,446 74,446 — — Real estate partnerships 11,807 2,791 — 9,016 Private equity 63,699 — — 63,699 Hedge funds 200,811 125,309 — 75,502 Guaranteed deposit fund 10,415 — — 10,415 361,178 202,546 — 158,632 Total(e) $ 1,831,773 $ 1,373,040 $ 300,101 $ 158,632 Fair Value Measurement of Plan Assets At December 31, 2017 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) (In thousands) Asset category: Money-market investments $ 117,648 $ 62,706 $ 54,942 $ — Equity securities: M&T 154,818 154,818 — — Domestic(a) 240,763 240,763 — — International(b) 13,349 13,349 — — Mutual funds: Domestic(a) 205,509 205,509 — — International(b) 405,200 405,200 — — 1,019,639 1,019,639 — — Debt securities: Corporate(c) 89,751 — 89,751 — Government 235,984 — 235,984 — International 2,176 — 2,176 — Mutual funds: Domestic(d) 243,456 243,456 — — 571,367 243,456 327,911 — Other: Diversified mutual fund 80,227 80,227 — — Real estate partnerships 3,747 842 — 2,905 Private equity 31,484 — — 31,484 Hedge funds 178,080 125,966 — 52,114 Guaranteed deposit fund 10,925 — — 10,925 304,463 207,035 — 97,428 Total(e) $ 2,013,117 $ 1,532,836 $ 382,853 $ 97,428 (a) (b) (c) (d) (e)
Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis	The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2018 were as follows: Balance – January 1, 2018 Purchases (Sales) Total Realized/ Unrealized Gains (Losses) Balance – December 31, 2018 (In thousands) Other Real estate partnerships $ 2,905 $ 4,717 $ 1,394 $ 9,016 Private equity 31,484 30,396 1,819 63,699 Hedge funds 52,114 19,971 3,417 75,502 Guaranteed deposit fund 10,925 — (510 ) 10,415 Total $ 97,428 $ 55,084 $ 6,120 $ 158,632
Defined Benefit Plan Estimated Future Benefit Payments	Estimated benefits expected to be paid in future years related to the Company’s defined benefit pension and other postretirement benefits plans are as follows: Pension Benefits Other Postretirement Benefits (In thousands) Year ending December 31: 2019 $ 94,427 $ 7,108 2020 99,361 6,975 2021 103,502 4,284 2022 106,270 4,196 2023 110,753 4,108 2024 through 2028 600,961 19,065

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Components of Income Tax Expense	The components of income tax expense were as follows: Year Ended December 31 2018 2017 2016 (In thousands) Current Federal $ 408,428 $ 363,043 $ 428,750 State and local 113,706 94,714 95,426 Total current 522,134 457,757 524,176 Deferred Federal (12,780 ) 367,308 147,662 State and local 28,637 33,482 26,351 Total deferred 15,857 400,790 174,013 Amortization of investments in qualified affordable housing projects 52,169 57,009 45,095 Total income taxes applicable to pre-tax income $ 590,160 $ 915,556 $ 743,284
Schedule of Income Tax Expense Benefit Reconciliation	Total income taxes differed from the amount computed by applying the statutory federal income tax rate to pre-tax income as follows: Year Ended December 31 2018 2017 2016 (In thousands) Income taxes at statutory federal income tax rate $ 526,730 $ 813,352 $ 720,439 Increase (decrease) in taxes: Tax-exempt income (26,186 ) (40,778 ) (35,364 ) State and local income taxes, net of federal income tax effect 112,451 83,327 79,155 Qualified affordable housing project federal tax credits, net (12,240 ) (16,015 ) (15,091 ) Initial impact of enactment of Tax Act — 85,431 — Other (10,595 ) (9,761 ) (5,855 ) $ 590,160 $ 915,556 $ 743,284
Deferred Tax Assets (Liabilities)	Deferred tax assets (liabilities) were comprised of the following at December 31: 2018 2017 2016 (In thousands) Losses on loans and other assets $ 322,818 $ 345,609 $ 590,288 Retirement benefits 30,057 45,322 143,067 Postretirement and other employee benefits 23,563 26,009 52,512 Incentive and other compensation plans 24,796 25,050 36,616 Interest on loans — 37,900 61,266 Stock-based compensation 26,759 26,676 52,181 Unrealized losses 52,580 — 10,741 Other 43,880 66,247 106,876 Gross deferred tax assets 524,453 572,813 1,053,547 Leasing transactions (186,787 ) (181,159 ) (266,268 ) Unrealized gains — (94,285 ) — Capitalized servicing rights (54,894 ) (51,781 ) (71,108 ) Depreciation and amortization (61,881 ) (52,733 ) (63,959 ) Interest on loans (18,920 ) — — Other (28,350 ) (21,599 ) (87,200 ) Gross deferred tax liabilities (350,832 ) (401,557 ) (488,535 ) Net deferred tax asset $ 173,621 $ 171,256 $ 565,012
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits follows: Federal, State and Local Tax Accrued Interest Unrecognized Income Tax Benefits (In thousands) Gross unrecognized tax benefits at January 1, 2016 $ 24,537 $ 7,969 $ 32,506 Increases as a result of tax positions taken during 2016 12,237 — 12,237 Increases as a result of tax positions taken in prior years — 656 656 Decreases as a result of tax positions taken in prior years (885 ) (710 ) (1,595 ) Gross unrecognized tax benefits at December 31, 2016 35,889 7,915 43,804 Increases as a result of tax positions taken during 2017 13,019 — 13,019 Increases as a result of tax positions taken in prior years — 1,379 1,379 Decreases as a result of settlements with taxing authorities (332 ) (168 ) (500 ) Decreases as a result of tax positions taken in prior years (3,144 ) (3,475 ) (6,619 ) Gross unrecognized tax benefits at December 31, 2017 45,432 5,651 51,083 Increases as a result of tax positions taken during 2018 13,426 — 13,426 Increases as a result of tax positions taken in prior years — 1,969 1,969 Decreases as a result of settlements with taxing authorities (664 ) (289 ) (953 ) Decreases as a result of tax positions taken in prior years (1,920 ) (702 ) (2,622 ) Gross unrecognized tax benefits at December 31, 2018 $ 56,274 $ 6,629 62,903 Less: Federal, state and local income tax benefits (13,209 ) Net unrecognized tax benefits at December 31, 2018 that, if recognized, would impact the effective income tax rate $ 49,694

Earnings per common share (Tabl

Earnings per common share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Computations of Basic Earnings Per Common Share	The computations of basic earnings per common share follow: Year Ended December 31 2018 2017 2016 (In thousands, except per share) Income available to common shareholders: Net income $ 1,918,080 $ 1,408,306 $ 1,315,114 Less: Preferred stock dividends(a) (72,521 ) (72,734 ) (81,270 ) Net income available to common equity 1,845,559 1,335,572 1,233,844 Less: Income attributable to unvested stock-based compensation awards (9,531 ) (8,069 ) (10,385 ) Net income available to common shareholders $ 1,836,028 $ 1,327,503 $ 1,223,459 Weighted-average shares outstanding: Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards 144,740 153,092 158,121 Less: Unvested stock-based compensation awards (748 ) (933 ) (1,341 ) Weighted-average shares outstanding 143,992 152,159 156,780 Basic earnings per common share $ 12.75 $ 8.72 $ 7.80 (a)
Computations of Diluted Earnings Per Common Share	The computations of diluted earnings per common share follow: Year Ended December 31 2018 2017 2016 (In thousands, except per share) Net income available to common equity $ 1,845,559 $ 1,335,572 $ 1,233,844 Less: Income attributable to unvested stock-based compensation awards (9,524 ) (8,055 ) (10,363 ) Net income available to common shareholders $ 1,836,035 $ 1,327,517 $ 1,223,481 Adjusted weighted-average shares outstanding: Common and unvested stock-based compensation awards 144,740 153,092 158,121 Less: Unvested stock-based compensation awards (748 ) (933 ) (1,341 ) Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock 159 392 524 Adjusted weighted-average shares outstanding 144,151 152,551 157,304 Diluted earnings per common share $ 12.74 $ 8.70 $ 7.78

Comprehensive income (Tables)

Comprehensive income (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Impact of Reclassification from AOCI to Retained Earnings	The impact of that reclassification was an increase in retained earnings as of December 31, 2017 resulting from items remaining in AOCI as of that date as follows: (In thousands) Net unrealized losses on investment securities $ 8,065 Defined benefit plans liability adjustments 53,960 Cash flow hedges and other 2,004 Increase to retained earnings $ 64,029
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 Investment Defined Benefit Total Amount Income Securities (a) Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2018 $ (59,957 ) (413,168 ) (20,165 ) $ (493,290 ) 129,476 $ (363,814 ) Cumulative effect of change in accounting principle — equity securities (22,795 ) — — (22,795 ) 5,942 (16,853 ) Other comprehensive income before reclassifications: Unrealized holding losses, net (121,589 ) — — (121,589 ) 31,946 (89,643 ) Foreign currency translation adjustment — — (2,817 ) (2,817 ) 592 (2,225 ) Unrealized losses on cash flow hedges — — (4,965 ) (4,965 ) 1,306 (3,659 ) Current year benefit plans gains — 19,871 — 19,871 (5,224 ) 14,647 Total other comprehensive income (loss) before reclassifications (121,589 ) 19,871 (7,782 ) (109,500 ) 28,620 (80,880 ) Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities 4,252 — — 4,252 (c) (1,118 ) 3,134 Gains realized in net income (18 ) — — (18 ) (d) 4 (14 ) Accretion of net gain on terminated cash flow hedges — — (111 ) (111 ) (e) 29 (82 ) Net yield adjustment from cash flow hedges currently in effect — — 13,339 13,339 (c) (3,507 ) 9,832 Amortization of prior service credit — (4,172 ) — (4,172 ) (f) 1,097 (3,075 ) Amortization of actuarial losses — 42,967 — 42,967 (f) (11,296 ) 31,671 Total other comprehensive income (loss) (117,355 ) 58,666 5,446 (53,243 ) 13,829 (39,414 ) Balance — December 31, 2018 $ (200,107 ) (354,502 ) (14,719 ) $ (569,328 ) 149,247 $ (420,081 ) (a) Beginning January 1, 2018, equity securities with readily determinable market values are required to be measured at fair value with changes in fair value recognized in the income statement. Separate presentation of investment securities with an other-than-temporary impairment change is no longer required. (b) Other-than-temporary impairment. (c) Included in interest income. (d) Included in gain (loss) on bank investment securities. (e) Included in interest expense. (f) Included in other costs of operations. Investment Securities Defined Benefit Total Amount Income With OTTI (b) All Other Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2017 $ 46,725 (73,785 ) (449,917 ) (8,268 ) $ (485,245 ) 190,609 $ (294,636 ) Other comprehensive income before reclassifications: Unrealized holding gains (losses), net (8,746 ) (6,259 ) — — (15,005 ) 7,269 (7,736 ) Foreign currency translation adjustment — — — 4,447 4,447 (2,206 ) 2,241 Unrealized losses on cash flow hedges — — — (12,291 ) (12,291 ) 4,837 (7,454 ) Current year benefit plans gains — — 9,276 — 9,276 (3,650 ) 5,626 Total other comprehensive income (loss) before reclassifications (8,746 ) (6,259 ) 9,276 (7,844 ) (13,573 ) 6,250 (7,323 ) Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities — 3,387 — — 3,387 (c) (1,333 ) 2,054 Gains realized in net income (18,351 ) (2,928 ) — — (21,279 ) (d) 7,195 (14,084 ) Accretion of net gain on terminated cash flow hedges — — — (137 ) (137 ) (e) 54 (83 ) Net yield adjustment from cash flow hedges currently in effect — — — (3,916 ) (3,916 ) (c) 1,541 (2,375 ) Amortization of prior service credit — — (802 ) — (802 ) (f) 315 (487 ) Amortization of actuarial losses — — 28,275 — 28,275 (f) (11,126 ) 17,149 Total other comprehensive income (loss) (27,097 ) (5,800 ) 36,749 (11,897 ) (8,045 ) 2,896 (5,149 ) Reclassification of income tax effects to retained earnings — — — — — (64,029 ) (64,029 ) Balance — December 31, 2017 $ 19,628 (79,585 ) (413,168 ) (20,165 ) $ (493,290 ) 129,476 $ (363,814 ) 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 30,366 (110,316 ) — — (79,950 ) 31,509 (48,441 ) Foreign currency translation adjustment — — — (4,020 ) (4,020 ) 1,406 (2,614 ) Current year benefit plans gains — — 14,125 — 14,125 (5,557 ) 8,568 Total other comprehensive income (loss) before reclassifications 30,366 (110,316 ) 14,125 (4,020 ) (69,845 ) 27,358 (42,487 ) Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities — 3,996 — — 3,996 (c) (1,572 ) 2,424 Gains realized in net income — (30,314 ) — — (30,314 ) (d) 11,925 (18,389 ) Accretion of net gain on terminated cash flow hedges — — — (155 ) (155 ) (e) 61 (94 ) Amortization of prior service credit — — (4,587 ) — (4,587 ) (f) 1,805 (2,782 ) Amortization of actuarial losses — — 30,205 — 30,205 (f) (11,886 ) 18,319 Total other comprehensive income (loss) 30,366 (136,634 ) 39,743 (4,175 ) (70,700 ) 27,691 (43,009 ) Balance — December 31, 2016 $ 46,725 (73,785 ) (449,917 ) (8,268 ) $ (485,245 ) 190,609 $ (294,636 ) (a) Beginning January 1, 2018, equity securities with readily determinable market values are required to be measured at fair value with changes in fair value recognized in the income statement. Separate presentation of investment securities with an other-than-temporary impairment change is no longer required. (b) Other-than-temporary impairment. (c) Included in interest income. (d) Included in gain (loss) on bank investment securities. (e) Included in interest expense. (f) Included in other costs of operations.
Accumulated Other Comprehensive Income (Loss), Net	Accumulated other comprehensive income (loss), net consisted of the following: Defined Investment Securities Benefit Plans Other Total (In thousands) Balance at January 1, 2016 $ 48,087 $ (296,979 ) $ (2,735 ) $ (251,627 ) Net gain (loss) during 2016 (64,406 ) 24,105 (2,708 ) (43,009 ) Balance at December 31, 2016 (16,319 ) (272,874 ) (5,443 ) (294,636 ) Net gain (loss) during 2017 (19,766 ) 22,288 (7,671 ) (5,149 ) Reclassification of income tax effects to retained earnings (8,065 ) (53,960 ) (2,004 ) (64,029 ) Balance at December 31, 2017 (44,150 ) (304,546 ) (15,118 ) (363,814 ) Cumulative effect of change in accounting principle — equity securities (16,853 ) — — (16,853 ) Net gain (loss) during 2018 (86,523 ) 43,243 3,866 (39,414 ) Balance at December 31, 2018 $ (147,526 ) $ (261,303 ) $ (11,252 ) $ (420,081 )

Other income and other expense

Other income and other expense (Tables)	12 Months Ended
	Dec. 31, 2018
Other Income And Expenses [Abstract]
Other Income and Other Expense	The following items, which exceeded 1% of total interest income and other income in the respective period, were included in either “other revenues from operations” or “other costs of operations” in the consolidated statement of income: Year Ended December 31 2018 2017 2016 (In thousands) Other income: Credit-related fee income $ 82,614 $ 77,580 $ 70,424 Other expense: Professional services 312,998 289,862 268,060 Accrual for Wilmington Trust Corporation legal-related matters 135,000

Derivative financial instrume_2

Derivative financial instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Information about Interest Rate Swap Agreements	Information about interest rate swap agreements entered into for interest rate risk management purposes summarized by type of financial instrument the swap agreements were intended to hedge follows: Weighted- Average Rate Estimated Notional Average Fair Value Amount Maturity Fixed Variable Gain (a) (In thousands) (In years) (In December 31, 2018 Fair value hedges: Fixed rate long-term borrowings (b) $ 4,450,000 2.8 2.47 % 3.02 % $ 4,219 Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(c) 15,400,000 1.3 1.52 % 2.35 % 1,311 Total $ 19,850,000 1.7 $ 5,530 December 31, 2017 Fair value hedges: Fixed rate long-term borrowings (b) $ 4,550,000 2.9 2.27 % 2.09 % $ 573 Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(d) 4,850,000 2.0 1.52 % 1.36 % 66 Total $ 9,400,000 2.5 $ 639 (a) C ertain clearinghouse exchange rules provide that required payments by counterparties for variation margin are treated as settlements of those positions. The impact of such settlements at December 31, 2018 and December 31, 2017 was a reduction of the estimated fair value losses on interest rate swap agreements designated as fair value hedges of $54.7 million and $41.1 million, respectively, and on interest rate swap agreements designated as cash flow hedges of $9.1 million and $16.3 million, respectively. (b) Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate. (c) Includes notional amount and terms of $12.6 billion of forward-starting interest rate swap agreements that will become effective in 2019 and 2020. (d) Includes notional amount and terms of $2.0 billion of forward-starting interest rate swap agreements that will become effective in 2019.
Notional Amount of Interest Rate Swap Agreements Outstanding Maturity	The notional amount of interest rate swap agreements entered into for risk management purposes that were outstanding at December 31, 2018 mature as follows: (In thousands) Year ending December 31: 2019 $ 3,500,000 2020 11,200,000 2021 3,500,000 2022 650,000 2023 500,000 2027 500,000 $ 19,850,000
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 December 31 December 31 2018 2017 2018 2017 (In thousands) Derivatives designated and qualifying as hedging instruments Interest rate swap agreements (a) $ 5,530 $ 639 $ — $ — Commitments to sell real estate loans (a) 1,090 734 6,434 283 6,620 1,373 6,434 283 Derivatives not designated and qualifying as hedging instruments Mortgage-related commitments to originate real estate loans for sale (a) 9,304 8,797 1,592 494 Commitments to sell real estate loans (a) 3,702 2,526 4,535 1,019 Trading: Interest rate contracts (b) 118,687 74,164 169,255 132,104 Foreign exchange and other option and futures contracts (b) 10,549 5,657 8,870 5,286 142,242 91,144 184,252 138,903 Total derivatives $ 148,862 $ 92,517 $ 190,686 $ 139,186 (a) (b) Carrying Amount of the Hedged Item Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item December 31 December 31 2018 2017 2018 2017 (In thousands) Location in the Consolidated Balance Sheet of the Hedged Items in Fair Value Hedges Long-term debt $ 4,394,109 $ 4,504,029 $ (51,102 ) $ (40,133 )
Information about Fair Values of Derivative Instruments in Consolidated Statement of Income	Amount of Gain (Loss) Recognized Year Ended December 31, 2018 Year Ended December 31, 2017 Year Ended December 31, 2016 Derivative Hedged Item Derivative Hedged Item Derivative Hedged Item (In thousands) Derivatives in fair value hedging relationships Interest rate swap agreements: Fixed rate long-term borrowings (a) $ (10,006 ) 10,969 $ (52,392 ) 51,628 $ (32,000 ) 30,906 Derivatives not designated as hedging Trading: Interest rate contracts (b) $ 4,506 $ 5,398 $ 14,042 Foreign exchange and other option and futures contracts (b) 9,416 6,821 7,665 Total $ 13,922 $ 12,219 $ 21,707 (a) (b)

Fair value measurements (Tables

Fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis	The following tables present assets and liabilities at December 31, 2018 and 2017 measured at estimated fair value on a recurring basis: Fair Value Measurements Level 1 (a) Level 2 (a) Level 3 (In thousands) December 31, 2018 Trading account assets $ 185,584 $ 46,018 $ 139,566 $ — Investment securities available for sale: U.S. Treasury and federal agencies 1,336,931 — 1,336,931 — Obligations of states and political subdivisions 1,659 — 1,659 — Mortgage-backed securities: Government issued or guaranteed 7,216,991 — 7,216,991 — Privately issued 22 — — 22 Other debt securities 126,906 — 126,906 — 8,682,509 — 8,682,487 22 Equity securities 93,917 71,989 21,928 — Real estate loans held for sale 551,697 — 551,697 — Other assets (b) 19,626 — 10,322 9,304 Total assets $ 9,533,333 $ 118,007 $ 9,406,000 $ 9,326 Trading account liabilities $ 178,125 $ — $ 178,125 $ — Other liabilities (b) 12,561 — 10,969 1,592 Total liabilities $ 190,686 $ — $ 189,094 $ 1,592 December 31, 2017 Trading account assets $ 132,909 $ 47,873 $ 85,036 $ — Investment securities available for sale: U.S. Treasury and federal agencies 1,947,487 — 1,947,487 — Obligations of states and political subdivisions 2,589 — 2,589 — Mortgage-backed securities: Government issued or guaranteed 8,716,392 — 8,716,392 — Privately issued 28 — — 28 Other debt securities 128,832 — 128,832 — Equity securities 100,956 73,232 27,724 — 10,896,284 73,232 10,823,024 28 Real estate loans held for sale 378,047 — 378,047 — Other assets (b) 12,696 — 3,899 8,797 Total assets $ 11,419,936 $ 121,105 $ 11,290,006 $ 8,825 Trading account liabilities $ 137,390 $ — $ 137,390 $ — Other liabilities (b) 1,796 — 1,302 494 Total liabilities $ 139,186 $ — $ 138,692 $ 494 (a) (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 years ended December 31, 2018, 2017 and 2016 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets (In thousands) 2018 Balance — January 1, 2018 $ 28 $ 8,303 Total gains realized/unrealized: Included in earnings — 58,740 (b) Settlements (6 ) — Transfers out of Level 3 (a) — (59,331 ) (e) Balance — December 31, 2018 $ 22 7,712 Changes in unrealized gains included in earnings related to assets still held at December 31, 2018 $ — 7,386 (b) 2017 Balance — January 1, 2017 $ 44 7,325 Total gains realized/unrealized: Included in earnings — 77,832 (b) Settlements (16 ) — Transfers out of Level 3 (a) — (76,854 ) (e) Balance — December 31, 2017 $ 28 8,303 Changes in unrealized gains included in earnings related to assets still held at December 31, 2017 $ — 7,978 (b) Investment Securities Available for Sale Privately Issued Mortgage-Backed Collateralized Other Assets (In thousands) 2016 Balance — January 1, 2016 $ 74 47,393 9,879 Total gains (losses) realized/unrealized: Included in earnings — 30,041 (c) 110,937 (b) Included in other comprehensive income — (18,268 ) (d) — Sales — (58,296 ) — Settlements (30 ) (870 ) — Transfers out of Level 3 (a) — — (113,491 ) (e) Balance — December 31, 2016 $ 44 — 7,325 Changes in unrealized gains included in earnings related to assets still held at December 31, 2016 $ — — 7,256 (b) (a) (b) (c) (d) (e)
Quantitative Information Related to Significant Unobservable Inputs	The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for Level 3 assets and liabilities at December 31, 2018 and 2017: Fair Value Valuation Technique Unobservable Inputs/Assumptions Range (Weighted- Average) (In December 31, 2018 Recurring fair value measurements Privately issued mortgage-backed securities $ 22 Two independent pricing quotes — — Net other assets (liabilities) (a) 7,712 Discounted cash flow Commitment expirations 0%-95% (13%) December 31, 2017 Recurring fair value measurements Privately issued mortgage-backed securities $ 28 Two independent pricing quotes — — Net other assets (liabilities) (a) 8,303 Discounted cash flow Commitment expirations 0%-78% (22%) (a)
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 tables: December 31, 2018 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,605,439 1,605,439 1,528,302 77,137 — Interest-bearing deposits at banks 8,105,197 8,105,197 — 8,105,197 — Trading account assets 185,584 185,584 46,018 139,566 — Investment securities 12,692,813 12,631,656 71,989 12,456,467 103,200 Loans and leases: Commercial loans and leases 22,977,976 22,587,387 — — 22,587,387 Commercial real estate loans 34,363,556 33,832,558 — 346,775 33,485,783 Residential real estate loans 17,154,446 16,974,545 — 3,920,447 13,054,098 Consumer loans 13,970,499 13,819,545 — — 13,819,545 Allowance for credit losses (1,019,444 ) — — — — Loans and leases, net 87,447,033 87,214,035 — 4,267,222 82,946,813 Accrued interest receivable 353,965 353,965 — 353,965 — Financial liabilities: Noninterest-bearing deposits $ (32,256,668 ) (32,256,668 ) — (32,256,668 ) — Savings and interest-checking deposits (50,963,744 ) (50,963,744 ) — (50,963,744 ) — Time deposits (6,124,254 ) (6,201,957 ) — (6,201,957 ) — Deposits at Cayman Islands office (811,906 ) (811,906 ) — (811,906 ) — Short-term borrowings (4,398,378 ) (4,398,378 ) — (4,398,378 ) — Long-term borrowings (8,444,914 ) (8,385,289 ) — (8,385,289 ) — Accrued interest payable (95,274 ) (95,274 ) — (95,274 ) — Trading account liabilities (178,125 ) (178,125 ) — (178,125 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 7,712 7,712 — — 7,712 Commitments to sell real estate loans (6,177 ) (6,177 ) — (6,177 ) — Other credit-related commitments (131,688 ) (131,688 ) — — (131,688 ) Interest rate swap agreements used for interest rate risk management 5,530 5,530 — 5,530 — December 31, 2017 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,420,888 1,420,888 1,352,035 68,853 — Interest-bearing deposits at banks 5,078,903 5,078,903 — 5,078,903 — Trading account assets 132,909 132,909 47,873 85,036 — Investment securities 14,664,525 14,653,074 73,232 14,469,127 110,715 Loans and leases: Commercial loans and leases 21,742,651 21,321,282 — — 21,321,282 Commercial real estate loans 33,366,373 32,950,724 — 22,130 32,928,594 Residential real estate loans 19,613,344 19,596,826 — 4,440,645 15,156,181 Consumer loans 13,266,615 13,161,517 — — 13,161,517 Allowance for credit losses (1,017,198 ) — — — — Loans and leases, net 86,971,785 87,030,349 — 4,462,775 82,567,574 Accrued interest receivable 327,170 327,170 — 327,170 — Financial liabilities: Noninterest-bearing deposits $ (33,975,180 ) (33,975,180 ) — (33,975,180 ) — Savings and interest-checking deposits (51,698,008 ) (51,698,008 ) — (51,698,008 ) — Time deposits (6,580,962 ) (6,635,048 ) — (6,635,048 ) — Deposits at Cayman Islands office (177,996 ) (177,996 ) — (177,996 ) — Short-term borrowings (175,099 ) (175,099 ) — (175,099 ) — Long-term borrowings (8,141,430 ) (8,193,783 ) — (8,193,783 ) — Accrued interest payable (75,641 ) (75,641 ) — (75,641 ) — Trading account liabilities (137,390 ) (137,390 ) — (137,390 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 8,303 8,303 — — 8,303 Commitments to sell real estate loans 1,958 1,958 — 1,958 — Other credit-related commitments (125,281 ) (125,281 ) — — (125,281 ) Interest rate swap agreements used for interest rate risk management 639 639 — 639 —

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
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. December 31 2018 2017 (In thousands) Commitments to extend credit Home equity lines of credit $ 5,484,197 5,482,622 Commercial real estate loans to be sold 229,401 194,763 Other commercial real estate 7,556,722 6,050,569 Residential real estate loans to be sold 245,211 347,113 Other residential real estate 219,351 201,426 Commercial and other 14,363,803 12,733,815 Standby letters of credit 2,326,991 2,497,844 Commercial letters of credit 55,808 46,739 Financial guarantees and indemnification contracts 3,529,136 3,434,381 Commitments to sell real estate loans 940,692 812,217
Minimum Lease Payments Under Noncancelable Operating Leases	Minimum lease payments under noncancelable operating leases are summarized in the following table: (In thousands) Year ending December 31: 2019 $ 89,547 2020 82,536 2021 67,985 2022 54,504 2023 39,578 Later years 104,280 $ 438,430

Segment information (Tables)

Segment information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Information about Company's Segments	Information about the Company’s segments is presented in the accompanying table. Income statement amounts are in thousands of dollars. Balance sheet amounts are in millions of dollars. For the Years Ended December 31, 2018, 2017 and 2016 Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio 2018 2017 2016 2018 2017 2016 2018 2017 2016 2018 2017 2016 Net interest income(a) $ 434,579 $ 393,948 $ 371,889 $ 821,812 $ 809,301 $ 785,339 $ 665,220 $ 649,378 $ 608,385 $ 228,051 $ 277,095 $ 345,926 Noninterest income 111,600 112,512 108,783 288,908 283,447 274,923 183,955 169,966 179,706 (9,690 ) 23,851 26,075 546,179 506,460 480,672 1,110,720 1,092,748 1,060,262 849,175 819,344 788,091 218,361 300,946 372,001 Provision for credit losses 10,916 15,598 12,709 8,976 11,876 34,903 3,159 (7,524 ) (3,447 ) 6,683 31,119 32,925 Amortization of core deposit and other intangible assets — — — — — — 1,060 1,060 — — — — Depreciation and other amortization 382 393 404 496 509 520 25,852 24,410 20,120 187 279 472 Other noninterest expense 305,340 294,493 292,124 364,102 339,936 327,616 217,387 207,493 204,965 65,393 76,021 95,300 Income (loss) before taxes 229,541 195,976 175,435 737,146 740,427 697,223 601,717 593,905 566,453 146,098 193,527 243,304 Income tax expense (benefit) 61,279 80,043 71,677 198,229 303,556 285,844 148,807 229,770 216,095 29,872 58,559 79,766 Net income (loss) $ 168,262 $ 115,933 $ 103,758 $ 538,917 $ 436,871 $ 411,379 $ 452,910 $ 364,135 $ 350,358 $ 116,226 $ 134,968 $ 163,538 Average total assets (in millions) $ 5,631 $ 5,602 $ 5,456 $ 26,626 $ 26,573 $ 25,592 $ 22,885 $ 22,741 $ 21,131 $ 32,123 $ 37,203 $ 40,867 Capital expenditures (in millions) $ — $ — $ — $ — $ — $ — $ — $ 1 $ — $ 1 $ — $ — For the Years Ended December 31, 2018, 2017 and 2016 Residential Mortgage Banking Retail Banking All Other Total 2018 2017 2016 2018 2017 2016 2018 2017 2016 2018 2017 2016 Net interest income(a) $ 13,933 $ 30,328 $ 29,809 $ 1,351,165 $ 1,210,066 $ 1,107,388 $ 557,542 $ 410,928 $ 221,151 $ 4,072,302 $ 3,781,044 $ 3,469,887 Noninterest income 305,560 321,589 342,858 324,228 329,833 323,176 651,439 609,945 570,475 1,856,000 1,851,143 1,825,996 319,493 351,917 372,667 1,675,393 1,539,899 1,430,564 1,208,981 1,020,873 791,626 5,928,302 5,632,187 5,295,883 Provision for credit losses (2,178 ) 1,254 (3,617 ) 112,572 107,412 120,437 (8,128 ) 8,265 (3,910 ) 132,000 168,000 190,000 Amortization of core deposit and other intangible assets — — — — — — 23,462 30,306 42,613 24,522 31,366 42,613 Depreciation and other amortization 24,288 32,011 30,264 35,274 38,234 37,657 68,004 69,923 68,541 154,483 165,759 157,978 Other noninterest expense 241,624 247,639 258,141 789,783 758,153 776,123 1,125,428 1,019,465 892,625 3,109,057 2,943,200 2,846,894 Income (loss) before taxes 55,759 71,013 87,879 737,764 636,100 496,347 215 (107,086 ) (208,243 ) 2,508,240 2,323,862 2,058,398 Income tax expense (benefit) 10,272 25,446 32,426 196,467 258,934 201,974 (54,766 ) (40,752 ) (144,498 ) 590,160 915,556 743,284 Net income (loss) $ 45,487 $ 45,567 $ 55,453 $ 541,297 $ 377,166 $ 294,373 $ 54,981 $ (66,334 ) $ (63,745 ) $ 1,918,080 $ 1,408,306 $ 1,315,114 Average total assets (in millions) $ 2,161 $ 2,355 $ 2,569 $ 13,656 $ 12,702 $ 11,840 $ 13,877 $ 13,684 $ 16,885 $ 116,959 $ 120,860 $ 124,340 Capital expenditures (in millions) $ 1 $ — $ — $ 31 $ 34 $ 46 $ 65 $ 44 $ 62 $ 98 $ 79 $ 108 (a)
Intersegment Activity Eliminated in Arriving at Consolidated Totals was Included in "All Other" Category	The amount of intersegment activity eliminated in arriving at consolidated totals was included in the “All Other” category as follows: Year Ended December 31 2018 2017 2016 (In thousands) Revenues $ (41,285 ) $ (43,941 ) $ (48,625 ) Expenses (24,660 ) (32,623 ) (40,422 ) Income taxes (benefit) (4,371 ) (4,606 ) (3,338 ) Net income (loss) (12,254 ) (6,712 ) (4,865 )

Regulatory matters (Tables)

Regulatory matters (Tables)	12 Months Ended
	Dec. 31, 2018
Banking And Thrift [Abstract]
Summary of Required Minimum and Well Capitalized Capital Ratios	Pursuant to the rules in effect as of December 31, 2018, the required minimum and well capitalized capital ratios are as follows: Well Minimum Capitalized ● Common equity Tier 1 ("CET1") to risk-weighted assets 4.5 % 6.5 % ● Tier 1 capital to risk-weighted assets 6.0 % 8.0 % ● Total capital to risk-weighted assets 8.0 % 10.0 % ● Leverage — Tier 1 capital to average total assets, as defined 4.0 % 5.0 %
Capital Ratios and Amounts of Company and its Banking Subsidiaries	The capital ratios and amounts of the Company and its banking subsidiaries as of December 31, 2018 and 2017 are presented below: M&T (Consolidated) M&T Bank Wilmington Trust, N.A. (Dollars in thousands) December 31, 2018: Common equity Tier 1 capital Amount $ 9,960,811 $ 10,636,136 $ 585,767 Ratio(a) 10.13 % 10.84 % 60.69 % Tier 1 capital Amount 11,193,770 10,636,136 585,767 Ratio(a) 11.38 % 10.84 % 60.69 % Total capital Amount 13,454,137 12,475,296 589,671 Ratio(a) 13.68 % 12.72 % 61.10 % Leverage Amount 11,193,770 10,636,136 585,767 Ratio(b) 9.88 % 9.42 % 12.51 % December 31, 2017: Common equity Tier 1 capital Amount $ 10,675,735 $ 9,978,163 $ 529,988 Ratio(a) 10.99 % 10.30 % 48.16 % Tier 1 capital Amount 11,908,166 9,978,163 529,988 Ratio(a) 12.26 % 10.30 % 48.16 % Total capital Amount 14,328,467 12,012,171 534,235 Ratio(a) 14.75 % 12.40 % 48.54 % Leverage Amount 11,908,166 9,978,163 529,988 Ratio(b) 10.31 % 8.68 % 13.03 % (a) (b)

Parent company financial stat_2

Parent company financial statements (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheet	Condensed Balance Sheet December 31 2018 2017 (In thousands) Assets Cash in subsidiary bank $ 40,609 $ 13,379 Due from consolidated bank subsidiaries Money-market savings 856,881 1,616,147 Current income tax receivable 1,117 4,437 Total due from consolidated bank subsidiaries 857,998 1,620,584 Investments in consolidated subsidiaries Banks 15,491,277 14,841,794 Other 324,360 253,904 Investments in trust preferred entities (note 19) 23,241 23,453 Other assets 64,187 66,023 Total assets $ 16,801,672 $ 16,819,137 Liabilities Accrued expenses and other liabilities $ 63,719 $ 49,093 Long-term borrowings 1,277,762 519,225 Total liabilities 1,341,481 568,318 Shareholders’ equity 15,460,191 16,250,819 Total liabilities and shareholders’ equity $ 16,801,672 $ 16,819,137
Condensed Statement of Income	Condensed Statement of Income Year Ended December 31 2018 2017 2016 (In thousands, except per share) Income Dividends from consolidated bank subsidiaries $ 1,250,000 $ 1,540,000 $ 1,930,000 Equity in earnings of Bayview Lending Group LLC 23,500 352 (10,752 ) Other income 2,417 9,493 5,530 Total income 1,275,917 1,549,845 1,924,778 Expense Interest on long-term borrowings 36,354 21,591 18,963 Other expense 23,894 19,636 21,361 Total expense 60,248 41,227 40,324 Income before income taxes and equity in undistributed income of subsidiaries 1,215,669 1,508,618 1,884,454 Income tax credits 8,446 26,453 17,247 Income before equity in undistributed income of subsidiaries 1,224,115 1,535,071 1,901,701 Equity in undistributed income of subsidiaries Net income of subsidiaries 1,943,965 1,413,235 1,343,413 Less: dividends received (1,250,000 ) (1,540,000 ) (1,930,000 ) Equity in undistributed income of subsidiaries 693,965 (126,765 ) (586,587 ) Net income $ 1,918,080 $ 1,408,306 $ 1,315,114 Net income per common share Basic $ 12.75 $ 8.72 $ 7.80 Diluted 12.74 8.70 7.78
Condensed Statement of Cash Flow	Condensed Statement of Cash Flows Year Ended December 31 2018 2017 2016 (In thousands) Cash flows from operating activities Net income $ 1,918,080 $ 1,408,306 $ 1,315,114 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed income of subsidiaries (693,965 ) 126,765 586,587 Benefit (provision) for deferred income taxes 4,949 4,543 (3,157 ) Net change in accrued income and expense (8,242 ) (170 ) 12,898 Gain on sale of assets — (2,995 ) (2,342 ) Net cash provided by operating activities 1,220,822 1,536,449 1,909,100 Cash flows from investing activities Proceeds from sales or maturities of investment securities — — 51 Other, net 29,933 12,407 13,619 Net cash provided by investing activities 29,933 12,407 13,670 Cash flows from financing activities Purchases of treasury stock (2,194,396 ) (1,205,905 ) (641,334 ) Dividends paid — common (510,382 ) (457,402 ) (441,891 ) Dividends paid — preferred (72,521 ) (72,734 ) (81,270 ) Proceeds from long-term borrowings 748,595 — — Redemption of Series D preferred stock — — (500,000 ) Proceeds from issuance of Series F preferred stock — — 495,000 Other, net 45,913 34,524 143,764 Net cash used by financing activities (1,982,791 ) (1,701,517 ) (1,025,731 ) Net increase (decrease) in cash and cash equivalents (732,036 ) (152,661 ) 897,039 Cash and cash equivalents at beginning of year 1,629,526 1,782,187 885,148 Cash and cash equivalents at end of year $ 897,490 $ 1,629,526 $ 1,782,187 Supplemental disclosure of cash flow information Interest received during the year $ 2,219 $ 2,313 $ 1,931 Interest paid during the year 17,482 18,498 15,918 Income taxes received during the year 6,362 21,740 8,877

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Delinquent period of loans resulting in accrued interest being charged against income	90 days
Delinquent period of loans secured by real estate resulting in charge off	150 days
Maximum [Member]
Significant Accounting Policies [Line Items]
Loans secured by real estate delinquent period threshold for return to accrual status	90 days
Consumer loan delinquent period threshold for consideration for charge off	180 days
Estimated useful lives	10 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Consumer loan delinquent period threshold for consideration for charge off	91 days
Estimated useful lives	5 years
Income tax benefit recognition criteria percentage threshold	50.00%

Investment Securities - Additio

Investment Securities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018USD ($)Investment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Investment Holdings [Line Items]
Gain (loss) on bank investment securities	$ (6,301,000)	$ 21,279,000	$ 30,314,000
Gross realized gains on investment securities		23,251,000	30,545,000
Gross realized gains(loss) on sale of investment securities	$ 0	0	0
Number of investment securities with aggregate gross unrealized losses | Investment	1,402
Unrealized losses on individual investment securities	$ 281,000,000	169,036,000
Cost method investment securities	600,000,000
Investment securities pledged to secure debt carrying value	2,605,034,000
Pledged securities that can be sold or repledged	487,365,000	487,151,000
Available-for-Sale Securities [Member]
Investment Holdings [Line Items]
Investment securities pledged to secure debt carrying value	$ 2,040,362,000
Government Agency [Member]
Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity | Investment	0
Non-U.S. Government [Member]
Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity | Investment	0
Government Issued or Guaranteed [Member]
Investment Holdings [Line Items]
Number of investment securities that exceeded ten percent of shareholders' equity | Investment	0
Collateralized Debt Obligations [Member]
Investment Holdings [Line Items]
Net gain on securities sold			$ 30,000,000
Collateralized Debt Obligations [Member] | Fannie Mae And Freddie Mac Preferred Stock
Investment Holdings [Line Items]
Net gain on securities sold		$ 18,000,000
Retained Earnings [Member] | Adjustments for New Accounting Pronouncement [Member]
Investment Holdings [Line Items]
Reclassification from accumulated comprehensive income to retained earnings, net of tax	$ 17,000,000

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	$ 8,869,423	$ 10,938,796
Investment securities available for sale, gross unrealized gains	16,528	85,154
Investment securities available for sale, gross unrealized losses	203,442	127,666
Investment securities available for sale, estimated fair value	8,682,509	10,896,284
Amortized cost for held to maturity	3,316,640	3,353,213
Gross unrealized gains for held to maturity	16,532	29,919
Gross unrealized losses for held to maturity	77,689	41,370
Estimated fair value for held to maturity	3,255,483	3,341,762
Equity and other securities, Amortized Cost	677,187	415,028
Equity securities, Gross Unrealized Gains	17,295
Equity securities, Gross Unrealized Losses	818
Equity and other securities, Estimated Fair Value	693,664	415,028
Other securities, Amortized cost	599,747	415,028
Other securities, Estimated fair value	599,747	415,028
Total debt securities Amortized cost	12,186,063
Total debt securities Gross unrealized gains	33,060
Total debt securities Gross unrealized losses	281,131
Total debt securities Estimated fair value	11,937,992
Readily marketable securities Amortized cost	77,440
Readily marketable securities Gross unrealized gains	17,295
Readily marketable securities Gross unrealized losses	818
Readily marketable securities Estimated fair value	93,917
Total Amortized cost		14,707,037
Total for Gross unrealized gains		115,073
Total for Gross unrealized losses	281,000	169,036
Total for Estimated fair value		14,653,074
U.S. Treasury and Federal Agencies [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	1,346,782	1,965,665
Investment securities available for sale, gross unrealized losses	9,851	18,178
Investment securities available for sale, estimated fair value	1,336,931	1,947,487
Amortized cost for held to maturity	446,542
Gross unrealized losses for held to maturity	239
Estimated fair value for held to maturity	446,303
Obligations of States and Political Subdivisions [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	1,660	2,555
Investment securities available for sale, gross unrealized gains	4	36
Investment securities available for sale, gross unrealized losses	5	2
Investment securities available for sale, estimated fair value	1,659	2,589
Amortized cost for held to maturity	7,494	24,562
Gross unrealized gains for held to maturity	22	109
Gross unrealized losses for held to maturity	12	49
Estimated fair value for held to maturity	7,504	24,622
Government Issued or Guaranteed [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	7,383,340	8,755,482
Investment securities available for sale, gross unrealized gains	15,754	59,497
Investment securities available for sale, gross unrealized losses	182,103	98,587
Investment securities available for sale, estimated fair value	7,216,991	8,716,392
Amortized cost for held to maturity	2,745,776	3,187,953
Gross unrealized gains for held to maturity	4,165	27,236
Gross unrealized losses for held to maturity	55,111	13,746
Estimated fair value for held to maturity	2,694,830	3,201,443
Privately Issued [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	24	28
Investment securities available for sale, gross unrealized losses	2
Investment securities available for sale, estimated fair value	22	28
Amortized cost for held to maturity	113,160	135,688
Gross unrealized gains for held to maturity	12,345	2,574
Gross unrealized losses for held to maturity	22,327	27,575
Estimated fair value for held to maturity	103,178	110,687
Other Debt Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	137,617	136,905
Investment securities available for sale, gross unrealized gains	770	2,402
Investment securities available for sale, gross unrealized losses	11,481	10,475
Investment securities available for sale, estimated fair value	126,906	128,832
Amortized cost for held to maturity	3,668	5,010
Estimated fair value for held to maturity	$ 3,668	5,010
Equity Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost		78,161
Investment securities available for sale, gross unrealized gains		23,219
Investment securities available for sale, gross unrealized losses		424
Investment securities available for sale, estimated fair value		$ 100,956

Investment Securities - Investm

Investment Securities - Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	$ 263,623
Total securities with disclosed rating, Estimated Fair Value	242,937
A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	30,510
BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	60,356
BB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	31,053
B or Less [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	34,180
Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	86,838
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	9,154
Total securities with disclosed rating, Estimated Fair Value	9,163
Obligations of States and Political Subdivisions [Member] | A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	8,637
Obligations of States and Political Subdivisions [Member] | BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	526
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	113,184
Total securities with disclosed rating, Estimated Fair Value	103,200
Privately Issued [Member] | A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	17,055
Privately Issued [Member] | BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	16
Privately Issued [Member] | B or Less [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	34,180
Privately Issued [Member] | Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	51,949
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	141,285
Total securities with disclosed rating, Estimated Fair Value	130,574
Other Debt Securities [Member] | A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	4,818
Other Debt Securities [Member] | BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	59,814
Other Debt Securities [Member] | BB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	31,053
Other Debt Securities [Member] | Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	$ 34,889

Investment Securities - Amort_2

Investment Securities - Amortized Cost and Estimated Fair Value of Collateralized Mortgage Obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost And Fair Value Debt Securities [Abstract]
Collateralized mortgage obligations, Amortized cost	$ 115,171	$ 138,527
Collateralized mortgage obligations, Estimated fair value	$ 105,155	$ 113,516

Investment Securities - Amort_3

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt securities available for sale:
Due in one year or less	$ 1,344,408
Due after one year through five years	9,555
Due after five years through ten years	102,081
Due after ten years	30,015
Total available for sale (amortized cost)	1,486,059
Mortgage-backed securities available for sale	7,383,364
Investment securities available for sale, amortized cost	8,869,423	$ 10,938,796
Debt securities held to maturity:
Due in one year or less	449,468
Due after one year through five years	4,568
Due after ten years	3,668
Total available for held to maturity (amortized cost)	457,704
Mortgage-backed securities held to maturity	2,858,936
Amortized cost for held to maturity	3,316,640	3,353,213
Debt securities available for sale:
Due in one year or less	1,334,695
Due after one year through five years	9,319
Due after five years through ten years	95,653
Due after ten years	25,829
Total available for sale (fair value)	1,465,496
Mortgage-backed securities available for sale	7,217,013
Total	8,682,509	10,896,284
Debt securities held to maturity:
Due in one year or less	449,237
Due after one year through five years	4,570
Due after ten years	3,668
Total available for held to maturity (fair value)	457,475
Mortgage-backed securities held to maturity	2,798,008
Total	$ 3,255,483	$ 3,341,762

Investment Securities - Inves_2

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 459,960	$ 2,387,341
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(5,088)	(15,482)
Estimated fair value, 12 months or more	7,048,346	4,887,991
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(198,354)	(112,184)
Held to maturity, Estimated fair value, Less than 12 months	625,657	1,339,774
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(1,228)	(8,256)
Held to maturity, Estimated fair value, 12 months or more	2,137,792	327,060
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(76,461)	(33,114)
Total investment securities, fair value less than 12 months	1,085,617	3,727,115
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(6,316)	(23,738)
Total of investment securities, fair value, 12 Months or More	9,186,138	5,215,051
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(274,815)	(145,298)
U.S. Treasury and Federal Agencies [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	273	278,132
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(2)	(1,761)
Estimated fair value, 12 months or more	1,335,559	1,669,355
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(9,849)	(16,417)
Held to maturity, Estimated fair value, Less than 12 months	446,303
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(239)
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	629
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(5)
Estimated fair value, 12 months or more		474
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses		(2)
Held to maturity, Estimated fair value, Less than 12 months		2,954
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		(4)
Held to maturity, Estimated fair value, 12 months or more	3,126	6,110
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(12)	(45)
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	405,558	2,106,142
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(2,892)	(13,695)
Estimated fair value, 12 months or more	5,646,773	3,138,841
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(179,211)	(84,892)
Held to maturity, Estimated fair value, Less than 12 months	179,354	1,331,759
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(989)	(7,036)
Held to maturity, Estimated fair value, 12 months or more	2,082,723	265,695
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(54,122)	(6,710)
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	22
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(2)
Held to maturity, Estimated fair value, Less than 12 months		5,061
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses		(1,216)
Held to maturity, Estimated fair value, 12 months or more	51,943	55,255
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(22,327)	(26,359)
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	53,478	3,067
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(2,187)	(26)
Estimated fair value, 12 months or more	66,014	61,159
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	$ (9,294)	(10,449)
Equity Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, 12 months or more		18,162
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses		$ (424)

Loans and Leases - Total Loans

Loans and Leases - Total Loans and Leases Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans
Commercial, financial, etc.	$ 21,730,012	$ 20,474,696
Real estate:
Residential	17,150,658	19,619,259
Commercial	25,666,200	25,345,779
Construction	8,823,635	8,125,925
Consumer	13,956,086	13,251,665
Total loans	87,326,591	86,817,324
Leases
Commercial	1,406,901	1,425,562
Total loans and leases	88,733,492	88,242,886
Unearned discount	(267,015)	(253,903)
Loans and leases, net of unearned discount	$ 88,466,477	$ 87,988,983

Loans and Leases - Additional I

Loans and Leases - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans And Leases Receivable [Line Items]
Commercial real estate loans held for sale	$ 347,000,000	$ 22,000,000
Charges incurred for reimbursement of loan	0	0	$ 0
Interest income that would have been recognized on nonaccrual and renegotiated loans if those loans were accruing interest at their originally contracted terms	68,745,000	63,872,000	68,371,000
Interest on nonaccrual and renegotiated loans included in interest income	32,983,000	31,425,000	$ 33,941,000
Contractual principal and interest payments	303,000,000	410,000,000
Guaranteed amount included in the estimated residual value of leased assets associated with direct financing leases	39,000,000	37,000,000
Amount of foreclosed residential real estate property held	77,000,000	108,000,000
Loans secured by residential real estate that were in the process of foreclosure	$ 391,000,000	497,000,000
Percentage loans in the process of foreclosure, serviced by other entities, classified as purchased impaired	39.00%
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	21.00%
Director and Certain Officers [Member]
Loans And Leases Receivable [Line Items]
Exclusion limit of loans from related party disclosure	less than $60,000
Borrowing by directors and certain officers of M&T and its banking subsidiaries and their associates	$ 77,414,000	$ 93,103,000
New borrowings by directors, certain officers and their associates	1,900,000
Repayments and other reductions of borrowings by directors, certain officers and their associates	$ 17,589,000
Maximum [Member]
Loans And Leases Receivable [Line Items]
Purchased impaired loans as a percentage of total assets	1.00%	1.00%
Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Loans serviced for others sold with credit recourse	$ 3,400,000,000
Loans pledged to secure outstanding borrowings from the FHLB of New York	13,200,000,000
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	205,000,000	$ 356,000,000
Loans pledged to secure outstanding borrowings from the FHLB of New York	12,800,000,000
Commercial Loans and Leases [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	11,600,000,000
Home Equity Loans and Lines of Credit [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	2,400,000,000
Other Consumer Loans [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	$ 6,100,000,000

Loans and Leases - Summary of C

Loans and Leases - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 86,140,950	$ 85,325,604
30-89 Days Past Due	866,337	1,078,943
Accruing Loans Past Due 90 Days or More	222,527	244,405
Purchased Impaired	303,305	410,015
Nonaccrual	893,608	882,598
Loans and leases, net of unearned discount	88,466,477	87,988,983
Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	39,750	47,418
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	22,701,020	21,332,234
30-89 Days Past Due	39,798	167,756
Accruing Loans Past Due 90 Days or More	2,567	1,322
Purchased Impaired		21
Nonaccrual	234,423	240,991
Loans and leases, net of unearned discount	22,977,976	21,742,651
Commercial, Financial, Leasing, etc. [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	168	327
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	25,250,983	24,910,381
30-89 Days Past Due	134,474	166,305
Accruing Loans Past Due 90 Days or More	11,457	4,444
Purchased Impaired	9,769	16,815
Nonaccrual	203,672	184,982
Loans and leases, net of unearned discount	25,610,365	25,288,943
Commercial [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	10	6,016
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,665,178	1,618,973
30-89 Days Past Due	20,333	5,159
Purchased Impaired		1,135
Nonaccrual	4,798	6,451
Loans and leases, net of unearned discount	1,690,309	1,631,718
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	6,982,077	6,407,451
30-89 Days Past Due	43,615	23,467
Accruing Loans Past Due 90 Days or More	14,344
Purchased Impaired	641	4,706
Nonaccrual	22,205	10,088
Loans and leases, net of unearned discount	7,062,882	6,445,712
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	13,591,790	15,376,759
30-89 Days Past Due	404,808	474,372
Accruing Loans Past Due 90 Days or More	189,682	233,437
Purchased Impaired	203,044	282,102
Nonaccrual	233,352	235,834
Loans and leases, net of unearned discount	14,629,326	16,610,086
Residential [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	6,650	7,582
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	2,278,040	2,718,019
30-89 Days Past Due	72,544	83,898
Purchased Impaired	89,851	105,236
Nonaccrual	84,685	96,105
Loans and leases, net of unearned discount	2,525,120	3,003,258
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,758,513	5,171,345
30-89 Days Past Due	25,416	38,546
Nonaccrual	71,292	74,500
Loans and leases, net of unearned discount	4,860,254	5,293,782
Home Equity Lines and Loans [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	5,033	9,391
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,085,781	3,229,570
30-89 Days Past Due	29,947	23,802
Nonaccrual	11,199	6,509
Loans and leases, net of unearned discount	4,127,162	3,260,427
Recreational Finance [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	235	546
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,555,757	3,441,371
30-89 Days Past Due	79,804	78,511
Nonaccrual	23,359	23,781
Loans and leases, net of unearned discount	3,658,920	3,543,663
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,271,811	1,119,501
30-89 Days Past Due	15,598	17,127
Accruing Loans Past Due 90 Days or More	4,477	5,202
Nonaccrual	4,623	3,357
Loans and leases, net of unearned discount	1,324,163	1,168,743
Other [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More	$ 27,654	$ 23,556

Loans and Leases - Outstanding

Loans and Leases - Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 1,016,785	$ 1,394,188
Carrying amount	727,491	1,003,399
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	27,073	31,105
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	135,047	228,054
Residential Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	473,511	620,827
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 91,860	$ 123,413

Loans and Leases - Summary of_2

Loans and Leases - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 157,918	$ 154,233	$ 184,618
Interest income	(37,819)	(47,452)	(52,769)
Reclassifications from nonaccretable balance	27,111	51,137	22,384
Balance at end of period	147,210	157,918	154,233
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	133,162	201,153	296,434
Interest income	(63,856)	(82,605)	(123,044)
Reclassifications from nonaccretable balance	22,849	16,437	22,677
Other	4,752	(1,823)	5,086
Balance at end of period	$ 96,907	$ 133,162	$ 201,153

Loans and Leases - Loan Modific

Loans and Leases - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)Modification	Dec. 31, 2017USD ($)Modification	Dec. 31, 2016USD ($)Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	557	654	739
Pre-modification Recorded Investment	$ 175,583	$ 216,063	$ 279,696
Post- modification	$ 180,224	$ 191,522	$ 268,415
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	83	83	81
Pre-modification Recorded Investment	$ 30,217	$ 44,924	$ 44,870
Post- modification	30,731	40,882	43,737
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	90,639	62,302	164,883
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	16,870	17,039	23,558
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	978
Interest Rate Reduction [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	175
Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	10,896	7,818	4,676
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	4,686	868	4,576
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	77,711	121,402	98,856
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 9,000	$ 22,975	$ 15,603
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	203	217	164
Pre-modification Recorded Investment	$ 102,445	$ 111,036	$ 154,093
Post- modification	102,914	88,663	144,119
Commercial, Financial, Leasing, etc. [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	50,490	25,051	102,446
Commercial, Financial, Leasing, etc. [Member] | Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	803
Commercial, Financial, Leasing, etc. [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	6,210	6,459
Commercial, Financial, Leasing, etc. [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 45,411	$ 57,153	$ 41,673
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	134	141	119
Pre-modification Recorded Investment	$ 34,798	$ 31,827	$ 20,057
Post- modification	38,072	34,607	21,138
Residential [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	19,962	16,633	11,771
Residential [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 18,110	$ 17,974	$ 9,367
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	9	20	21
Pre-modification Recorded Investment	$ 1,887	$ 4,230	$ 3,560
Post- modification	2,250	4,572	3,964
Residential Limited Documentation [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	827	911	1,047
Residential Limited Documentation [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 1,423	$ 3,661	$ 2,917
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	47	110	103
Pre-modification Recorded Investment	$ 3,952	$ 10,049	$ 11,870
Post- modification	3,979	10,213	11,871
Home Equity Lines and Loans [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	224	1,137	761
Home Equity Lines and Loans [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		491
Home Equity Lines and Loans [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 3,755	$ 8,585	$ 11,110
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	73	69	163
Pre-modification Recorded Investment	$ 1,330	$ 1,378	$ 1,264
Post- modification	1,330	1,378	1,264
Automobile [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	1,318	1,203	1,124
Automobile [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			55
Automobile [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 12	$ 175	$ 85
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			69
Pre-modification Recorded Investment			$ 891
Post- modification			891
Other [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			698
Other [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			25
Other [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 168
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		3	6
Pre-modification Recorded Investment		$ 12,291	$ 39,660
Post- modification		10,879	38,081
Residential Builder and Developer [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			22,958
Residential Builder and Developer [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		$ 10,879	$ 15,123
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	2	3
Pre-modification Recorded Investment	$ 752	$ 168	$ 3,113
Post- modification	746	168	3,032
Other Commercial Construction [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 746	$ 168	250
Other Commercial Construction [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 2,782
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	7	9	10
Pre-modification Recorded Investment	$ 202	$ 160	$ 318
Post- modification	202	160	318
Recreational Finance [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 202	$ 160	270
Recreational Finance [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			20
Recreational Finance [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 28

Loans and Leases - Summary of L

Loans and Leases - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Direct financings:
Lease payments receivable	$ 1,155,464	$ 1,159,584
Estimated residual value of leased assets	85,169	89,666
Unearned income	(110,458)	(110,261)
Investment in direct financings	1,130,175	1,138,989
Leveraged leases:
Lease payments receivable	85,007	87,821
Estimated residual value of leased assets	81,261	88,491
Unearned income	(33,717)	(35,792)
Investment in leveraged leases	132,551	140,520
Total investment in leases	1,262,726	1,279,509
Deferred taxes payable arising from leveraged leases	$ 74,995	$ 81,359

Loans and Leases - Minimum Futu

Loans and Leases - Minimum Future Lease Payments to be Received from Lease Financings (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Receivables [Abstract]
2,019	$ 326,898
2,020	310,255
2,021	224,150
2,022	141,244
2,023	88,182
Later years	149,742
Total	$ 1,240,471

Allowance for Credit Losses - C

Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,017,198	$ 988,997	$ 955,992
Provision for credit losses	132,000	168,000	190,000
Net charge-offs
Charge-offs	(231,241)	(224,598)	(231,255)
Recoveries	101,487	84,799	74,260
Net (charge-offs) recoveries	(129,754)	(139,799)	(156,995)
Ending balance	1,019,444	1,017,198	988,997
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	328,599	330,833	300,404
Provision for credit losses	33,967	41,511	59,506
Net charge-offs
Charge-offs	(60,414)	(64,941)	(59,244)
Recoveries	27,903	21,196	30,167
Net (charge-offs) recoveries	(32,511)	(43,745)	(29,077)
Ending balance	330,055	328,599	330,833
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	374,085	362,719	326,831
Provision for credit losses	(41,181)	6,715	33,627
Net charge-offs
Charge-offs	(12,286)	(7,931)	(4,805)
Recoveries	21,037	12,582	7,066
Net (charge-offs) recoveries	8,751	4,651	2,261
Ending balance	341,655	374,085	362,719
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	65,405	61,127	72,238
Provision for credit losses	12,401	16,094	6,902
Net charge-offs
Charge-offs	(15,345)	(20,799)	(26,133)
Recoveries	6,664	8,983	8,120
Net (charge-offs) recoveries	(8,681)	(11,816)	(18,013)
Ending balance	69,125	65,405	61,127
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	170,809	156,288	178,320
Provision for credit losses	127,068	103,410	90,134
Net charge-offs
Charge-offs	(143,196)	(130,927)	(141,073)
Recoveries	45,883	42,038	28,907
Net (charge-offs) recoveries	(97,313)	(88,889)	(112,166)
Ending balance	200,564	170,809	156,288
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	78,300	78,030	78,199
Provision for credit losses	(255)	270	(169)
Net charge-offs
Ending balance	$ 78,045	$ 78,300	$ 78,030

Allowance for Credit Losses - I

Allowance for Credit Losses - Impaired Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	$ 542,255	$ 499,152
Unpaid principal balance with related allowance	630,609	585,903
Related allowance	79,646	75,762
Recorded investment with no related allowance	254,196	261,157
Unpaid principal balance with no related allowance	305,559	314,587
Recorded investment	796,451	760,309
Unpaid principal balance	936,168	900,490
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	110,253	67,199
Unpaid principal balance with related allowance	125,117	75,084
Related allowance	11,937	9,140
Recorded investment with no related allowance	113,376	138,356
Unpaid principal balance with no related allowance	124,657	149,716
Recorded investment	223,629	205,555
Unpaid principal balance	249,774	224,800
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	3,527	13,498
Unpaid principal balance with related allowance	3,599	15,737
Related allowance	729	2,811
Recorded investment	3,527	13,498
Unpaid principal balance	3,599	15,737
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	153,478	177,250
Unpaid principal balance with related allowance	175,549	194,257
Related allowance	46,034	45,488
Recorded investment with no related allowance	105,507	89,126
Unpaid principal balance with no related allowance	136,128	115,327
Recorded investment	258,985	266,376
Unpaid principal balance	311,677	309,584
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	5,981	5,320
Unpaid principal balance with related allowance	6,557	5,641
Related allowance	462	308
Recorded investment with no related allowance	2,593	5,057
Unpaid principal balance with no related allowance	2,602	5,296
Recorded investment	8,574	10,377
Unpaid principal balance	9,159	10,937
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	10,563	4,817
Unpaid principal balance with related allowance	11,113	20,357
Related allowance	640	647
Recorded investment with no related allowance	11,710	5,456
Unpaid principal balance with no related allowance	11,880	9,130
Recorded investment	22,273	10,273
Unpaid principal balance	22,993	29,487
Residential [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	124,974	101,724
Unpaid principal balance with related allowance	147,817	122,602
Related allowance	5,402	4,000
Recorded investment with no related allowance	15,379	13,574
Unpaid principal balance with no related allowance	20,496	18,980
Recorded investment	140,353	115,298
Unpaid principal balance	168,313	141,582
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	74,156	77,277
Unpaid principal balance with related allowance	90,066	92,439
Related allowance	3,000	3,900
Recorded investment with no related allowance	5,631	9,588
Unpaid principal balance with no related allowance	9,796	16,138
Recorded investment	79,787	86,865
Unpaid principal balance	99,862	108,577
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	47,982	48,847
Unpaid principal balance with related allowance	53,248	53,914
Related allowance	9,135	8,812
Recorded investment	47,982	48,847
Unpaid principal balance	53,248	53,914
Recreational Finance [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	6,138	1,496
Unpaid principal balance with related allowance	9,163	3,680
Related allowance	1,261	299
Recorded investment	6,138	1,496
Unpaid principal balance	9,163	3,680
Other [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with related allowance	5,203	1,724
Unpaid principal balance with related allowance	8,380	2,192
Related allowance	1,046	357
Recorded investment	5,203	1,724
Unpaid principal balance	$ 8,380	$ 2,192

Allowance for Credit Losses -_2

Allowance for Credit Losses - Interest Income Recognized on Impaired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	$ 754,197	$ 748,598	$ 769,259
Interest income recognized, Total	41,461	31,983	31,397
Interest income recognized, Cash basis	29,565	21,316	21,885
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	194,451	207,616	175,877
Interest income recognized, Total	10,880	4,497	4,878
Interest income recognized, Cash basis	10,880	4,497	4,878
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	263,018	240,157	277,647
Interest income recognized, Total	7,873	3,894	8,342
Interest income recognized, Cash basis	7,873	3,894	8,342
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	8,699	16,209	29,237
Interest income recognized, Total	1,779	6,419	2,300
Interest income recognized, Cash basis	1,779	6,419	2,300
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	11,467	15,142	19,697
Interest income recognized, Total	3,474	1,001	644
Interest income recognized, Cash basis	3,474	1,001	644
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	129,593	110,646	98,394
Interest income recognized, Total	8,386	7,177	6,227
Interest income recognized, Cash basis	3,456	3,406	3,154
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	82,854	93,097	103,060
Interest income recognized, Total	6,118	5,981	5,999
Interest income recognized, Cash basis	1,723	1,607	1,975
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	48,591	47,323	36,493
Interest income recognized, Total	1,698	1,681	1,325
Interest income recognized, Cash basis	289	400	410
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	1,849	1,041	2,549
Interest income recognized, Total	333	212	147
Interest income recognized, Cash basis	9	9	49
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	9,262	15,045	19,636
Interest income recognized, Total	690	1,025	1,242
Interest income recognized, Cash basis	69	81	99
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average recorded investment	4,413	2,322	6,669
Interest income recognized, Total	230	96	293
Interest income recognized, Cash basis	$ 13	$ 2	$ 34

Allowance for Credit Losses - S

Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 88,466,477	$ 87,988,983
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	22,977,976	21,742,651
Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	21,693,705	20,490,486
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,049,848	1,011,174
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	234,423	240,991
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	25,610,365	25,288,943
Commercial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	24,539,706	24,380,184
Commercial [Member] | Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	866,987	723,777
Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	203,672	184,982
Residential Builder and Developer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,690,309	1,631,718
Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,546,002	1,485,148
Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	139,509	140,119
Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	4,798	6,451
Other Commercial Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,062,882	6,445,712
Other Commercial Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	6,890,562	6,270,812
Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	150,115	164,812
Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 22,205	$ 10,088

Allowance for Credit Losses - A

Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum delinquency period for loan level collectability analysis consumer mortgage	150 days
Residential Mortgage Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of loans for which partial charge-off has been recognized	$ 29	$ 34
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount	21	20
Home Equity Loans and Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of loans for which partial charge-off has been recognized	23	25
Mortgage loans on real real estate not requiring charge off due to collateral carrying amount	$ 31	$ 32

Allowance for Credit Losses -_3

Allowance for Credit Losses - Allocation of Allowance for Credit Losses on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 79,646	$ 75,762
Allowance for credit losses	849,356	853,276
Allowance for credit losses	1,019,444	1,017,198	$ 988,997	$ 955,992
Purchased Impaired [Member] | Receivables Acquired with Deteriorated Credit Quality [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	12,397	9,860
Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	941,399	938,898
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	78,045	78,300	$ 78,030	$ 78,199
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	46,034	45,488
Allowance for credit losses	284,021	283,111
Commercial, Financial, Leasing, etc. [Member] | Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	330,055	328,599
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	13,039	10,095
Allowance for credit losses	328,616	363,990
Commercial Real Estate [Member] | Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	341,655	374,085
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	8,402	7,900
Allowance for credit losses	48,326	47,645
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	12,397	9,860
Residential Real Estate [Member] | Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	69,125	65,405
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	12,171	12,279
Allowance for credit losses	188,393	158,530
Consumer Loans [Member] | Allocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for credit losses	$ 200,564	$ 170,809

Allowance for Credit Losses - R

Allowance for Credit Losses - Recorded Investment in Loans and Leases on Basis of Company's Impairment Methodology (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 88,466,477	$ 87,988,983
Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	796,451	760,309
Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	87,366,721	86,818,659
Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	303,305	410,015
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	22,977,976	21,742,651
Commercial, Financial, Leasing, etc. [Member] | Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	258,985	266,376
Commercial, Financial, Leasing, etc. [Member] | Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	22,718,991	21,476,254
Commercial, Financial, Leasing, etc. [Member] | Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount		21
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	34,363,556	33,366,373
Commercial Real Estate [Member] | Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	254,476	226,205
Commercial Real Estate [Member] | Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	34,098,670	33,117,512
Commercial Real Estate [Member] | Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	10,410	22,656
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	17,154,446	19,613,344
Residential Real Estate [Member] | Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	220,140	202,163
Residential Real Estate [Member] | Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,641,411	19,023,843
Residential Real Estate [Member] | Purchased Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	292,895	387,338
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	13,970,499	13,266,615
Consumer Loans [Member] | Individually Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	62,850	65,565
Consumer Loans [Member] | Collectively Evaluated for Impairment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 13,907,649	$ 13,201,050

Premises and Equipment - Summar

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Land	$ 97,082	$ 98,077
Buildings	465,482	454,610
Leasehold improvements	240,731	239,956
Premises and equipment, gross	1,491,659	1,487,347
Less: accumulated depreciation and amortization	844,251	840,896
Premises and equipment, net	647,408	646,451
Owned Assets [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	669,782	676,665
Less: accumulated depreciation and amortization	835,218	830,832
Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	18,582	18,039
Less: accumulated depreciation and amortization	$ 9,033	$ 10,064

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment Capitalized Interest Costs [Abstract]
Net lease expense for all operating leases	$ 110,703,000	$ 114,362,000	$ 113,663,000

Capitalized Servicing Assets -

Capitalized Servicing Assets - Changes in Capitalized Servicing Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Residential Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	$ 114,978	$ 117,351	$ 118,303
Originations	28,985	28,792	28,618
Purchases	454	699	638
Amortization	(23,908)	(31,864)	(30,208)
Amortized value, ending balance	120,509	114,978	117,351
Ending balance, net	120,509	114,978	117,351
Commercial Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	114,076	103,764	83,692
Originations	26,298	34,620	40,117
Amortization	(25,711)	(24,308)	(20,045)
Amortized value, ending balance	114,663	114,076	103,764
Ending balance, net	$ 114,663	$ 114,076	$ 103,764

Capitalized Servicing Assets _2

Capitalized Servicing Assets - Additional Information (Detail) - USD ($) $ in Millions	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Residential Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others		$ 22,200	$ 22,600	$ 22,200	$ 22,600	$ 22,800
Fair value of residential loan servicing assets		$ 240	$ 234	$ 240	$ 234
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets		11.40%	12.20%
Residential Mortgage Loans [Member] | LIBOR [Member]
Servicing Assets at Fair Value [Line Items]
Discounted rate represented weighted-average option-adjusted basis spread point percentage				9.63%	10.67%
Residential Mortgage Sub Servicing Loan [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others		$ 56,800	$ 56,600	$ 56,800	$ 56,600	30,400
Residential Real Estate Loans [Member] | Subsequent Event [Member]
Servicing Assets at Fair Value [Line Items]
Fair value of residential loan servicing assets	$ 13,300
Purchase price of servicing rights	$ 146
Commercial Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others		15,500	13,600	15,500	13,600	$ 11,800
Fair value of residential loan servicing assets		$ 135	$ 132	$ 135	132
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets		18.00%	18.00%	18.00%
Commercial Mortgage Sub Servicing Loan [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others		$ 2,700	$ 2,600	$ 2,700	$ 2,600

Capitalized Servicing Assets _3

Capitalized Servicing Assets - Economic Assumptions Used to Determine Fair Value of Capitalized Servicing Rights and Sensitivity of Value to Changes in Assumptions (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018
Residential Mortgage Loans [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted-average prepayment speeds			10.99%
Impact on fair value of 10% adverse change	$ (9,327)		$ (9,327)
Impact on fair value of 20% adverse change	$ (17,925)		$ (17,925)
Weighted-average OAS	9.63%		9.63%
Impact on fair value of 10% adverse change	$ (6,758)		$ (6,758)
Impact on fair value of 20% adverse change	$ (13,135)		$ (13,135)
Weighted-average discount rate	11.40%	12.20%
Commercial Mortgage Loans [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted-average discount rate	18.00%	18.00%	18.00%
Impact on fair value of 10% adverse change	$ (6,029)		$ (6,029)
Impact on fair value of 20% adverse change	$ (11,626)		$ (11,626)

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Total Amortizing Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,070,027	$ 1,070,027
Accumulated Amortization	1,022,960	998,438
Net Carrying Amount	47,067	71,589
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	887,459	887,459
Accumulated Amortization	843,572	820,110
Net Carrying Amount	43,887	67,349
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	182,568	182,568
Accumulated Amortization	179,388	178,328
Net Carrying Amount	$ 3,180	$ 4,240

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Other Intangible Assets [Line Items]
Amortization of core deposit and other intangible assets	$ 24,522,000	$ 31,366,000	$ 42,613,000
Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	5 years
Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	10 years
Core Deposit and Other Intangible Assets [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	8 years
Amortization of core deposit and other intangible assets	$ 24,522,000	$ 31,366,000	$ 42,613,000
Core Deposit and Other Intangible Assets [Member] | Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	5 years
Core Deposit and Other Intangible Assets [Member] | Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	10 years

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Estimated Amortization Expense in Future Years (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2,019	$ 19,086
2,020	14,383
2,021	9,681
2,022	3,917
Net Carrying Amount	$ 47,067	$ 71,589

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets - Summary of Goodwill Assigned to Reportable Segments for Purposes of Testing for Impairment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill	$ 4,593,112	$ 4,593,112
Business Banking [Member]
Goodwill [Line Items]
Goodwill	864,366
Commercial Banking [Member]
Goodwill [Line Items]
Goodwill	1,401,873
Commercial Real Estate [Member]
Goodwill [Line Items]
Goodwill	654,389
Retail Banking [Member]
Goodwill [Line Items]
Goodwill	1,309,191
All Other [Member]
Goodwill [Line Items]
Goodwill	$ 363,293

Borrowings - Amounts and Intere

Borrowings - Amounts and Interest Rates of Short-term Borrowings (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	2.58%	0.92%	0.32%
Daily-average amount outstanding	$ 330,665,000	$ 204,623,000	$ 893,822,000
Weighted-average interest rate	1.63%	0.74%	0.41%
Federal funds purchased and short term borrowings	$ 4,398,378,000	$ 175,099,000	$ 163,442,000
Federal Funds Purchased and Repurchase Agreements [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	1.68%	0.92%	0.32%
Highest amount at a month-end	$ 2,654,416,000	$ 204,977,000	$ 225,940,000
Daily-average amount outstanding	$ 261,200,000	$ 188,459,000	$ 203,853,000
Weighted-average interest rate	1.49%	0.69%	0.28%
Federal Funds Purchased and Repurchase Agreements	$ 198,378,000	$ 175,099,000	$ 163,442,000
Other Short-term Borrowings [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	2.63%
Highest amount at a month-end	$ 4,200,000,000	1,500,000,000	1,974,013,000
Daily-average amount outstanding	$ 69,465,000	$ 16,164,000	$ 689,969,000
Weighted-average interest rate	2.16%	1.27%	0.44%
Other Short-term Borrowings	$ 4,200,000,000

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Short-term borrowings	$ 4,398,378,000	$ 175,099,000	$ 163,442,000
Minimum contractual interest rates of long-term agreements to repurchase securities	4.09%	4.09%
Maximum contractual interest rates of long-term agreements to repurchase securities	4.58%	4.58%
Weighted-average contractual interest rates of long term agreements to repurchase securities	4.31%	4.31%
Repurchase dates of the long-term agreements outstanding	2,020
Collateral posted	$ 428,000,000	$ 442,000,000
Debt Maturity, Start Year	Jan. 1, 2027
Debt Maturity, End Year	Dec. 31, 2033
Minimum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	3.39%	2.23%
Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	5.69%	4.71%
FHLBs Facility [Member]
Debt Instrument [Line Items]
Borrowing facilities available with FHLB's amount	$ 18,800,000,000
Federal Reserve Bank of New York [Member]
Debt Instrument [Line Items]
Line of credit facility	$ 13,700,000,000
Senior Notes Issued in July 2018 [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	2.51%
Variable Rate Senior Notes [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures		2.05%
Weighted-average variable rates payable	2.96%
Variable Rate Senior Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	2.76%
Variable Rate Senior Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	3.25%
Long-term Fixed Rate Advances From FHLB [Member]
Debt Instrument [Line Items]
Advances from the FHLB maturity date	2,035
Long-term Fixed Rate Advances From FHLB [Member] | Minimum [Member]
Debt Instrument [Line Items]
Variable contractual interest rate of long-term debt	1.97%
Long-term Fixed Rate Advances From FHLB [Member] | Maximum [Member]
Debt Instrument [Line Items]
Variable contractual interest rate of long-term debt	5.98%
Long-term Fixed Rate Advances From FHLB [Member] | Weighted Average [Member]
Debt Instrument [Line Items]
Variable contractual interest rate of long-term debt	2.06%
Subordinated Capital Notes [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument	3.72%	2.78%
Subordinated Variable Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument	3.38%	2.12%
Wilmington Due Two Zero One Eight [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument	8.50%	8.50%
Debt maturity date	2,018	2,018
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Weighted-average variable rates payable	3.94%	2.83%
Short-term Borrowings [Member]
Debt Instrument [Line Items]
Stated maturity	1 year
Short-term Borrowings [Member] | FHLB [Member] | Maturity Date, January 1, 2019 [Member]
Debt Instrument [Line Items]
Short-term borrowings	$ 3,000,000,000
Short-term Borrowings [Member] | FHLB [Member] | Maturity Date, February 1, 2019 [Member]
Debt Instrument [Line Items]
Short-term borrowings	$ 1,200,000,000
Short-term Borrowings 3.0 Billion [Member]
Debt Instrument [Line Items]
Short-term borrowings, maturity date	Jan. 1, 2019
Short-term Borrowings 1.2 Billion [Member]
Debt Instrument [Line Items]
Short-term borrowings, maturity date	Feb. 1, 2019

Borrowings - Lines of Credit Un

Borrowings - Lines of Credit Under Formal Agreements (Detail) - M&T Bank [Member] $ in Thousands	Dec. 31, 2018USD ($)
Schedule Of Borrowings [Line Items]
Outstanding borrowings	$ 4,776,510
Unused	$ 27,637,030

Borrowings - Long-term Borrowin

Borrowings - Long-term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Borrowings [Line Items]
Fixed rates advances from FHLB	$ 576,446	$ 576,876
Agreements to repurchase securities	409,154	421,771
Other	35,174	9,635
Long-term borrowings	8,444,914	8,141,430
Variable Rate Term Loans Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	249,688
Variable Rate Term Loans Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	349,794
3.55% Fixed Rate Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	506,021
Variable Rate Term Loans Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	249,658	249,558
Fixed Rate Term Loans 1.45% Due 2018 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount		499,907
Fixed Rate Term Loans 2.25% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	645,801	644,977
Fixed Rate Term Loans 2.30% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount		746,919
Fixed Rate Term Loans 2.05% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	737,793	739,961
Fixed Rate Term Loans 2.10% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	741,965	743,788
Fixed Rate Term Loans 2.625% Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	646,301
Fixed Rate Term Loans 2.50% Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	634,525	638,872
Fixed Rate Term Loans 2.90% Due 2025 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,488	749,404
8.5% due 2018 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes		200,000
Variable Rate Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	409,361	409,361
Variable Rate Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	500,000	500,000
3.40% due 2027 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	481,692	491,176
BSB Capital Trust I - 8.125%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	15,705	15,682
Provident Trust I - 8.29%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	27,489	26,847
Southern Financial Statutory Trust I - 10.60%, due 2030 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	6,713	6,664
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	147,333	146,794
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	149,280	148,617
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	96,785	96,640
BSB Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	15,464	15,464
Provident Statutory Trust III - Due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	55,143	54,466
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	$ 8,141	$ 8,051

Borrowings - Long-term Borrow_2

Borrowings - Long-term Borrowings (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Variable Rate Term Loans Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,023	2,023
Variable Rate Term Loans Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,021	2,021
3.55% Fixed Rate Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,023	2,023
Interest rate of debt instrument	3.55%	3.55%
Variable Rate Term Loans Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,022	2,022
Fixed Rate Term Loans 1.45% Due 2018 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,018	2,018
Interest rate of debt instrument	1.45%	1.45%
Fixed Rate Term Loans 2.25% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,019	2,019
Interest rate of debt instrument	2.25%	2.25%
Fixed Rate Term Loans 2.30% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,019	2,019
Interest rate of debt instrument	2.30%	2.30%
Fixed Rate Term Loans 2.10% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,020	2,020
Interest rate of debt instrument	2.10%	2.10%
Fixed Rate Term Loans 2.05% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,020	2,020
Interest rate of debt instrument	2.05%	2.05%
Fixed Rate Term Loans 2.625% Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,021	2,021
Interest rate of debt instrument	2.625%	2.625%
Fixed Rate Term Loans 2.90% Due 2025 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,025	2,025
Interest rate of debt instrument	2.90%	2.90%
Fixed Rate Term Loans 2.50% Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,022	2,022
Interest rate of debt instrument	2.50%	2.50%
8.5% due 2018 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,018	2,018
Interest rate of debt instrument	8.50%	8.50%
Variable Rate Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,020	2,020
Variable Rate Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,021	2,021
3.40% due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,027	2,027
Interest rate of debt instrument	3.40%	3.40%
BSB Capital Trust I - 8.125%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,028	2,028
Interest rate of debt instrument	8.125%	8.125%
Provident Trust I - 8.29%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,028	2,028
Interest rate of debt instrument	8.29%	8.29%
Southern Financial Statutory Trust I - 10.60%, due 2030 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,030	2,030
Interest rate of debt instrument	10.60%	10.60%
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,027	2,027
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,027	2,027
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,029	2,029
BSB Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,033	2,033
Provident Statutory Trust III - Due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,033	2,033
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2,033	2,033

Borrowings - Maturity of Long-t

Borrowings - Maturity of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2,019	$ 1,525,057
2,020	1,994,450
2,021	1,522,796
2,022	891,731
2,023	755,710
Later years	1,755,170
Long-term borrowings	$ 8,444,914	$ 8,141,430

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Equity [Abstract]
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, par value	$ 1	$ 1

Shareholders' Equity - Issued a

Shareholders' Equity - Issued and Outstanding Preferred Stock (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
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 E Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, Shares Issued	350,000	350,000
Preferred stock, Shares Outstanding	350,000	350,000
Carrying Value	$ 350,000	$ 350,000
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, Shares Issued	50,000	500,000
Preferred stock, Shares Outstanding	50,000	500,000
Carrying Value	$ 500,000	$ 500,000

Shareholders' Equity - Issued_2

Shareholders' Equity - Issued and Outstanding Preferred Stock (Parenthetical) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Series A Warrants [Member]
Class of Stock [Line Items]
Warrants and rights outstanding	257,630	374,786
Exercise of warrants into shares of common stock	136,676	204,133
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%
Warrants, date of expiration	Dec. 23, 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
Preferred stock dividend rate	6.375%
Series E Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Preferred stock dividend rate	6.45%	6.45%
Date of change in the dividend rate	Feb. 14, 2024	Feb. 14, 2024
London Interbank offered rate plus basis points	3.61%	3.61%
Preferred shares redemption date	Feb. 15, 2024	Feb. 15, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	5.125%	5.125%
Date of change in the dividend rate	Oct. 31, 2026	Oct. 31, 2026
London Interbank offered rate plus basis points	3.52%	3.52%
Preferred shares redemption date	Nov. 1, 2026	Nov. 1, 2026
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Uncollected amounts receivable	$ 56
Accrued interest and other liabilities [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue	43
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Expense recognized on credit card rewards in other costs of operations	$ 14	$ 13	$ 6

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Additional Information (Detail1)	Dec. 31, 2018
Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2018-01-01
Disaggregation Of Revenue [Line Items]
Period of satisfaction of contract with customer	1 year

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Summary of Sources of Company's Noninterest Income that are Subject to the Amended Guidance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 51,069	$ 61,445	$ 63,423
Other revenues from operations:
Total other income	1,856,000	1,851,143	1,825,996
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	429,337	427,372	419,102
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	537,585	$ 501,381	$ 472,184
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	51,069
Other revenues from operations:
Merchant discount and credit card fees	105,953
Other	90,369
Total other income	1,214,313
ASU 2014-09 [Member] | Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	34,557
Total other income	96,889
ASU 2014-09 [Member] | Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	52,051
Other	8,796
Total other income	158,171
ASU 2014-09 [Member] | Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	2,213
Other	7,259
Total other income	19,342
ASU 2014-09 [Member] | Discretionary Portfolio [Member]
Other revenues from operations:
Other	1,738
Total other income	1,738
ASU 2014-09 [Member] | Residential Mortgage Banking [Member]
Other revenues from operations:
Other	3,814
Total other income	3,824
ASU 2014-09 [Member] | Retail Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	14,924
Other	38,529
Total other income	308,043
ASU 2014-09 [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	51,069
Other revenues from operations:
Merchant discount and credit card fees	2,208
Other	30,233
Total other income	626,306
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	429,337
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member] | Business Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	62,323
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member] | Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	96,407
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member] | Commercial Real Estate [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	9,870
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member] | Residential Mortgage Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	10
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member] | Retail Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	254,590
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	6,137
ASU 2014-09 [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	537,585
ASU 2014-09 [Member] | Trust Income [Member] | Business Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	9
ASU 2014-09 [Member] | Trust Income [Member] | Commercial Banking [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	917
ASU 2014-09 [Member] | Trust Income [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 536,659

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 66,000,000	$ 61,000,000	$ 65,000,000
Recognized income tax benefits related to stock-based compensation	$ 24,000,000	$ 35,000,000	$ 31,000,000
Shares under equity incentive compensation plan for future grant	2,833,428	3,278,036
Stock Options Outstanding, Granted	116,852
Directors Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	6,271	7,505
Shares issued in connection with deferred compensation plans	269,373
Deferred Bonus Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	18,292	19,633
Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	58,167	66,504	97,880
Common stock authorized for issuance	2,500,000
Cash received from exercise of stock options	$ 9,987,000	$ 9,730,000	$ 9,528,000
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years	3 years	3 years	4 years
Unrecognized compensation cost expected to be recognized over a weighted-average period (in years)	1 year
Unrecognized compensation cost related to non-vested awards	$ 5,000,000
Shares issued	0	181,939	218,341
Restricted Stock Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value		$ 29,557,000	$ 24,085,000
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost related to non-vested awards	$ 18,000,000
Shares issued	348,512	235,983	348,297
Weighted-average grant date fair value	$ 66,050,000	$ 38,364,000	$ 38,795,000
Stock Option Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years	4 years
Stock options exercisable period, maximum	10 years 1 day
Cash realized from exercise of stock options	$ 60,000,000	$ 72,000,000	172,000,000
Tax benefits realized from exercise of stock options	3,000,000	10,000,000	15,000,000
Intrinsic value of stock options exercised	$ 16,000,000	$ 31,000,000	$ 42,000,000

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans - Summary of Restricted Stock and Restricted Stock Unit Activity (Detail)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance | shares	482,557
Restricted Stock Outstanding, Granted | shares	348,512
Restricted Stock Outstanding, Vested | shares	(265,027)
Restricted Stock Outstanding, Cancelled | shares	(9,167)
Restricted Stock Outstanding, Unvested, Ending balance | shares	556,875
Weighted-Average Grant Price, Unvested, Beginning balance | $ / shares	$ 133.05
Weighted-Average Grant Price, Granted | $ / shares	189.52
Weighted-Average Grant Price, Vested | $ / shares	127.39
Weighted-Average Grant Price, Cancelled | $ / shares	194.45
Weighted-Average Grant Price, Unvested, Ending balance | $ / shares	$ 170.07
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance | shares	373,744
Restricted Stock Outstanding, Vested | shares	(182,905)
Restricted Stock Outstanding, Cancelled | shares	(11,400)
Restricted Stock Outstanding, Unvested, Ending balance | shares	179,439
Weighted-Average Grant Price, Unvested, Beginning balance | $ / shares	$ 135.41
Weighted-Average Grant Price, Vested | $ / shares	126.60
Weighted-Average Grant Price, Cancelled | $ / shares	138.52
Weighted-Average Grant Price, Unvested, Ending balance | $ / shares	$ 144.18

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options Outstanding, Beginning balance | shares	665,412
Stock Options Outstanding, Granted | shares	116,852
Stock Options Outstanding, Exercised | shares	(535,724)
Stock Options Outstanding, Expired | shares	(25,949)
Stock Options Outstanding, Ending balance | shares	220,591
Stock Options Outstanding, Exercisable | shares	103,725
Weighted-Average Exercise Price, Outstanding, Beginning balance | $ / shares	$ 152.23
Weighted-Average Exercise Price, Granted | $ / shares	190.78
Weighted-Average Exercise Price, Exercised | $ / shares	154.91
Weighted-Average Exercise Price, Expired | $ / shares	221.81
Weighted-Average Exercise Price, Outstanding, Ending balance | $ / shares	157.98
Weighted-Average Exercise Price, Exercisable | $ / shares	$ 121.11
Weighted-Average Life (In Years), Outstanding, Ending balance	5 years 3 months 18 days
Weighted-Average Life (In Years), Exercisable	5 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding, Ending balance | $	$ 2,739
Aggregate Intrinsic Value, Exercisable | $	$ 2,737

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefits - Net Periodic Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 20,346	$ 20,193	$ 25,037
Interest cost on benefit obligation	74,704	79,270	83,410
Expected return on plan assets	(123,127)	(108,524)	(108,473)
Amortization of prior service cost (credit)	557	557	(3,228)
Recognized net actuarial (gain) loss	43,793	29,263	30,145
Net periodic benefit cost	16,273	20,759	26,891
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	938	1,172	1,595
Interest cost on benefit obligation	2,293	3,716	4,971
Amortization of prior service cost (credit)	(4,729)	(1,359)	(1,359)
Recognized net actuarial (gain) loss	(826)	(988)	60
Net periodic benefit cost	$ (2,324)	$ 2,541	$ 5,267

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefits - Data Relating to Funding Position of Defined Benefit Plans (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in plan assets:
Fair value of plan assets at beginning of year	$ 2,013,117,000
Employer contributions	0	$ 200,000,000	$ 0
Fair value of plan assets at end of year	1,831,773,000	2,013,117,000
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	2,188,736,000	2,007,158,000
Service cost	20,346,000	20,193,000	25,037,000
Interest cost	74,704,000	79,270,000	83,410,000
Actuarial (gain) loss	(228,897,000)	172,180,000
Benefits paid	(105,276,000)	(90,065,000)
Benefit obligation at end of year	1,949,613,000	2,188,736,000	2,007,158,000
Change in plan assets:
Fair value of plan assets at beginning of year	2,014,891,000	1,642,131,000
Actual return on plan assets	(90,657,000)	251,381,000
Employer contributions	14,875,000	211,444,000
Benefits paid	(105,276,000)	(90,065,000)
Fair value of plan assets at end of year	1,833,833,000	2,014,891,000	1,642,131,000
Funded status	(115,780,000)	(173,845,000)
Accrued liabilities recognized in the consolidated balance sheet	(115,780,000)	(173,845,000)
Net loss (gain)	401,716,000	460,622,000
Net prior service cost (credit)	2,391,000	2,948,000
Pre-tax adjustment to AOCI	404,107,000	463,570,000
Taxes	(106,240,000)	(121,873,000)
Net adjustment to AOCI	297,867,000	341,697,000
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	68,637,000	109,922,000
Service cost	938,000	1,172,000	1,595,000
Interest cost	2,293,000	3,716,000	4,971,000
Plan participants’ contributions	2,974,000	2,929,000
Amendments and curtailments		(30,088,000)
Actuarial (gain) loss	(4,758,000)	(8,511,000)
Medicare Part D reimbursement	508,000	630,000
Benefits paid	(10,601,000)	(11,133,000)
Benefit obligation at end of year	59,991,000	68,637,000	$ 109,922,000
Change in plan assets:
Employer contributions	7,119,000	7,574,000
Plan participants’ contributions	2,974,000	2,929,000
Medicare Part D reimbursement	508,000	630,000
Benefits paid	(10,601,000)	(11,133,000)
Funded status	(59,991,000)	(68,637,000)
Accrued liabilities recognized in the consolidated balance sheet	(59,991,000)	(68,637,000)
Net loss (gain)	(17,868,000)	(13,936,000)
Net prior service cost (credit)	(31,737,000)	(36,466,000)
Pre-tax adjustment to AOCI	(49,605,000)	(50,402,000)
Taxes	13,041,000	13,251,000
Net adjustment to AOCI	$ (36,564,000)	$ (37,151,000)

Pension Plans and Other Postr_5

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Minimum pension liability	$ 354,502,000
Minimum pension liability adjustment net of tax	$ 261,303,000
Decrease in minimum liability adjustment		$ 58,666,000
Discount rate	4.25%	3.50%
Defined contribution pension and retirement savings plans total expense	$ 29,000,000	$ 30,000,000	$ 25,000,000
Assumptions used calculating net periodic benefit sensitivity rate increase decrease discount rate	0.25%
Effect of 25 basis point increase in rate of return on pension expense	$ 5,000,000
Effect of 25 basis point decrease in rate of return on pension expense	7,000,000
Effect of 25 basis point decrease in discount rate on benefit obligation	62,000,000
Effect of 25 basis point increase in discount rate on benefit obligation	$ 65,000,000
Annual rate of increase in health care cost assumed for next fiscal year	6.25%
Defined Benefit Plan, ultimate health care cost trend rate	5.00%
Period for decreasing the annual rate	over ten years
Defined benefit pension plans	$ 361,178,000
Percentage of total assets	20.00%
Defined benefit plan fair value of plan assets	$ 1,831,773,000	2,013,117,000
Qualified benefit pension plans	$ 0	0
Percentage of pension plan assets that is not exceeded by investment in security of single Non-US Government of Government agency	10.00%
Employer contributions	$ 0	200,000,000	0
Percentage of eligible employees contribution for Retirement Savings Plan	50.00%
Percentage of employer matching contribution to employee's contribution	75.00%
Maximum employer contribution on Employee's qualified contribution	4.50%
Qualified defined contribution plans expense during the period	$ 42,897,000	38,229,000	36,776,000
Equity Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	25.00%
Equity Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	60.00%
Total Debt Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	10.00%
Total Debt Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	65.00%
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 361,178,000	304,463,000
Other Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	10.00%
Other Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	85.00%
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 125,299,000	$ 154,818,000
Percentage of common stock in total plan assets	7.00%	8.00%
Supplemental Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 143,406,000	$ 165,210,000
Accumulated benefit obligation	143,406,000	165,210,000
Employer contributions	14,875,000	11,444,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	1,949,613,000	2,188,736,000	2,007,158,000
Accumulated benefit obligation	1,925,741,000	$ 2,158,601,000
Minimum pension liability	$ 404,107,000
Discount rate	4.25%	3.50%
Defined benefit plan fair value of plan assets	$ 1,833,833,000	$ 2,014,891,000	1,642,131,000
Employer contributions	14,875,000	211,444,000
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	59,991,000	$ 68,637,000	$ 109,922,000
Minimum pension liability	$ 49,605,000
Discount rate	4.25%	3.50%
Employer contributions	$ 7,119,000	$ 7,574,000

Pension Plans and Other Postr_6

Pension Plans and Other Postretirement Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss (gain)	$ (19,871)	$ 20,812
Amendments and curtailments		(30,088)
Amortization of prior service (cost) credit	4,172	802	$ 4,587
Amortization of actuarial (loss) gain	(42,967)	(28,275)	$ (30,205)
Total recognized in other comprehensive income, pre-tax	(58,666)	(36,749)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss (gain)	(15,113)	29,323
Amortization of prior service (cost) credit	(557)	(557)
Amortization of actuarial (loss) gain	(43,793)	(29,263)
Total recognized in other comprehensive income, pre-tax	(59,463)	(497)
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss (gain)	(4,758)	(8,511)
Amendments and curtailments		(30,088)
Amortization of prior service (cost) credit	4,729	1,359
Amortization of actuarial (loss) gain	826	988
Total recognized in other comprehensive income, pre-tax	$ 797	$ (36,252)

Pension Plans and other Postr_7

Pension Plans and other Postretirement Benefits - Amortization of Amounts in Accumulated Other Comprehensive Income Expected to be Recognized as Components of Net Periodic Benefit Expense (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Amortization of net prior service cost (credit)	$ 557
Amortization of net loss (gain)	17,755
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Amortization of net prior service cost (credit)	(4,730)
Amortization of net loss (gain)	$ 1,168

Pension Plans and Other Postr_8

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Benefit Obligations (Detail)	Dec. 31, 2018	Dec. 31, 2017
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.25%	3.50%
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.25%	3.50%
Rate of increase in future compensation levels	4.31%	4.33%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.25%	3.50%

Pension Plans and Other Postr_9

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Net Benefit Expense (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.50%	4.00%	4.25%
Long-term rate of return on plan assets	6.50%	6.50%	6.50%
Rate of increase in future compensation levels	4.33%	4.39%	4.37%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.50%	4.00%	4.25%

Pension Plans and Other Post_10

Pension Plans and Other Postretirement Benefits - Effects on One-Percentage Point Change in Assumed Health Care Cost Trend Rates (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Compensation And Retirement Disclosure [Abstract]
Service and interest cost	$ 55
Accumulated postretirement benefit obligation	1,204
Service and interest cost	(50)
Accumulated postretirement benefit obligation	$ (1,094)

Pension Plans and Other Post_11

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 1,831,773,000	$ 2,013,117,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,373,040,000	1,532,836,000
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	300,101,000	382,853,000
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	158,632,000	97,428,000
Money-Market Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	23,049,000	117,648,000
Money-Market Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	10,794,000	62,706,000
Money-Market Investments [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	12,255,000	54,942,000
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	858,137,000	1,019,639,000
Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	858,137,000	1,019,639,000
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	125,299,000	154,818,000
M&T Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	125,299,000	154,818,000
Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	191,640,000	240,763,000
Domestic Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	191,640,000	240,763,000
International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	7,752,000	13,349,000
International Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	7,752,000	13,349,000
Domestic Mutual Fund Equity securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	216,523,000	205,509,000
Domestic Mutual Fund Equity securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	216,523,000	205,509,000
International Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	316,923,000	405,200,000
International Mutual Fund Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	316,923,000	405,200,000
Total Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	589,409,000	571,367,000
Total Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	301,563,000	243,456,000
Total Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	287,846,000	327,911,000
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	103,672,000	89,751,000
Corporate Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	103,672,000	89,751,000
Government Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	182,034,000	235,984,000
Government Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	182,034,000	235,984,000
International Debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	2,140,000	2,176,000
International Debt securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	2,140,000	2,176,000
Domestic Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	280,902,000	243,456,000
Domestic Mutual Fund Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	280,902,000	243,456,000
International Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	20,661,000
International Mutual Fund Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	20,661,000
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	361,178,000	304,463,000
Other Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	202,546,000	207,035,000
Other Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	158,632,000	97,428,000
Other Diversified Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	74,446,000	80,227,000
Other Diversified Mutual Fund [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	74,446,000	80,227,000
Other Real Estate Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	11,807,000	3,747,000
Other Real Estate Partnerships [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	2,791,000	842,000
Other Real Estate Partnerships [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	9,016,000	2,905,000
Other Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	63,699,000	31,484,000
Other Private Equity [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	63,699,000	31,484,000
Other Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	200,811,000	178,080,000
Other Hedge Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	125,309,000	125,966,000
Other Hedge Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	75,502,000	52,114,000
Guaranteed Deposit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	10,415,000	10,925,000
Guaranteed Deposit Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 10,415,000	$ 10,925,000

Pension Plans and Other Post_12

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Interest and dividend receivable on plan assets	$ 2,060,000	$ 1,774,000
Investment Grade Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in mutual funds	77.00%	77.00%
High-Yielding Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in mutual funds	23.00%	23.00%

Pension Plans and Other Post_13

Pension Plans and Other Postretirement Benefits - Changes in Level 3 Pension Plan Assets Measured at Fair Value on Recurring Basis (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	$ 2,013,117
Fair value of plan assets at end of year	1,831,773
Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	97,428
Fair value of plan assets at end of year	158,632
Other Real Estate Partnerships [Member] | Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	2,905
Purchase(Sales)	4,717
Total Realized/Unrealized Gains (Losses)	1,394
Fair value of plan assets at end of year	9,016
Other Private Equity [Member] | Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	31,484
Purchase(Sales)	30,396
Total Realized/Unrealized Gains (Losses)	1,819
Fair value of plan assets at end of year	63,699
Other Hedge Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	52,114
Purchase(Sales)	19,971
Total Realized/Unrealized Gains (Losses)	3,417
Fair value of plan assets at end of year	75,502
Guaranteed Deposit Fund [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	10,925
Fair value of plan assets at end of year	10,415
Guaranteed Deposit Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	10,925
Total Realized/Unrealized Gains (Losses)	(510)
Fair value of plan assets at end of year	10,415
Other Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	304,463
Fair value of plan assets at end of year	361,178
Other Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	97,428
Purchase(Sales)	55,084
Total Realized/Unrealized Gains (Losses)	6,120
Fair value of plan assets at end of year	$ 158,632

Pension Plans and Other Post_14

Pension Plans and Other Postretirement Benefits - Defined Benefit Plan Estimated Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2,019	$ 94,427
2,020	99,361
2,021	103,502
2,022	106,270
2,023	110,753
2024 through 2028	600,961
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2,019	7,108
2,020	6,975
2,021	4,284
2,022	4,196
2,023	4,108
2024 through 2028	$ 19,065

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal	$ 408,428	$ 363,043	$ 428,750
State and local	113,706	94,714	95,426
Total current	522,134	457,757	524,176
Deferred
Federal	(12,780)	367,308	147,662
State and local	28,637	33,482	26,351
Total deferred	15,857	400,790	174,013
Amortization of investments in qualified affordable housing projects	52,169	57,009	45,095
Income taxes	$ 590,160	$ 915,556	$ 743,284

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2018USD ($)State	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Income Tax Disclosure [Line Items]
Tax bad debt reserve		$ 137,121,000
Income taxes attributable to gains or losses on bank investment securities		$ (1,628,000)	$ 7,195,000	$ 11,925,000
Alternative minimum tax expense recognized for gains or losses on bank investment securities			$ 0	$ 0
Federal income tax rate		21.00%	35.00%
Incremental income tax expense related to Tax Act	$ 85,000,000
Reduction in income tax expense due to reduction of federal tax rate		$ 15,000,000
Number of state and local jurisdictions where company files income tax returns | State		40
ASU 2016-09 [Member]
Income Tax Disclosure [Line Items]
New accounting pronouncement or change in accounting principle effect of adoption change in income tax expense (benefit)		$ (9,000,000)	$ (22,000,000)

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Taxes Expenses Benefit Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income taxes at statutory federal income tax rate	$ 526,730	$ 813,352	$ 720,439
Increase (decrease) in taxes:
Tax-exempt income	(26,186)	(40,778)	(35,364)
State and local income taxes, net of federal income tax effect	112,451	83,327	79,155
Qualified affordable housing project federal tax credits, net	(12,240)	(16,015)	(15,091)
Initial impact of enactment of Tax Act		85,431
Other	(10,595)	(9,761)	(5,855)
Income taxes	$ 590,160	$ 915,556	$ 743,284

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Losses on loans and other assets	$ 322,818	$ 345,609	$ 590,288
Retirement benefits	30,057	45,322	143,067
Postretirement and other employee benefits	23,563	26,009	52,512
Incentive and other compensation plans	24,796	25,050	36,616
Interest on loans		37,900	61,266
Stock-based compensation	26,759	26,676	52,181
Unrealized losses	52,580		10,741
Other	43,880	66,247	106,876
Gross deferred tax assets	524,453	572,813	1,053,547
Leasing transactions	(186,787)	(181,159)	(266,268)
Unrealized gains		(94,285)
Capitalized servicing rights	(54,894)	(51,781)	(71,108)
Depreciation and amortization	(61,881)	(52,733)	(63,959)
Interest on loans	(18,920)
Other	(28,350)	(21,599)	(87,200)
Gross deferred tax liabilities	(350,832)	(401,557)	(488,535)
Net deferred tax asset	$ 173,621	$ 171,256	$ 565,012

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal, State and Local Tax [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 45,432	$ 35,889	$ 24,537
Increases as a result of tax positions taken during the period	13,426	13,019	12,237
Decreases as a result of settlements with taxing authorities	(664)	(332)
Decreases as a result of tax positions taken in prior years	(1,920)	(3,144)	(885)
Ending Balance	56,274	45,432	35,889
Accrued Interest [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	5,651	7,915	7,969
Increases as a result of tax positions taken in prior years	1,969	1,379	656
Decreases as a result of settlements with taxing authorities	(289)	(168)
Decreases as a result of tax positions taken in prior years	(702)	(3,475)	(710)
Ending Balance	6,629	5,651	7,915
Unrecognized Income Tax Benefits [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	51,083	43,804	32,506
Increases as a result of tax positions taken during the period	13,426	13,019	12,237
Increases as a result of tax positions taken in prior years	1,969	1,379	656
Decreases as a result of settlements with taxing authorities	(953)	(500)
Decreases as a result of tax positions taken in prior years	(2,622)	(6,619)	(1,595)
Ending Balance	62,903	$ 51,083	$ 43,804
Less: Federal, state and local income tax benefits	(13,209)
Net unrecognized tax benefits that, if recognized, would impact the effective income tax rate	$ 49,694

Earnings Per Common Share - Com

Earnings Per Common Share - Computations of Basic Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income available to common shareholders:
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Less: Preferred stock dividends	(72,521)	(72,734)	(81,270)
Net income available to common equity	1,845,559	1,335,572	1,233,844
Less: Income attributable to unvested stock-based compensation awards	(9,531)	(8,069)	(10,385)
Net income available to common shareholders	$ 1,836,028	$ 1,327,503	$ 1,223,459
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	144,740	153,092	158,121
Less: Unvested stock-based compensation awards	(748)	(933)	(1,341)
Weighted-average shares outstanding	143,992	152,159	156,780
Basic earnings per common share	$ 12.75	$ 8.72	$ 7.80

Earnings Per Common Share - C_2

Earnings Per Common Share - Computations of Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income available to common equity	$ 1,845,559	$ 1,335,572	$ 1,233,844
Less: Income attributable to unvested stock-based compensation awards	(9,524)	(8,055)	(10,363)
Net income available to common shareholders	$ 1,836,035	$ 1,327,517	$ 1,223,481
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	144,740	153,092	158,121
Less: Unvested stock-based compensation awards	(748)	(933)	(1,341)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	159	392	524
Adjusted weighted-average shares outstanding	144,151	152,551	157,304
Diluted earnings per common share	$ 12.74	$ 8.70	$ 7.78

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	194,000	401,000	2,171,000

Comprehensive Income - Addition

Comprehensive Income - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Federal income tax rate	21.00%	35.00%

Comprehensive Income - Impact o

Comprehensive Income - Impact of Reclassification from AOCI to Retained Earnings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings	$ 17,000	$ 64,029
Net Unrealized Losses on Investment Securities [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings		8,065
Defined Benefit Plans Liability Adjustments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings		53,960
Cash Flow Hedges and Other [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Increase to retained earnings		$ 2,004

Comprehensive Income - Componen

Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (493,290)	$ (485,245)	$ (414,545)
Cumulative effect of change in accounting principles — equity securities, before tax	(22,795)
Unrealized holding gains (losses), net, before tax	(121,589)	(15,005)	(79,950)
Foreign currency translation adjustment, before tax	(2,817)	4,447	(4,020)
Unrealized losses on cash flow hedges, before tax	(4,965)	(12,291)
Current year benefit plans gains, before tax	19,871	9,276	14,125
Total other comprehensive income (loss) before reclassifications, before tax	(109,500)	(13,573)	(69,845)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax	4,252	3,387	3,996
Gains realized in net income, before tax	(18)	(21,279)	(30,314)
Accretion of net gain (losses) on terminated cash flow hedges, before tax	(111)	(137)	(155)
Net yield adjustment from cash flow hedges currently in effect, before tax	13,339	(3,916)
Amortization of prior service credit, before tax	(4,172)	(802)	(4,587)
Amortization of actuarial losses, before tax	42,967	28,275	30,205
Total other comprehensive income (loss), before tax	(53,243)	(8,045)	(70,700)
Ending balance, before tax	(569,328)	(493,290)	(485,245)
Beginning balance, tax	129,476	190,609	162,918
Cumulative effect of change in accounting principles — equity securities, tax	5,942
Unrealized holding gains (losses), net, tax	31,946	7,269	31,509
Foreign currency translation adjustment, tax	592	(2,206)	1,406
Unrealized losses on cash flow hedges, tax	1,306	4,837
Current year benefit plans gains, tax	(5,224)	(3,650)	(5,557)
Total other comprehensive income (loss) before reclassifications, tax	28,620	6,250	27,358
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, tax	(1,118)	(1,333)	(1,572)
Gains realized in net income, tax	4	7,195	11,925
Accretion of net gain on terminated cash flow hedges, tax	29	54	61
Net yield adjustment from cash flow hedges currently in effect, tax	(3,507)	1,541
Amortization of prior service credit, tax	1,097	315	1,805
Amortization of actuarial losses, tax	(11,296)	(11,126)	(11,886)
Total other comprehensive income (loss), tax	13,829	2,896	27,691
Reclassification of income tax effects to retained earnings, tax		(64,029)
Ending balance, tax	149,247	129,476	190,609
Beginning balance, net of tax	(363,814)	(294,636)	(251,627)
Cumulative effect of change in accounting principle — equity securities	(16,853)
Unrealized holding gains (losses), net of tax	(89,643)	(7,736)	(48,441)
Foreign currency translation adjustment	(2,225)	2,241	(2,614)
Unrealized losses on cash flow hedges, net of tax	(3,659)	(7,454)
Current year benefit plans gains, net of tax	14,647	5,626	8,568
Total other comprehensive income (loss) before reclassifications, net of tax	(80,880)	(7,323)	(42,487)
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, net of tax	3,134	2,054	2,424
Gains realized in net income, net of tax	(14)	(14,084)	(18,389)
Accretion of net gain on terminated cash flow hedges, net of tax	(82)	(83)	(94)
Net yield adjustment from cash flow hedges currently in effect, net of tax	9,832	(2,375)
Amortization of prior service credit, net of tax	(3,075)	(487)	(2,782)
Amortization of actuarial losses, net of tax	31,671	17,149	18,319
Total other comprehensive loss	(39,414)	(5,149)	(43,009)
Reclassification of income tax effects to retained earnings, net of tax		(64,029)
Ending balance, net of tax	(420,081)	(363,814)	(294,636)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(59,957)
Cumulative effect of change in accounting principles — equity securities, before tax	(22,795)
Unrealized holding gains (losses), net, before tax	(121,589)
Total other comprehensive income (loss) before reclassifications, before tax	(121,589)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax	4,252
Gains realized in net income, before tax	(18)
Total other comprehensive income (loss), before tax	(117,355)
Ending balance, before tax	(200,107)	(59,957)
Cumulative effect of change in accounting principle — equity securities	(16,853)
Total other comprehensive loss	(86,523)	(19,766)	(64,406)
Reclassification of income tax effects to retained earnings, net of tax		8,065
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(413,168)	(449,917)	(489,660)
Current year benefit plans gains, before tax	19,871	9,276	14,125
Total other comprehensive income (loss) before reclassifications, before tax	19,871	9,276	14,125
Amortization of prior service credit, before tax	(4,172)	(802)	(4,587)
Amortization of actuarial losses, before tax	42,967	28,275	30,205
Total other comprehensive income (loss), before tax	58,666	36,749	39,743
Ending balance, before tax	(354,502)	(413,168)	(449,917)
Total other comprehensive loss	43,243	22,288	24,105
Reclassification of income tax effects to retained earnings, net of tax		53,960
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(20,165)	(8,268)	(4,093)
Foreign currency translation adjustment, before tax	(2,817)	4,447	(4,020)
Unrealized losses on cash flow hedges, before tax	(4,965)	(12,291)
Total other comprehensive income (loss) before reclassifications, before tax	(7,782)	(7,844)	(4,020)
Accretion of net gain (losses) on terminated cash flow hedges, before tax	(111)	(137)	(155)
Net yield adjustment from cash flow hedges currently in effect, before tax	13,339	(3,916)
Total other comprehensive income (loss), before tax	5,446	(11,897)	(4,175)
Ending balance, before tax	(14,719)	(20,165)	(8,268)
Investment Securities With OTTI [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	19,628	46,725	16,359
Unrealized holding gains (losses), net, before tax		(8,746)	30,366
Total other comprehensive income (loss) before reclassifications, before tax		(8,746)	30,366
Gains realized in net income, before tax		(18,351)
Total other comprehensive income (loss), before tax		(27,097)	30,366
Ending balance, before tax		19,628	46,725
Investment Securities All Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (79,585)	(73,785)	62,849
Unrealized holding gains (losses), net, before tax		(6,259)	(110,316)
Total other comprehensive income (loss) before reclassifications, before tax		(6,259)	(110,316)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax		3,387	3,996
Gains realized in net income, before tax		(2,928)	(30,314)
Total other comprehensive income (loss), before tax		(5,800)	(136,634)
Ending balance, before tax		$ (79,585)	$ (73,785)

Comprehensive Income - Accumula

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 16,250,819	$ 16,486,622	$ 16,173,289
Net gain (loss) during period	(39,414)	(5,149)	(43,009)
Reclassification of income tax effects to retained earnings		64,029
Cumulative effect of change in accounting principle — equity securities	(16,853)
Ending balance	15,460,191	16,250,819	16,486,622
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(44,150)	(16,319)	48,087
Net gain (loss) during period	(86,523)	(19,766)	(64,406)
Reclassification of income tax effects to retained earnings		(8,065)
Cumulative effect of change in accounting principle — equity securities	(16,853)
Ending balance	(147,526)	(44,150)	(16,319)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(304,546)	(272,874)	(296,979)
Net gain (loss) during period	43,243	22,288	24,105
Reclassification of income tax effects to retained earnings		(53,960)
Ending balance	(261,303)	(304,546)	(272,874)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(15,118)	(5,443)	(2,735)
Net gain (loss) during period	3,866	(7,671)	(2,708)
Reclassification of income tax effects to retained earnings		(2,004)
Ending balance	(11,252)	(15,118)	(5,443)
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(363,814)	(294,636)	(251,627)
Net gain (loss) during period	(39,414)	(5,149)	(43,009)
Reclassification of income tax effects to retained earnings		(64,029)
Cumulative effect of change in accounting principle — equity securities	(16,853)
Ending balance	$ (420,081)	$ (363,814)	$ (294,636)

Other Income and Other Expens_2

Other Income and Other Expense - Other Income and Other Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other income:
Credit-related fee income	$ 82,614	$ 77,580	$ 70,424
Other expense:
Professional services	312,998	$ 289,862	$ 268,060
Wilmington Trust Corporation [Member]
Other expense:
Accrual for Wilmington Trust Corporation legal-related matters	$ 135,000

International Activities - Addi

International Activities - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
International Activities [Line Items]
Revenues from international trust-related services	$ 29,000	$ 24,000	$ 25,000
Loans to foreign borrowers	87,447,033	86,971,785
Deposits at foreign office	811,906	177,996
Cayman Islands [Member]
International Activities [Line Items]
Deposits at foreign office	812	178
Canada [Member]
International Activities [Line Items]
Deposits at foreign office	22,000	45,000
Geographic Distribution, Foreign [Member]
International Activities [Line Items]
Loans to foreign borrowers	$ 172,000	$ 159,000
Geographic Concentration Risk [Member] | Assets, Total [Member]
International Activities [Line Items]
Concentration risk percentage	1.00%
Geographic Concentration Risk [Member] | Sales Revenue, Net [Member]
International Activities [Line Items]
Concentration risk percentage	1.00%

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 19,850,000,000	$ 9,400,000,000
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	18,000,000	16,000,000
Aggregate fair value of derivative financial instruments in a liability position	21,000,000	13,000,000
Aggregate fair value of derivative financial instruments in asset position	18,000,000	13,000,000
Collateral relating to net asset positions	16,000,000	12,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	18,000,000	12,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	65,000,000	52,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	(25,000,000)	25,000,000	$ 37,000,000
Notional amounts of derivative contracts entered into for trading account purposes	19,850,000,000
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	42,900,000,000	29,900,000,000
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	763,000,000	$ 530,000,000
Credit Risk Derivative [Member]
Derivative [Line Items]
Fair value of additional collateral to be posted for derivative financial instruments	$ 0

Derivative Financial Instrume_4

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 19,850,000,000	$ 9,400,000,000
Average Maturity (in years)	1 year 8 months 12 days	2 years 6 months
Estimated Fair Value Gain	$ 5,530,000	$ 639,000
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 15,400,000,000	$ 4,850,000,000
Average Maturity (in years)	1 year 3 months 18 days	2 years
Weighted-Average Rate, Fixed	1.52%	1.52%
Weighted-Average Rate, Variable	2.35%	1.36%
Estimated Fair Value Gain	$ 1,311,000	$ 66,000
Fixed Rate Long-Term Borrowings [Member] | Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 4,450,000,000	$ 4,550,000,000
Average Maturity (in years)	2 years 9 months 18 days	2 years 10 months 24 days
Weighted-Average Rate, Fixed	2.47%	2.27%
Weighted-Average Rate, Variable	3.02%	2.09%
Estimated Fair Value Gain	$ 4,219,000	$ 573,000

Derivative Financial Instrume_5

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional Amount	$ 19,850,000,000	$ 9,400,000,000
Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount		2,000,000,000
Fair Value Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value losses on hedging instruments	54,700,000	41,100,000
Cash Flow Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value losses on hedging instruments	9,100,000	$ 16,300,000
Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	$ 12,600,000,000

Derivative Financial Instrume_6

Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Total	$ 19,850,000,000	$ 9,400,000,000
Interest Rate Swap Agreements [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
2,019	3,500,000,000
2,020	11,200,000,000
2,021	3,500,000,000
2,022	650,000,000
2,023	500,000,000
2,027	500,000,000
Total	$ 19,850,000,000

Derivative Financial Instrume_7

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 148,862	$ 92,517
Liability Derivatives, Fair Value	190,686	139,186
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	142,242	91,144
Liability Derivatives, Fair Value	184,252	138,903
Fair Value Hedges [Member] | Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	6,620	1,373
Liability Derivatives, Fair Value	6,434	283
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	5,530	639
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	3,702	2,526
Liability Derivatives, Fair Value	4,535	1,019
Commitments to Sell Real Estate Loans [Member] | Fair Value Hedges [Member] | Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,090	734
Liability Derivatives, Fair Value	6,434	283
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	9,304	8,797
Liability Derivatives, Fair Value	1,592	494
Interest Rate Contracts [Member] | Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	118,687	74,164
Liability Derivatives, Fair Value	169,255	132,104
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	10,549	5,657
Liability Derivatives, Fair Value	$ 8,870	$ 5,286

Derivative Financial Instrume_8

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ 170.7	$ 136.2
Reduction in estimated fair value of interest rate contracts in liability position	$ 49.7	$ 12.2

Derivative Financial Instrume_9

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 13,922	$ 12,219	$ 21,707
Interest Rate Swap Agreements [Member] | Fixed Rate Long-Term Borrowings [Member] | Derivatives Designated and Qualifying as Hedging Instruments [Member] | Fair Value Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, Derivatives	(10,006)	(52,392)	(32,000)
Derivatives in fair value hedging relationships, Hedged item	10,969	51,628	30,906
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	4,506	5,398	14,042
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 9,416	$ 6,821	$ 7,665

Derivative Financial Instrum_10

Derivative Financial Instruments - Information about Hedged Items Included in Consolidated Balance Sheet (Detail) - Long-term Debt [Member] - Derivatives Designated and Qualifying as Hedging Instruments [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 4,394,109	$ 4,504,029
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ (51,102)	$ (40,133)

Variable Interest Entities - Ad

Variable Interest Entities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity Disclosure [Abstract]
Loss on securitization of assets	$ 0	$ 0	$ 0
Other assets for its "investment" in the common securities recognized by the company of various trusts	23,000,000	23,000,000
Total assets of partnerships in which the company invested	1,100,000,000	1,000,000,000
Maximum exposure to loss of investments in real estate partnerships	523,000,000	420,000,000
Unfunded commitments included in company's maximum exposure to loss of investments in real estate partnerships	$ 280,000,000	$ 201,000,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	$ 185,584	$ 132,909
Investment securities	8,682,509	10,896,284
U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	1,336,931	1,947,487
Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	1,659	2,589
Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	7,216,991	8,716,392
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	126,906	128,832
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	185,584	132,909
Investment securities	8,682,509	10,896,284
Equity securities	93,917	100,956
Real estate loans held for sale	551,697	378,047
Other assets	19,626	12,696
Total assets	9,533,333	11,419,936
Trading account liabilities	178,125	137,390
Other liabilities	12,561	1,796
Total liabilities	190,686	139,186
Fair Value Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	46,018	47,873
Investment securities		73,232
Equity securities	71,989	73,232
Total assets	118,007	121,105
Fair Value Measurements, Recurring [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	139,566	85,036
Investment securities	8,682,487	10,823,024
Equity securities	21,928	27,724
Real estate loans held for sale	551,697	378,047
Other assets	10,322	3,899
Total assets	9,406,000	11,290,006
Trading account liabilities	178,125	137,390
Other liabilities	10,969	1,302
Total liabilities	189,094	138,692
Fair Value Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	22	28
Other assets	9,304	8,797
Total assets	9,326	8,825
Other liabilities	1,592	494
Total liabilities	1,592	494
Fair Value Measurements, Recurring [Member] | U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	1,336,931	1,947,487
Fair Value Measurements, Recurring [Member] | U.S. Treasury and Federal Agencies [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	1,336,931	1,947,487
Fair Value Measurements, Recurring [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	1,659	2,589
Fair Value Measurements, Recurring [Member] | Obligations of States and Political Subdivisions [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	1,659	2,589
Fair Value Measurements, Recurring [Member] | Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	7,216,991	8,716,392
Fair Value Measurements, Recurring [Member] | Government Issued or Guaranteed [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	7,216,991	8,716,392
Fair Value Measurements, Recurring [Member] | Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	22	28
Fair Value Measurements, Recurring [Member] | Privately Issued Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	22	28
Fair Value Measurements, Recurring [Member] | Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	126,906	128,832
Fair Value Measurements, Recurring [Member] | Other Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 126,906	$ 128,832

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - Fair Value Measurements, Recurring [Member] - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 28	$ 44	$ 74
Total gains (losses) realized/unrealized:
Settlements	(6)	(16)	(30)
Ending Balance	22	28	44
Other Assets and Other Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	8,303	7,325	9,879
Total gains (losses) realized/unrealized:
Included in earnings	58,740	77,832	110,937
Transfers out of Level 3	(59,331)	(76,854)	(113,491)
Ending Balance	7,712	8,303	7,325
Changes in unrealized gains included in earnings related to assets still held at end of period	$ 7,386	$ 7,978	7,256
Collateralized Debt Obligations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance			47,393
Total gains (losses) realized/unrealized:
Included in earnings			30,041
Included in other comprehensive income			(18,268)
Settlements			(870)
Sales			$ (58,296)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input [Extensible List]	us-gaap:MeasurementInputComparabilityAdjustmentMember
Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations	10.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations	85.00%
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value of nonrecurring fair value measured loans for charge-offs and impairment reserves	$ 83	$ 56	$ 71
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	268	210	293
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	28	53
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	120	145	153
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	$ 148	$ 65	$ 140

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Privately Issued Mortgage-Backed Securities [Member] | Two Independent Pricing Quotes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements for certain Level 3 Assets and Liabilities	$ 22	$ 28
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements for certain Level 3 Assets and Liabilities	$ 7,712	$ 8,303
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	95.00%	78.00%
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	13.00%	22.00%

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial assets:
Interest-bearing deposits at banks	$ 8,105,197	$ 5,078,903
Trading account assets	185,584	132,909
Investment securities	12,692,813	14,664,525
Loans and leases:
Residential real estate loans	17,150,658	19,619,259
Consumer loans	13,956,086	13,251,665
Allowance for credit losses	(1,019,444)	(1,017,198)	$ (988,997)	$ (955,992)
Loans and leases, net	87,447,033	86,971,785
Financial liabilities:
Noninterest-bearing deposits	(32,256,668)	(33,975,180)
Savings and interest-checking deposits	(50,963,744)	(51,698,008)
Time deposits	(6,124,254)	(6,580,962)
Deposits at Cayman Islands office	(811,906)	(177,996)
Long-term borrowings	(8,444,914)	(8,141,430)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,605,439	1,420,888
Interest-bearing deposits at banks	8,105,197	5,078,903
Trading account assets	185,584	132,909
Investment securities	12,692,813	14,664,525
Loans and leases:
Commercial loans and leases	22,977,976	21,742,651
Commercial real estate loans	34,363,556	33,366,373
Residential real estate loans	17,154,446	19,613,344
Consumer loans	13,970,499	13,266,615
Allowance for credit losses	(1,019,444)	(1,017,198)
Loans and leases, net	87,447,033	86,971,785
Accrued interest receivable	353,965	327,170
Financial liabilities:
Noninterest-bearing deposits	(32,256,668)	(33,975,180)
Savings and interest-checking deposits	(50,963,744)	(51,698,008)
Time deposits	(6,124,254)	(6,580,962)
Deposits at Cayman Islands office	(811,906)	(177,996)
Short-term borrowings	(4,398,378)	(175,099)
Long-term borrowings	(8,444,914)	(8,141,430)
Accrued interest payable	(95,274)	(75,641)
Trading account liabilities	(178,125)	(137,390)
Other financial instruments:
Commitments to originate real estate loans for sale	7,712	8,303
Commitments to sell real estate loans	(6,177)	1,958
Other credit-related commitments	(131,688)	(125,281)
Interest rate swap agreements used for interest rate risk management	5,530	639
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,605,439	1,420,888
Interest-bearing deposits at banks	8,105,197	5,078,903
Trading account assets	185,584	132,909
Investment securities	12,631,656	14,653,074
Loans and leases:
Commercial loans and leases	22,587,387	21,321,282
Commercial real estate loans	33,832,558	32,950,724
Residential real estate loans	16,974,545	19,596,826
Consumer loans	13,819,545	13,161,517
Loans and leases, net	87,214,035	87,030,349
Accrued interest receivable	353,965	327,170
Financial liabilities:
Noninterest-bearing deposits	(32,256,668)	(33,975,180)
Savings and interest-checking deposits	(50,963,744)	(51,698,008)
Time deposits	(6,201,957)	(6,635,048)
Deposits at Cayman Islands office	(811,906)	(177,996)
Short-term borrowings	(4,398,378)	(175,099)
Long-term borrowings	(8,385,289)	(8,193,783)
Accrued interest payable	(95,274)	(75,641)
Trading account liabilities	(178,125)	(137,390)
Other financial instruments:
Commitments to originate real estate loans for sale	7,712	8,303
Commitments to sell real estate loans	(6,177)	1,958
Other credit-related commitments	(131,688)	(125,281)
Interest rate swap agreements used for interest rate risk management	5,530	639
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,528,302	1,352,035
Trading account assets	46,018	47,873
Investment securities	71,989	73,232
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member] | Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	77,137	68,853
Interest-bearing deposits at banks	8,105,197	5,078,903
Trading account assets	139,566	85,036
Investment securities	12,456,467	14,469,127
Loans and leases:
Commercial real estate loans	346,775	22,130
Residential real estate loans	3,920,447	4,440,645
Loans and leases, net	4,267,222	4,462,775
Accrued interest receivable	353,965	327,170
Financial liabilities:
Noninterest-bearing deposits	(32,256,668)	(33,975,180)
Savings and interest-checking deposits	(50,963,744)	(51,698,008)
Time deposits	(6,201,957)	(6,635,048)
Deposits at Cayman Islands office	(811,906)	(177,996)
Short-term borrowings	(4,398,378)	(175,099)
Long-term borrowings	(8,385,289)	(8,193,783)
Accrued interest payable	(95,274)	(75,641)
Trading account liabilities	(178,125)	(137,390)
Other financial instruments:
Commitments to sell real estate loans	(6,177)	1,958
Interest rate swap agreements used for interest rate risk management	5,530	639
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	103,200	110,715
Loans and leases:
Commercial loans and leases	22,587,387	21,321,282
Commercial real estate loans	33,485,783	32,928,594
Residential real estate loans	13,054,098	15,156,181
Consumer loans	13,819,545	13,161,517
Loans and leases, net	82,946,813	82,567,574
Other financial instruments:
Commitments to originate real estate loans for sale	7,712	8,303
Other credit-related commitments	$ (131,688)	$ (125,281)

Commitments and Contingencies -

Commitments and Contingencies - Company's Significant Commitments (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Commitments to extend credit
Home equity lines of credit	$ 5,484,197	$ 5,482,622
Commercial real estate loans to be sold	229,401	194,763
Other commercial real estate	7,556,722	6,050,569
Residential real estate loans to be sold	245,211	347,113
Other residential real estate	219,351	201,426
Commercial and other	14,363,803	12,733,815
Standby letters of credit	2,326,991	2,497,844
Commercial letters of credit	55,808	46,739
Financial guarantees and indemnification contracts	3,529,136	3,434,381
Commitments to sell real estate loans	$ 940,692	$ 812,217

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers		$ 8,600,000,000	$ 8,100,000,000
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program		$ 3,400,000,000	$ 3,300,000,000
Period of noncancelable operating lease in years		23 years
Increase in litigation reserve	$ 135,000,000
Payment of legal settlement expense	$ 200,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses		$ 0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses		$ 50,000,000

Commitments and Contingencies_3

Commitments and Contingencies - Minimum Lease Payments Under Noncancellable Operating Leases (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,019	$ 89,547
2,020	82,536
2,021	67,985
2,022	54,504
2,023	39,578
Later years	104,280
Total	$ 438,430

Segment Information - Informati

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net interest income	$ 4,072,302	$ 3,781,044	$ 3,469,887
Noninterest income	1,856,000	1,851,143	1,825,996
Total income	5,928,302	5,632,187	5,295,883
Provision for credit losses	132,000	168,000	190,000
Amortization of core deposit and other intangible assets	24,522	31,366	42,613
Depreciation and other amortization	154,483	165,759	157,978
Other noninterest expense	3,109,057	2,943,200	2,846,894
Income before taxes	2,508,240	2,323,862	2,058,398
Income tax expense (benefit)	590,160	915,556	743,284
Net income	1,918,080	1,408,306	1,315,114
Average total assets	116,959,000	120,860,000	124,340,000
Capital expenditures	98,000	79,000	108,000
All Other [Member]
Segment Reporting Information [Line Items]
Net interest income	557,542	410,928	221,151
Noninterest income	651,439	609,945	570,475
Total income	1,208,981	1,020,873	791,626
Provision for credit losses	(8,128)	8,265	(3,910)
Amortization of core deposit and other intangible assets	23,462	30,306	42,613
Depreciation and other amortization	68,004	69,923	68,541
Other noninterest expense	1,125,428	1,019,465	892,625
Income before taxes	215	(107,086)	(208,243)
Income tax expense (benefit)	(54,766)	(40,752)	(144,498)
Net income	54,981	(66,334)	(63,745)
Average total assets	13,877,000	13,684,000	16,885,000
Capital expenditures	65,000	44,000	62,000
Business Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	434,579	393,948	371,889
Noninterest income	111,600	112,512	108,783
Total income	546,179	506,460	480,672
Provision for credit losses	10,916	15,598	12,709
Depreciation and other amortization	382	393	404
Other noninterest expense	305,340	294,493	292,124
Income before taxes	229,541	195,976	175,435
Income tax expense (benefit)	61,279	80,043	71,677
Net income	168,262	115,933	103,758
Average total assets	5,631,000	5,602,000	5,456,000
Commercial Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	821,812	809,301	785,339
Noninterest income	288,908	283,447	274,923
Total income	1,110,720	1,092,748	1,060,262
Provision for credit losses	8,976	11,876	34,903
Depreciation and other amortization	496	509	520
Other noninterest expense	364,102	339,936	327,616
Income before taxes	737,146	740,427	697,223
Income tax expense (benefit)	198,229	303,556	285,844
Net income	538,917	436,871	411,379
Average total assets	26,626,000	26,573,000	25,592,000
Commercial Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	665,220	649,378	608,385
Noninterest income	183,955	169,966	179,706
Total income	849,175	819,344	788,091
Provision for credit losses	3,159	(7,524)	(3,447)
Amortization of core deposit and other intangible assets	1,060	1,060
Depreciation and other amortization	25,852	24,410	20,120
Other noninterest expense	217,387	207,493	204,965
Income before taxes	601,717	593,905	566,453
Income tax expense (benefit)	148,807	229,770	216,095
Net income	452,910	364,135	350,358
Average total assets	22,885,000	22,741,000	21,131,000
Capital expenditures		1,000
Discretionary Portfolio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	228,051	277,095	345,926
Noninterest income	(9,690)	23,851	26,075
Total income	218,361	300,946	372,001
Provision for credit losses	6,683	31,119	32,925
Depreciation and other amortization	187	279	472
Other noninterest expense	65,393	76,021	95,300
Income before taxes	146,098	193,527	243,304
Income tax expense (benefit)	29,872	58,559	79,766
Net income	116,226	134,968	163,538
Average total assets	32,123,000	37,203,000	40,867,000
Capital expenditures	1,000
Residential Mortgage Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	13,933	30,328	29,809
Noninterest income	305,560	321,589	342,858
Total income	319,493	351,917	372,667
Provision for credit losses	(2,178)	1,254	(3,617)
Depreciation and other amortization	24,288	32,011	30,264
Other noninterest expense	241,624	247,639	258,141
Income before taxes	55,759	71,013	87,879
Income tax expense (benefit)	10,272	25,446	32,426
Net income	45,487	45,567	55,453
Average total assets	2,161,000	2,355,000	2,569,000
Capital expenditures	1,000
Retail Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	1,351,165	1,210,066	1,107,388
Noninterest income	324,228	329,833	323,176
Total income	1,675,393	1,539,899	1,430,564
Provision for credit losses	112,572	107,412	120,437
Depreciation and other amortization	35,274	38,234	37,657
Other noninterest expense	789,783	758,153	776,123
Income before taxes	737,764	636,100	496,347
Income tax expense (benefit)	196,467	258,934	201,974
Net income	541,297	377,166	294,373
Average total assets	13,656,000	12,702,000	11,840,000
Capital expenditures	$ 31,000	$ 34,000	$ 46,000

Segment Information - Informa_2

Segment Information - Information about Company's Segments (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Taxable-equivalent adjustment	$ 21,897,000	$ 34,570,000	$ 26,962,000

Segment Information - Intersegm

Segment Information - Intersegment Activity Eliminated in Arriving at Consolidated Totals was Included in "All Other" Category (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 5,928,302	$ 5,632,187	$ 5,295,883
Income taxes (benefit)	590,160	915,556	743,284
Net income (loss)	1,918,080	1,408,306	1,315,114
Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Revenues	(41,285)	(43,941)	(48,625)
Expenses	(24,660)	(32,623)	(40,422)
Income taxes (benefit)	(4,371)	(4,606)	(3,338)
Net income (loss)	$ (12,254)	$ (6,712)	$ (4,865)

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Percent of maximum revenue from single customer on total revenues	10.00%

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail) - USD ($)	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Funds available for payment of dividends to M&T from banking subsidiaries		$ 669,000,000
Required subsidiary noninterest-earning reserves against certain deposit liabilities		$ 683,740,000	$ 679,401,000
Capital conservation buffer		1.875%	1.25%
Subsequent Event [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital conservation buffer	2.50%

Regulatory Matters - Summary of

Regulatory Matters - Summary of Required Minimum and Well Capitalized Capital Ratios (Detail)	Dec. 31, 2018
Banking And Thrift [Abstract]
Common equity Tier 1 ("CET1") to risk-weighted assets, Minimum	4.50%
Tier 1 capital to risk-weighted assets, Minimum	6.00%
Total capital to risk-weighted assets, Minimum	8.00%
Leverage — Tier 1 capital to average total assets, as defined, Minimum	4.00%
Common equity Tier 1 ("CET1") to risk-weighted assets, Well Capitalized	6.50%
Tier 1 capital to risk-weighted assets, Well capitalized	8.00%
Total capital to risk-weighted assets, Well capitalized	10.00%
Leverage — Tier 1 capital to average total assets, as defined, Well capitalized	5.00%

Regulatory Matters - Capital Ra

Regulatory Matters - Capital Ratios and Amounts of Company and its Banking Subsidiaries (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio	4.50%
Ratio	6.00%
Ratio	8.00%
M&T Bank Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 9,960,811	$ 10,675,735
Ratio	10.13%	10.99%
Amount	$ 11,193,770	$ 11,908,166
Ratio	11.38%	12.26%
Amount	$ 13,454,137	$ 14,328,467
Ratio	13.68%	14.75%
Amount	$ 11,193,770	$ 11,908,166
Ratio	9.88%	10.31%
M&T Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 10,636,136	$ 9,978,163
Ratio	10.84%	10.30%
Amount	$ 10,636,136	$ 9,978,163
Ratio	10.84%	10.30%
Amount	$ 12,475,296	$ 12,012,171
Ratio	12.72%	12.40%
Amount	$ 10,636,136	$ 9,978,163
Ratio	9.42%	8.68%
Wilmington Trust, N.A. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 585,767	$ 529,988
Ratio	60.69%	48.16%
Amount	$ 585,767	$ 529,988
Ratio	60.69%	48.16%
Amount	$ 589,671	$ 534,235
Ratio	61.10%	48.54%
Amount	$ 585,767	$ 529,988
Ratio	12.51%	13.03%

Relationship with Bayview Len_2

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 8,444,914	$ 8,141,430
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	$ 0
Bayview Lending Group [Member] | Other Revenues From Operations [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	24,000	0	$ (11,000)
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	2,500,000	3,000,000
Revenue from contract with customer	14,000	17,000	19,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	56,800,000	56,600,000
Revenues from sub-servicing	114,000	103,000	$ 98,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	113,000	$ 136,000
Bayview Financial [Member] | Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	900,000
Bayview Financial [Member] | Syndicated Loan Facility [Member] | M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 127,000

Parent Company Financial Stat_3

Parent Company Financial Statements - Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments in consolidated subsidiaries
Total assets	$ 120,097,403	$ 118,593,487
Liabilities
Long-term borrowings	8,444,914	8,141,430
Total liabilities	104,637,212	102,342,668
Shareholders’ equity	15,460,191	16,250,819	$ 16,486,622	$ 16,173,289
Total liabilities and shareholders’ equity	120,097,403	118,593,487
Parent Company [Member]
Assets
Cash in subsidiary bank	40,609	13,379
Due from consolidated bank subsidiaries
Money-market savings	856,881	1,616,147
Current income tax receivable	1,117	4,437
Total due from consolidated bank subsidiaries	857,998	1,620,584
Investments in consolidated subsidiaries
Banks	15,491,277	14,841,794
Other	324,360	253,904
Investments in trust preferred entities (note 19)	23,241	23,453
Other assets	64,187	66,023
Total assets	16,801,672	16,819,137
Liabilities
Accrued expenses and other liabilities	63,719	49,093
Long-term borrowings	1,277,762	519,225
Total liabilities	1,341,481	568,318
Shareholders’ equity	15,460,191	16,250,819
Total liabilities and shareholders’ equity	$ 16,801,672	$ 16,819,137

Parent Company Financial Stat_4

Parent Company Financial Statements - Condensed Statement of Income (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Expense
Interest on long-term borrowings	$ 248,556	$ 189,372	$ 231,017
Other expense	3,288,062	3,140,325	3,047,485
Income tax credits	(590,160)	(915,556)	(743,284)
Equity in undistributed income of subsidiaries
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Net income per common share
Basic	$ 12.75	$ 8.72	$ 7.80
Diluted	$ 12.74	$ 8.70	$ 7.78
Parent Company [Member]
Income
Dividends from consolidated bank subsidiaries	$ 1,250,000	$ 1,540,000	$ 1,930,000
Equity in earnings of Bayview Lending Group LLC	23,500	352	(10,752)
Other income	2,417	9,493	5,530
Total income	1,275,917	1,549,845	1,924,778
Expense
Interest on long-term borrowings	36,354	21,591	18,963
Other expense	23,894	19,636	21,361
Total expense	60,248	41,227	40,324
Income before income taxes and equity in undistributed income of subsidiaries	1,215,669	1,508,618	1,884,454
Income tax credits	8,446	26,453	17,247
Income before equity in undistributed income of subsidiaries	1,224,115	1,535,071	1,901,701
Equity in undistributed income of subsidiaries
Net income of subsidiaries	1,943,965	1,413,235	1,343,413
Less: dividends received	(1,250,000)	(1,540,000)	(1,930,000)
Equity in undistributed income of subsidiaries	693,965	(126,765)	(586,587)
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Net income per common share
Basic	$ 12.75	$ 8.72	$ 7.80
Diluted	$ 12.74	$ 8.70	$ 7.78

Parent Company Financial Stat_5

Parent Company Financial Statements - Condensed Statement of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 1,918,080	$ 1,408,306	$ 1,315,114
Adjustments to reconcile net income to net cash provided by operating activities
Benefit (provision) for deferred income taxes	15,857	400,790	174,013
Net gain on sales of assets	(23,503)	(53,467)	(63,222)
Net cash provided by operating activities	2,089,852	2,781,935	1,183,411
Cash flows from investing activities
Other, net	47,904	19,825	277,961
Cash flows from financing activities
Purchases of treasury stock	(2,194,396)	(1,205,905)	(641,334)
Dividends paid — common	(510,382)	(457,402)	(441,891)
Dividends paid — preferred	(72,521)	(72,734)	(81,270)
Redemption of Series D preferred stock			(500,000)
Other, net	17,167	10,675	161,691
Proceeds from long-term borrowings	1,773,189	2,145,950
Supplemental disclosure of cash flow information
Interest received during the year	4,568,991	4,155,723	3,903,374
Income taxes received during the year	375,116	494,205	276,866
Parent Company [Member]
Cash flows from operating activities
Net income	1,918,080	1,408,306	1,315,114
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed income of subsidiaries	(693,965)	126,765	586,587
Benefit (provision) for deferred income taxes	4,949	4,543	(3,157)
Net change in accrued income and expense	(8,242)	(170)	12,898
Net gain on sales of assets		(2,995)	(2,342)
Net cash provided by operating activities	1,220,822	1,536,449	1,909,100
Cash flows from investing activities
Proceeds from sales or maturities of investment securities			51
Other, net	29,933	12,407	13,619
Net cash provided by investing activities	29,933	12,407	13,670
Cash flows from financing activities
Purchases of treasury stock	(2,194,396)	(1,205,905)	(641,334)
Dividends paid — common	(510,382)	(457,402)	(441,891)
Dividends paid — preferred	(72,521)	(72,734)	(81,270)
Redemption of Series D preferred stock			(500,000)
Proceeds from issuance of Series F preferred stock			495,000
Other, net	45,913	34,524	143,764
Net cash used by financing activities	(1,982,791)	(1,701,517)	(1,025,731)
Proceeds from long-term borrowings	748,595
Net increase (decrease) in cash and cash equivalents	(732,036)	(152,661)	897,039
Cash and cash equivalents at beginning of year	1,629,526	1,782,187	885,148
Cash and cash equivalents at end of year	897,490	1,629,526	1,782,187
Supplemental disclosure of cash flow information
Interest received during the year	2,219	2,313	1,931
Interest paid during the year	17,482	18,498	15,918
Income taxes received during the year	$ 6,362	$ 21,740	$ 8,877

Recent Accounting Developments

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification from accumulated other comprehensive income to retained earnings	$ 17,000	$ 64,029
ASU 2016-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lessee, operating lease term	12 months
Recognized right of use asset	$ 394,000
Recognizing lease liabilities	$ 399,000