M&T Bank (MTB) 10-K 22 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	M&T BANK CORPORATION
Entity Central Index Key	0000036270
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Public Float			$ 12,939,363,542
Entity Common Stock, Shares Outstanding		128,636,592
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common Stock, $.50 par value
Trading Symbol	MTB
Security Exchange Name	NYSE
Entity File Number	1-9861
Entity Incorporation, State or Country Code	NY
Entity Tax Identification Number	16-0968385
Entity Address, Address Line One	One M&T Plaza
Entity Address, City or Town	Buffalo
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	14203
City Area Code	716
Local Phone Number	635-4000
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference [Text Block]	(1) Portions of the Proxy Statement for the 2021 Annual Meeting of Shareholders of M&T Bank Corporation in Parts II and III.

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets
Cash and due from banks	$ 1,552,743	$ 1,432,805
Interest-bearing deposits at banks	23,663,810	7,190,154
Federal funds sold		3,500
Trading account	1,068,581	470,129
Investment securities (includes pledged securities that can be sold or repledged of $105,136 at December 31, 2020; $200,339 at December 31, 2019)
Available for sale (cost: $4,621,027 at December 31, 2020; $6,258,276 at December 31, 2019)	4,822,606	6,318,776
Held to maturity (fair value: $1,842,281 at December 31, 2020; $2,699,206 at December 31, 2019)	1,748,989	2,656,917
Equity and other securities (cost: $449,008 at December 31, 2020; $487,041 at December 31, 2019)	474,102	521,558
Total investment securities	7,045,697	9,497,251
Loans and leases	98,875,788	91,188,525
Unearned discount	(339,921)	(265,656)
Loans and leases, net of unearned discount	98,535,867	90,922,869
Allowance for credit losses	(1,736,387)	(1,051,071)
Loans and leases, net	96,799,480	89,871,798
Premises and equipment	1,161,558	1,140,924
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	14,165	29,034
Accrued interest and other assets	6,701,959	5,644,050
Total assets	142,601,105	119,872,757
Liabilities
Noninterest-bearing deposits	47,572,884	32,396,407
Savings and interest-checking deposits	67,680,840	54,932,162
Time deposits	3,899,910	5,757,456
Deposits at Cayman Islands office	652,104	1,684,044
Total deposits	119,805,738	94,770,069
Short-term borrowings	59,482	62,363
Accrued interest and other liabilities	2,166,409	2,337,490
Long-term borrowings	4,382,193	6,986,186
Total liabilities	126,413,822	104,156,108
Shareholders' equity
Preferred stock, $1.00 par, 1,000,000 shares authorized; Issued and outstanding: Liquidation preference of $1,000 per share: 350,000 shares at December 31, 2020 and December 31, 2019; Liquidation preference of $10,000 per share: 90,000 shares at December 31, 2020 and December 31, 2019	1,250,000	1,250,000
Common stock, $.50 par, 250,000,000 shares authorized, 159,741,898 shares issued at December 31, 2020 and December 31, 2019	79,871	79,871
Common stock issuable, 18,113 shares at December 31, 2020; 21,534 shares at December 31, 2019	1,344	1,566
Additional paid-in capital	6,617,404	6,593,539
Retained earnings	13,444,428	12,820,916
Accumulated other comprehensive income (loss), net	(63,032)	(206,680)
Treasury stock — common, at cost — 31,426,742 shares at December 31, 2020; 29,174,402 shares at December 31, 2019	(5,142,732)	(4,822,563)
Total shareholders’ equity	16,187,283	15,716,649
Total liabilities and shareholders’ equity	$ 142,601,105	$ 119,872,757

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Pledged securities that can be sold or repledged	$ 105,136	$ 200,339
Investment securities, available for sale, amortized cost	4,621,027	6,258,276
Investment securities, held to maturity, fair value	1,842,281	2,699,206
Equity and other securities, cost	$ 449,008	$ 487,041
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	159,741,898	159,741,898
Common stock issuable, shares	18,113	21,534
Treasury stock, common shares	31,426,742	29,174,402
Series A Series C Series And E Preferred Stock [Member]
Preferred stock, shares issued	350,000	350,000
Preferred stock, shares outstanding	350,000	350,000
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series F And Series G Preferred Stock [Member]
Preferred stock, shares issued	90,000	90,000
Preferred stock, shares outstanding	90,000	90,000
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, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest income
Loans and leases, including fees	$ 3,975,053	$ 4,442,182	$ 4,164,561
Investment securities
Fully taxable	176,469	288,532	323,912
Exempt from federal taxes	183	321	665
Deposits at banks	32,956	141,397	108,182
Other	8,051	7,161	1,391
Total interest income	4,192,712	4,879,593	4,598,711
Interest expense
Savings and interest-checking deposits	146,701	368,003	215,411
Time deposits	66,280	95,426	51,423
Deposits at Cayman Islands office	4,054	21,917	5,633
Short-term borrowings	28	24,741	5,386
Long-term borrowings	109,332	239,242	248,556
Total interest expense	326,395	749,329	526,409
Net interest income	3,866,317	4,130,264	4,072,302
Provision for credit losses	800,000	176,000	132,000
Net interest income after provision for credit losses	3,066,317	3,954,264	3,940,302
Other income
Brokerage services income	47,428	48,922	51,069
Trading account and foreign exchange gains	40,536	62,044	32,547
Gain (loss) on bank investment securities	(9,421)	18,037	(6,301)
Other revenues from operations	470,588	469,320	451,321
Total other income	2,088,444	2,061,679	1,856,000
Other expense
Salaries and employee benefits	1,950,692	1,900,797	1,752,264
Equipment and net occupancy	322,037	324,079	298,828
Outside data processing and software	258,480	229,731	199,025
FDIC assessments	53,803	41,535	68,526
Advertising and marketing	61,904	93,472	85,710
Printing, postage and supplies	39,869	39,893	35,658
Amortization of core deposit and other intangible assets	14,869	19,490	24,522
Other costs of operations	683,586	819,685	823,529
Total other expense	3,385,240	3,468,682	3,288,062
Income before taxes	1,769,521	2,547,261	2,508,240
Income taxes	416,369	618,112	590,160
Net income	1,353,152	1,929,149	1,918,080
Net income available to common shareholders
Basic	1,279,066	1,849,509	1,836,028
Diluted	$ 1,279,068	$ 1,849,511	$ 1,836,035
Net income per common share
Basic	$ 9.94	$ 13.76	$ 12.75
Diluted	$ 9.94	$ 13.75	$ 12.74
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 566,641	$ 457,770	$ 360,442
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	370,788	432,978	429,337
Trust Income [Member]
Other income
Revenue from contract with customer	$ 601,884	$ 572,608	$ 537,585

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Partners Capital [Abstract]
Net income	$ 1,353,152	$ 1,929,149	$ 1,918,080
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	107,222	184,906	(86,523)
Cash flow hedges adjustments	172,787	108,520	6,091
Foreign currency translation adjustments	2,284	1,091	(2,225)
Defined benefit plans liability adjustments	(138,645)	(81,116)	43,243
Total other comprehensive income (loss)	143,648	213,401	(39,414)
Total comprehensive income	$ 1,496,800	$ 2,142,550	$ 1,878,666

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income	$ 1,353,152	$ 1,929,149	$ 1,918,080
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	800,000	176,000	132,000
Depreciation and amortization of premises and equipment	220,598	209,937	104,864
Amortization of capitalized servicing rights	84,821	71,888	49,619
Amortization of core deposit and other intangible assets	14,869	19,490	24,522
Provision for deferred income taxes	(31,291)	57,548	15,857
Asset write-downs	21,014	7,701	24,774
Net (gain) loss on sales of assets	(19,441)	31,526	(23,503)
Net change in accrued interest receivable, payable	(132,252)	30,923	(7,162)
Net change in other accrued income and expense	(418,752)	75,930	13,436
Net change in loans originated for sale	(542,078)	130,230	(150,695)
Net change in trading account assets and liabilities	(561,453)	(382,767)	(11,940)
Net cash provided by operating activities	789,187	2,357,555	2,089,852
Cash flows from investing activities
Proceeds from sales of investment securities Available for sale		107	418
Proceeds from sales of investment securities equity and other	67,036	1,169,876	650,858
Proceeds from maturities of investment securities Available for sale	1,614,557	2,621,603	1,997,263
Proceeds from maturities of investment securities Held to maturity	911,555	1,162,820	478,172
Purchases of investment securities Available for sale	(7,581)	(28,120)	(12,494)
Purchases of investment securities Held to maturity	(11,993)	(495,277)	(444,703)
Purchases of investment securities equity and other	(29,004)	(979,734)	(834,856)
Net increase in loans and leases	(7,231,694)	(2,795,263)	(475,895)
Net increase (decrease) in interest-bearing deposits at banks	(16,473,656)	915,043	(3,026,294)
Capital expenditures, net	(172,289)	(178,049)	(97,676)
Net (increase) decrease in loan servicing advances	(754,823)	(470,078)	307,252
Other, net	67,411	(195,921)	47,904
Net cash provided (used) by investing activities	(22,020,481)	727,007	(1,410,051)
Cash flows from financing activities
Net increase (decrease) in deposits	25,037,167	4,616,082	(2,272,505)
Net increase (decrease) in short-term borrowings	(2,881)	(4,336,015)	4,223,279
Proceeds from long-term borrowings			1,773,189
Payments on long-term borrowings	(2,665,023)	(1,553,493)	(1,459,081)
Purchases of treasury stock	(373,750)	(1,349,785)	(2,194,396)
Dividends paid — common	(568,112)	(552,138)	(510,382)
Dividends paid — preferred	(68,256)	(67,454)	(72,521)
Redemption of Series A and Series C preferred stock		(381,500)
Other, net	(11,413)	(25,393)	17,167
Net cash provided (used) by financing activities	21,347,732	(3,253,696)	(495,250)
Net increase (decrease) in cash, cash equivalents and restricted cash	116,438	(169,134)	184,551
Cash, cash equivalents and restricted cash at beginning of period	1,436,305	1,605,439	1,420,888
Cash, cash equivalents and restricted cash at end of period	1,552,743	1,436,305	1,605,439
Supplemental disclosure of cash flow information
Interest received during the period	4,135,990	4,892,301	4,568,991
Interest paid during the period	372,291	735,787	516,230
Income taxes paid during the period	275,558	320,513	375,116
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	20,646	90,072	72,408
Securitization of residential mortgage loans allocated to Available-for-sale investment securities		5,379	22,448
Securitization of residential mortgage loans allocated to capitalized servicing rights		83	$ 365
Adoption of lease accounting standard - Right-of-use assets		393,877
Adoption of lease accounting standard - Other liabilities		398,810
Additions to right-of-use assets under operating leases	$ 70,754	132,219
Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock		$ 396,000

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	ASU 2016-13 [Member]	Series A And Series C [Member]	Series G Preferred Stock [Member]	Preferred Stock [Member]	Preferred Stock [Member]Series A And Series C [Member]	Preferred Stock [Member]Series G Preferred Stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member]Series G Preferred Stock [Member]	Additional Paid-in Capital [Member]Series A Warrants [Member]	Retained Earnings [Member]	Retained Earnings [Member]ASU 2016-13 [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]	Treasury Stock [Member]Series A Warrants [Member]
Beginning balance at Dec. 31, 2017	$ 16,250,819				$ 1,231,500			$ 79,909	$ 1,847	$ 6,590,855			$ 10,164,804		$ (363,814)	$ (1,454,282)
Cumulative effect of change in accounting principle — equity securities	(16,853)												16,853		(16,853)
Total comprehensive income	1,878,666												1,918,080		(39,414)
Preferred stock cash dividends	(72,521)												(72,521)
Exercise of 257,630 Series A stock warrants into 136,676 shares of common stock												$ (22,394)					$ 22,394
Purchases of treasury stock	(2,194,396)															(2,194,396)
Stock-based compensation transactions, net	108,081							(26)	(121)	10,881			(86)			97,433
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)
Total comprehensive income	2,142,550												1,929,149		213,401
Preferred stock cash dividends	(72,482)												(72,482)
Redemption of Series A and Series C preferred stock			$ (381,500)			$ (381,500)
Issuance of Series G preferred stock				$ 396,000			$ 400,000				$ (4,000)
Purchases of treasury stock	(1,349,785)															(1,349,785)
Stock-based compensation transactions, net	73,891							(12)	(160)	18,197			(207)			56,073
Common stock cash dividends	(552,216)												(552,216)
Ending balance at Dec. 31, 2019	15,716,649				1,250,000			79,871	1,566	6,593,539			12,820,916		(206,680)	(4,822,563)
Cumulative effect of change inaccounting principle — credit losses		$ (91,925)												$ (91,925)
Total comprehensive income	1,496,800												1,353,152		143,648
Preferred stock cash dividends	(68,228)												(68,228)
Purchases of treasury stock	(373,750)															(373,750)
Stock-based compensation transactions, net	76,813								(222)	23,865			(411)			53,581
Common stock cash dividends	(569,076)												(569,076)
Ending balance at Dec. 31, 2020	$ 16,187,283				$ 1,250,000			$ 79,871	$ 1,344	$ 6,617,404			$ 13,444,428		$ (63,032)	$ (5,142,732)

Consolidated Statement of Cha_2

Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Treasury Stock [Member] | Series A Warrants [Member]
Exercise of warrants into shares of common stock			257,630
Exercise of warrants into shares of common stock			136,676
Retained Earnings [Member]
Common stock per share dividend amount	$ 4.40	$ 4.10	$ 3.55

Significant accounting policies

Significant accounting policies	12 Months Ended
	Dec. 31, 2020
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 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. 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. Effective January 1, 2020, the Company adopted amended accounting guidance that requires an allowance for credit losses be deducted from the amortized cost basis of financial assets, including investment securities held to maturity, to present the net carrying value at the amount that is expected to be collected over the contractual term. In cases where fair value of an available for sale debt security is less than its amortized cost basis and the Company does not intend to sell the available for sale debt security and it is not more likely than not that the Company will be required to sell the security before recovery of the amortized cost basis, the difference between the fair value and the amortized cost basis is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount related to the credit loss is recognized as an allowance for credit losses while the amount related to other factors is recognized in other comprehensive income, net of applicable income taxes. If the Company intends to sell the security or it is more likely than not to be required to sell the security before recovery of the amortized cost basis, the security is written down to fair value with the entire amount recognized in earnings. Subsequently, the Company accounts for the debt security as if the security had been purchased on the measurement date of the write down at an amortized cost basis equal to the previous amortized cost basis less the amount of the write down recognized in earnings. Prior to 2020 individual debt securities were written down through a charge to earnings when declines in value below the cost basis of the security were considered other than temporary. 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 or acquired by the Company. Originated loans and leases 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. 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 all past due principal and interest payments have been paid by the borrower. Loan balances are charged off when it becomes evident that such balances are not fully collectable. 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. During the normal course of business, the Company modifies loans to maximize recovery efforts. If a borrower is experiencing financial difficulty and a concession to the terms of the loan agreement is granted that the Company would not otherwise consider, the modification is considered a troubled debt restructuring and such loans are classified as either nonaccrual or renegotiated loans. The United States has been operating under a state of emergency related to the Coronavirus Disease 2019 (“COVID-19”) pandemic since March 13, 2020. The direct and indirect effects of the COVID-19 pandemic resulted in a dramatic reduction in the economic activity that severely hampered the ability for businesses and consumers to meet their repayment obligations. The Coronavirus Aid, Relief, and Economic Security Act and the Consolidated Appropriations Act, 2021 (collectively “CARES Act”), in addition to providing financial assistance to both businesses and consumers, creates a forbearance program for federally-backed mortgage loans, protects borrowers from negative credit reporting due to loan accommodations related to the national emergency, and provides financial institutions the option to temporarily suspend certain requirements under GAAP related to troubled debt restructurings to account for the effects of COVID-19. The bank regulatory agencies likewise issued guidance encouraging financial institutions to work prudently with borrowers who are, or may be, unable to meet their contractual payment obligations because of the effects of COVID-19. The guidance, with concurrence of the Financial Accounting Standards Board, and provisions of the CARES Act allow modifications made on a good faith basis in response to COVID-19 to borrowers who were current with their payments prior to any relief, to not be treated as troubled debt restructurings nor be reported as past due. Modifications may include payment deferrals (including maturity extensions), covenant waivers and fee waivers. The Company has been working with its customers affected by COVID-19 and has granted modifications across many of its loan portfolios. To the extent that such modifications meet the criteria described, the modified loans have not been classified as troubled debt restructurings nor reported as past due. 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 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.” Acquired loans and leases Effective January 1, 2020, expected credit losses for purchased loans with credit deterioration are initially recognized as an allowance for credit losses and are added to the purchase price to determine the amortized cost basis of the loans. Any non-credit discount or premium resulting from acquiring such loans is recognized as an adjustment to interest income over the remaining lives of the loans. Subsequent changes in the amount of expected credit losses on such loans are recognized in the allowance for credit losses in the same manner as originated loans. Prior to January 1, 2020, loans acquired in a business combination were initially recorded at fair value with no carry-over of an acquired entity’s previously established allowance for credit losses. Purchased impaired loans represented 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 was recognized as interest income over the remaining lives of the loans. Subsequent decreases in the expected cash flows required the Company to evaluate the need for additions to the Company’s allowance for credit losses. Subsequent improvements in expected cash flows resulted 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. The Company generally recognized the excess of cash flows expected at acquisition over the estimated fair value of the acquired loans as interest income over the remaining lives of such loans regardless of the borrower’s repayment status. 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 Effective January 1, 2020 the Company adopted amended accounting guidance which requires an allowance for credit losses be deducted from the amortized cost basis of financial assets to present the net carrying value at the amount that is expected to be collected over the contractual term of the asset considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. In estimating expected losses in the loan and lease portfolio, borrower-specific financial data and macro-economic assumptions are utilized to project losses over a reasonable and supportable forecast period. Assumptions and judgment are applied to measure amounts and timing of expected future cash flows, collateral values and other factors used to determine the borrowers’ abilities to repay obligations. Subsequent to the forecast period, the Company utilizes longer-term historical loss experience to estimate losses over the remaining contractual life of the loans. Prior to 2020, the allowance for credit losses represented the amount that in management’s judgment reflected incurred credit losses inherent in the loan and lease portfolio as of the balance sheet date. 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 initially 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 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. 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 Compensation expense is recognized over the vesting period of stock-based awards based on estimated grant date value, 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. 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 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, 2020
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. T he 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, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 9,154 $ 198 $ 14 $ 9,338 Mortgage-backed securities: Government issued or guaranteed 4,475,406 208,787 755 4,683,438 Privately issued 16 — — 16 Other debt securities 136,451 1,664 8,301 129,814 4,621,027 210,649 9,070 4,822,606 Investment securities held to maturity: U.S. Treasury and federal agencies 2,999 — — 2,999 Obligations of states and political subdivisions 1,531 9 — 1,540 Mortgage-backed securities: Government issued or guaranteed 1,664,443 100,176 11 1,764,608 Privately issued 77,155 11,056 17,938 70,273 Other debt securities 2,861 — — 2,861 1,748,989 111,241 17,949 1,842,281 Total debt securities $ 6,370,016 $ 321,890 $ 27,019 $ 6,664,887 Equity and other securities: Readily marketable equity — at fair value $ 67,891 $ 25,094 $ — $ 92,985 Other — at cost 381,117 — — 381,117 Total equity and other securities $ 449,008 $ 25,094 $ — $ 474,102 December 31, 2019 Investment securities available for sale: U.S. Treasury and federal agencies $ 9,742 $ 41 $ 16 $ 9,767 Obligations of states and political subdivisions 776 2 3 775 Mortgage-backed securities: Government issued or guaranteed 6,113,913 88,634 21,607 6,180,940 Privately issued 16 — — 16 Other debt securities 133,829 2,046 8,597 127,278 6,258,276 90,723 30,223 6,318,776 Investment securities held to maturity: U.S. Treasury and federal agencies 249,862 286 — 250,148 Obligations of states and political subdivisions 4,140 16 — 4,156 Mortgage-backed securities: Government issued or guaranteed 2,306,180 50,381 1,992 2,354,569 Privately issued 93,496 11,779 18,181 87,094 Other debt securities 3,239 — — 3,239 2,656,917 62,462 20,173 2,699,206 Total debt securities $ 8,915,193 $ 153,185 $ 50,396 $ 9,017,982 Equity and other securities: Readily marketable equity — at fair value $ 105,524 $ 34,786 $ 269 $ 140,041 Other — at cost 381,517 — — 381,517 Total equity and other securities $ 487,041 $ 34,786 $ 269 $ 521,558 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, 2020. As of December 31, 2020, 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 $ 1,531 $ 1,540 $ 1,540 $ — $ — $ — $ — Privately issued mortgage-backed securities 77,171 70,289 1,533 — — 490 68,266 Other debt securities 139,312 132,675 7,302 62,016 31,303 — 32,054 Total $ 218,014 $ 204,504 $ 10,375 $ 62,016 $ 31,303 $ 490 $ 100,320 The amortized cost and estimated fair value of collateralized mortgage obligations included in mortgage-backed securities were as follows: December 31 2020 2019 (In thousands) Collateralized mortgage obligations: Amortized cost $ 77,964 $ 94,817 Estimated fair value 71,099 88,410 There were no significant gross realized gains or losses from sales of investment securities in 2020, 2019 or 2018. At December 31, 2020, 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 $ 4,950 4,945 Due after one year through five years 12,051 12,585 Due after five years through ten years 98,604 97,301 Due after ten years 30,000 24,321 145,605 139,152 Mortgage-backed securities available for sale 4,475,422 4,683,454 $ 4,621,027 4,822,606 Debt securities held to maturity: Due in one year or less $ 4,355 4,361 Due after one year through five years 175 178 Due after ten years 2,861 2,861 7,391 7,400 Mortgage-backed securities held to maturity 1,741,598 1,834,881 $ 1,748,989 1,842,281 A summary of investment securities that as of December 31, 2020 and 2019 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, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 985 (14 ) — — Mortgage-backed securities: Government issued or guaranteed 18,687 (356 ) 16,556 (399 ) Other debt securities 16,055 (181 ) 63,462 (8,120 ) 35,727 (551 ) 80,018 (8,519 ) Investment securities held to maturity: Mortgage-backed securities: Government issued or guaranteed 2,039 (11 ) — — Privately issued — — 52,418 (17,938 ) 2,039 (11 ) 52,418 (17,938 ) Total $ 37,766 (562 ) 132,436 (26,457 ) December 31, 2019 Investment securities available for sale: U.S. Treasury and federal agencies $ 1,406 (7 ) 2,893 (9 ) Obligations of states and political subdivisions — — 277 (3 ) Mortgage-backed securities: Government issued or guaranteed 117,299 (222 ) 2,002,364 (21,385 ) Other debt securities 6,600 (354 ) 56,313 (8,243 ) 125,305 (583 ) 2,061,847 (29,640 ) Investment securities held to maturity: Mortgage-backed securities: Government issued or guaranteed 2,727 (5 ) 145,235 (1,987 ) Privately issued — — 49,656 (18,181 ) 2,727 (5 ) 194,891 (20,168 ) Total $ 128,032 (588 ) 2,256,738 (49,808 ) The Company owned 264 individual debt securities with aggregate gross unrealized losses of $27 million at December 31, 2020. Based on a review of each of the securities in the investment securities portfolio at December 31, 2020, the Company concluded that it expected to recover the amortized cost basis of its investment. As of December 31, 2020, 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, 2020, the Company has not identified events or changes in circumstances which may have a significant adverse effect on the fair value of the $381 million of cost method investment securities. As described in notes 4 and 26, on January 1, 2020 the Company adopted amended accounting guidance that requires an allowance for credit losses be deducted from the amortized cost basis of financial assets, including investment securities held to maturity, to present the net carrying value at the amount that is expected to be collected over the contractual term of the asset. The Company estimated no material allowance for credit losses for its investment securities classified as held-to-maturity at January 1, 2020 or December 31, 2020, as the substantial majority of such investment securities are obligations backed by the U.S government or its agencies. At December 31, 2020, investment securities with a carrying value of $4.2 billion, including $2.9 billion 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 $105 million at December 31, 2020. 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, 2020
Receivables [Abstract]
Loans and leases	3. Loans and leases Total loans and leases outstanding were comprised of the following: December 31 2020 2019 (In thousands) Loans Commercial, financial, etc. $ 26,554,486 $ 22,575,700 Real estate: Residential 16,708,644 16,098,125 Commercial 27,738,732 26,718,325 Construction 10,068,141 9,010,297 Consumer 16,558,889 15,373,881 Total loans 97,628,892 89,776,328 Leases Commercial 1,246,896 1,412,197 Total loans and leases 98,875,788 91,188,525 Less: unearned discount (339,921 ) (265,656 ) Total loans and leases, net of unearned discount $ 98,535,867 $ 90,922,869 One-to-four family residential mortgage loans held for sale were $777 million at December 31, 2020 and $414 million at December 31, 2019. Commercial real estate loans held for sale were $278 million at December 31, 2020 and $28 million at December 31, 2019. As of December 31, 2020, approximately $4.0 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, 2020, 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 2020, 2019 or 2018. The amount of foreclosed residential real estate property held by the Company was $28 million and $76 million at December 31, 2020 and 2019, respectively. There were $214 million and $402 million at December 31, 2020 and 2019 , 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, 2020 , approximately 41 % were government guaranteed. 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 $72 million and $28 million at December 31, 2020 and 2019, respectively. During 2020, new borrowings by such persons amounted to $46 million (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 $2 million. At December 31, 2020, approximately $10.2 A summary of current, past due and nonaccrual loans as of December 31, 2020 and 2019 follows: Current 30-89 Days Past Due Accruing Loans Due 90 Days or More Nonaccrual Total (In thousands) December 31, 2020 Commercial, financial, leasing, etc. $ 27,196,862 60,822 10,053 306,827 $ 27,574,564 Real estate: Commercial 26,688,515 168,917 47,014 775,894 27,680,340 Residential builder and developer 1,246,095 1,693 856 1,094 1,249,738 Other commercial construction 8,523,591 66,365 3,816 114,039 8,707,811 Residential 13,764,836 200,406 792,888 365,729 15,123,859 Residential — limited documentation 1,462,277 19,687 — 147,170 1,629,134 Consumer: Home equity lines and loans 3,881,885 24,329 — 79,392 3,985,606 Recreational finance 7,002,643 47,161 — 25,519 7,075,323 Automobile 4,007,349 55,498 — 39,404 4,102,251 Other 1,346,868 17,561 4,581 38,231 1,407,241 Total $ 95,120,921 662,439 859,208 1,893,299 $ 98,535,867 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, 2019 Commercial, financial, leasing, etc. $ 23,290,797 184,011 16,776 27 — 346,557 $ 23,838,168 Real estate: Commercial 26,311,414 165,579 6,740 — 15,601 158,474 26,657,808 Residential builder and developer 1,521,315 21,195 — — 753 3,982 1,547,245 Other commercial construction 7,204,148 95,346 3,360 — 1,237 32,770 7,336,861 Residential 12,760,040 451,274 486,515 5,788 143,145 235,663 14,082,425 Residential — limited documentation 1,858,037 65,215 181 — 66,809 83,427 2,073,669 Consumer: Home equity lines and loans 4,386,511 30,229 — 1,662 — 63,215 4,481,617 Recreational finance 5,484,997 36,827 — 99 — 14,219 5,536,142 Automobile 3,787,221 78,478 — — — 21,293 3,886,992 Other 1,395,240 45,978 5,156 32,056 — 3,512 1,481,942 Total $ 87,999,720 1,174,132 518,728 39,632 227,545 963,112 $ 90,922,869 (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 $96 million in 2020, $68 million in 2019 and $69 million in 2018. The actual amounts included in interest income on such loans were $44 million in 2020 and $33 A summary of outstanding loan balances for which COVID-19 related modifications were granted as of December 31, 2020 is presented below. These loans meet the criteria described in note 1 and, as such, are not considered past due or otherwise in default of loan terms as of the dates presented. Substantially all of modifications noted below expire during the first half of 2021. COVID-19 Related Modifications December 31, 2020 Payment Deferrals (1) Other Forbearances (2) Total (In thousands) Commercial, financial, leasing, etc. $ 95,823 $ 291,957 $ 387,780 Real estate: Commercial 728,511 374,509 1,103,020 Residential builder and developer 653 — 653 Other commercial construction 61,235 145,770 207,005 Residential 2,447,422 (3) — 2,447,422 Residential — limited documentation 337,108 — 337,108 Consumer: Home equity lines and loans 18,440 — 18,440 Recreational finance 24,428 — 24,428 Automobile 51,550 — 51,550 Other 2,353 — 2,353 Total $ 3,767,523 $ 812,236 $ 4,579,759 (1) (2) (3) Includes $1.7 billion of government-guaranteed loans. The outstanding principal balance and the carrying amount of loans acquired at a discount that were recorded at fair value at the acquisition date for which interest income was recognized based on expected future cash flows that were included in the consolidated balance sheet at December 31, 2019 were as follows: (In thousands) Outstanding principal balance $ 769,414 Carrying amount: Commercial, financial, leasing, etc. 21,114 Commercial real estate 94,890 Residential real estate 341,807 Consumer 77,785 $ 535,596 Purchased impaired loans included in the table above totaled $228 million at December 31, 2019, representing less than 1% of the Company’s assets. A summary of changes in the accretable yield for loans acquired at a discount for the years ended December 31, 2019 and 2018 follows: For the Year Ended December 31, 2019 2018 Purchased Impaired Other Acquired Purchased Impaired Other Acquired (In thousands) Balance at beginning of period $ 147,210 $ 96,907 $ 157,918 $ 133,162 Interest income (49,017 ) (36,452 ) (37,819 ) (63,856 ) Reclassifications from nonaccretable balance 36,718 15,534 27,111 22,849 Other (a) — (3,909 ) — 4,752 Balance at end of period $ 134,911 $ 72,080 $ 147,210 $ 96,907 (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, 2020, 2019 and 2018: Post-modification (a) Year Ended December 31, 2020 Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total (Dollars in thousands) Commercial, financial, leasing, etc. 394 $ 246,479 $ 70,671 $ 298 $ 31,605 $ 97,344 $ 199,918 Real estate: Commercial 161 310,578 204,591 505 4,874 85,261 295,231 Residential builder and developer 1 91 — — — 90 90 Other commercial construction 2 13,602 13,573 — — — 13,573 Residential 631 202,985 183,878 — — 23,639 207,517 Residential — limited documentation 30 7,413 7,100 — — 1,232 8,332 Consumer: Home equity lines and loans 259 17,228 5,882 — — 11,372 17,254 Recreational finance 428 16,392 16,388 — — 4 16,392 Automobile 2,249 39,951 39,949 — — 2 39,951 Other 1,095 7,788 3,383 — — 4,405 7,788 Total 5,250 $ 862,507 $ 545,415 $ 803 $ 36,479 $ 223,349 $ 806,046 Year Ended December 31, 2019 Commercial, financial, leasing, etc. 150 $ 63,715 $ 10,485 $ — $ — $ 52,871 $ 63,356 Real estate: Commercial 51 48,315 5,193 — — 26,152 31,345 Residential builder and developer 2 1,330 1,068 — — — 1,068 Other commercial construction 3 1,559 — — — 1,500 1,500 Residential 83 21,695 10,819 — — 11,907 22,726 Residential — limited documentation 6 1,409 399 — — 1,044 1,443 Consumer: Home equity lines and loans 41 4,127 176 — — 4,004 4,180 Recreational finance 10 265 265 — — — 265 Automobile 66 1,141 1,076 — — 65 1,141 Total 412 $ 143,556 $ 29,481 $ — $ — $ 97,543 $ 127,024 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 (a) Loans that were modified as troubled debt restructurings during the twelve months ended December 31, 2020, 2019 and 2018 and for which there was a subsequent payment default during the respective year were not material. The Company’s loan and lease portfolio includes commercial lease financing receivables consisting of direct financing and leveraged leases for machinery and equipment, railroad equipment, commercial trucks and trailers, and aircraft. Certain leases contain payment schedules that are tied to variable interest rate indices. In general, early termination options are provided if the lessee is not in default, returns the leased equipment and pays an early termination fee. Additionally, options to purchase the underlying asset by the lessee are generally at the fair market value of the equipment. A summary of lease financing receivables follows: December 31, 2020 2019 (In thousands) Commercial leases: Direct financings: Lease payments receivable $ 1,017,222 $ 1,164,567 Estimated residual value of leased assets 79,621 84,540 Unearned income (83,673 ) (106,780 ) Investment in direct financings 1,013,170 1,142,327 Leveraged leases: Lease payments receivable 76,453 82,065 Estimated residual value of leased assets 73,600 81,025 Unearned income (28,388 ) (31,596 ) Investment in leveraged leases 121,665 131,494 Total investment in leases $ 1,134,835 $ 1,273,821 Deferred taxes payable arising from leveraged leases $ 61,905 $ 70,245 Included within the estimated residual value of leased assets at December 31, 2020 and 2019 were $34 million and $37 million, respectively, in residual value associated with direct financing leases that are guaranteed by the lessees or others. At December 31, 2020, the minimum future lease payments to be received from lease financings were as follows: (In thousands) Year ending December 31: 2021 $ 320,428 2022 288,322 2023 187,740 2024 122,735 2025 70,400 Later years 104,050 $ 1,093,675

Allowance for credit losses

Allowance for credit losses	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Allowance for credit losses	4. Allowance for credit losses Effective January 1, 2020 the Company adopted amended accounting guidance which requires an allowance for credit losses be deducted from the amortized cost basis of financial assets to present the net carrying value at the amount that is expected to be collected over the contractual term of the asset considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. The new guidance replaced the previous incurred loss model for determining the allowance for credit losses. Changes in the allowance for credit losses for the years ended December 31, 2020, 2019 and 2018 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) 2020 Beginning balance $ 366,094 322,201 56,033 229,118 77,625 $ 1,051,071 Adoption of new accounting standard (61,474 ) 23,656 53,896 194,004 (77,625 ) 132,457 Provision for credit losses 220,544 356,203 (3,172 ) 226,425 — 800,000 Net charge-offs Charge-offs (135,083 ) (35,891 ) (10,283 ) (152,250 ) — (333,507 ) Recoveries 15,765 4,550 7,116 58,935 — 86,366 Net charge-offs (119,318 ) (31,341 ) (3,167 ) (93,315 ) — (247,141 ) Ending balance $ 405,846 670,719 103,590 556,232 — $ 1,736,387 2019 Beginning balance $ 330,055 341,655 69,125 200,564 78,045 $ 1,019,444 Provision for credit losses 69,702 (10,726 ) (8,585 ) 126,029 (420 ) 176,000 Net charge-offs Charge-offs (58,244 ) (12,664 ) (12,711 ) (154,089 ) — (237,708 ) Recoveries 24,581 3,936 8,204 56,614 — 93,335 Net charge-offs (33,663 ) (8,728 ) (4,507 ) (97,475 ) — (144,373 ) Ending balance $ 366,094 322,201 56,033 229,118 77,625 $ 1,051,071 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 Despite the allocation in the preceding tables, the allowance for credit losses is general in nature and is available to absorb losses from any loan or lease type. In establishing the allowance for credit losses subsequent to December 31, 2019, the Company estimates losses attributable to specific troubled credits identified through both normal and targeted credit review processes and also estimates losses for loans and leases with similar risk characteristics on a collective basis. The amounts of specific 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. Such loss estimates are typically based on expected future cash flows, collateral values and other factors that may impact the borrower’s ability to pay. To the extent that those loans are collateral-dependent, they are evaluated based on the fair value of the loan’s collateral as estimated at or near the financial statement date. As the quality of a loan deteriorates to the point of classifying the loan as “criticized,” the process of obtaining updated collateral valuation information is usually initiated, unless it is not considered warranted given factors such as the relative size of the loan, the characteristics of the collateral or the age of the last valuation. In those cases where current appraisals may not yet be available, prior appraisals are utilized with adjustments, as deemed necessary, for estimates of subsequent declines in values as determined by line of business and/or loan workout personnel. Those adjustments are reviewed and assessed for reasonableness by the Company’s credit department. Accordingly, for real estate collateral securing larger nonaccrual commercial loans and commercial real estate loans, estimated collateral values are based on current appraisals and estimates of value. For non-real estate loans, collateral is assigned a discounted estimated liquidation value and, depending on the nature of the collateral, is verified through field exams or other procedures. In assessing collateral, real estate and non-real estate values are reduced by an estimate of selling costs. For residential real estate loans, including home equity loans and lines of credit, the excess of the loan balance over the net realizable value of the property collateralizing the loan is charged-off when the loan becomes 150 days delinquent. That charge-off is based on recent indications of value from external parties that are generally obtained shortly after a loan becomes nonaccrual. Loans to consumers that file for bankruptcy are generally charged-off to estimated net collateral value shortly after the Company is notified of such filings. When evaluating individual home equity loans and lines of credit for charge off and for purposes of estimating losses in determining the allowance for credit losses, the Company gives consideration to the required repayment of any first lien positions related to collateral property. Modified loans, including smaller balance homogenous loans, that are considered to be troubled debt restructurings are evaluated for impairment giving consideration to the impact of the modified loan terms on the present value of the loan’s expected cash flows. Information with respect to loans and leases that were considered nonaccrual at the beginning and end of the reporting period and the interest income recognized on such loans for the years ended December 31, 2020, 2019 and 2018 follows. December 31, 2020 January 1, 2020 Year Ended December 2020 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 226,897 $ 79,930 $ 306,827 $ 346,743 $ 11,269 Real estate: Commercial 364,110 411,784 775,894 173,796 7,821 Residential builder and developer 1,094 — 1,094 4,708 1,694 Other commercial construction 20,992 93,047 114,039 35,881 8,457 Residential 159,006 206,723 365,729 322,504 18,069 Residential — limited documentation 84,568 62,602 147,170 114,667 634 Consumer: Home equity lines and loans 61,031 18,361 79,392 65,039 4,092 Recreational finance 19,434 6,085 25,519 14,308 626 Automobile 34,044 5,360 39,404 21,293 186 Other 3,606 34,625 38,231 35,394 1,369 Total $ 974,782 $ 918,517 $ 1,893,299 $ 1,134,333 $ 54,217 December 31, 2019 January 1, 2019 Year Ended December 31, 2019 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 206,644 $ 139,913 $ 346,557 $ 234,423 $ 8,960 Real estate: Commercial 40,847 117,627 158,474 203,672 5,850 Residential builder and developer 604 3,378 3,982 4,798 357 Other commercial construction 12,425 20,345 32,770 22,205 634 Residential 59,982 175,681 235,663 233,352 12,630 Residential — limited documentation 26,710 56,717 83,427 84,685 1,092 Consumer: Home equity lines and loans 24,812 38,403 63,215 71,292 5,987 Recreational finance 9,054 5,165 14,219 11,199 575 Automobile 14,805 6,488 21,293 23,359 214 Other 3,391 121 3,512 4,623 508 Total $ 399,274 $ 563,838 $ 963,112 $ 893,608 $ 36,807 December 31, 2018 January 1, 2018 Year Ended December 31, 2018 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 126,753 $ 107,670 $ 234,423 $ 240,991 $ 7,873 Real estate: Commercial 90,296 113,376 203,672 184,982 10,880 Residential builder and developer 2,205 2,593 4,798 6,451 1,779 Other commercial construction 14,604 7,601 22,205 10,088 3,474 Residential 57,346 176,006 233,352 235,834 14,065 Residential — limited documentation 26,808 57,877 84,685 96,105 1,980 Consumer: Home equity lines and loans 30,819 40,473 71,292 74,500 5,535 Recreational finance 6,016 5,183 11,199 6,509 333 Automobile 16,271 7,088 23,359 23,781 689 Other 4,591 32 4,623 3,357 230 Total $ 375,709 $ 517,899 $ 893,608 $ 882,598 $ 46,838 For purposes of determining the level of the allowance for credit losses, the Company evaluates its loan and lease portfolio by type. Accruing loans with similar risk characteristics are generally evaluated collectively. The Company utilizes statistically developed models to project principal balances over the remaining contractual lives of the loan portfolios and to determine estimated credit losses through a reasonable and supportable forecast period. Individual loan credit quality indicators including loan grade and borrower repayment performance inform the models, which have been statistically developed based on historical correlations of credit losses with prevailing economic metrics, including unemployment, gross domestic product and real estate prices. Model forecasts may be adjusted for inherent limitations or biases that have been identified through independent validation and back-testing of model performance to actual realized results. At both January 1 and December 31, 2020, the Company utilized a reasonable and supportable forecast period of two years. Subsequent to this forecast period the Company reverted, ratably over a one-year period, to historical loss experience to inform its estimate of losses for the remaining contractual life of each portfolio. The Company also considered the impact of portfolio concentrations, changes in underwriting practices, product expansions into new markets, imprecision in its economic forecasts, geopolitical conditions and other risk factors that might influence its loss estimation process. Prior to 2020, the allowance for credit losses was estimated for incurred credit losses inherent in the loan and lease portfolio as of the balance sheet date, but did not consider reasonable and supportable forecasts that could have affected the collectability of the reported amounts. The Company utilizes a loan grading system to differentiate risk amongst its commercial loans and commercial real estate loans. 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. Loan officers in different geographic locations with the support of the Company’s credit department personnel continuously review and reassign loan grades based on their detailed knowledge of individual borrowers and their judgment of the impact on such borrowers resulting from changing conditions in their respective regions. Factors considered in assigning loan grades 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. At least annually, updated financial information is obtained from commercial borrowers associated with pass grade loans and additional analysis is performed. On a quarterly basis, the Company’s centralized credit department reviews all criticized commercial loans and commercial real estate loans greater than $1 million to determine the appropriateness of the assigned loan grade, including whether the loan should be reported as accruing or nonaccruing. The following table summarizes the loan grades applied at December 31, 2020 to the various classes of the Company’s commercial loans and commercial real estate loans by origination year. Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Commercial, financial, leasing, etc.: Loan grades: Pass $ 7,732,728 2,277,233 1,505,486 930,834 719,796 1,387,695 11,352,416 21,286 $ 25,927,474 Criticized accrual 388,326 84,358 113,940 41,587 39,930 73,401 584,751 13,970 1,340,263 Criticized nonaccrual 7,720 27,309 56,227 16,808 19,681 45,471 125,893 7,718 306,827 Total commercial, financial, leasing, etc. $ 8,128,774 2,388,900 1,675,653 989,229 779,407 1,506,567 12,063,060 42,974 $ 27,574,564 Real estate: Commercial: Loan grades: Pass $ 3,353,450 4,681,834 3,299,095 2,628,061 2,746,165 5,698,834 875,348 — $ 23,282,787 Criticized accrual 526,037 400,154 579,507 290,885 568,144 1,212,672 44,260 — 3,621,659 Criticized nonaccrual 26,876 121,899 47,144 99,293 197,319 248,949 34,414 — 775,894 Total commercial real estate $ 3,906,363 5,203,887 3,925,746 3,018,239 3,511,628 7,160,455 954,022 — $ 27,680,340 Residential builder and developer: Loan grades: Pass $ 506,295 223,880 109,453 15,048 10,976 11,320 236,943 — $ 1,113,915 Criticized accrual 3,690 106,847 14,836 3,421 — 1,885 4,050 — 134,729 Criticized nonaccrual — 518 — — — 576 — — 1,094 Total residential builder and developer $ 509,985 331,245 124,289 18,469 10,976 13,781 240,993 — $ 1,249,738 Other commercial construction: Loan grades: Pass $ 1,050,258 2,998,921 2,048,063 945,339 233,127 294,030 74,611 — $ 7,644,349 Criticized accrual 37,192 148,492 381,091 225,949 144,665 12,034 — — 949,423 Criticized nonaccrual 335 65,592 13,522 4,213 12,097 12,873 5,407 — 114,039 Total other commercial construction $ 1,087,785 3,213,005 2,442,676 1,175,501 389,889 318,937 80,018 — $ 8,707,811 Increases to criticized loans during 2020 were predominantly attributable to effects of the COVID-19 pandemic and the related re-grading of loans. The Company considers repayment performance a significant indicator of credit quality for its residential real estate loan and consumer loan portfolios . A summary of loans in accrual and nonaccrual status at December 31, 2020 for the various classes of the Company’s residential real estate loans and consumer loans by origination year is as follows. Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Residential: Current $ 2,722,862 1,416,259 618,736 1,318,094 718,235 6,898,756 71,894 — $ 13,764,836 30-89 days past due 13,496 7,781 7,258 13,477 7,947 150,447 — — 200,406 Accruing loans past due 90 days or more 579 15,234 38,145 212,818 45,804 480,308 — — 792,888 Nonaccrual 3,133 14,439 5,183 6,408 2,900 333,466 200 — 365,729 Total residential $ 2,740,070 1,453,713 669,322 1,550,797 774,886 7,862,977 72,094 — $ 15,123,859 Residential - limited documentation: Current $ — — — — — 1,462,277 — — $ 1,462,277 30-89 days past due — — — — — 19,687 — — 19,687 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — — — — — 147,170 — — 147,170 Total residential - limited documentation $ — — — — — 1,629,134 — — $ 1,629,134 Consumer: Home equity lines and loans: Current $ 773 3,983 1,591 2,016 162 51,554 2,569,621 1,252,185 $ 3,881,885 30-89 days past due — — — — — 1,148 939 22,242 24,329 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — — — — — 6,148 5,752 67,492 79,392 Total home equity lines and loans $ 773 3,983 1,591 2,016 162 58,850 2,576,312 1,341,919 $ 3,985,606 Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Recreational finance: Current $ 2,796,359 1,751,766 907,595 630,151 352,414 564,358 — — $ 7,002,643 30-89 days past due 9,548 11,255 8,519 6,638 2,938 8,263 — — 47,161 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,854 3,883 4,072 4,194 2,733 8,783 — — 25,519 Total recreational finance $ 2,807,761 1,766,904 920,186 640,983 358,085 581,404 — — $ 7,075,323 Automobile: Current $ 1,595,636 1,106,782 629,338 440,604 171,017 63,972 — — $ 4,007,349 30-89 days past due 6,461 14,140 12,542 12,899 6,373 3,083 — — 55,498 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,615 7,144 10,788 10,061 5,991 3,805 — — 39,404 Total automobile $ 1,603,712 1,128,066 652,668 463,564 183,381 70,860 — — $ 4,102,251 Other: Current $ 160,424 137,617 53,702 32,556 4,526 28,970 927,217 1,856 $ 1,346,868 30-89 days past due 1,879 1,130 577 2,301 42 557 10,594 481 17,561 Accruing loans past due 90 days or more — — — — — 374 4,207 — 4,581 Nonaccrual 1,493 492 339 183 31 501 35,044 148 38,231 Total other $ 163,796 139,239 54,618 35,040 4,599 30,402 977,062 2,485 $ 1,407,241 Total loans and leases at December 31, 2020 $ 20,949,019 15,628,942 10,466,749 7,893,838 6,013,013 19,233,367 16,963,561 1,387,378 $ 98,535,867 The following table summarizes the loan grades applied at December 31, 2019 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, 2019 Pass $ 22,595,821 25,728,725 1,419,162 7,092,799 Criticized accrual 895,790 770,609 124,101 211,292 Criticized nonaccrual 346,557 158,474 3,982 32,770 Total $ 23,838,168 26,657,808 1,547,245 7,336,861 The Company’s reserve for off-balance sheet credit exposures was not material at December 31, 2020 and December 31, 2019.

Premises and equipment

Premises and equipment	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Premises and equipment	5. Premises and equipment The detail of premises and equipment was as follows: December 31 2020 2019 (In thousands) Land $ 94,929 $ 96,118 Buildings 513,290 482,182 Leasehold improvements 302,246 262,438 Furniture and equipment — owned 807,701 739,724 Furniture and equipment — capital leases 8,630 14,232 1,726,796 1,594,694 Less: accumulated depreciation and amortization Owned assets 971,979 882,272 Capital leases 5,933 8,425 977,912 890,697 Right of use assets — operating leases 412,674 436,927 Premises and equipment, net $ 1,161,558 $ 1,140,924 The right-of-use assets and lease liabilities relate to banking offices and other space occupied by the Company and use of certain equipment under noncancelable operating lease agreements. The Company’s noncancelable operating lease agreements expire at various dates over the next 21 years. Real estate leases generally consist of fixed monthly rental payments with certain leases containing escalation clauses. Any variable lease payments or payments for nonlease components are recognized in the consolidated statement of income as a component of “equipment and net occupancy” expense based on actual costs incurred. Some leases contain lessee options to extend the term. Those options are included in the lease term when it is determined that it is reasonably certain the option will be exercised. The Company has noncancelable operating lease agreements for certain equipment related to ATMs, servers, printers and mail machines that are used in the normal course of operations. The ATM leases are either based on the rights to a specific square footage or a license agreement whereby the Company has the right to operate an ATM in a landlord's location. The lease terms generally contain both fixed payments and variable payments that are transaction-based. Given the transaction-based nature of the variable payments, such payments are excluded from the measurement of the right-of-use asset and lease liability and are recognized in the consolidated statement of income as a component of “equipment and net occupancy” expense when incurred. The following table presents information about the Company’s lease costs for operating leases recorded in the consolidated balance sheet, cash paid toward lease liabilities, and the weighted-average remaining term and discount rates of the operating leases. Year Ended December 31, 2020 2019 (Dollars in thousands) Lease cost Operating lease cost $ 104,158 $ 100,669 Short-term lease cost 198 105 Variable lease cost 1,565 2,332 Total lease cost $ 105,921 $ 103,106 Other information Right-of-use assets obtained in exchange for new operating lease liabilities $ 70,754 $ 132,219 Cash paid toward lease liabilities 104,396 101,869 Weighted-average remaining lease term 7 years 7 years Weighted-average discount rate 2.74 % 3.01 % Minimum lease payments under noncancelable operating leases are summarized in the following table. (In thousands) Year ending December 31: 2021 $ 105,445 2022 93,621 2023 75,698 2024 61,412 2025 46,023 Later years 130,475 Total lease payments 512,674 Less: imputed interest 45,354 Total $ 467,320 Net lease expense for all operating leases totaled

Capitalized servicing assets

Capitalized servicing assets	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 2020 2019 2018 (In thousands) Beginning balance $ 244,411 $ 120,509 $ 114,978 $ 130,636 $ 114,663 $ 114,076 Originations 45,101 26,067 28,985 29,306 41,370 26,298 Purchases — 144,326 454 — — — Amortization (58,308 ) (46,491 ) (23,908 ) (26,513 ) (25,397 ) (25,711 ) 231,204 244,411 120,509 133,429 130,636 114,663 Valuation allowance (30,000 ) (7,000 ) — — — — Ending balance, net $ 201,204 $ 237,411 $ 120,509 $ 133,429 $ 130,636 $ 114,663 Residential mortgage loans serviced for others were $26.3 billion at December 31, 2020, $32.3 billion at December 31, 2019 and $22.2 billion at December 31, 2018. Excluded from residential mortgage loans serviced for others were loans sub-serviced for others of $68.1 billion, $62.8 billion and $56.8 billion at December 31, 2020, 2019, and 2018, 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 $144 million. Commercial mortgage loans serviced for others were $18.9 billion at December 31, 2020, $17.6 billion at December 31, 2019 and $15.5 billion at December 31, 2018. Excluded from commercial mortgage loans serviced for others were loans sub-serviced for others of $3.3 billion at December 31, 2020, $3.4 billion at December 31, 2019 and $2.7 billion at December 31, 2018. The estimated fair value of capitalized residential mortgage loan servicing assets was approximately $240 million at December 31, 2020 and $297 million at December 31, 2019. The fair value of capitalized residential mortgage loan servicing assets was estimated using weighted-average discount rates of 9.4% and 10.6% at December 31, 2020 and 2019, respectively, and contemporaneous prepayment assumptions that vary by loan type. At December 31, 2020 and 2019, the discount rate represented a weighted-average option-adjusted spread (“OAS”) of 918 basis points (hundredths of one percent) and 928 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 $160 million and $153 million at December 31, 2020 and 2019, respectively. An 18% discount rate was used to estimate the fair value of capitalized commercial mortgage loan servicing rights at December 31, 2020 and 2019 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, 2020 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 14.50 % Impact on fair value of 10% adverse change $ (15,279 ) Impact on fair value of 20% adverse change (29,189 ) Weighted-average OAS 9.18 % Impact on fair value of 10% adverse change $ (7,230 ) Impact on fair value of 20% adverse change (14,020 ) Weighted-average discount rate 18.00 % Impact on fair value of 10% adverse change $ (7,024 ) Impact on fair value of 20% adverse change (13,556 )

Goodwill and other intangible a

Goodwill and other intangible assets	12 Months Ended
	Dec. 31, 2020
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, 2020 Core deposit $ 131,664 $ 119,125 $ 12,539 Other 6,757 5,131 1,626 Total $ 138,421 $ 124,256 $ 14,165 December 31, 2019 Core deposit $ 131,664 $ 105,802 $ 25,862 Other 6,757 3,585 3,172 Total $ 138,421 $ 109,387 $ 29,034 Amortization of core deposit and other intangible assets was generally computed using accelerated methods over original amortization periods of three to seven years. The weighted-average original amortization period was approximately seven years. Amortization expense for core deposit and other intangible assets was $15 million, $19 million and $25 million for the years ended December 31, 2020, 2019 and 2018, respectively. Estimated amortization expense in future years for such intangible assets is as follows: (In thousands) Year ending December 31: 2021 $ 10,167 2022 3,998 $ 14,165 The Company completed annual goodwill impairment tests as of October 1, 2020, 2019 and 2018. 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, 2020 and 2019 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, 2020
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, 2020 Amount outstanding $ 59,482 $ — $ 59,482 Weighted-average interest rate 0.01 % — 0.01 % For the year ended December 31, 2020 Highest amount at a month-end $ 82,893 $ — Daily-average amount outstanding 61,551 — $ 61,551 Weighted-average interest rate 0.05 % — 0.05 % At December 31, 2019 Amount outstanding $ 62,363 $ — $ 62,363 Weighted-average interest rate 0.14 % — 0.14 % For the year ended December 31, 2019 Highest amount at a month-end $ 3,402,566 $ 5,000,000 Daily-average amount outstanding 260,322 799,068 $ 1,059,390 Weighted-average interest rate 1.86 % 2.49 % 2.34 % 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 % Short-term borrowings have a stated maturity of one year or less at the date the Company enters into the obligation. In general, short-term repurchase agreements outstanding at December 31, 2020 matured on the next business day following year-end. At December 31, 2020, M&T Bank had lines of credit under formal agreements as follows: (In thousands) Outstanding borrowings $ 1,727 Unused 32,010,950 At December 31, 2020, M&T Bank had borrowing facilities available with the FHLBs whereby M&T Bank could borrow up to approximately $19.0 billion. Additionally, M&T Bank had an available line of credit with the Federal Reserve Bank of New York totaling approximately $13.0 billion at December 31, 2020. 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, 2020 2019 (In thousands) Senior notes of M&T: Variable rate due 2023 $ 249,824 $ 249,756 3.55% due 2023 533,369 520,454 Senior notes of M&T Bank: Variable rate due 2021 349,992 349,893 Variable rate due 2022 249,858 249,758 2.05% due 2020 — 749,254 2.10% due 2020 — 749,864 2.625% due 2021 — 654,136 2.50% due 2022 664,400 652,714 2.90% due 2025 749,656 749,572 Advances from FHLB: Fixed rates 1,683 1,815 Agreements to repurchase securities — 101,679 Subordinated notes of M&T Bank: Variable rate due 2020 — 409,361 Variable rate due 2021 500,000 500,000 3.40% due 2027 552,194 514,353 Junior subordinated debentures of M&T associated with preferred capital securities: Fixed rates: BSB Capital Trust I — 8.125%, due 2028 15,752 15,728 Provident Trust I — 8.29%, due 2028 29,099 28,235 Southern Financial Statutory Trust I — 10.60%, due 2030 6,836 6,770 Variable rates: First Maryland Capital I — due 2027 148,409 147,871 First Maryland Capital II — due 2027 150,606 149,943 Allfirst Asset Trust — due 2029 97,075 96,930 BSB Capital Trust III — due 2033 15,464 15,464 Provident Statutory Trust III — due 2033 56,641 55,867 Southern Financial Capital Trust III — due 2033 8,338 8,236 Other 2,997 8,533 $ 4,382,193 $ 6,986,186 The variable rate notes of M&T pay interest quarterly at a rate that is indexed to the three-month LIBOR. The contractual interest rates for those notes were .90% at December 31, 2020 and 2.62% at December 31, 2019. 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 .49% to .83% at December 31, 2020 and 2.21% to 2.54% at December 31, 2019. The weighted-average contractual interest rate was 0.63% at December 31, 2020 and 2.34% at December 31, 2019. Long-term fixed rate advances from the FHLB had weighted-average contractual interest rates of 5.82% at December 31, 2020 and December 31, 2019. Advances from the FHLB outstanding at December 31, 2020 mature in 2029 and 2035 and are secured by residential real estate loans, commercial real estate loans and investment securities. The agreement to repurchase securities outstanding at December 31, 2019 had a contractual interest rate of 4.29%. The Company posted collateral consisting primarily of government guaranteed mortgage-backed securities of $108 million at December 31, 2019. The subordinated notes of M&T Bank are unsecured and are subordinate to the claims of its other creditors. The notes that were repaid in 2020 paid interest monthly at a rate that was indexed to the one-month LIBOR. The contractual interest rate was 3.02% at maturity and December 31, 2019. 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 0.87% at December 31, 2020 and 2.55% at December 31, 2019. 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 1.06% to 3.59% at December 31, 2020 and from 2.76% to 5.34% at December 31, 2019. The weighted-average variable rates payable on those Junior Subordinated Debentures were 1.65% at December 31, 2020 and 3.37% at December 31, 2019. 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, 2020 mature as follows: (In thousands) Year ending December 31: 2021 $ 849,976 2022 917,270 2023 783,193 2024 — 2025 749,656 Later years 1,082,098 $ 4,382,193

Shareholders' equity

Shareholders' equity	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019 is presented below: Shares Issued and Outstanding Carrying Value (Dollars in thousands) Series E (a) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share 350,000 $ 350,000 Series F (b) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share 50,000 $ 500,000 Series G (c) Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share 40,000 $ 400,000 (a) 90 days (b) 90 days (c) Dividends, if declared, are paid semi-annually at a rate of 5.0% through July 31, 2024 and thereafter will be paid semiannually at a rate of the five-year U.S. Treasury rate plus 3.174%. The shares are redeemable in whole or in part on or after August 1, 2024. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days

Revenue from contracts with cus

Revenue from contracts with customers	12 Months Ended
	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Revenue from contracts with customers	10. Revenue from contracts with customers A significant amount of the Company’s revenues are derived from net interest income on financial assets and liabilities, mortgage banking revenues, trading account and foreign exchange gains, investment securities gains, loan and letter of credit fees, income from bank-owned life insurance, and certain other revenues that are generally excluded from the scope of accounting guidance for revenue from contracts with customers. For noninterest income revenue streams, the Company recognizes the expected amount of consideration as revenue when the performance obligations related to the services under the terms of a contract are satisfied. The Company’s contracts generally do not contain terms that necessitate significant judgment to determine the amount of revenue to recognize. The Company generally charges customer accounts or otherwise bills customers upon completion of its services. Typically the Company’s contracts with customers have a duration of one year or less and payment for services is received at least annually, but oftentimes more frequently as services are provided. At December 31, 2020 and 2019, the Company had $67 million and $62 million, respectively, of amounts receivable related to recognized revenue from the sources in the accompanying tables. Such amounts are classified in accrued interest and other assets in the consolidated balance sheet. In certain situations the Company is paid in advance of providing services and defers the recognition of revenue until its service obligation is satisfied. At December 31, 2020 and 2019, the Company had deferred revenue of $42 million and $43 million, respectively, related to the sources in the accompanying tables and recorded such amounts in accrued interest and other liabilities in the consolidated balance sheet. The following tables summarize sources of the Company’s noninterest income during 2020, 2019, and 2018 that are subject to the noted accounting guidance. Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total Year Ended December 31, 2020 (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 50,119 92,720 10,252 — — 211,858 5,839 $ 370,788 Trust income 18 442 — — — — 601,424 601,884 Brokerage services income — — — — — — 47,428 47,428 Other revenues from operations: Merchant discount and credit card fees 40,475 45,528 2,221 — — 13,481 767 102,472 Other — 9,408 6,218 1,625 4,732 20,813 41,815 84,611 $ 90,612 148,098 18,691 1,625 4,732 246,152 697,273 $ 1,207,183 Year Ended December 31, 2019 Classification in consolidated statement of income Service charges on deposit accounts $ 60,690 93,044 9,828 — 4 263,659 5,753 $ 432,978 Trust income 31 963 — — — — 571,614 572,608 Brokerage services income — — — — — — 48,922 48,922 Other revenues from operations: Merchant discount and credit card fees 36,844 52,161 2,516 — — 12,140 3,381 107,042 Other — 7,498 8,615 1,776 3,492 36,144 34,088 91,613 $ 97,565 153,666 20,959 1,776 3,496 311,943 663,758 $ 1,253,163 Year Ended December 31, 2018 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. 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, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based compensation plans	11. Stock-based compensation plans Stock-based compensation expense was $80 million in 2020, $76 million in 2019 and $66 million in 2018. The Company recognized income tax benefits related to stock-based compensation of $17 million in 2020, $19 million in 2019 and $24 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 and restricted stock units, including performance-based awards. At December 31, 2020 and 2019, respectively, there were 3,100,665 and 3,742,478 shares available for future grant under the Company’s equity incentive compensation plan. Stock awards Stock awards are comprised of restricted stock and restricted stock units. Stock awards granted since 2014 generally vest over three years. Stock awards granted prior to 2014 vested over four years. A portion of stock awards granted after 2013 require a performance condition to be met before such awards vest. The Company may issue shares from treasury stock to the extent available or issue new shares. There were no restricted shares issued in 2020, 2019 or 2018. The number of restricted stock units issued was 480,949 in 2020, 448,487 in 2019 and 348,512 in 2018, with a weighted-average grant date fair value of $81 million, $74 million and $66 million, respectively. Unrecognized compensation expense associated with restricted stock units was $ 29 million as of December 31, 2020 and is expected to be recognized over a weighted-average period of approximately one year . 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, 2020 691,227 $ 171.72 63,591 $ 162.45 Granted 480,949 168.71 — — Vested (334,795 ) 172.56 (49,468 ) 162.48 Cancelled (20,431 ) 171.91 (573 ) 158.02 Unvested at December 31, 2020 816,950 $ 169.60 13,550 $ 162.50 Stock option awards Stock options issued generally vest over three years and are exercisable over terms not exceeding ten years and one day. The Company granted 187,088, 164,244 and 116,852 stock options in 2020, 2019 and 2018, respectively. The Company used an option pricing model to estimate the grant date present value of stock options granted, which was not material in each of 2020, 2019 and 2018. 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, 2020 305,452 $ 170.15 Granted 187,088 173.04 Exercised (25,047 ) 117.81 Expired (2,070 ) 174.09 Outstanding at December 31, 2020 465,423 $ 174.11 8.2 $ 38 Exercisable at December 31, 2020 133,098 $ 178.58 7.4 $ 38 For 2020, 2019 and 2018, M&T received $3 million, $9 million and $60 million, respectively, in cash from the exercise of stock options. The intrinsic value of stock options exercised during 2020 was $1 million, compared with $3 million and $16 million in 2019 and 2018, respectively, and the related tax benefits realized by the Company were not material in any of those three years. As of December 31, 2020, 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 2020, 2019 and 2018 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, shares of M&T common stock issued were 77,170 in 2020, 71,676 in 2019 and 58,167 in 2018. As of December 31, 2020, there were 2,233,581 shares available for issuance under the plan. M&T received cash for shares purchased through the employee stock purchase plan of $12 million, $11 million and $10 million in 2020, 2019 and 2018, respectively. Compensation expense recognized for the stock purchase plan was not material in 2020 , 2019 or 2018 . 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 14,304 and 16,491 at December 31, 2020 and 2019, 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 that allows such members to receive all or a portion of their compensation in shares of M&T common stock. Through December 31, 2020, 295,182 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 3,809 and 5,043 at December 31, 2020 and 2019, 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, 2020
Compensation And Retirement Disclosure [Abstract]
Pension plans and other postretirement benefits	12. Pension plans and other postretirement benefits The Company provides defined 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 2020 2019 2018 (In thousands) Service cost $ 19,944 $ 17,294 $ 20,346 Interest cost on benefit obligation 71,421 81,579 74,704 Expected return on plan assets (125,512 ) (122,139 ) (123,127 ) Amortization of prior service cost 557 557 557 Recognized net actuarial loss 58,096 21,992 43,793 Net periodic pension cost (benefit) $ 24,506 $ (717 ) $ 16,273 Net other postretirement benefits expense for defined benefit plans consisted of the following: Year Ended December 31 2020 2019 2018 (In thousands) Service cost $ 970 $ 859 $ 938 Interest cost on benefit obligation 1,741 2,344 2,293 Amortization of prior service credit (4,738 ) (4,730 ) (4,729 ) Recognized net actuarial gain (1,236 ) (1,247 ) (826 ) Net other postretirement benefits $ (3,263 ) $ (2,774 ) $ (2,324 ) 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 2020 2019 2020 2019 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 2,247,329 $ 1,949,613 $ 56,492 $ 59,991 Service cost 19,944 17,294 970 859 Interest cost 71,421 81,579 1,741 2,344 Plan participants’ contributions — — 2,386 2,749 Actuarial (gain) loss 288,944 298,713 2,371 (687 ) Medicare Part D reimbursement — — 574 370 Benefits paid (106,346 ) (99,870 ) (9,253 ) (9,134 ) Benefit obligation at end of year 2,521,292 2,247,329 55,281 56,492 Change in plan assets: Fair value of plan assets at beginning of year 2,037,940 1,833,833 — — Actual return on plan assets 178,610 293,546 — — Employer contributions 310,378 10,431 6,293 6,015 Plan participants’ contributions — — 2,386 2,749 Medicare Part D reimbursement — — 574 370 Benefits paid (106,346 ) (99,870 ) (9,253 ) (9,134 ) Fair value of plan assets at end of year 2,420,582 2,037,940 — — Funded status $ (100,710 ) $ (209,389 ) $ (55,281 ) $ (56,492 ) Prepaid asset recognized in the consolidated balance sheet 64,670 — — — Accrued liability recognized in the consolidated balance sheet (165,380 ) (209,389 ) (55,281 ) (56,492 ) Net accrued liability recognized in the consolidated balance sheet $ (100,710 ) $ (209,389 ) $ (55,281 ) $ (56,492 ) Amounts recognized in accumulated other comprehensive income (“AOCI”) were: Net loss (gain) $ 684,780 $ 507,029 $ (13,701 ) $ (17,308 ) Net prior service cost (credit) 1,277 1,834 (22,269 ) (27,007 ) Pre-tax adjustment to AOCI 686,057 508,863 (35,970 ) (44,315 ) Taxes (178,375 ) (133,779 ) 9,352 11,650 Net adjustment to AOCI $ 507,682 $ 375,084 $ (26,618 ) $ (32,665 ) 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 $165 million as of December 31, 2020 and $154 million as of December 31, 2019. The accumulated benefit obligation for all defined benefit pension plans was $2.5 billion and $2.2 billion at December 31, 2020 and 2019, 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 market-related fair value of the plan assets. As indicated in the preceding table, as of December 31, 2020 the Company recorded a minimum liability adjustment of $650 million ($686 million related to pension plans and $(36) million related to other postretirement benefits) with a corresponding reduction of shareholders’ equity, net of applicable deferred taxes, of $481 million. In aggregate, the benefit plans realized a net loss during 2020 that resulted in an increase to the minimum liability adjustment from that which was recorded at December 31, 2019 of $186 million. The net loss in 2020 was mainly the result of lowering the discount rate used to measure the benefit obligation of all plans to 2.50% at December 31, 2020 from 3.25% used at the prior year-end and the migration to recent mortality tables published by the Society of Actuaries, offset, in part, by the amortization of actuarial losses and a return on plan assets that exceeded the assumed expected return. Pension Plans Other Postretirement Benefit Plans Total (In thousands) 2020 Net loss $ 235,847 $ 2,371 $ 238,218 Amortization of prior service (cost) credit (557 ) 4,738 4,181 Amortization of actuarial (loss) gain (58,096 ) 1,236 (56,860 ) Total recognized in other comprehensive income, pre-tax $ 177,194 $ 8,345 $ 185,539 2019 Net loss (gain) $ 127,305 $ (687 ) $ 126,618 Amortization of prior service (cost) credit (557 ) 4,730 4,173 Amortization of actuarial (loss) gain (21,992 ) 1,247 (20,745 ) Total recognized in other comprehensive income, pre-tax $ 104,756 $ 5,290 $ 110,046 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 2020, 2019 and 2018 associated with the defined contribution pension plan was $35 million, $32 million and $29 million, respectively. Assumptions The assumed weighted-average rates used to determine benefit obligations at December 31 were: Pension Benefits Other Postretirement Benefits 2020 2019 2020 2019 Discount rate 2.50 % 3.25 % 2.50 % 3.25 % Rate of increase in future compensation levels 3.37 % 4.29 % — — The assumed weighted-average rates used to determine net benefit expense for the years ended December 31 were: Pension Benefits Other Postretirement Benefits 2020 2019 2018 2020 2019 2018 Discount rate 3.25 % 4.25 % 3.50 % 3.25 % 4.25 % 3.50 % Long-term rate of return on plan assets 6.50 % 6.50 % 6.50 % — — — Rate of increase in future compensation levels 4.29 % 4.31 % 4.33 % — — — 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 $9 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 $86 million and a decrease of 25 basis points in the discount rate would have increased the benefit obligation by $91 million at December 31, 2020. 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 2021. The rate was assumed to decrease to 5.00% over eight years. 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 5 to 60 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 $479 million (20% of total assets) of real estate funds, private investments, hedge funds and other investments at December 31, 2020. 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, 2020 and 2019, by asset category, were as follows: Fair Value Measurement of Plan Assets At December 31, 2020 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 $ 65,263 $ 48,322 $ 16,941 $ — Equity securities: M&T 111,441 111,441 — — Domestic(a) 308,220 308,220 — — International(b) 13,648 13,648 — — Mutual funds: Domestic(a) 302,094 302,094 — — International(b) 422,601 422,601 — — 1,158,004 1,158,004 — — Debt securities: Corporate(c) 172,762 — 172,762 — Government 234,232 — 234,232 — International 6,413 — 6,413 — Mutual funds: Domestic(d) 302,635 302,635 — — 716,042 302,635 413,407 — Other: Diversified mutual fund 83,507 83,507 — — Real estate partnerships 26,847 3,616 — 23,231 Private equity / debt 97,124 — — 97,124 Hedge funds 261,417 108,516 — 152,901 Guaranteed deposit fund 10,498 — — 10,498 479,393 195,639 — 283,754 Total(e) $ 2,418,702 $ 1,704,600 $ 430,348 $ 283,754 Fair Value Measurement of Plan Assets At December 31, 2019 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 $ 38,461 $ 33,870 $ 4,591 $ — Equity securities: M&T 148,603 148,603 — — Domestic(a) 219,663 219,663 — — International(b) 10,476 10,476 — — Mutual funds: Domestic(a) 238,872 238,872 — — International(b) 381,433 381,433 — — 999,047 999,047 — — Debt securities: Corporate(c) 112,783 — 112,783 — Government 190,679 — 190,679 — International 6,648 — 6,648 — Mutual funds: Domestic(d) 249,075 249,075 — — 559,185 249,075 310,110 — Other: Diversified mutual fund 86,980 86,980 — — Real estate partnerships 21,905 3,939 — 17,966 Private equity / debt 87,966 — — 87,966 Hedge funds 231,807 116,029 — 115,778 Guaranteed deposit fund 10,527 — — 10,527 439,185 206,948 — 232,237 Total(e) $ 2,035,878 $ 1,488,940 $ 314,701 $ 232,237 (a) (b) (c) (d) (e) Pension plan assets included common stock of M&T with a fair value of $111 million (5% of total plan assets) at December 31, 2020 and $149 million (7% of total plan assets) at December 31, 2019. No investment in securities of a non-U.S. Government or government agency issuer exceeded ten percent of plan assets at December 31, 2020. The changes in Level 3 pension plan assets measured at estimated fair value on a recurring basis during the year ended December 31, 2020 were as follows: Balance – January 1, 2020 Purchases (Sales) Total Realized/ Unrealized Gains (Losses) Balance – December 31, 2020 (In thousands) Other Real estate partnerships $ 17,966 $ 3,581 $ 1,684 $ 23,231 Private equity/debt 87,966 7,206 1,952 97,124 Hedge funds 115,778 30,000 7,123 152,901 Guaranteed deposit fund 10,527 — (29 ) 10,498 Total $ 232,237 $ 40,787 $ 10,730 $ 283,754 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 a voluntary contribution of $300 million to the qualified defined benefit pension plan in 2020. The Company did not make any contributions to the plan in 2019. The Company is not required to make contributions to the qualified defined benefit plan in 2021, however, subject to the impact of actual events and circumstances that may occur in 2021, the Company may make contributions, but the amount of any such contributions has not been determined. The Company regularly funds the payment of benefit obligations for the supplemental defined benefit pension and postretirement benefit plans because such plans do not hold assets for investment. Payments made by the Company for supplemental pension benefits were $10 million in each of 2020 and 2019. Payments made by the Company for postretirement benefits were $6 million in each of 2020 and 2019. Payments for supplemental pension and other postretirement benefits for 2021 are not expected to differ from those made in 2020 by an amount that will be material to the Company’s consolidated financial position. 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: 2021 $ 106,285 $ 3,238 2022 109,880 3,269 2023 114,938 3,131 2024 119,402 2,974 2025 121,456 2,789 2026 through 2030 645,515 10,656 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 RSP was amended in 2020 to increase the employer matching contribution to 100 % from 75 % in prior years and also to increase the employee's qualified compensation limits to 5 % from 4.5 %. 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 $ 62 million, $ 48 million and $ 43 million in 2020 , 2019 and 2018 , respectively.

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income taxes	13. Income taxes The components of income tax expense were as follows: Year Ended December 31 2020 2019 2018 (In thousands) Current Federal $ 267,550 $ 359,668 $ 408,428 State and local 98,431 132,696 113,706 Total current 365,981 492,364 522,134 Deferred Federal (22,894 ) 40,769 (12,780 ) State and local (8,397 ) 16,779 28,637 Total deferred (31,291 ) 57,548 15,857 Amortization of investments in qualified affordable housing projects 81,679 68,200 52,169 Total income taxes applicable to pre-tax income $ 416,369 $ 618,112 $ 590,160 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, 2020, M&T Bank’s tax bad debt reserve for which no federal income taxes have been provided was $137 million. 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 an expense of $2 million in 2020 and $5 million in 2019 and a benefit of $2 million in 2018. 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 2020 2019 2018 (In thousands) Income taxes at statutory federal income tax rate $ 371,599 $ 534,925 $ 526,730 Increase (decrease) in taxes: Tax-exempt income (22,806 ) (27,319 ) (26,186 ) State and local income taxes, net of federal income tax effect 71,127 118,085 112,451 Qualified affordable housing project federal tax credits, net (14,826 ) (15,324 ) (12,240 ) Other 11,275 7,745 (10,595 ) $ 416,369 $ 618,112 $ 590,160 Deferred tax assets (liabilities) were comprised of the following at December 31: 2020 2019 2018 (In thousands) Losses on loans and other assets $ 471,767 $ 309,523 $ 322,818 Operating lease liabilities 121,216 128,178 — Retirement benefits 26,185 55,048 30,057 Postretirement and other employee benefits 28,004 24,023 23,563 Incentive and other compensation plans 18,984 26,861 24,796 Stock-based compensation 29,507 27,912 26,759 Unrealized losses — — 52,580 Losses on cash flow hedges — — 1,861 Other 66,763 69,863 43,880 Gross deferred tax assets 762,426 641,408 526,314 Right of use assets and other leasing transactions (285,311 ) (326,626 ) (186,787 ) Unrealized gains (50,785 ) (13,322 ) — Capitalized servicing rights (50,235 ) (56,649 ) (54,894 ) Depreciation and amortization (95,684 ) (66,925 ) (61,881 ) Interest on loans (8,113 ) (23,552 ) (18,920 ) Gains on cash flow hedges (97,004 ) (36,845 ) — Other (62,581 ) (40,472 ) (30,211 ) Gross deferred tax liabilities (649,713 ) (564,391 ) (352,693 ) Net deferred tax asset $ 112,713 $ 77,017 $ 173,621 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, 2018 $ 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 Increases as a result of tax positions taken during 2019 6,996 — 6,996 Increases as a result of tax positions taken in prior years 3,265 3,255 6,520 Decreases as a result of tax positions taken in prior years (7,566 ) (2,685 ) (10,251 ) Gross unrecognized tax benefits at December 31, 2019 58,969 7,199 66,168 Increases as a result of tax positions taken in prior years — 2,800 2,800 Decreases as a result of tax positions taken in prior years (10,107 ) (2,384 ) (12,491 ) Gross unrecognized tax benefits at December 31, 2020 $ 48,862 $ 7,615 56,477 Less: Federal, state and local income tax benefits (11,174 ) Net unrecognized tax benefits at December 31, 2020 that, if recognized, would impact the effective income tax rate $ 45,303 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, 2020 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 2019, although under statute the income tax returns from 2017 through 2019 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, 2020
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 2020 2019 2018 (In thousands, except per share) Income available to common shareholders: Net income $ 1,353,152 $ 1,929,149 $ 1,918,080 Less: Preferred stock dividends(a) (68,228 ) (69,441 ) (72,521 ) Net income available to common equity 1,284,924 1,859,708 1,845,559 Less: Income attributable to unvested stock-based compensation awards (5,858 ) (10,199 ) (9,531 ) Net income available to common shareholders $ 1,279,066 $ 1,849,509 $ 1,836,028 Weighted-average shares outstanding: Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards 129,404 135,169 144,740 Less: Unvested stock-based compensation awards (766 ) (741 ) (748 ) Weighted-average shares outstanding 128,638 134,428 143,992 Basic earnings per common share $ 9.94 $ 13.76 $ 12.75 (a) The computations of diluted earnings per common share follow: Year Ended December 31 2020 2019 2018 (In thousands, except per share) Net income available to common equity $ 1,284,924 $ 1,859,708 $ 1,845,559 Less: Income attributable to unvested stock-based compensation awards (5,856 ) (10,197 ) (9,524 ) Net income available to common shareholders $ 1,279,068 $ 1,849,511 $ 1,836,035 Adjusted weighted-average shares outstanding: Common and unvested stock-based compensation awards 129,404 135,169 144,740 Less: Unvested stock-based compensation awards (766 ) (741 ) (748 ) Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock 66 34 159 Adjusted weighted-average shares outstanding 128,704 134,462 144,151 Diluted earnings per common share $ 9.94 $ 13.75 $ 12.74 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, 2020
Equity [Abstract]
Comprehensive income	15. Comprehensive 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 Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2020 $ 50,701 $ (464,548 ) $ 133,888 $ (279,959 ) $ 73,279 $ (206,680 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 141,081 — — 141,081 (36,498 ) 104,583 Foreign currency translation adjustment — — 2,724 2,724 (440 ) 2,284 Unrealized gains on cash flow hedges — — 505,042 505,042 (130,432 ) 374,610 Current year benefit plans losses — (238,218 ) — (238,218 ) 60,208 (178,010 ) Total other comprehensive income (loss) before reclassifications 141,081 (238,218 ) 507,766 410,629 (107,162 ) 303,467 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities 3,606 — — 3,606 (a) (966 ) 2,640 Gains realized in net income (2 ) — — (2 ) (b) 1 (1 ) Accretion of net gain on terminated cash flow hedges — — (125 ) (125 ) (c) 34 (91 ) Net yield adjustment from cash flow hedges currently in effect — — (271,971 ) (271,971 ) (a) 70,239 (201,732 ) Amortization of prior service credit — (4,181 ) — (4,181 ) (d) 1,057 (3,124 ) Amortization of actuarial losses — 56,860 — 56,860 (d) (14,371 ) 42,489 Total other comprehensive income (loss) 144,685 (185,539 ) 235,670 194,816 (51,168 ) 143,648 Balance — December 31, 2020 $ 195,386 $ (650,087 ) $ 369,558 $ (85,143 ) $ 22,111 $ (63,032 ) Balance — January 1, 2019 $ (200,107 ) $ (354,502 ) $ (14,719 ) $ (569,328 ) $ 149,247 $ (420,081 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 247,411 — — 247,411 (65,009 ) 182,402 Foreign currency translation adjustment — — 1,381 1,381 (290 ) 1,091 Unrealized gains on cash flow hedges — — 160,373 160,373 (42,163 ) 118,210 Current year benefit plans losses — (126,618 ) — (126,618 ) 33,287 (93,331 ) Total other comprehensive income (loss) before reclassifications 247,411 (126,618 ) 161,754 282,547 (74,175 ) 208,372 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities 3,394 — — 3,394 (a) (892 ) 2,502 Losses realized in net income 3 — — 3 (b) (1 ) 2 Accretion of net gain on terminated cash flow hedges — — (136 ) (136 ) (c) 36 (100 ) Net yield adjustment from cash flow hedges currently in effect — — (13,011 ) (13,011 ) (a) 3,421 (9,590 ) Amortization of prior service credit — (4,173 ) — (4,173 ) (d) 1,097 (3,076 ) Amortization of actuarial losses — 20,745 — 20,745 (d) (5,454 ) 15,291 Total other comprehensive income (loss) 250,808 (110,046 ) 148,607 289,369 (75,968 ) 213,401 Balance — December 31, 2019 $ 50,701 $ (464,548 ) $ 133,888 $ (279,959 ) $ 73,279 $ (206,680 ) Investment Defined Benefit Total Amount Income Securities 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 (e) (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) Amortization of unrealized holding losses on HTM securities 4,252 — — 4,252 (a) (1,118 ) 3,134 Gains realized in net income (18 ) — — (18 ) (b) 4 (14 ) Accretion of net gain on terminated cash flow hedges — — (111 ) (111 ) (c) 29 (82 ) Net yield adjustment from cash flow hedges currently in effect — — 13,339 13,339 (a) (3,507 ) 9,832 Amortization of prior service credit — (4,172 ) — (4,172 ) (d) 1,097 (3,075 ) Amortization of actuarial losses — 42,967 — 42,967 (d) (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) Included in interest income. (b) Included in gain (loss) on bank investment securities. (c) Included in interest expense. (d) Included in other costs of operations. (e) 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. Prior to that date, such changes in fair value were reflected in other comprehensive income. Accumulated other comprehensive income (loss), net consisted of the following: Investment Securities Defined Benefit Plans Other Total (In thousands) Balance at January 1, 2018 $ (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 ) Net gain (loss) during 2019 184,906 (81,116 ) 109,611 213,401 Balance at December 31, 2019 37,380 (342,419 ) 98,359 (206,680 ) Net gain (loss) during 2020 107,222 (138,645 ) 175,071 143,648 Balance at December 31, 2020 $ 144,602 $ (481,064 ) $ 273,430 $ (63,032 )

Other income and other expense

Other income and other expense	12 Months Ended
	Dec. 31, 2020
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 2020 2019 2018 (In thousands) Other income: Credit-related fee income $ 70,387 $ 86,792 $ 82,614 Other expense: Professional services 240,047 330,900 312,998 Accrual for Wilmington Trust Corporation legal-related matters 135,000 Amortization of capitalized mortgage servicing rights 84,821 71,888

International activities

International activities	12 Months Ended
	Dec. 31, 2020
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 $170 million and $186 million of loans to foreign borrowers at December 31, 2020 and 2019, respectively. Deposits at M&T Bank’s Cayman Islands office were $652 million and $1.68 billion at December 31, 2020 and 2019, respectively. Deposits at M&T Bank’s office in Ontario, Canada were $32 million at December 31, 2020 and $23 million at December 31, 2019. Revenues from providing international trust-related services were approximately $36 million in 2020, $32 million in 2019 and $29 million in 2018.

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Dec. 31, 2020
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, 2020. The net effect of interest rate swap agreements was to increase net interest income by $312 million in 2020, and to decrease net interest income by $2 million in 2019 and $25 million in 2018. 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- Estimated Notional Average Average Rate Fair Value Amount Maturity Fixed Variable Gain (In thousands) (In (In December 31, 2020 Fair value hedges: Fixed rate long-term borrowings (b) $ 1,650,000 3.3 2.86 % 0.79 % $ 651 Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(c) 49,400,000 0.9 2.22 % 0.15 % 425 Total $ 51,050,000 1.0 $ 1,076 December 31, 2019 Fair value hedges: Fixed rate long-term borrowings (b) $ 3,800,000 2.2 2.51 % 2.27 % $ (567 ) Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(d) 53,750,000 1.4 2.44 % 1.73 % (1,195 ) Total $ 57,550,000 1.5 $ (1,762 ) (a) C ertain clearinghouse exchanges consider payments by counterparties for variation margin on derivative instruments to be settlements of those positions. The impact of such treatment at December 31, 2020 was a reduction of the estimated fair value gains on interest rate swap agreements designated as fair value hedges of $101.5 million and on interest rate swap agreements designated as cash flow hedges of $372.2 million. The impact of such treatment at December 31, 2019 was a reduction of estimated fair value gains on agreements designated as fair value hedges of $45.1 million and agreements designated as cash flow hedges of $140.7 million. (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 $32.1 billion of forward-starting interest rate swap agreements that become effective in 2021-2022. (d) Includes notional amount and terms of $40.4 billion of forward-starting interest rate swap agreement that become effective in 2020-2022 . The notional amount of interest rate swap agreements entered into for risk management purposes that were outstanding at December 31, 2020 mature as follows: (In thousands) Year ending December 31: 2021 $ 27,700,000 2022 16,500,000 2023 6,350,000 2027 500,000 $ 51,050,000 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 $37.8 billion and $48.6 billion at December 31, 2020 and 2019, respectively. The notional amounts of foreign currency and other option and futures contracts entered into for trading account purposes aggregated $776 million and $1.2 billion at December 31, 2020 and 2019, 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, December 31, December 31, 2020 2019 2020 2019 (In thousands) Derivatives designated and qualifying as hedging instruments Interest rate swap agreements (a) $ 1,968 $ 232 $ 892 $ 1,994 Commitments to sell real estate loans (a) 1,488 1,195 8,458 421 3,456 1,427 9,350 2,415 Derivatives not designated and qualifying as hedging instruments Mortgage-related commitments to originate real estate loans for sale (a) 43,599 11,965 365 1,225 Commitments to sell real estate loans (a) 2,409 3,074 13,868 3,548 Trading: Interest rate contracts (b) 1,008,913 398,295 105,768 68,103 Foreign exchange and other option and futures contracts (b) 9,608 12,506 11,134 11,800 1,064,529 425,840 131,135 84,676 Total derivatives $ 1,067,985 $ 427,267 $ 140,485 $ 87,091 (a) (b) Amount of Gain (Loss) Recognized Year Ended December 31, 2020 Year Ended December 31, 2019 Year Ended December 31, 2018 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) $ 57,611 (57,686 ) $ 95,006 (94,742 ) $ (10,006 ) 10,969 Derivatives not designated as hedging Trading: Interest rate contracts (b) $ 6,344 $ 24,701 $ 4,506 Foreign exchange and other option and futures contracts (b) 7,363 8,511 9,416 Total $ 13,707 $ 33,212 $ 13,922 (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, 2020 December 31, 2019 December 31, 2020 December 31, 2019 (In thousands) Location in the of the Hedged Items in Fair Value Long-term debt $ 1,750,048 $ 3,840,775 $ 101,326 $ 43,640 The amount of interest income recognized in the consolidated statement of income associated with derivatives designated as cash flow hedges was $272 million and $13 million for 2020 and 2019, respectively. As of December 31, 2020, the unrealized gain recognized in other comprehensive income related to cash flow hedges was $373 million, of which $156 million, $170 million and $47 million relate to interest rate swap agreements maturing in 2021, 2022 and 2023, respectively. 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 $64 million and $18 million at December 31, 2020 and 2019, 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 $114 million and $51 million at December 31, 2020 and 2019, respectively. The Company was required to post collateral relating to those positions of $103 million and $50 million at December 31, 2020 and 2019, 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, 2020 was not material. The aggregate fair value of derivative financial instruments in an asset position and the net asset positions with counterparties, which are subject to enforceable master netting arrangements, was $3 million and $6 million at December 31, 2020 and 2019, respectively. Counterparties posted collateral relating to those positions of $3 million and $5 million at December 31, 2020 and 2019, 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 $135 million and $84 million at December 31, 2020 and 2019, 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. In conjunction with changes made by the clearinghouse to prepare for reference rate reform, the Company changed the discount rate index used to value interest rate swaps from the Federal Funds Overnight Index swap rate to the Secured Overnight Financial Rate in October 2020. The change did not have a material impact on the Company's consolidated financial statements.

Variable interest entities and

Variable interest entities and asset securitizations	12 Months Ended
	Dec. 31, 2020
Text Block [Abstract]
Variable interest entities and asset securitizations	19. Variable interest entities and asset securitizations The Company’s securitization activity has consisted of securitizing loans originated for sale into government issued or guaranteed mortgage-backed securities that are then retained by the Company. The amounts of those securitizations in 2020, 2019 and 2018 are presented in the Company’s consolidated statement of cash flows. The Company has not recognized any losses as a result of having securitized assets. As described in note 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, 2020 and 2019, 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 $2.3 billion at December 31, 2020 and $1.5 billion at December 31, 2019. Those partnerships generally construct or acquire properties for which the investing partners are eligible to receive certain federal income tax credits in accordance with government guidelines. Such investments may also provide tax deductible losses to the partners. The partnership investments also assist the Company in achieving its community reinvestment initiatives. As a limited partner, there is no recourse to the Company by creditors of the partnerships. However, the tax credits that result from the Company’s investments in such partnerships are generally subject to recapture should a partnership fail to comply with the respective government regulations. The Company’s carrying amount of its investments in such partnerships was $861 million, including $406 million of unfunded commitments, at December 31, 2020 and $748 million, including $414 million of unfunded commitments, at December 31, 2019. Contingent commitments to provide additional capital contributions to these partnerships were not material at December 31, 2020. The Company has not provided financial or other support to the partnerships that was not contractually required. The Company’s maximum exposure to loss from its investments in such partnerships as of December 31, 2020 was $1.2 billion, including possible recapture of certain tax credits. Management currently estimates that no material losses are probable as a result of the Company’s involvement with such entities. The Company, in its position as limited partner, does not direct the activities that most significantly impact the economic performance of the partnerships and, therefore, in accordance with the accounting provisions for variable interest entities, the partnership entities are not included in the Company’s consolidated financial statements. The Company’s investment in qualified affordable housing projects is amortized to income taxes in the consolidated statement of income as tax credits and other tax benefits resulting from deductible losses associated with the projects are received. The Company 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, 2020
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, 2020. 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, 2020 and 2019 measured at estimated fair value on a recurring basis: Fair Value Measurements Level 1 Level 2 Level 3 (In thousands) December 31, 2020 Trading account assets $ 1,068,581 $ 50,060 $ 1,018,521 $ — Investment securities available for sale: U.S. Treasury and federal agencies 9,338 — 9,338 — Mortgage-backed securities: Government issued or guaranteed 4,683,438 — 4,683,438 — Privately issued 16 — — 16 Other debt securities 129,814 — 129,814 — 4,822,606 — 4,822,590 16 Equity securities 92,985 63,129 29,856 — Real estate loans held for sale 1,054,676 — 1,054,676 — Other assets (a) 49,464 — 5,865 43,599 Total assets $ 7,088,312 $ 113,189 $ 6,931,508 $ 43,615 Trading account liabilities $ 116,902 $ — $ 116,902 $ — Other liabilities (a) 23,583 — 23,218 365 Total liabilities $ 140,485 $ — $ 140,120 $ 365 December 31, 2019 Trading account assets $ 470,129 $ 49,040 $ 421,089 $ — Investment securities available for sale: U.S. Treasury and federal agencies 9,767 — 9,767 — Obligations of states and political subdivisions 775 — 775 — Mortgage-backed securities: Government issued or guaranteed 6,180,940 — 6,180,940 — Privately issued 16 — — 16 Other debt securities 127,278 — 127,278 — 6,318,776 — 6,318,760 16 Equity securities 140,041 100,637 39,404 — Real estate loans held for sale 442,079 — 442,079 — Other assets (a) 16,466 — 4,501 11,965 Total assets $ 7,387,491 $ 149,677 $ 7,225,833 $ 11,981 Trading account liabilities $ 79,903 $ — $ 79,903 $ — Other liabilities (a) 7,188 — 5,963 1,225 Total liabilities $ 87,091 $ — $ 85,866 $ 1,225 (a) The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the years ended December 31, 2020, 2019 and 2018 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets (In thousands) 2020 Balance — January 1, 2020 $ 16 $ 10,740 Total gains realized/unrealized: Included in earnings — 194,469 (a) Transfers out of Level 3 — (161,975 ) (b) Balance — December 31, 2020 $ 16 $ 43,234 Changes in unrealized gains included in earnings related to assets still held at December 31, 2020 $ — $ 42,597 (a) 2019 Balance — January 1, 2019 $ 22 $ 7,712 Total gains realized/unrealized: Included in earnings — 129,398 (a) Settlements (6 ) — Transfers out of Level 3 — (126,370 ) (b) Balance — December 31, 2019 $ 16 $ 10,740 Changes in unrealized gains included in earnings related to assets still held at December 31, 2019 $ — $ 11,146 (a) 2018 Balance — January 1, 2018 $ 28 $ 8,303 Total gains realized/unrealized: Included in earnings — 58,740 (a) Settlements (6 ) — Transfers out of Level 3 — (59,331 ) (b) 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 (a) (a) (b) 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 uncollectable 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 15 % to 90 % with a weighted-average of 38% at December 31, 2020 . 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, which at December 31, 2020 was 50%. 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 $652 million at December 31, 2020 , ( $339 million and $313 million of which were classified as Level 2 and Level 3, respectively), $ 305 million at December 31, 2019 ($ 115 million and $ 190 million of which were classified as Level 2 and Level 3, respectively), and $ 268 million at December 31, 2018 ($ 120 million and $ 148 million of which were classified as Level 2 and Level 3, respectively). Changes in fair value recognized during the years ended December 31, 2020 , 2019 and 2018 for partial charge-offs of loans and loan impairment reserves on loans held by the Company at the end of each of those years were decreases of $222 million, $ 110 million and $ 83 million, respectively. Assets taken in foreclosure of defaulted loans Assets taken in foreclosure of defaulted loans are primarily comprised of commercial and residential real property and are generally measured at the lower of cost or fair value less costs to sell. The fair value of the real property is generally determined using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace, and the related nonrecurring fair value measurement adjustments have generally been classified as Level 2. Assets taken in foreclosure of defaulted loans subject to nonrecurring fair value measurement were $22 Capitalized servicing rights Capitalized servicing rights are initially measured at fair value in the Company’s consolidated balance sheet. The Company utilizes the amortization method to subsequently measure its capitalized servicing assets. In accordance with GAAP, the Company must record impairment charges, on a nonrecurring basis, when the carrying value of certain strata exceed their estimated fair value. To estimate the fair value of servicing rights, the Company considers market prices for similar assets, if available, and the present value of expected future cash flows associated with the servicing rights calculated using assumptions that market participants would use in estimating future servicing income and expense. Such assumptions include estimates of the cost of servicing loans, loan default rates, an appropriate discount rate, and prepayment speeds. For purposes of evaluating and measuring impairment of capitalized servicing rights, the Company stratifies such assets based on the predominant risk characteristics of the underlying financial instruments that are expected to have the most impact on projected prepayments, cost of servicing and other factors affecting future cash flows associated with the servicing rights. Such factors may include financial asset or loan type, note rate and term. The amount of impairment recognized is the amount by which the carrying value of the capitalized servicing rights for a stratum exceed estimated fair value. Impairment is recognized through a valuation allowance. The determination of fair value of capitalized servicing rights is considered a Level 3 valuation. Capitalized servicing rights related to residential mortgage loans of $ 159 million and $ 188 million at December 31, 2020 and December 31, 2019, respectively, required a valuation allowance of $ 30 million and $ 7 million, respectively. Significant unobservable inputs used in this Level 3 valuation included weighted-average prepayment speeds of 16.01% and 18.50% at December 31, 2020 and December 31, 2019, respectively, and a weighted-average option-adjusted spread of 900 basis points at each date. Changes recognized for impairment of capitalized servicing rights were $ 23 million and $ 7 million during the years ended December 31, 2020 and 2019, respectively . 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, 2020 and 2019: Fair Value Valuation Technique Unobservable Inputs/Assumptions Range (Weighted- Average) (In December 31, 2020 Recurring fair value measurements Privately issued mortgage- backed securities $ 16 Two independent pricing quotes — — Net other assets (liabilities) (a) 43,234 Discounted cash flow Commitment expirations 0% - 98% (16%) December 31, 2019 Recurring fair value measurements Privately issued mortgage- backed securities $ 16 Two independent pricing quotes — — Net other assets (liabilities) (a) 10,740 Discounted cash flow Commitment expirations 0% - 99% (13%) (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, 2020 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,552,743 1,552,743 1,497,457 55,286 — Interest-bearing deposits at banks 23,663,810 23,663,810 — 23,663,810 — Trading account assets 1,068,581 1,068,581 50,060 1,018,521 — Investment securities 7,045,697 7,138,989 63,129 7,005,571 70,289 Loans and leases: Commercial loans and leases 27,574,564 27,220,699 — — 27,220,699 Commercial real estate loans 37,637,889 36,816,580 — 277,911 36,538,669 Residential real estate loans 16,752,993 17,089,141 — 4,135,655 12,953,486 Consumer loans 16,570,421 16,554,050 — — 16,554,050 Allowance for credit losses (1,736,387 ) — — — — Loans and leases, net 96,799,480 97,680,470 — 4,413,566 93,266,904 Accrued interest receivable 419,936 419,936 — 419,936 — Financial liabilities: Noninterest-bearing deposits $ (47,572,884 ) (47,572,884 ) — (47,572,884 ) — Savings and interest-checking deposits (67,680,840 ) (67,680,840 ) — (67,680,840 ) — Time deposits (3,899,910 ) (3,919,367 ) — (3,919,367 ) — Deposits at Cayman Islands office (652,104 ) (652,104 ) — (652,104 ) — Short-term borrowings (59,482 ) (59,482 ) — (59,482 ) — Long-term borrowings (4,382,193 ) (4,490,433 ) — (4,490,433 ) — Accrued interest payable (59,916 ) (59,916 ) — (59,916 ) — Trading account liabilities (116,902 ) (116,902 ) — (116,902 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 43,234 43,234 — — 43,234 Commitments to sell real estate loans (18,429 ) (18,429 ) — (18,429 ) — Other credit-related commitments (133,354 ) (133,354 ) — — (133,354 ) Interest rate swap agreements used for interest rate risk management 1,076 1,076 — 1,076 — December 31, 2019 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,432,805 1,432,805 1,394,984 37,821 — Interest-bearing deposits at banks 7,190,154 7,190,154 — 7,190,154 — Federal funds sold 3,500 3,500 — 3,500 — Trading account assets 470,129 470,129 49,040 421,089 — Investment securities 9,497,251 9,539,540 100,637 9,351,793 87,110 Loans and leases: Commercial loans and leases 23,838,168 23,510,908 — — 23,510,908 Commercial real estate loans 35,541,914 35,517,180 — 28,338 35,488,842 Residential real estate loans 16,156,094 16,227,274 — 3,990,848 12,236,426 Consumer loans 15,386,693 15,413,262 — — 15,413,262 Allowance for credit losses (1,051,071 ) — — — — Loans and leases, net 89,871,798 90,668,624 — 4,019,186 86,649,438 Accrued interest receivable 333,142 333,142 — 333,142 — Financial liabilities: Noninterest-bearing deposits $ (32,396,407 ) (32,396,407 ) — (32,396,407 ) — Savings and interest-checking deposits (54,932,162 ) (54,932,162 ) — (54,932,162 ) — Time deposits (5,757,456 ) (5,829,347 ) — (5,829,347 ) — Deposits at Cayman Islands office (1,684,044 ) (1,684,044 ) — (1,684,044 ) — Short-term borrowings (62,363 ) (62,363 ) — (62,363 ) — Long-term borrowings (6,986,186 ) (7,063,165 ) — (7,063,165 ) — Accrued interest payable (105,374 ) (105,374 ) — (105,374 ) — Trading account liabilities (79,903 ) (79,903 ) — (79,903 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 10,740 10,740 — — 10,740 Commitments to sell real estate loans 300 300 — 300 — Other credit-related commitments (136,470 ) (136,470 ) — — (136,470 ) Interest rate swap agreements used for interest rate risk management (1,762 ) (1,762 ) — (1,762 ) — 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, 2020
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, December 31, 2020 2019 (In thousands) Commitments to extend credit Home equity lines of credit $ 5,563,854 $ 5,442,160 Commercial real estate loans to be sold 363,735 164,076 Other commercial real estate 7,237,367 9,029,608 Residential real estate loans to be sold 1,026,118 423,056 Other residential real estate 665,259 448,375 Commercial and other 19,427,886 16,170,731 Standby letters of credit 2,241,417 2,441,432 Commercial letters of credit 27,332 41,059 Financial guarantees and indemnification contracts 4,220,531 4,108,572 Commitments to sell real estate loans 2,108,823 906,037 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 $10.4 billion and $9.1 billion at December 31, 2020 and 2019, 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 predominantly comprised of recourse obligations associated with sold loans and other guarantees and commitments. 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 $4.0 billion and $3.9 billion at December 31, 2020 and 2019, 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 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, 2020, the Company believes that its obligation to loan purchasers was not material to the Company’s consolidated financial position. 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 $25 million at December 31, 2020. 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, 2020
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, 2020, 2019 and 2018 Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio 2020 2019 2018 2020 2019 2018 2020 2019 2018 2020 2019 2018 Net interest income(a) $ 462,614 $ 451,307 $ 434,579 $ 864,149 $ 828,888 $ 821,812 $ 673,894 $ 692,526 $ 665,220 $ 486,831 $ 209,807 $ 228,051 Noninterest income 103,837 113,855 111,600 276,791 289,558 288,908 208,367 214,970 183,955 (1,735 ) 26,919 (9,690 ) 566,451 565,162 546,179 1,140,940 1,118,446 1,110,720 882,261 907,496 849,175 485,096 236,726 218,361 Provision for credit losses 25,928 16,501 10,916 73,099 25,580 8,976 107,210 1,537 3,159 1,508 3,608 6,683 Amortization of core deposit and other intangible assets — — — — — — 1,060 1,060 1,060 — — — Depreciation and other amortization 1,482 2,066 382 2,421 2,353 496 28,187 26,963 25,852 285 279 187 Other noninterest expense 322,868 317,482 305,340 375,769 382,214 364,102 256,428 239,333 217,387 54,339 52,885 65,393 Income (loss) before taxes 216,173 229,113 229,541 689,651 708,299 737,146 489,376 638,603 601,717 428,964 179,954 146,098 Income tax expense (benefit) 56,953 60,617 61,279 181,179 187,835 198,229 107,548 152,977 148,807 101,673 36,342 29,872 Net income (loss) $ 159,220 $ 168,496 $ 168,262 $ 508,472 $ 520,464 $ 538,917 $ 381,828 $ 485,626 $ 452,910 $ 327,291 $ 143,612 $ 116,226 Average total assets (in millions) $ 8,152 $ 5,793 $ 5,631 $ 30,338 $ 28,142 $ 26,626 $ 25,792 $ 23,921 $ 22,885 $ 27,726 $ 29,081 $ 32,123 Capital expenditures (in millions) $ — $ 1 $ — $ — $ 2 $ — $ — $ — $ — $ — $ — $ 1 For the Years Ended December 31, 2020, 2019 and 2018 Residential Mortgage Banking Retail Banking All Other Total 2020 2019 2018 2020 2019 2018 2020 2019 2018 2020 2019 2018 Net interest income(a) $ 52,712 $ 20,008 $ 13,933 $ 1,204,309 $ 1,389,788 $ 1,351,165 $ 121,808 $ 537,940 $ 557,542 $ 3,866,317 $ 4,130,264 $ 4,072,302 Noninterest income 515,549 393,372 305,560 260,163 327,562 324,228 725,472 695,443 651,439 2,088,444 2,061,679 1,856,000 568,261 413,380 319,493 1,464,472 1,717,350 1,675,393 847,280 1,233,383 1,208,981 5,954,761 6,191,943 5,928,302 Provision for credit losses 1,785 382 (2,178 ) 108,268 122,135 112,572 482,202 6,257 (8,128 ) 800,000 176,000 132,000 Amortization of core deposit and other intangible assets — — — — — — 13,809 18,430 23,462 14,869 19,490 24,522 Depreciation and other amortization 60,129 48,248 24,288 95,936 93,312 35,274 116,979 108,604 68,004 305,419 281,825 154,483 Other noninterest expense 332,028 273,067 241,624 764,262 784,718 789,783 959,258 1,117,668 1,125,428 3,064,952 3,167,367 3,109,057 Income (loss) before taxes 174,319 91,683 55,759 496,006 717,185 737,764 (724,968 ) (17,576 ) 215 1,769,521 2,547,261 2,508,240 Income tax expense (benefit) 40,667 19,355 10,272 130,745 189,611 196,467 (202,396 ) (28,625 ) (54,766 ) 416,369 618,112 590,160 Net income (loss) $ 133,652 $ 72,328 $ 45,487 $ 365,261 $ 527,574 $ 541,297 $ (522,572 ) $ 11,049 $ 54,981 $ 1,353,152 $ 1,929,149 $ 1,918,080 Average total assets (in millions) $ 4,038 $ 2,611 $ 2,161 $ 16,438 $ 15,083 $ 13,656 $ 22,996 $ 14,953 $ 13,877 $ 135,480 $ 119,584 $ 116,959 Capital expenditures (in millions) $ — $ 1 $ 1 $ 34 $ 76 $ 31 $ 138 $ 98 $ 65 $ 172 $ 178 $ 98 (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 2020 2019 2018 (In thousands) Revenues $ (47,604 ) $ (48,559 ) $ (41,285 ) Expenses (14,038 ) (18,218 ) (24,660 ) Income taxes (8,824 ) (7,976 ) (4,371 ) Net income (24,742 ) (22,365 ) (12,254 ) 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, 2020
Regulatory Capital Requirements [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, 2020, approximately $1.3 billion 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 were previously required to maintain reserves against certain deposit liabilities. Effective March 26, 2020, the federal banking agencies eliminated reserve requirements for depository institutions to support lending to households and businesses. During the maintenance period that included December 31, 2019, cash and due from banks and interest-earning deposits at banks included a daily average of $666 million 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, 2020, 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 require a “capital conservation buffer” of 2.5% composed entirely of CET1 on top of the minimum risk-weighted asset ratios. The capital ratios and amounts of the Company and its banking subsidiaries as of December 31, 2020 and 2019 are presented below: M&T (Consolidated) M&T Bank Wilmington Trust, N.A. (Dollars in thousands) December 31, 2020: Common equity Tier 1 capital Amount $ 10,623,368 $ 11,550,462 $ 630,574 Ratio(a) 10.00 % 10.90 % 46.57 % Tier 1 capital Amount 11,873,317 11,550,462 630,574 Ratio(a) 11.17 % 10.90 % 46.57 % Total capital Amount 14,207,937 13,373,416 632,506 Ratio(a) 13.37 % 12.62 % 46.72 % Leverage Amount 11,873,317 11,550,462 630,574 Ratio(b) 8.48 % 8.27 % 10.73 % December 31, 2019: Common equity Tier 1 capital Amount $ 10,053,887 $ 10,649,953 $ 606,538 Ratio(a) 9.73 % 10.34 % 56.35 % Tier 1 capital Amount 11,303,836 10,649,953 606,538 Ratio(a) 10.94 % 10.34 % 56.35 % Total capital Amount 13,480,612 12,342,834 608,130 Ratio(a) 13.05 % 11.99 % 56.50 % Leverage Amount 11,303,836 10,649,953 606,538 Ratio(b) 9.59 % 9.08 % 13.12 % (a) (b)

Relationship with Bayview Lendi

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.	12 Months Ended
	Dec. 31, 2020
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. That investment had no remaining carrying value at December 31, 2020 as a result of cumulative losses recognized and cash distributions received in prior years. Cash distributions now received from BLG are recognized as income by M&T and included in other revenues from operations. That income totaled $53 million in 2020, $37 million in 2019 and $24 million in 2018. 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 $ 1.9 billion and $ 2.2 billion at December 31, 2020 and 2019 , respectively. Revenues from those servicing rights were $ 10 million, $ 12 million and $ 14 million during 2020 , 2019 and 2018 , respectively. The Company sub-services residential mortgage loans for Bayview Financial having outstanding principal balances of $ 68.1 billion and $ 62.8 billion at December 31, 2020 and 2019 , respectively. Revenues earned for sub-servicing loans for Bayview Financial were $ 129 million, $ 125 million and $ 114 million in 2020 , 2019 and 2018 , respectively. In addition, the Company held $ 77 million and $ 93 million of mortgage-backed securities in its held-to-maturity portfolio at December 31, 2020 and 2019 , respectively, that were securitized by Bayview Financial. At December 31, 2020, the Company held $ 210 million of Bayview Financial’s $ 1.2 billion syndicated loan facility. During the second quarter of 2020 the Company extended two $ 100 million secured loan facilities to certain funds managed by Bayview Financial. One of the two loans was still outstanding as of December 31, 2020 with a remaining balance of $ 60 million. In early 2021 the Company purchased $ 965 million of delinquent FHA guaranteed mortgage loans, including past due accrued interest, from Bayview Financial for $ 1.0 billion. The servicing rights for such loans were retained by Bayview Financial, but the Company continues to sub-service the loans.

Parent company financial statem

Parent company financial statements	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Parent company financial statements	25. Parent company financial statements Condensed Balance Sheet December 31 2020 2019 (In thousands) Assets Cash in subsidiary bank $ 100,593 $ 83,531 Due from consolidated bank subsidiaries Money-market savings 699,476 876,819 Current income tax receivable — 1,261 Total due from consolidated bank subsidiaries 699,476 878,080 Investments in consolidated subsidiaries Banks 16,554,287 15,732,008 Other 125,988 301,765 Investments in trust preferred entities (note 19) 22,846 23,022 Other assets 92,170 67,732 Total assets $ 17,595,360 $ 17,086,138 Liabilities Accrued expenses and other liabilities $ 96,664 $ 74,235 Long-term borrowings 1,311,413 1,295,254 Total liabilities 1,408,077 1,369,489 Shareholders’ equity 16,187,283 15,716,649 Total liabilities and shareholders’ equity $ 17,595,360 $ 17,086,138 Condensed Statement of Income Year Ended December 31 2020 2019 2018 (In thousands, except per share) Income Dividends from consolidated subsidiaries $ 708,500 $ 2,025,000 $ 1,250,000 Income from Bayview Lending Group LLC 52,940 36,740 23,500 Other income 5,110 7,216 2,417 Total income 766,550 2,068,956 1,275,917 Expense Interest on long-term borrowings 31,924 51,938 36,354 Other expense 33,704 25,236 23,894 Total expense 65,628 77,174 60,248 Income before income taxes and equity in undistributed income of subsidiaries 700,922 1,991,782 1,215,669 Income tax credits 1,984 8,313 8,446 Income before equity in undistributed income of subsidiaries 702,906 2,000,095 1,224,115 Equity in undistributed income of subsidiaries Net income of subsidiaries 1,358,746 1,954,054 1,943,965 Less: dividends received (708,500 ) (2,025,000 ) (1,250,000 ) Equity in undistributed income of subsidiaries 650,246 (70,946 ) 693,965 Net income $ 1,353,152 $ 1,929,149 $ 1,918,080 Net income per common share Basic $ 9.94 $ 13.76 $ 12.75 Diluted 9.94 13.75 12.74 Condensed Statement of Cash Flows Year Ended December 31 2020 2019 2018 (In thousands) Cash flows from operating activities Net income $ 1,353,152 $ 1,929,149 $ 1,918,080 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed income of subsidiaries (650,246 ) 70,946 (693,965 ) Provision for deferred income taxes 1,079 5,263 4,949 Net change in accrued income and expense (24,206 ) (34,525 ) (8,242 ) Net cash provided by operating activities 679,779 1,970,833 1,220,822 Cash flows from investing activities Proceeds from sales or maturities of investment securities — 100 — Other, net 176,050 51,235 29,933 Net cash provided by investing activities 176,050 51,335 29,933 Cash flows from financing activities Purchases of treasury stock (373,750 ) (1,349,785 ) (2,194,396 ) Dividends paid — common (568,112 ) (552,138 ) (510,382 ) Dividends paid — preferred (68,256 ) (67,454 ) (72,521 ) Proceeds from long-term borrowings — — 748,595 Redemption of Series A and Series C preferred stock — (381,500 ) — Proceeds from issuance of Series G preferred stock — 396,000 — Other, net (5,992 ) (4,431 ) 45,913 Net cash used by financing activities (1,016,110 ) (1,959,308 ) (1,982,791 ) Net increase (decrease) in cash and cash equivalents (160,281 ) 62,860 (732,036 ) Cash and cash equivalents at beginning of year 960,350 897,490 1,629,526 Cash and cash equivalents at end of year $ 800,069 $ 960,350 $ 897,490 Supplemental disclosure of cash flow information Interest received during the year $ 1,493 $ 1,752 $ 2,219 Interest paid during the year 30,913 49,451 17,482 Income taxes received during the year 11,528 6,251 6,362

Recent accounting developments

Recent accounting developments	12 Months Ended
	Dec. 31, 2020
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 2020 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 2020 Measurement of Credit Losses on Financial Instruments The amended guidance replaced the 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 represents 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 reflects 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) are estimated considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability 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 is added to the purchase price at acquisition rather than being reported as an expense. Subsequent changes in the allowance are recorded in the income statement as an adjustment the to the provision for credit losses. In addition, the amended guidance requires credit losses relating to debt securities to be recorded through an allowance for credit losses. January 1, 2020 The Company adopted the guidance on January 1, 2020. The Company’s approach for estimating current expected credit losses for loans includes utilizing macro-economic assumptions to project losses over a reasonable and supportable forecast period. Subsequent to the forecast period, the Company reverts to longer term historical loss experience to estimate expected credit losses over the remaining contractual life. Based on portfolio composition, then current economic conditions, and reasonable and supportable forecasts of future conditions, the Company recognized an increase to the allowance for credit losses of $132 million upon adoption of the standard as of January 1, 2020 as compared with the allowance for credit losses recognized on its consolidated balance sheet at December 31, 2019. The $132 million increase was recognized as a cumulative-effect adjustment to retained earnings as of January 1, 2020. The effect on the allowance for credit losses at the adoption date was primarily attributable to increases in reserves for residential mortgage loans and consumer loans, which generally have longer estimated lives as compared with commercial and commercial real estate loans. The adoption did not have a material effect on the allowance for credit losses for debt securities. Simplifying the Test for Goodwill Impairment The amended guidance eliminates step 2 from the goodwill impairment test. January 1, 2020 The Company adopted the amended guidance effective January 1, 2020 using a prospective transition method and will incorporate the guidance as necessary when circumstances arise for the guidance to be utilized. 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 Adopted in 2020 Changes to the Disclosure Requirements for Fair Value Measurements The amendments remove, modify, and add certain disclosure requirements related to fair value measurements. The disclosure requirements 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 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 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 The Company adopted the amended disclosure effective January 1, 2020. Such disclosures relate 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 measurement uncertainty. The adoption of the guidance did not have a material impact on the Company’s 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 the internal-use software guidance to determine which implementation costs to capitalize and which costs to expense. January 1, 2020 The Company adopted the amended guidance effective January 1, 2020 using a prospective transition method. The impact of the guidance on the Company’s consolidated financial statements is dependent on the nature and amount of actual expenditures but was not material for the year ended December 31, 2020. 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 The guidance did not have a material impact on the Company’s consolidated financial statements. Standard Description Required date of adoption Effect on consolidated financial statements Standards Adopted in 2020 Reference Rate Reform The amendments provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform. The amendments apply only to contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform. The amendments (1) apply to contract modifications that replace a reference rate affected by reference rate reform, (2) provide exceptions to existing guidance related to changes to the critical terms of a hedging relationship due to reference rate reform (3) provide optional expedients for fair value hedging relationships, cash flow hedging relationships, and net investment hedging relationships, and (4) provide a onetime election to sell, transfer, or both sell and transfer debt securities classified as held to maturity that reference a rate affected by reference rate reform and that are classified as held to maturity before January 1, 2020. Beginning March 12, 2020 Adopted October 1, 2020 The Company adopted the amended guidance on October 1, 2020 using a prospective transition method for the amendments. The Company applied certain optional expedients associated with the change in the discount rate index used to value interest rate swaps from the Federal Funds Overnight Index Swap rate to the Secured Overnight Financing Rate that occurred in October 2020, the effects of which were not material to the Company’s consolidated financial statements. The impact related to optional expedients that are anticipated to be implemented prospectively is dependent on how reference rate reform ultimately impacts values of financial instruments in transitioning from a discontinued reference rate to a replacement reference rate and how well the optional expedients mitigate any potential differences. The Company has not yet determined if it will make a onetime election to sell, transfer, or both sell and transfer debt securities classified as held to maturity that reference a rate affected by reference rate reform. 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 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, 2020 Adopted December 31, 2020 The Company has amended its disclosures related to its defined benefit plans at December 31, 2020 to comply with the amended guidance. Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of December 31, 2020 Clarifying the Interactions Between Equity Securities, Equity Method and Joint Ventures, and Derivatives and Hedging The amendments clarify the following guidance: 1. That an entity should consider observable transactions that require it to either apply or discontinue the equity method of accounting for the purposes of applying the measurement alternative in the equity securities investments guidance immediately before applying or upon discontinuing the equity method of accounting. 2. For the purpose of applying the derivatives and hedging guidance an entity should not consider whether, upon the settlement of a forward contract or exercise of a purchased option, individually or with existing investments, the underlying securities would be accounted for under the equity method of accounting or the fair value option in accordance with the financial instruments guidance. An entity also would evaluate the remaining characteristics in the derivatives and hedging guidance to determine the accounting for those forward contracts and purchased options. January 1, 2021 Early adoption permitted The Company adopted the amended guidance effective January 1, 2021 using a prospective transition method. The Company does not expect the guidance will have a material impact on its consolidated financial statements. Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of December 31, 2020 Simplifying the Accounting for Income Taxes The amendments remove the following exceptions for accounting for income taxes: 1. Exception to the incremental approach for intraperiod tax allocation when there is a loss from continuing operations and income or a gain from other items (for example, discontinued operations or other comprehensive income). 2. Exception to the requirement to recognize a deferred tax liability for equity method investments when a foreign subsidiary becomes an equity method investment. 3. Exception to the ability not to recognize a deferred tax liability for a foreign subsidiary when a foreign equity method investment becomes a subsidiary. 4. Exception to the general methodology for calculating income taxes in an interim period when a year-to-date loss exceeds the anticipated loss for the year. The amendments also simplify the accounting for income taxes by doing the following: 1. Requiring that an entity recognize a franchise tax (or similar tax) that is partially based on income as an income-based tax and account for any incremental amount incurred as a non-income-based tax. 2. Requiring that an entity evaluate when a step up in the tax basis of goodwill should be considered part of the business combination in which the book goodwill was originally recognized and when it should be considered a separate transaction. 3. Specifying that an entity is not required to allocate the consolidated amount of current and deferred tax expense to a legal entity that is not subject to tax in its separate financial statements. However, an entity may elect to do so (on an entity-by-entity basis) for a legal entity that is both not subject to tax and disregarded by the taxing authority. 4. Requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. 5. Making minor Codification improvements for income taxes related to employee stock ownership plans and investments in qualified affordable housing projects accounted for using the equity method. January 1, 2021 Early adoption permitted The Company adopted the amended guidance effective January 1, 2021. The amendments requiring retrospective or modified retrospective application related to separate financial statements of legal entities that are not subject to tax, changes in ownership of foreign equity method investments or foreign subsidiaries, and franchise taxes that are partially based on income had no material impact to the Company’s consolidated financial statements at adoption. All other amendments should be applied on a prospective basis and are not expected to have a material effect on the Company’s consolidated financial statements. Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of December 31, 2020 Changes to Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity The amendments reduce the number of accounting models for convertible debt instruments and convertible preferred stock. The amendments also reduce form-over-substance-based guidance for the derivatives scope exception for contacts in an entity’s own equity. For convertible instruments, embedded conversion features no longer are separated from the host contract for convertible instruments with conversion features that are not required to be accounted for as derivatives, or that do not result in substantial premiums accounted for as paid-in capital. Consequently, a convertible debt instrument will be accounted for as a single liability measured at its amortized cost and a convertible preferred stock will be accounted for as a single equity instrument measured at its historical cost, as long as no other features require bifurcation and recognition as derivatives. By removing those separation models, the interest rate of convertible debt instruments typically will be closer to the coupon interest rate on the instrument. The amendments also require certain changes to EPS calculations for convertible instruments as well as additional disclosures relating to conditions that cause conversion features to be met. For contacts in an entity’s own equity, the amendments revise the derivatives scope exception guidance as follows: 1. Remove the settlement in unregistered shares, collateral, and shareholder rights conditions from the settlement guidance. 2. Clarify that payment penalties for failure to timely file do not preclude equity classification. 3. Require instruments that are required to be classified as an asset or liability to be measured subsequently at fair value, with changes reported in earnings and disclosed in the financial statements. 4. Clarify that the scope of the disclosure requirements in the Contracts in an Entity’s Own Equity section of the Derivatives guidance applies only to freestanding instruments. 5. Clarify that the scope of the reassessment guidance in the Contracts in an Entity’s Own Equity section of the Derivatives guidance applies to both freestanding instruments and embedded features. January 1, 2022 Early adoption permitted but no earlier than January 1, 2021 The amendments can be applied either on a modified retrospective method of transition or a fully retrospective method of transition. In applying the modified retrospective method, the guidance should be applied to transactions outstanding as of the beginning of the fiscal year in which the amendments are adopted. Transactions that were settled (or expired) during prior reporting periods are unaffected. The cumulative effect of the change should be recognized as an adjustment to the opening balance of retained earnings at the date of adoption. If applying the fully retrospective method of transition, the cumulative effect of the change should be recognized as an adjustment to the opening balance of retained earnings in the first comparative period presented. The fair value option is allowed to be irrevocably elected for any financial instrument that is a convertible security upon adoption of the amendments. The Company has not yet decided on which transition method will be applied to the extent applicable. The Company does not expect the guidance will have a material impact on its consolidated financial statements.

Subsequent event

Subsequent event	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent event	27. Subsequent event On February 22, 2021, M&T announced that it had entered into a definitive agreement with People’s United Financial, Inc. (“People’s United”), headquartered in Bridgeport, Connecticut, under which M&T will acquire People’s United in an all-stock transaction with a total market value of approximately $7.6 billion. Under the terms of the merger agreement, People’s United shareholders will receive 0.118 of a share of M&T common stock for each People’s United share they own. In addition, at the effective time of the merger, each outstanding share of fixed-to-floating rate non-cumulative perpetual preferred stock, Series A, of People’s United will be converted into a right to receive a share of newly created series of M&T preferred stock. The merger has been unanimously approved by the boards of directors of each company. The merger is expected to close in the fourth quarter of 2021, subject to the satisfaction of customary closing conditions, including the receipt of regulatory approvals and approval by the shareholders of M&T and People’s United. In a press release dated January 21, 2021, People’s United preliminarily reported total assets of approximately $63 billion, including loans of $44 billion, and deposits of $52 billion.

Significant accounting polici_2

Significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2020
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 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. 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. Effective January 1, 2020, the Company adopted amended accounting guidance that requires an allowance for credit losses be deducted from the amortized cost basis of financial assets, including investment securities held to maturity, to present the net carrying value at the amount that is expected to be collected over the contractual term. In cases where fair value of an available for sale debt security is less than its amortized cost basis and the Company does not intend to sell the available for sale debt security and it is not more likely than not that the Company will be required to sell the security before recovery of the amortized cost basis, the difference between the fair value and the amortized cost basis is separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount related to the credit loss is recognized as an allowance for credit losses while the amount related to other factors is recognized in other comprehensive income, net of applicable income taxes. If the Company intends to sell the security or it is more likely than not to be required to sell the security before recovery of the amortized cost basis, the security is written down to fair value with the entire amount recognized in earnings. Subsequently, the Company accounts for the debt security as if the security had been purchased on the measurement date of the write down at an amortized cost basis equal to the previous amortized cost basis less the amount of the write down recognized in earnings. Prior to 2020 individual debt securities were written down through a charge to earnings when declines in value below the cost basis of the security were considered other than temporary. 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 or acquired by the Company. Originated loans and leases 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. 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 all past due principal and interest payments have been paid by the borrower. Loan balances are charged off when it becomes evident that such balances are not fully collectable. 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. During the normal course of business, the Company modifies loans to maximize recovery efforts. If a borrower is experiencing financial difficulty and a concession to the terms of the loan agreement is granted that the Company would not otherwise consider, the modification is considered a troubled debt restructuring and such loans are classified as either nonaccrual or renegotiated loans. The United States has been operating under a state of emergency related to the Coronavirus Disease 2019 (“COVID-19”) pandemic since March 13, 2020. The direct and indirect effects of the COVID-19 pandemic resulted in a dramatic reduction in the economic activity that severely hampered the ability for businesses and consumers to meet their repayment obligations. The Coronavirus Aid, Relief, and Economic Security Act and the Consolidated Appropriations Act, 2021 (collectively “CARES Act”), in addition to providing financial assistance to both businesses and consumers, creates a forbearance program for federally-backed mortgage loans, protects borrowers from negative credit reporting due to loan accommodations related to the national emergency, and provides financial institutions the option to temporarily suspend certain requirements under GAAP related to troubled debt restructurings to account for the effects of COVID-19. The bank regulatory agencies likewise issued guidance encouraging financial institutions to work prudently with borrowers who are, or may be, unable to meet their contractual payment obligations because of the effects of COVID-19. The guidance, with concurrence of the Financial Accounting Standards Board, and provisions of the CARES Act allow modifications made on a good faith basis in response to COVID-19 to borrowers who were current with their payments prior to any relief, to not be treated as troubled debt restructurings nor be reported as past due. Modifications may include payment deferrals (including maturity extensions), covenant waivers and fee waivers. The Company has been working with its customers affected by COVID-19 and has granted modifications across many of its loan portfolios. To the extent that such modifications meet the criteria described, the modified loans have not been classified as troubled debt restructurings nor reported as past due. 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 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.” Acquired loans and leases Effective January 1, 2020, expected credit losses for purchased loans with credit deterioration are initially recognized as an allowance for credit losses and are added to the purchase price to determine the amortized cost basis of the loans. Any non-credit discount or premium resulting from acquiring such loans is recognized as an adjustment to interest income over the remaining lives of the loans. Subsequent changes in the amount of expected credit losses on such loans are recognized in the allowance for credit losses in the same manner as originated loans. Prior to January 1, 2020, loans acquired in a business combination were initially recorded at fair value with no carry-over of an acquired entity’s previously established allowance for credit losses. Purchased impaired loans represented 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 was recognized as interest income over the remaining lives of the loans. Subsequent decreases in the expected cash flows required the Company to evaluate the need for additions to the Company’s allowance for credit losses. Subsequent improvements in expected cash flows resulted 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. The Company generally recognized the excess of cash flows expected at acquisition over the estimated fair value of the acquired loans as interest income over the remaining lives of such loans regardless of the borrower’s repayment status. 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 Effective January 1, 2020 the Company adopted amended accounting guidance which requires an allowance for credit losses be deducted from the amortized cost basis of financial assets to present the net carrying value at the amount that is expected to be collected over the contractual term of the asset considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. In estimating expected losses in the loan and lease portfolio, borrower-specific financial data and macro-economic assumptions are utilized to project losses over a reasonable and supportable forecast period. Assumptions and judgment are applied to measure amounts and timing of expected future cash flows, collateral values and other factors used to determine the borrowers’ abilities to repay obligations. Subsequent to the forecast period, the Company utilizes longer-term historical loss experience to estimate losses over the remaining contractual life of the loans. Prior to 2020, the allowance for credit losses represented the amount that in management’s judgment reflected incurred credit losses inherent in the loan and lease portfolio as of the balance sheet date.
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 initially 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 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. 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 Compensation expense is recognized over the vesting period of stock-based awards based on estimated grant date value, 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.
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	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, 2020
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. T he 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, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 9,154 $ 198 $ 14 $ 9,338 Mortgage-backed securities: Government issued or guaranteed 4,475,406 208,787 755 4,683,438 Privately issued 16 — — 16 Other debt securities 136,451 1,664 8,301 129,814 4,621,027 210,649 9,070 4,822,606 Investment securities held to maturity: U.S. Treasury and federal agencies 2,999 — — 2,999 Obligations of states and political subdivisions 1,531 9 — 1,540 Mortgage-backed securities: Government issued or guaranteed 1,664,443 100,176 11 1,764,608 Privately issued 77,155 11,056 17,938 70,273 Other debt securities 2,861 — — 2,861 1,748,989 111,241 17,949 1,842,281 Total debt securities $ 6,370,016 $ 321,890 $ 27,019 $ 6,664,887 Equity and other securities: Readily marketable equity — at fair value $ 67,891 $ 25,094 $ — $ 92,985 Other — at cost 381,117 — — 381,117 Total equity and other securities $ 449,008 $ 25,094 $ — $ 474,102 December 31, 2019 Investment securities available for sale: U.S. Treasury and federal agencies $ 9,742 $ 41 $ 16 $ 9,767 Obligations of states and political subdivisions 776 2 3 775 Mortgage-backed securities: Government issued or guaranteed 6,113,913 88,634 21,607 6,180,940 Privately issued 16 — — 16 Other debt securities 133,829 2,046 8,597 127,278 6,258,276 90,723 30,223 6,318,776 Investment securities held to maturity: U.S. Treasury and federal agencies 249,862 286 — 250,148 Obligations of states and political subdivisions 4,140 16 — 4,156 Mortgage-backed securities: Government issued or guaranteed 2,306,180 50,381 1,992 2,354,569 Privately issued 93,496 11,779 18,181 87,094 Other debt securities 3,239 — — 3,239 2,656,917 62,462 20,173 2,699,206 Total debt securities $ 8,915,193 $ 153,185 $ 50,396 $ 9,017,982 Equity and other securities: Readily marketable equity — at fair value $ 105,524 $ 34,786 $ 269 $ 140,041 Other — at cost 381,517 — — 381,517 Total equity and other securities $ 487,041 $ 34,786 $ 269 $ 521,558
Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities	As of December 31, 2020, 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 $ 1,531 $ 1,540 $ 1,540 $ — $ — $ — $ — Privately issued mortgage-backed securities 77,171 70,289 1,533 — — 490 68,266 Other debt securities 139,312 132,675 7,302 62,016 31,303 — 32,054 Total $ 218,014 $ 204,504 $ 10,375 $ 62,016 $ 31,303 $ 490 $ 100,320
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 2020 2019 (In thousands) Collateralized mortgage obligations: Amortized cost $ 77,964 $ 94,817 Estimated fair value 71,099 88,410
Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity	At December 31, 2020, 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 $ 4,950 4,945 Due after one year through five years 12,051 12,585 Due after five years through ten years 98,604 97,301 Due after ten years 30,000 24,321 145,605 139,152 Mortgage-backed securities available for sale 4,475,422 4,683,454 $ 4,621,027 4,822,606 Debt securities held to maturity: Due in one year or less $ 4,355 4,361 Due after one year through five years 175 178 Due after ten years 2,861 2,861 7,391 7,400 Mortgage-backed securities held to maturity 1,741,598 1,834,881 $ 1,748,989 1,842,281
Investment Securities in Continuous Unrealized Loss Position	A summary of investment securities that as of December 31, 2020 and 2019 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, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 985 (14 ) — — Mortgage-backed securities: Government issued or guaranteed 18,687 (356 ) 16,556 (399 ) Other debt securities 16,055 (181 ) 63,462 (8,120 ) 35,727 (551 ) 80,018 (8,519 ) Investment securities held to maturity: Mortgage-backed securities: Government issued or guaranteed 2,039 (11 ) — — Privately issued — — 52,418 (17,938 ) 2,039 (11 ) 52,418 (17,938 ) Total $ 37,766 (562 ) 132,436 (26,457 ) December 31, 2019 Investment securities available for sale: U.S. Treasury and federal agencies $ 1,406 (7 ) 2,893 (9 ) Obligations of states and political subdivisions — — 277 (3 ) Mortgage-backed securities: Government issued or guaranteed 117,299 (222 ) 2,002,364 (21,385 ) Other debt securities 6,600 (354 ) 56,313 (8,243 ) 125,305 (583 ) 2,061,847 (29,640 ) Investment securities held to maturity: Mortgage-backed securities: Government issued or guaranteed 2,727 (5 ) 145,235 (1,987 ) Privately issued — — 49,656 (18,181 ) 2,727 (5 ) 194,891 (20,168 ) Total $ 128,032 (588 ) 2,256,738 (49,808 )

Loans and Leases (Tables)

Loans and Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Total Loans and Leases Outstanding	Total loans and leases outstanding were comprised of the following: December 31 2020 2019 (In thousands) Loans Commercial, financial, etc. $ 26,554,486 $ 22,575,700 Real estate: Residential 16,708,644 16,098,125 Commercial 27,738,732 26,718,325 Construction 10,068,141 9,010,297 Consumer 16,558,889 15,373,881 Total loans 97,628,892 89,776,328 Leases Commercial 1,246,896 1,412,197 Total loans and leases 98,875,788 91,188,525 Less: unearned discount (339,921 ) (265,656 ) Total loans and leases, net of unearned discount $ 98,535,867 $ 90,922,869
Summary of Current, Past Due and Nonaccrual Loans	A summary of current, past due and nonaccrual loans as of December 31, 2020 and 2019 follows: Current 30-89 Days Past Due Accruing Loans Due 90 Days or More Nonaccrual Total (In thousands) December 31, 2020 Commercial, financial, leasing, etc. $ 27,196,862 60,822 10,053 306,827 $ 27,574,564 Real estate: Commercial 26,688,515 168,917 47,014 775,894 27,680,340 Residential builder and developer 1,246,095 1,693 856 1,094 1,249,738 Other commercial construction 8,523,591 66,365 3,816 114,039 8,707,811 Residential 13,764,836 200,406 792,888 365,729 15,123,859 Residential — limited documentation 1,462,277 19,687 — 147,170 1,629,134 Consumer: Home equity lines and loans 3,881,885 24,329 — 79,392 3,985,606 Recreational finance 7,002,643 47,161 — 25,519 7,075,323 Automobile 4,007,349 55,498 — 39,404 4,102,251 Other 1,346,868 17,561 4,581 38,231 1,407,241 Total $ 95,120,921 662,439 859,208 1,893,299 $ 98,535,867 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, 2019 Commercial, financial, leasing, etc. $ 23,290,797 184,011 16,776 27 — 346,557 $ 23,838,168 Real estate: Commercial 26,311,414 165,579 6,740 — 15,601 158,474 26,657,808 Residential builder and developer 1,521,315 21,195 — — 753 3,982 1,547,245 Other commercial construction 7,204,148 95,346 3,360 — 1,237 32,770 7,336,861 Residential 12,760,040 451,274 486,515 5,788 143,145 235,663 14,082,425 Residential — limited documentation 1,858,037 65,215 181 — 66,809 83,427 2,073,669 Consumer: Home equity lines and loans 4,386,511 30,229 — 1,662 — 63,215 4,481,617 Recreational finance 5,484,997 36,827 — 99 — 14,219 5,536,142 Automobile 3,787,221 78,478 — — — 21,293 3,886,992 Other 1,395,240 45,978 5,156 32,056 — 3,512 1,481,942 Total $ 87,999,720 1,174,132 518,728 39,632 227,545 963,112 $ 90,922,869 (a) (b) (c)
Summary Of Outstanding Loan Balances Related To Covid-19 Modifications Granted	A summary of outstanding loan balances for which COVID-19 related modifications were granted as of December 31, 2020 is presented below. These loans meet the criteria described in note 1 and, as such, are not considered past due or otherwise in default of loan terms as of the dates presented. Substantially all of modifications noted below expire during the first half of 2021. COVID-19 Related Modifications December 31, 2020 Payment Deferrals (1) Other Forbearances (2) Total (In thousands) Commercial, financial, leasing, etc. $ 95,823 $ 291,957 $ 387,780 Real estate: Commercial 728,511 374,509 1,103,020 Residential builder and developer 653 — 653 Other commercial construction 61,235 145,770 207,005 Residential 2,447,422 (3) — 2,447,422 Residential — limited documentation 337,108 — 337,108 Consumer: Home equity lines and loans 18,440 — 18,440 Recreational finance 24,428 — 24,428 Automobile 51,550 — 51,550 Other 2,353 — 2,353 Total $ 3,767,523 $ 812,236 $ 4,579,759 (1) (2) (3) Includes $1.7 billion of government-guaranteed loans.
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 for which interest income was recognized based on expected future cash flows that were included in the consolidated balance sheet at December 31, 2019 were as follows: (In thousands) Outstanding principal balance $ 769,414 Carrying amount: Commercial, financial, leasing, etc. 21,114 Commercial real estate 94,890 Residential real estate 341,807 Consumer 77,785 $ 535,596
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, 2019 and 2018 follows: For the Year Ended December 31, 2019 2018 Purchased Impaired Other Acquired Purchased Impaired Other Acquired (In thousands) Balance at beginning of period $ 147,210 $ 96,907 $ 157,918 $ 133,162 Interest income (49,017 ) (36,452 ) (37,819 ) (63,856 ) Reclassifications from nonaccretable balance 36,718 15,534 27,111 22,849 Other (a) — (3,909 ) — 4,752 Balance at end of period $ 134,911 $ 72,080 $ 147,210 $ 96,907 (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, 2020, 2019 and 2018: Post-modification (a) Year Ended December 31, 2020 Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total (Dollars in thousands) Commercial, financial, leasing, etc. 394 $ 246,479 $ 70,671 $ 298 $ 31,605 $ 97,344 $ 199,918 Real estate: Commercial 161 310,578 204,591 505 4,874 85,261 295,231 Residential builder and developer 1 91 — — — 90 90 Other commercial construction 2 13,602 13,573 — — — 13,573 Residential 631 202,985 183,878 — — 23,639 207,517 Residential — limited documentation 30 7,413 7,100 — — 1,232 8,332 Consumer: Home equity lines and loans 259 17,228 5,882 — — 11,372 17,254 Recreational finance 428 16,392 16,388 — — 4 16,392 Automobile 2,249 39,951 39,949 — — 2 39,951 Other 1,095 7,788 3,383 — — 4,405 7,788 Total 5,250 $ 862,507 $ 545,415 $ 803 $ 36,479 $ 223,349 $ 806,046 Year Ended December 31, 2019 Commercial, financial, leasing, etc. 150 $ 63,715 $ 10,485 $ — $ — $ 52,871 $ 63,356 Real estate: Commercial 51 48,315 5,193 — — 26,152 31,345 Residential builder and developer 2 1,330 1,068 — — — 1,068 Other commercial construction 3 1,559 — — — 1,500 1,500 Residential 83 21,695 10,819 — — 11,907 22,726 Residential — limited documentation 6 1,409 399 — — 1,044 1,443 Consumer: Home equity lines and loans 41 4,127 176 — — 4,004 4,180 Recreational finance 10 265 265 — — — 265 Automobile 66 1,141 1,076 — — 65 1,141 Total 412 $ 143,556 $ 29,481 $ — $ — $ 97,543 $ 127,024 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 (a)
Summary of Lease Financing Receivables	A summary of lease financing receivables follows: December 31, 2020 2019 (In thousands) Commercial leases: Direct financings: Lease payments receivable $ 1,017,222 $ 1,164,567 Estimated residual value of leased assets 79,621 84,540 Unearned income (83,673 ) (106,780 ) Investment in direct financings 1,013,170 1,142,327 Leveraged leases: Lease payments receivable 76,453 82,065 Estimated residual value of leased assets 73,600 81,025 Unearned income (28,388 ) (31,596 ) Investment in leveraged leases 121,665 131,494 Total investment in leases $ 1,134,835 $ 1,273,821 Deferred taxes payable arising from leveraged leases $ 61,905 $ 70,245
Minimum Future Lease Payments to be Received from Lease Financings	At December 31, 2020, the minimum future lease payments to be received from lease financings were as follows: (In thousands) Year ending December 31: 2021 $ 320,428 2022 288,322 2023 187,740 2024 122,735 2025 70,400 Later years 104,050 $ 1,093,675

Allowance for credit losses (Ta

Allowance for credit losses (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Changes in Allowance for Credit Losses	Changes in the allowance for credit losses for the years ended December 31, 2020, 2019 and 2018 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) 2020 Beginning balance $ 366,094 322,201 56,033 229,118 77,625 $ 1,051,071 Adoption of new accounting standard (61,474 ) 23,656 53,896 194,004 (77,625 ) 132,457 Provision for credit losses 220,544 356,203 (3,172 ) 226,425 — 800,000 Net charge-offs Charge-offs (135,083 ) (35,891 ) (10,283 ) (152,250 ) — (333,507 ) Recoveries 15,765 4,550 7,116 58,935 — 86,366 Net charge-offs (119,318 ) (31,341 ) (3,167 ) (93,315 ) — (247,141 ) Ending balance $ 405,846 670,719 103,590 556,232 — $ 1,736,387 2019 Beginning balance $ 330,055 341,655 69,125 200,564 78,045 $ 1,019,444 Provision for credit losses 69,702 (10,726 ) (8,585 ) 126,029 (420 ) 176,000 Net charge-offs Charge-offs (58,244 ) (12,664 ) (12,711 ) (154,089 ) — (237,708 ) Recoveries 24,581 3,936 8,204 56,614 — 93,335 Net charge-offs (33,663 ) (8,728 ) (4,507 ) (97,475 ) — (144,373 ) Ending balance $ 366,094 322,201 56,033 229,118 77,625 $ 1,051,071 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
Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans	Information with respect to loans and leases that were considered nonaccrual at the beginning and end of the reporting period and the interest income recognized on such loans for the years ended December 31, 2020, 2019 and 2018 follows. December 31, 2020 January 1, 2020 Year Ended December 2020 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 226,897 $ 79,930 $ 306,827 $ 346,743 $ 11,269 Real estate: Commercial 364,110 411,784 775,894 173,796 7,821 Residential builder and developer 1,094 — 1,094 4,708 1,694 Other commercial construction 20,992 93,047 114,039 35,881 8,457 Residential 159,006 206,723 365,729 322,504 18,069 Residential — limited documentation 84,568 62,602 147,170 114,667 634 Consumer: Home equity lines and loans 61,031 18,361 79,392 65,039 4,092 Recreational finance 19,434 6,085 25,519 14,308 626 Automobile 34,044 5,360 39,404 21,293 186 Other 3,606 34,625 38,231 35,394 1,369 Total $ 974,782 $ 918,517 $ 1,893,299 $ 1,134,333 $ 54,217 December 31, 2019 January 1, 2019 Year Ended December 31, 2019 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 206,644 $ 139,913 $ 346,557 $ 234,423 $ 8,960 Real estate: Commercial 40,847 117,627 158,474 203,672 5,850 Residential builder and developer 604 3,378 3,982 4,798 357 Other commercial construction 12,425 20,345 32,770 22,205 634 Residential 59,982 175,681 235,663 233,352 12,630 Residential — limited documentation 26,710 56,717 83,427 84,685 1,092 Consumer: Home equity lines and loans 24,812 38,403 63,215 71,292 5,987 Recreational finance 9,054 5,165 14,219 11,199 575 Automobile 14,805 6,488 21,293 23,359 214 Other 3,391 121 3,512 4,623 508 Total $ 399,274 $ 563,838 $ 963,112 $ 893,608 $ 36,807 December 31, 2018 January 1, 2018 Year Ended December 31, 2018 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 126,753 $ 107,670 $ 234,423 $ 240,991 $ 7,873 Real estate: Commercial 90,296 113,376 203,672 184,982 10,880 Residential builder and developer 2,205 2,593 4,798 6,451 1,779 Other commercial construction 14,604 7,601 22,205 10,088 3,474 Residential 57,346 176,006 233,352 235,834 14,065 Residential — limited documentation 26,808 57,877 84,685 96,105 1,980 Consumer: Home equity lines and loans 30,819 40,473 71,292 74,500 5,535 Recreational finance 6,016 5,183 11,199 6,509 333 Automobile 16,271 7,088 23,359 23,781 689 Other 4,591 32 4,623 3,357 230 Total $ 375,709 $ 517,899 $ 893,608 $ 882,598 $ 46,838
Summary of Loan grades applied various classes of Commercial and Real Estate Loans	The following table summarizes the loan grades applied at December 31, 2020 to the various classes of the Company’s commercial loans and commercial real estate loans by origination year. Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Commercial, financial, leasing, etc.: Loan grades: Pass $ 7,732,728 2,277,233 1,505,486 930,834 719,796 1,387,695 11,352,416 21,286 $ 25,927,474 Criticized accrual 388,326 84,358 113,940 41,587 39,930 73,401 584,751 13,970 1,340,263 Criticized nonaccrual 7,720 27,309 56,227 16,808 19,681 45,471 125,893 7,718 306,827 Total commercial, financial, leasing, etc. $ 8,128,774 2,388,900 1,675,653 989,229 779,407 1,506,567 12,063,060 42,974 $ 27,574,564 Real estate: Commercial: Loan grades: Pass $ 3,353,450 4,681,834 3,299,095 2,628,061 2,746,165 5,698,834 875,348 — $ 23,282,787 Criticized accrual 526,037 400,154 579,507 290,885 568,144 1,212,672 44,260 — 3,621,659 Criticized nonaccrual 26,876 121,899 47,144 99,293 197,319 248,949 34,414 — 775,894 Total commercial real estate $ 3,906,363 5,203,887 3,925,746 3,018,239 3,511,628 7,160,455 954,022 — $ 27,680,340 Residential builder and developer: Loan grades: Pass $ 506,295 223,880 109,453 15,048 10,976 11,320 236,943 — $ 1,113,915 Criticized accrual 3,690 106,847 14,836 3,421 — 1,885 4,050 — 134,729 Criticized nonaccrual — 518 — — — 576 — — 1,094 Total residential builder and developer $ 509,985 331,245 124,289 18,469 10,976 13,781 240,993 — $ 1,249,738 Other commercial construction: Loan grades: Pass $ 1,050,258 2,998,921 2,048,063 945,339 233,127 294,030 74,611 — $ 7,644,349 Criticized accrual 37,192 148,492 381,091 225,949 144,665 12,034 — — 949,423 Criticized nonaccrual 335 65,592 13,522 4,213 12,097 12,873 5,407 — 114,039 Total other commercial construction $ 1,087,785 3,213,005 2,442,676 1,175,501 389,889 318,937 80,018 — $ 8,707,811
Summary of loans in Accrual and Nonaccrual Status	. A summary of loans in accrual and nonaccrual status at December 31, 2020 for the various classes of the Company’s residential real estate loans and consumer loans by origination year is as follows. Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Residential: Current $ 2,722,862 1,416,259 618,736 1,318,094 718,235 6,898,756 71,894 — $ 13,764,836 30-89 days past due 13,496 7,781 7,258 13,477 7,947 150,447 — — 200,406 Accruing loans past due 90 days or more 579 15,234 38,145 212,818 45,804 480,308 — — 792,888 Nonaccrual 3,133 14,439 5,183 6,408 2,900 333,466 200 — 365,729 Total residential $ 2,740,070 1,453,713 669,322 1,550,797 774,886 7,862,977 72,094 — $ 15,123,859 Residential - limited documentation: Current $ — — — — — 1,462,277 — — $ 1,462,277 30-89 days past due — — — — — 19,687 — — 19,687 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — — — — — 147,170 — — 147,170 Total residential - limited documentation $ — — — — — 1,629,134 — — $ 1,629,134 Consumer: Home equity lines and loans: Current $ 773 3,983 1,591 2,016 162 51,554 2,569,621 1,252,185 $ 3,881,885 30-89 days past due — — — — — 1,148 939 22,242 24,329 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — — — — — 6,148 5,752 67,492 79,392 Total home equity lines and loans $ 773 3,983 1,591 2,016 162 58,850 2,576,312 1,341,919 $ 3,985,606 Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Recreational finance: Current $ 2,796,359 1,751,766 907,595 630,151 352,414 564,358 — — $ 7,002,643 30-89 days past due 9,548 11,255 8,519 6,638 2,938 8,263 — — 47,161 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,854 3,883 4,072 4,194 2,733 8,783 — — 25,519 Total recreational finance $ 2,807,761 1,766,904 920,186 640,983 358,085 581,404 — — $ 7,075,323 Automobile: Current $ 1,595,636 1,106,782 629,338 440,604 171,017 63,972 — — $ 4,007,349 30-89 days past due 6,461 14,140 12,542 12,899 6,373 3,083 — — 55,498 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,615 7,144 10,788 10,061 5,991 3,805 — — 39,404 Total automobile $ 1,603,712 1,128,066 652,668 463,564 183,381 70,860 — — $ 4,102,251 Other: Current $ 160,424 137,617 53,702 32,556 4,526 28,970 927,217 1,856 $ 1,346,868 30-89 days past due 1,879 1,130 577 2,301 42 557 10,594 481 17,561 Accruing loans past due 90 days or more — — — — — 374 4,207 — 4,581 Nonaccrual 1,493 492 339 183 31 501 35,044 148 38,231 Total other $ 163,796 139,239 54,618 35,040 4,599 30,402 977,062 2,485 $ 1,407,241 Total loans and leases at December 31, 2020 $ 20,949,019 15,628,942 10,466,749 7,893,838 6,013,013 19,233,367 16,963,561 1,387,378 $ 98,535,867
Summary of Loan Grades	The following table summarizes the loan grades applied at December 31, 2019 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, 2019 Pass $ 22,595,821 25,728,725 1,419,162 7,092,799 Criticized accrual 895,790 770,609 124,101 211,292 Criticized nonaccrual 346,557 158,474 3,982 32,770 Total $ 23,838,168 26,657,808 1,547,245 7,336,861

Premises and equipment (Tables)

Premises and equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Summary of Premises and Equipment	The detail of premises and equipment was as follows: December 31 2020 2019 (In thousands) Land $ 94,929 $ 96,118 Buildings 513,290 482,182 Leasehold improvements 302,246 262,438 Furniture and equipment — owned 807,701 739,724 Furniture and equipment — capital leases 8,630 14,232 1,726,796 1,594,694 Less: accumulated depreciation and amortization Owned assets 971,979 882,272 Capital leases 5,933 8,425 977,912 890,697 Right of use assets — operating leases 412,674 436,927 Premises and equipment, net $ 1,161,558 $ 1,140,924
Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases	The following table presents information about the Company’s lease costs for operating leases recorded in the consolidated balance sheet, cash paid toward lease liabilities, and the weighted-average remaining term and discount rates of the operating leases. Year Ended December 31, 2020 2019 (Dollars in thousands) Lease cost Operating lease cost $ 104,158 $ 100,669 Short-term lease cost 198 105 Variable lease cost 1,565 2,332 Total lease cost $ 105,921 $ 103,106 Other information Right-of-use assets obtained in exchange for new operating lease liabilities $ 70,754 $ 132,219 Cash paid toward lease liabilities 104,396 101,869 Weighted-average remaining lease term 7 years 7 years Weighted-average discount rate 2.74 % 3.01 %
Summary of 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: 2021 $ 105,445 2022 93,621 2023 75,698 2024 61,412 2025 46,023 Later years 130,475 Total lease payments 512,674 Less: imputed interest 45,354 Total $ 467,320

Capitalized servicing assets (T

Capitalized servicing assets (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 2019 2018 2020 2019 2018 (In thousands) Beginning balance $ 244,411 $ 120,509 $ 114,978 $ 130,636 $ 114,663 $ 114,076 Originations 45,101 26,067 28,985 29,306 41,370 26,298 Purchases — 144,326 454 — — — Amortization (58,308 ) (46,491 ) (23,908 ) (26,513 ) (25,397 ) (25,711 ) 231,204 244,411 120,509 133,429 130,636 114,663 Valuation allowance (30,000 ) (7,000 ) — — — — Ending balance, net $ 201,204 $ 237,411 $ 120,509 $ 133,429 $ 130,636 $ 114,663
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 14.50 % Impact on fair value of 10% adverse change $ (15,279 ) Impact on fair value of 20% adverse change (29,189 ) Weighted-average OAS 9.18 % Impact on fair value of 10% adverse change $ (7,230 ) Impact on fair value of 20% adverse change (14,020 ) Weighted-average discount rate 18.00 % Impact on fair value of 10% adverse change $ (7,024 ) Impact on fair value of 20% adverse change (13,556 )

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 Core deposit $ 131,664 $ 119,125 $ 12,539 Other 6,757 5,131 1,626 Total $ 138,421 $ 124,256 $ 14,165 December 31, 2019 Core deposit $ 131,664 $ 105,802 $ 25,862 Other 6,757 3,585 3,172 Total $ 138,421 $ 109,387 $ 29,034
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: 2021 $ 10,167 2022 3,998 $ 14,165
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, 2020 and 2019 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, 2020
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, 2020 Amount outstanding $ 59,482 $ — $ 59,482 Weighted-average interest rate 0.01 % — 0.01 % For the year ended December 31, 2020 Highest amount at a month-end $ 82,893 $ — Daily-average amount outstanding 61,551 — $ 61,551 Weighted-average interest rate 0.05 % — 0.05 % At December 31, 2019 Amount outstanding $ 62,363 $ — $ 62,363 Weighted-average interest rate 0.14 % — 0.14 % For the year ended December 31, 2019 Highest amount at a month-end $ 3,402,566 $ 5,000,000 Daily-average amount outstanding 260,322 799,068 $ 1,059,390 Weighted-average interest rate 1.86 % 2.49 % 2.34 % 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 %
Lines of Credit Under Formal Agreements	At December 31, 2020, M&T Bank had lines of credit under formal agreements as follows: (In thousands) Outstanding borrowings $ 1,727 Unused 32,010,950
Long-term Borrowings	Long-term borrowings were as follows: December 31, 2020 2019 (In thousands) Senior notes of M&T: Variable rate due 2023 $ 249,824 $ 249,756 3.55% due 2023 533,369 520,454 Senior notes of M&T Bank: Variable rate due 2021 349,992 349,893 Variable rate due 2022 249,858 249,758 2.05% due 2020 — 749,254 2.10% due 2020 — 749,864 2.625% due 2021 — 654,136 2.50% due 2022 664,400 652,714 2.90% due 2025 749,656 749,572 Advances from FHLB: Fixed rates 1,683 1,815 Agreements to repurchase securities — 101,679 Subordinated notes of M&T Bank: Variable rate due 2020 — 409,361 Variable rate due 2021 500,000 500,000 3.40% due 2027 552,194 514,353 Junior subordinated debentures of M&T associated with preferred capital securities: Fixed rates: BSB Capital Trust I — 8.125%, due 2028 15,752 15,728 Provident Trust I — 8.29%, due 2028 29,099 28,235 Southern Financial Statutory Trust I — 10.60%, due 2030 6,836 6,770 Variable rates: First Maryland Capital I — due 2027 148,409 147,871 First Maryland Capital II — due 2027 150,606 149,943 Allfirst Asset Trust — due 2029 97,075 96,930 BSB Capital Trust III — due 2033 15,464 15,464 Provident Statutory Trust III — due 2033 56,641 55,867 Southern Financial Capital Trust III — due 2033 8,338 8,236 Other 2,997 8,533 $ 4,382,193 $ 6,986,186
Maturity of Long-term Borrowings	Long-term borrowings at December 31, 2020 mature as follows: (In thousands) Year ending December 31: 2021 $ 849,976 2022 917,270 2023 783,193 2024 — 2025 749,656 Later years 1,082,098 $ 4,382,193

Shareholders' equity (Tables)

Shareholders' equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Issued and Outstanding Preferred Stock	Issued and outstanding preferred stock of M&T as of December 31, 2020 and 2019 is presented below: Shares Issued and Outstanding Carrying Value (Dollars in thousands) Series E (a) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $1,000 liquidation preference per share 350,000 $ 350,000 Series F (b) Fixed-to-Floating Rate Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share 50,000 $ 500,000 Series G (c) Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock, $10,000 liquidation preference per share 40,000 $ 400,000 (a) 90 days (b) 90 days (c) Dividends, if declared, are paid semi-annually at a rate of 5.0% through July 31, 2024 and thereafter will be paid semiannually at a rate of the five-year U.S. Treasury rate plus 3.174%. The shares are redeemable in whole or in part on or after August 1, 2024. Notwithstanding M&T’s option to redeem the shares, if an event occurs such that the shares no longer qualify as Tier 1 capital, M&T may redeem all of the shares within 90 days

Revenue from contracts with c_2

Revenue from contracts with customers (Tables)	12 Months Ended
	Dec. 31, 2020
ASU 2014-09 [Member]
Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance	The following tables summarize sources of the Company’s noninterest income during 2020, 2019, and 2018 that are subject to the noted accounting guidance. Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total Year Ended December 31, 2020 (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 50,119 92,720 10,252 — — 211,858 5,839 $ 370,788 Trust income 18 442 — — — — 601,424 601,884 Brokerage services income — — — — — — 47,428 47,428 Other revenues from operations: Merchant discount and credit card fees 40,475 45,528 2,221 — — 13,481 767 102,472 Other — 9,408 6,218 1,625 4,732 20,813 41,815 84,611 $ 90,612 148,098 18,691 1,625 4,732 246,152 697,273 $ 1,207,183 Year Ended December 31, 2019 Classification in consolidated statement of income Service charges on deposit accounts $ 60,690 93,044 9,828 — 4 263,659 5,753 $ 432,978 Trust income 31 963 — — — — 571,614 572,608 Brokerage services income — — — — — — 48,922 48,922 Other revenues from operations: Merchant discount and credit card fees 36,844 52,161 2,516 — — 12,140 3,381 107,042 Other — 7,498 8,615 1,776 3,492 36,144 34,088 91,613 $ 97,565 153,666 20,959 1,776 3,496 311,943 663,758 $ 1,253,163 Year Ended December 31, 2018 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, 2020
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, 2020 691,227 $ 171.72 63,591 $ 162.45 Granted 480,949 168.71 — — Vested (334,795 ) 172.56 (49,468 ) 162.48 Cancelled (20,431 ) 171.91 (573 ) 158.02 Unvested at December 31, 2020 816,950 $ 169.60 13,550 $ 162.50
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, 2020 305,452 $ 170.15 Granted 187,088 173.04 Exercised (25,047 ) 117.81 Expired (2,070 ) 174.09 Outstanding at December 31, 2020 465,423 $ 174.11 8.2 $ 38 Exercisable at December 31, 2020 133,098 $ 178.58 7.4 $ 38

Pension plans and other postr_2

Pension plans and other postretirement benefits (Tables)	12 Months Ended
	Dec. 31, 2020
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 2020 2019 2018 (In thousands) Service cost $ 19,944 $ 17,294 $ 20,346 Interest cost on benefit obligation 71,421 81,579 74,704 Expected return on plan assets (125,512 ) (122,139 ) (123,127 ) Amortization of prior service cost 557 557 557 Recognized net actuarial loss 58,096 21,992 43,793 Net periodic pension cost (benefit) $ 24,506 $ (717 ) $ 16,273 Net other postretirement benefits expense for defined benefit plans consisted of the following: Year Ended December 31 2020 2019 2018 (In thousands) Service cost $ 970 $ 859 $ 938 Interest cost on benefit obligation 1,741 2,344 2,293 Amortization of prior service credit (4,738 ) (4,730 ) (4,729 ) Recognized net actuarial gain (1,236 ) (1,247 ) (826 ) Net other postretirement benefits $ (3,263 ) $ (2,774 ) $ (2,324 )
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 2020 2019 2020 2019 (In thousands) Change in benefit obligation: Benefit obligation at beginning of year $ 2,247,329 $ 1,949,613 $ 56,492 $ 59,991 Service cost 19,944 17,294 970 859 Interest cost 71,421 81,579 1,741 2,344 Plan participants’ contributions — — 2,386 2,749 Actuarial (gain) loss 288,944 298,713 2,371 (687 ) Medicare Part D reimbursement — — 574 370 Benefits paid (106,346 ) (99,870 ) (9,253 ) (9,134 ) Benefit obligation at end of year 2,521,292 2,247,329 55,281 56,492 Change in plan assets: Fair value of plan assets at beginning of year 2,037,940 1,833,833 — — Actual return on plan assets 178,610 293,546 — — Employer contributions 310,378 10,431 6,293 6,015 Plan participants’ contributions — — 2,386 2,749 Medicare Part D reimbursement — — 574 370 Benefits paid (106,346 ) (99,870 ) (9,253 ) (9,134 ) Fair value of plan assets at end of year 2,420,582 2,037,940 — — Funded status $ (100,710 ) $ (209,389 ) $ (55,281 ) $ (56,492 ) Prepaid asset recognized in the consolidated balance sheet 64,670 — — — Accrued liability recognized in the consolidated balance sheet (165,380 ) (209,389 ) (55,281 ) (56,492 ) Net accrued liability recognized in the consolidated balance sheet $ (100,710 ) $ (209,389 ) $ (55,281 ) $ (56,492 ) Amounts recognized in accumulated other comprehensive income (“AOCI”) were: Net loss (gain) $ 684,780 $ 507,029 $ (13,701 ) $ (17,308 ) Net prior service cost (credit) 1,277 1,834 (22,269 ) (27,007 ) Pre-tax adjustment to AOCI 686,057 508,863 (35,970 ) (44,315 ) Taxes (178,375 ) (133,779 ) 9,352 11,650 Net adjustment to AOCI $ 507,682 $ 375,084 $ (26,618 ) $ (32,665 )
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) 2020 Net loss $ 235,847 $ 2,371 $ 238,218 Amortization of prior service (cost) credit (557 ) 4,738 4,181 Amortization of actuarial (loss) gain (58,096 ) 1,236 (56,860 ) Total recognized in other comprehensive income, pre-tax $ 177,194 $ 8,345 $ 185,539 2019 Net loss (gain) $ 127,305 $ (687 ) $ 126,618 Amortization of prior service (cost) credit (557 ) 4,730 4,173 Amortization of actuarial (loss) gain (21,992 ) 1,247 (20,745 ) Total recognized in other comprehensive income, pre-tax $ 104,756 $ 5,290 $ 110,046
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 2020 2019 2020 2019 Discount rate 2.50 % 3.25 % 2.50 % 3.25 % Rate of increase in future compensation levels 3.37 % 4.29 % — —
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 2020 2019 2018 2020 2019 2018 Discount rate 3.25 % 4.25 % 3.50 % 3.25 % 4.25 % 3.50 % Long-term rate of return on plan assets 6.50 % 6.50 % 6.50 % — — — Rate of increase in future compensation levels 4.29 % 4.31 % 4.33 % — — —
Fair Values of Company's Pension Plan Assets by Asset Category	The fair values of the Company’s pension plan assets at December 31, 2020 and 2019, by asset category, were as follows: Fair Value Measurement of Plan Assets At December 31, 2020 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 $ 65,263 $ 48,322 $ 16,941 $ — Equity securities: M&T 111,441 111,441 — — Domestic(a) 308,220 308,220 — — International(b) 13,648 13,648 — — Mutual funds: Domestic(a) 302,094 302,094 — — International(b) 422,601 422,601 — — 1,158,004 1,158,004 — — Debt securities: Corporate(c) 172,762 — 172,762 — Government 234,232 — 234,232 — International 6,413 — 6,413 — Mutual funds: Domestic(d) 302,635 302,635 — — 716,042 302,635 413,407 — Other: Diversified mutual fund 83,507 83,507 — — Real estate partnerships 26,847 3,616 — 23,231 Private equity / debt 97,124 — — 97,124 Hedge funds 261,417 108,516 — 152,901 Guaranteed deposit fund 10,498 — — 10,498 479,393 195,639 — 283,754 Total(e) $ 2,418,702 $ 1,704,600 $ 430,348 $ 283,754 Fair Value Measurement of Plan Assets At December 31, 2019 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 $ 38,461 $ 33,870 $ 4,591 $ — Equity securities: M&T 148,603 148,603 — — Domestic(a) 219,663 219,663 — — International(b) 10,476 10,476 — — Mutual funds: Domestic(a) 238,872 238,872 — — International(b) 381,433 381,433 — — 999,047 999,047 — — Debt securities: Corporate(c) 112,783 — 112,783 — Government 190,679 — 190,679 — International 6,648 — 6,648 — Mutual funds: Domestic(d) 249,075 249,075 — — 559,185 249,075 310,110 — Other: Diversified mutual fund 86,980 86,980 — — Real estate partnerships 21,905 3,939 — 17,966 Private equity / debt 87,966 — — 87,966 Hedge funds 231,807 116,029 — 115,778 Guaranteed deposit fund 10,527 — — 10,527 439,185 206,948 — 232,237 Total(e) $ 2,035,878 $ 1,488,940 $ 314,701 $ 232,237 (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, 2020 were as follows: Balance – January 1, 2020 Purchases (Sales) Total Realized/ Unrealized Gains (Losses) Balance – December 31, 2020 (In thousands) Other Real estate partnerships $ 17,966 $ 3,581 $ 1,684 $ 23,231 Private equity/debt 87,966 7,206 1,952 97,124 Hedge funds 115,778 30,000 7,123 152,901 Guaranteed deposit fund 10,527 — (29 ) 10,498 Total $ 232,237 $ 40,787 $ 10,730 $ 283,754
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: 2021 $ 106,285 $ 3,238 2022 109,880 3,269 2023 114,938 3,131 2024 119,402 2,974 2025 121,456 2,789 2026 through 2030 645,515 10,656

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Components of Income Tax Expense	The components of income tax expense were as follows: Year Ended December 31 2020 2019 2018 (In thousands) Current Federal $ 267,550 $ 359,668 $ 408,428 State and local 98,431 132,696 113,706 Total current 365,981 492,364 522,134 Deferred Federal (22,894 ) 40,769 (12,780 ) State and local (8,397 ) 16,779 28,637 Total deferred (31,291 ) 57,548 15,857 Amortization of investments in qualified affordable housing projects 81,679 68,200 52,169 Total income taxes applicable to pre-tax income $ 416,369 $ 618,112 $ 590,160
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 2020 2019 2018 (In thousands) Income taxes at statutory federal income tax rate $ 371,599 $ 534,925 $ 526,730 Increase (decrease) in taxes: Tax-exempt income (22,806 ) (27,319 ) (26,186 ) State and local income taxes, net of federal income tax effect 71,127 118,085 112,451 Qualified affordable housing project federal tax credits, net (14,826 ) (15,324 ) (12,240 ) Other 11,275 7,745 (10,595 ) $ 416,369 $ 618,112 $ 590,160
Deferred Tax Assets (Liabilities)	Deferred tax assets (liabilities) were comprised of the following at December 31: 2020 2019 2018 (In thousands) Losses on loans and other assets $ 471,767 $ 309,523 $ 322,818 Operating lease liabilities 121,216 128,178 — Retirement benefits 26,185 55,048 30,057 Postretirement and other employee benefits 28,004 24,023 23,563 Incentive and other compensation plans 18,984 26,861 24,796 Stock-based compensation 29,507 27,912 26,759 Unrealized losses — — 52,580 Losses on cash flow hedges — — 1,861 Other 66,763 69,863 43,880 Gross deferred tax assets 762,426 641,408 526,314 Right of use assets and other leasing transactions (285,311 ) (326,626 ) (186,787 ) Unrealized gains (50,785 ) (13,322 ) — Capitalized servicing rights (50,235 ) (56,649 ) (54,894 ) Depreciation and amortization (95,684 ) (66,925 ) (61,881 ) Interest on loans (8,113 ) (23,552 ) (18,920 ) Gains on cash flow hedges (97,004 ) (36,845 ) — Other (62,581 ) (40,472 ) (30,211 ) Gross deferred tax liabilities (649,713 ) (564,391 ) (352,693 ) Net deferred tax asset $ 112,713 $ 77,017 $ 173,621
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, 2018 $ 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 Increases as a result of tax positions taken during 2019 6,996 — 6,996 Increases as a result of tax positions taken in prior years 3,265 3,255 6,520 Decreases as a result of tax positions taken in prior years (7,566 ) (2,685 ) (10,251 ) Gross unrecognized tax benefits at December 31, 2019 58,969 7,199 66,168 Increases as a result of tax positions taken in prior years — 2,800 2,800 Decreases as a result of tax positions taken in prior years (10,107 ) (2,384 ) (12,491 ) Gross unrecognized tax benefits at December 31, 2020 $ 48,862 $ 7,615 56,477 Less: Federal, state and local income tax benefits (11,174 ) Net unrecognized tax benefits at December 31, 2020 that, if recognized, would impact the effective income tax rate $ 45,303

Earnings per common share (Tabl

Earnings per common share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Computations of Basic Earnings Per Common Share	The computations of basic earnings per common share follow: Year Ended December 31 2020 2019 2018 (In thousands, except per share) Income available to common shareholders: Net income $ 1,353,152 $ 1,929,149 $ 1,918,080 Less: Preferred stock dividends(a) (68,228 ) (69,441 ) (72,521 ) Net income available to common equity 1,284,924 1,859,708 1,845,559 Less: Income attributable to unvested stock-based compensation awards (5,858 ) (10,199 ) (9,531 ) Net income available to common shareholders $ 1,279,066 $ 1,849,509 $ 1,836,028 Weighted-average shares outstanding: Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards 129,404 135,169 144,740 Less: Unvested stock-based compensation awards (766 ) (741 ) (748 ) Weighted-average shares outstanding 128,638 134,428 143,992 Basic earnings per common share $ 9.94 $ 13.76 $ 12.75 (a)
Computations of Diluted Earnings Per Common Share	The computations of diluted earnings per common share follow: Year Ended December 31 2020 2019 2018 (In thousands, except per share) Net income available to common equity $ 1,284,924 $ 1,859,708 $ 1,845,559 Less: Income attributable to unvested stock-based compensation awards (5,856 ) (10,197 ) (9,524 ) Net income available to common shareholders $ 1,279,068 $ 1,849,511 $ 1,836,035 Adjusted weighted-average shares outstanding: Common and unvested stock-based compensation awards 129,404 135,169 144,740 Less: Unvested stock-based compensation awards (766 ) (741 ) (748 ) Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock 66 34 159 Adjusted weighted-average shares outstanding 128,704 134,462 144,151 Diluted earnings per common share $ 9.94 $ 13.75 $ 12.74

Comprehensive income (Tables)

Comprehensive income (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income	The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other Investment Defined Benefit Total Amount Income Securities Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2020 $ 50,701 $ (464,548 ) $ 133,888 $ (279,959 ) $ 73,279 $ (206,680 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 141,081 — — 141,081 (36,498 ) 104,583 Foreign currency translation adjustment — — 2,724 2,724 (440 ) 2,284 Unrealized gains on cash flow hedges — — 505,042 505,042 (130,432 ) 374,610 Current year benefit plans losses — (238,218 ) — (238,218 ) 60,208 (178,010 ) Total other comprehensive income (loss) before reclassifications 141,081 (238,218 ) 507,766 410,629 (107,162 ) 303,467 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities 3,606 — — 3,606 (a) (966 ) 2,640 Gains realized in net income (2 ) — — (2 ) (b) 1 (1 ) Accretion of net gain on terminated cash flow hedges — — (125 ) (125 ) (c) 34 (91 ) Net yield adjustment from cash flow hedges currently in effect — — (271,971 ) (271,971 ) (a) 70,239 (201,732 ) Amortization of prior service credit — (4,181 ) — (4,181 ) (d) 1,057 (3,124 ) Amortization of actuarial losses — 56,860 — 56,860 (d) (14,371 ) 42,489 Total other comprehensive income (loss) 144,685 (185,539 ) 235,670 194,816 (51,168 ) 143,648 Balance — December 31, 2020 $ 195,386 $ (650,087 ) $ 369,558 $ (85,143 ) $ 22,111 $ (63,032 ) Balance — January 1, 2019 $ (200,107 ) $ (354,502 ) $ (14,719 ) $ (569,328 ) $ 149,247 $ (420,081 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 247,411 — — 247,411 (65,009 ) 182,402 Foreign currency translation adjustment — — 1,381 1,381 (290 ) 1,091 Unrealized gains on cash flow hedges — — 160,373 160,373 (42,163 ) 118,210 Current year benefit plans losses — (126,618 ) — (126,618 ) 33,287 (93,331 ) Total other comprehensive income (loss) before reclassifications 247,411 (126,618 ) 161,754 282,547 (74,175 ) 208,372 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities 3,394 — — 3,394 (a) (892 ) 2,502 Losses realized in net income 3 — — 3 (b) (1 ) 2 Accretion of net gain on terminated cash flow hedges — — (136 ) (136 ) (c) 36 (100 ) Net yield adjustment from cash flow hedges currently in effect — — (13,011 ) (13,011 ) (a) 3,421 (9,590 ) Amortization of prior service credit — (4,173 ) — (4,173 ) (d) 1,097 (3,076 ) Amortization of actuarial losses — 20,745 — 20,745 (d) (5,454 ) 15,291 Total other comprehensive income (loss) 250,808 (110,046 ) 148,607 289,369 (75,968 ) 213,401 Balance — December 31, 2019 $ 50,701 $ (464,548 ) $ 133,888 $ (279,959 ) $ 73,279 $ (206,680 ) Investment Defined Benefit Total Amount Income Securities 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 (e) (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) Amortization of unrealized holding losses on HTM securities 4,252 — — 4,252 (a) (1,118 ) 3,134 Gains realized in net income (18 ) — — (18 ) (b) 4 (14 ) Accretion of net gain on terminated cash flow hedges — — (111 ) (111 ) (c) 29 (82 ) Net yield adjustment from cash flow hedges currently in effect — — 13,339 13,339 (a) (3,507 ) 9,832 Amortization of prior service credit — (4,172 ) — (4,172 ) (d) 1,097 (3,075 ) Amortization of actuarial losses — 42,967 — 42,967 (d) (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) Included in interest income. (b) Included in gain (loss) on bank investment securities. (c) Included in interest expense. (d) Included in other costs of operations. (e) 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. Prior to that date, such changes in fair value were reflected in other comprehensive income.
Accumulated Other Comprehensive Income (Loss), Net	Accumulated other comprehensive income (loss), net consisted of the following: Investment Securities Defined Benefit Plans Other Total (In thousands) Balance at January 1, 2018 $ (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 ) Net gain (loss) during 2019 184,906 (81,116 ) 109,611 213,401 Balance at December 31, 2019 37,380 (342,419 ) 98,359 (206,680 ) Net gain (loss) during 2020 107,222 (138,645 ) 175,071 143,648 Balance at December 31, 2020 $ 144,602 $ (481,064 ) $ 273,430 $ (63,032 )

Other income and other expense

Other income and other expense (Tables)	12 Months Ended
	Dec. 31, 2020
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 2020 2019 2018 (In thousands) Other income: Credit-related fee income $ 70,387 $ 86,792 $ 82,614 Other expense: Professional services 240,047 330,900 312,998 Accrual for Wilmington Trust Corporation legal-related matters 135,000 Amortization of capitalized mortgage servicing rights 84,821 71,888

Derivative financial instrume_2

Derivative financial instruments (Tables)	12 Months Ended
	Dec. 31, 2020
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- Estimated Notional Average Average Rate Fair Value Amount Maturity Fixed Variable Gain (In thousands) (In (In December 31, 2020 Fair value hedges: Fixed rate long-term borrowings (b) $ 1,650,000 3.3 2.86 % 0.79 % $ 651 Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(c) 49,400,000 0.9 2.22 % 0.15 % 425 Total $ 51,050,000 1.0 $ 1,076 December 31, 2019 Fair value hedges: Fixed rate long-term borrowings (b) $ 3,800,000 2.2 2.51 % 2.27 % $ (567 ) Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(d) 53,750,000 1.4 2.44 % 1.73 % (1,195 ) Total $ 57,550,000 1.5 $ (1,762 ) (a) C ertain clearinghouse exchanges consider payments by counterparties for variation margin on derivative instruments to be settlements of those positions. The impact of such treatment at December 31, 2020 was a reduction of the estimated fair value gains on interest rate swap agreements designated as fair value hedges of $101.5 million and on interest rate swap agreements designated as cash flow hedges of $372.2 million. The impact of such treatment at December 31, 2019 was a reduction of estimated fair value gains on agreements designated as fair value hedges of $45.1 million and agreements designated as cash flow hedges of $140.7 million. (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 $32.1 billion of forward-starting interest rate swap agreements that become effective in 2021-2022. (d) Includes notional amount and terms of $40.4 billion of forward-starting interest rate swap agreement that become effective in 2020-2022 .
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, 2020 mature as follows: (In thousands) Year ending December 31: 2021 $ 27,700,000 2022 16,500,000 2023 6,350,000 2027 500,000 $ 51,050,000
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, December 31, December 31, 2020 2019 2020 2019 (In thousands) Derivatives designated and qualifying as hedging instruments Interest rate swap agreements (a) $ 1,968 $ 232 $ 892 $ 1,994 Commitments to sell real estate loans (a) 1,488 1,195 8,458 421 3,456 1,427 9,350 2,415 Derivatives not designated and qualifying as hedging instruments Mortgage-related commitments to originate real estate loans for sale (a) 43,599 11,965 365 1,225 Commitments to sell real estate loans (a) 2,409 3,074 13,868 3,548 Trading: Interest rate contracts (b) 1,008,913 398,295 105,768 68,103 Foreign exchange and other option and futures contracts (b) 9,608 12,506 11,134 11,800 1,064,529 425,840 131,135 84,676 Total derivatives $ 1,067,985 $ 427,267 $ 140,485 $ 87,091 (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, 2020 December 31, 2019 December 31, 2020 December 31, 2019 (In thousands) Location in the of the Hedged Items in Fair Value Long-term debt $ 1,750,048 $ 3,840,775 $ 101,326 $ 43,640
Information about Fair Values of Derivative Instruments in Consolidated Statement of Income	Amount of Gain (Loss) Recognized Year Ended December 31, 2020 Year Ended December 31, 2019 Year Ended December 31, 2018 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) $ 57,611 (57,686 ) $ 95,006 (94,742 ) $ (10,006 ) 10,969 Derivatives not designated as hedging Trading: Interest rate contracts (b) $ 6,344 $ 24,701 $ 4,506 Foreign exchange and other option and futures contracts (b) 7,363 8,511 9,416 Total $ 13,707 $ 33,212 $ 13,922 (a) (b)

Fair value measurements (Tables

Fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020 and 2019 measured at estimated fair value on a recurring basis: Fair Value Measurements Level 1 Level 2 Level 3 (In thousands) December 31, 2020 Trading account assets $ 1,068,581 $ 50,060 $ 1,018,521 $ — Investment securities available for sale: U.S. Treasury and federal agencies 9,338 — 9,338 — Mortgage-backed securities: Government issued or guaranteed 4,683,438 — 4,683,438 — Privately issued 16 — — 16 Other debt securities 129,814 — 129,814 — 4,822,606 — 4,822,590 16 Equity securities 92,985 63,129 29,856 — Real estate loans held for sale 1,054,676 — 1,054,676 — Other assets (a) 49,464 — 5,865 43,599 Total assets $ 7,088,312 $ 113,189 $ 6,931,508 $ 43,615 Trading account liabilities $ 116,902 $ — $ 116,902 $ — Other liabilities (a) 23,583 — 23,218 365 Total liabilities $ 140,485 $ — $ 140,120 $ 365 December 31, 2019 Trading account assets $ 470,129 $ 49,040 $ 421,089 $ — Investment securities available for sale: U.S. Treasury and federal agencies 9,767 — 9,767 — Obligations of states and political subdivisions 775 — 775 — Mortgage-backed securities: Government issued or guaranteed 6,180,940 — 6,180,940 — Privately issued 16 — — 16 Other debt securities 127,278 — 127,278 — 6,318,776 — 6,318,760 16 Equity securities 140,041 100,637 39,404 — Real estate loans held for sale 442,079 — 442,079 — Other assets (a) 16,466 — 4,501 11,965 Total assets $ 7,387,491 $ 149,677 $ 7,225,833 $ 11,981 Trading account liabilities $ 79,903 $ — $ 79,903 $ — Other liabilities (a) 7,188 — 5,963 1,225 Total liabilities $ 87,091 $ — $ 85,866 $ 1,225 (a)
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, 2020, 2019 and 2018 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets (In thousands) 2020 Balance — January 1, 2020 $ 16 $ 10,740 Total gains realized/unrealized: Included in earnings — 194,469 (a) Transfers out of Level 3 — (161,975 ) (b) Balance — December 31, 2020 $ 16 $ 43,234 Changes in unrealized gains included in earnings related to assets still held at December 31, 2020 $ — $ 42,597 (a) 2019 Balance — January 1, 2019 $ 22 $ 7,712 Total gains realized/unrealized: Included in earnings — 129,398 (a) Settlements (6 ) — Transfers out of Level 3 — (126,370 ) (b) Balance — December 31, 2019 $ 16 $ 10,740 Changes in unrealized gains included in earnings related to assets still held at December 31, 2019 $ — $ 11,146 (a) 2018 Balance — January 1, 2018 $ 28 $ 8,303 Total gains realized/unrealized: Included in earnings — 58,740 (a) Settlements (6 ) — Transfers out of Level 3 — (59,331 ) (b) 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 (a) (a) (b)
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, 2020 and 2019: Fair Value Valuation Technique Unobservable Inputs/Assumptions Range (Weighted- Average) (In December 31, 2020 Recurring fair value measurements Privately issued mortgage- backed securities $ 16 Two independent pricing quotes — — Net other assets (liabilities) (a) 43,234 Discounted cash flow Commitment expirations 0% - 98% (16%) December 31, 2019 Recurring fair value measurements Privately issued mortgage- backed securities $ 16 Two independent pricing quotes — — Net other assets (liabilities) (a) 10,740 Discounted cash flow Commitment expirations 0% - 99% (13%) (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, 2020 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,552,743 1,552,743 1,497,457 55,286 — Interest-bearing deposits at banks 23,663,810 23,663,810 — 23,663,810 — Trading account assets 1,068,581 1,068,581 50,060 1,018,521 — Investment securities 7,045,697 7,138,989 63,129 7,005,571 70,289 Loans and leases: Commercial loans and leases 27,574,564 27,220,699 — — 27,220,699 Commercial real estate loans 37,637,889 36,816,580 — 277,911 36,538,669 Residential real estate loans 16,752,993 17,089,141 — 4,135,655 12,953,486 Consumer loans 16,570,421 16,554,050 — — 16,554,050 Allowance for credit losses (1,736,387 ) — — — — Loans and leases, net 96,799,480 97,680,470 — 4,413,566 93,266,904 Accrued interest receivable 419,936 419,936 — 419,936 — Financial liabilities: Noninterest-bearing deposits $ (47,572,884 ) (47,572,884 ) — (47,572,884 ) — Savings and interest-checking deposits (67,680,840 ) (67,680,840 ) — (67,680,840 ) — Time deposits (3,899,910 ) (3,919,367 ) — (3,919,367 ) — Deposits at Cayman Islands office (652,104 ) (652,104 ) — (652,104 ) — Short-term borrowings (59,482 ) (59,482 ) — (59,482 ) — Long-term borrowings (4,382,193 ) (4,490,433 ) — (4,490,433 ) — Accrued interest payable (59,916 ) (59,916 ) — (59,916 ) — Trading account liabilities (116,902 ) (116,902 ) — (116,902 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 43,234 43,234 — — 43,234 Commitments to sell real estate loans (18,429 ) (18,429 ) — (18,429 ) — Other credit-related commitments (133,354 ) (133,354 ) — — (133,354 ) Interest rate swap agreements used for interest rate risk management 1,076 1,076 — 1,076 — December 31, 2019 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,432,805 1,432,805 1,394,984 37,821 — Interest-bearing deposits at banks 7,190,154 7,190,154 — 7,190,154 — Federal funds sold 3,500 3,500 — 3,500 — Trading account assets 470,129 470,129 49,040 421,089 — Investment securities 9,497,251 9,539,540 100,637 9,351,793 87,110 Loans and leases: Commercial loans and leases 23,838,168 23,510,908 — — 23,510,908 Commercial real estate loans 35,541,914 35,517,180 — 28,338 35,488,842 Residential real estate loans 16,156,094 16,227,274 — 3,990,848 12,236,426 Consumer loans 15,386,693 15,413,262 — — 15,413,262 Allowance for credit losses (1,051,071 ) — — — — Loans and leases, net 89,871,798 90,668,624 — 4,019,186 86,649,438 Accrued interest receivable 333,142 333,142 — 333,142 — Financial liabilities: Noninterest-bearing deposits $ (32,396,407 ) (32,396,407 ) — (32,396,407 ) — Savings and interest-checking deposits (54,932,162 ) (54,932,162 ) — (54,932,162 ) — Time deposits (5,757,456 ) (5,829,347 ) — (5,829,347 ) — Deposits at Cayman Islands office (1,684,044 ) (1,684,044 ) — (1,684,044 ) — Short-term borrowings (62,363 ) (62,363 ) — (62,363 ) — Long-term borrowings (6,986,186 ) (7,063,165 ) — (7,063,165 ) — Accrued interest payable (105,374 ) (105,374 ) — (105,374 ) — Trading account liabilities (79,903 ) (79,903 ) — (79,903 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 10,740 10,740 — — 10,740 Commitments to sell real estate loans 300 300 — 300 — Other credit-related commitments (136,470 ) (136,470 ) — — (136,470 ) Interest rate swap agreements used for interest rate risk management (1,762 ) (1,762 ) — (1,762 ) —

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities 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, December 31, 2020 2019 (In thousands) Commitments to extend credit Home equity lines of credit $ 5,563,854 $ 5,442,160 Commercial real estate loans to be sold 363,735 164,076 Other commercial real estate 7,237,367 9,029,608 Residential real estate loans to be sold 1,026,118 423,056 Other residential real estate 665,259 448,375 Commercial and other 19,427,886 16,170,731 Standby letters of credit 2,241,417 2,441,432 Commercial letters of credit 27,332 41,059 Financial guarantees and indemnification contracts 4,220,531 4,108,572 Commitments to sell real estate loans 2,108,823 906,037

Segment information (Tables)

Segment information (Tables)	12 Months Ended
	Dec. 31, 2020
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, 2020, 2019 and 2018 Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio 2020 2019 2018 2020 2019 2018 2020 2019 2018 2020 2019 2018 Net interest income(a) $ 462,614 $ 451,307 $ 434,579 $ 864,149 $ 828,888 $ 821,812 $ 673,894 $ 692,526 $ 665,220 $ 486,831 $ 209,807 $ 228,051 Noninterest income 103,837 113,855 111,600 276,791 289,558 288,908 208,367 214,970 183,955 (1,735 ) 26,919 (9,690 ) 566,451 565,162 546,179 1,140,940 1,118,446 1,110,720 882,261 907,496 849,175 485,096 236,726 218,361 Provision for credit losses 25,928 16,501 10,916 73,099 25,580 8,976 107,210 1,537 3,159 1,508 3,608 6,683 Amortization of core deposit and other intangible assets — — — — — — 1,060 1,060 1,060 — — — Depreciation and other amortization 1,482 2,066 382 2,421 2,353 496 28,187 26,963 25,852 285 279 187 Other noninterest expense 322,868 317,482 305,340 375,769 382,214 364,102 256,428 239,333 217,387 54,339 52,885 65,393 Income (loss) before taxes 216,173 229,113 229,541 689,651 708,299 737,146 489,376 638,603 601,717 428,964 179,954 146,098 Income tax expense (benefit) 56,953 60,617 61,279 181,179 187,835 198,229 107,548 152,977 148,807 101,673 36,342 29,872 Net income (loss) $ 159,220 $ 168,496 $ 168,262 $ 508,472 $ 520,464 $ 538,917 $ 381,828 $ 485,626 $ 452,910 $ 327,291 $ 143,612 $ 116,226 Average total assets (in millions) $ 8,152 $ 5,793 $ 5,631 $ 30,338 $ 28,142 $ 26,626 $ 25,792 $ 23,921 $ 22,885 $ 27,726 $ 29,081 $ 32,123 Capital expenditures (in millions) $ — $ 1 $ — $ — $ 2 $ — $ — $ — $ — $ — $ — $ 1 For the Years Ended December 31, 2020, 2019 and 2018 Residential Mortgage Banking Retail Banking All Other Total 2020 2019 2018 2020 2019 2018 2020 2019 2018 2020 2019 2018 Net interest income(a) $ 52,712 $ 20,008 $ 13,933 $ 1,204,309 $ 1,389,788 $ 1,351,165 $ 121,808 $ 537,940 $ 557,542 $ 3,866,317 $ 4,130,264 $ 4,072,302 Noninterest income 515,549 393,372 305,560 260,163 327,562 324,228 725,472 695,443 651,439 2,088,444 2,061,679 1,856,000 568,261 413,380 319,493 1,464,472 1,717,350 1,675,393 847,280 1,233,383 1,208,981 5,954,761 6,191,943 5,928,302 Provision for credit losses 1,785 382 (2,178 ) 108,268 122,135 112,572 482,202 6,257 (8,128 ) 800,000 176,000 132,000 Amortization of core deposit and other intangible assets — — — — — — 13,809 18,430 23,462 14,869 19,490 24,522 Depreciation and other amortization 60,129 48,248 24,288 95,936 93,312 35,274 116,979 108,604 68,004 305,419 281,825 154,483 Other noninterest expense 332,028 273,067 241,624 764,262 784,718 789,783 959,258 1,117,668 1,125,428 3,064,952 3,167,367 3,109,057 Income (loss) before taxes 174,319 91,683 55,759 496,006 717,185 737,764 (724,968 ) (17,576 ) 215 1,769,521 2,547,261 2,508,240 Income tax expense (benefit) 40,667 19,355 10,272 130,745 189,611 196,467 (202,396 ) (28,625 ) (54,766 ) 416,369 618,112 590,160 Net income (loss) $ 133,652 $ 72,328 $ 45,487 $ 365,261 $ 527,574 $ 541,297 $ (522,572 ) $ 11,049 $ 54,981 $ 1,353,152 $ 1,929,149 $ 1,918,080 Average total assets (in millions) $ 4,038 $ 2,611 $ 2,161 $ 16,438 $ 15,083 $ 13,656 $ 22,996 $ 14,953 $ 13,877 $ 135,480 $ 119,584 $ 116,959 Capital expenditures (in millions) $ — $ 1 $ 1 $ 34 $ 76 $ 31 $ 138 $ 98 $ 65 $ 172 $ 178 $ 98 (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 2020 2019 2018 (In thousands) Revenues $ (47,604 ) $ (48,559 ) $ (41,285 ) Expenses (14,038 ) (18,218 ) (24,660 ) Income taxes (8,824 ) (7,976 ) (4,371 ) Net income (24,742 ) (22,365 ) (12,254 )

Regulatory matters (Tables)

Regulatory matters (Tables)	12 Months Ended
	Dec. 31, 2020
Regulatory Capital Requirements [Abstract]
Summary of Required Minimum and Well Capitalized Capital Ratios	Pursuant to the rules in effect as of December 31, 2020, 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, 2020 and 2019 are presented below: M&T (Consolidated) M&T Bank Wilmington Trust, N.A. (Dollars in thousands) December 31, 2020: Common equity Tier 1 capital Amount $ 10,623,368 $ 11,550,462 $ 630,574 Ratio(a) 10.00 % 10.90 % 46.57 % Tier 1 capital Amount 11,873,317 11,550,462 630,574 Ratio(a) 11.17 % 10.90 % 46.57 % Total capital Amount 14,207,937 13,373,416 632,506 Ratio(a) 13.37 % 12.62 % 46.72 % Leverage Amount 11,873,317 11,550,462 630,574 Ratio(b) 8.48 % 8.27 % 10.73 % December 31, 2019: Common equity Tier 1 capital Amount $ 10,053,887 $ 10,649,953 $ 606,538 Ratio(a) 9.73 % 10.34 % 56.35 % Tier 1 capital Amount 11,303,836 10,649,953 606,538 Ratio(a) 10.94 % 10.34 % 56.35 % Total capital Amount 13,480,612 12,342,834 608,130 Ratio(a) 13.05 % 11.99 % 56.50 % Leverage Amount 11,303,836 10,649,953 606,538 Ratio(b) 9.59 % 9.08 % 13.12 % (a) (b)

Parent company financial stat_2

Parent company financial statements (Tables)	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheet	Condensed Balance Sheet December 31 2020 2019 (In thousands) Assets Cash in subsidiary bank $ 100,593 $ 83,531 Due from consolidated bank subsidiaries Money-market savings 699,476 876,819 Current income tax receivable — 1,261 Total due from consolidated bank subsidiaries 699,476 878,080 Investments in consolidated subsidiaries Banks 16,554,287 15,732,008 Other 125,988 301,765 Investments in trust preferred entities (note 19) 22,846 23,022 Other assets 92,170 67,732 Total assets $ 17,595,360 $ 17,086,138 Liabilities Accrued expenses and other liabilities $ 96,664 $ 74,235 Long-term borrowings 1,311,413 1,295,254 Total liabilities 1,408,077 1,369,489 Shareholders’ equity 16,187,283 15,716,649 Total liabilities and shareholders’ equity $ 17,595,360 $ 17,086,138
Condensed Statement of Income	Condensed Statement of Income Year Ended December 31 2020 2019 2018 (In thousands, except per share) Income Dividends from consolidated subsidiaries $ 708,500 $ 2,025,000 $ 1,250,000 Income from Bayview Lending Group LLC 52,940 36,740 23,500 Other income 5,110 7,216 2,417 Total income 766,550 2,068,956 1,275,917 Expense Interest on long-term borrowings 31,924 51,938 36,354 Other expense 33,704 25,236 23,894 Total expense 65,628 77,174 60,248 Income before income taxes and equity in undistributed income of subsidiaries 700,922 1,991,782 1,215,669 Income tax credits 1,984 8,313 8,446 Income before equity in undistributed income of subsidiaries 702,906 2,000,095 1,224,115 Equity in undistributed income of subsidiaries Net income of subsidiaries 1,358,746 1,954,054 1,943,965 Less: dividends received (708,500 ) (2,025,000 ) (1,250,000 ) Equity in undistributed income of subsidiaries 650,246 (70,946 ) 693,965 Net income $ 1,353,152 $ 1,929,149 $ 1,918,080 Net income per common share Basic $ 9.94 $ 13.76 $ 12.75 Diluted 9.94 13.75 12.74
Condensed Statement of Cash Flow	Condensed Statement of Cash Flows Year Ended December 31 2020 2019 2018 (In thousands) Cash flows from operating activities Net income $ 1,353,152 $ 1,929,149 $ 1,918,080 Adjustments to reconcile net income to net cash provided by operating activities Equity in undistributed income of subsidiaries (650,246 ) 70,946 (693,965 ) Provision for deferred income taxes 1,079 5,263 4,949 Net change in accrued income and expense (24,206 ) (34,525 ) (8,242 ) Net cash provided by operating activities 679,779 1,970,833 1,220,822 Cash flows from investing activities Proceeds from sales or maturities of investment securities — 100 — Other, net 176,050 51,235 29,933 Net cash provided by investing activities 176,050 51,335 29,933 Cash flows from financing activities Purchases of treasury stock (373,750 ) (1,349,785 ) (2,194,396 ) Dividends paid — common (568,112 ) (552,138 ) (510,382 ) Dividends paid — preferred (68,256 ) (67,454 ) (72,521 ) Proceeds from long-term borrowings — — 748,595 Redemption of Series A and Series C preferred stock — (381,500 ) — Proceeds from issuance of Series G preferred stock — 396,000 — Other, net (5,992 ) (4,431 ) 45,913 Net cash used by financing activities (1,016,110 ) (1,959,308 ) (1,982,791 ) Net increase (decrease) in cash and cash equivalents (160,281 ) 62,860 (732,036 ) Cash and cash equivalents at beginning of year 960,350 897,490 1,629,526 Cash and cash equivalents at end of year $ 800,069 $ 960,350 $ 897,490 Supplemental disclosure of cash flow information Interest received during the year $ 1,493 $ 1,752 $ 2,219 Interest paid during the year 30,913 49,451 17,482 Income taxes received during the year 11,528 6,251 6,362

Significant Accounting Polici_3

Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020
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
Delinquent period of loans resulting in accrued interest being charged against income description	Certain loans greater than 90 days delinquent continue to accrue interest 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 generally continue to accrue interest
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, 2020USD ($)Investment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Jan. 01, 2020USD ($)
Investment Holdings [Line Items]
Retained earnings	$ 13,444,428,000	$ 12,820,916,000
Gross realized gains(loss) on sale of investment securities	$ 0	0	$ 0
Number of investment securities with aggregate gross unrealized losses | Investment	264
Unrealized losses on individual investment securities	$ 27,000,000
Cost method investment securities	381,000,000
Investment securities pledged to secure debt carrying value	4,200,000,000
Pledged securities that can be sold or repledged	105,136,000	$ 200,339,000
Available-for-Sale Securities [Member]
Investment Holdings [Line Items]
Allowance for credit losses	0			$ 0
Investment securities pledged to secure debt carrying value	$ 2,900,000,000
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
Adjustments for New Accounting Pronouncement [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment
Investment Holdings [Line Items]
Retained earnings	$ 17,000,000

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	$ 4,621,027	$ 6,258,276
Investment securities available for sale, gross unrealized gains	210,649	90,723
Investment securities available for sale, gross unrealized losses	9,070	30,223
Investment securities available for sale, estimated fair value	4,822,606	6,318,776
Amortized cost for held to maturity	1,748,989	2,656,917
Gross unrealized gains for held to maturity	111,241	62,462
Gross unrealized losses for held to maturity	17,949	20,173
Estimated fair value for held to maturity	1,842,281	2,699,206
Equity and other securities, Amortized Cost	449,008	487,041
Equity securities, Gross Unrealized Gains	25,094	34,786
Equity securities, Gross Unrealized Losses		269
Equity and other securities, Estimated Fair Value	474,102	521,558
Other securities, Amortized cost	381,117	381,517
Other securities, Estimated fair value	381,117	381,517
Total debt securities Amortized cost	6,370,016	8,915,193
Total debt securities Gross unrealized gains	321,890	153,185
Total debt securities Gross unrealized losses	27,019	50,396
Total debt securities Estimated fair value	6,664,887	9,017,982
Readily marketable securities Amortized cost	67,891	105,524
Readily marketable securities Gross unrealized gains	25,094	34,786
Readily marketable securities Gross unrealized losses		269
Readily marketable securities Estimated fair value	92,985	140,041
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	9,154	9,742
Investment securities available for sale, gross unrealized gains	198	41
Investment securities available for sale, gross unrealized losses	14	16
Investment securities available for sale, estimated fair value	9,338	9,767
Amortized cost for held to maturity	2,999	249,862
Gross unrealized gains for held to maturity		286
Estimated fair value for held to maturity	2,999	250,148
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		776
Investment securities available for sale, gross unrealized gains		2
Investment securities available for sale, gross unrealized losses		3
Investment securities available for sale, estimated fair value		775
Amortized cost for held to maturity	1,531	4,140
Gross unrealized gains for held to maturity	9	16
Estimated fair value for held to maturity	1,540	4,156
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	4,475,406	6,113,913
Investment securities available for sale, gross unrealized gains	208,787	88,634
Investment securities available for sale, gross unrealized losses	755	21,607
Investment securities available for sale, estimated fair value	4,683,438	6,180,940
Amortized cost for held to maturity	1,664,443	2,306,180
Gross unrealized gains for held to maturity	100,176	50,381
Gross unrealized losses for held to maturity	11	1,992
Estimated fair value for held to maturity	1,764,608	2,354,569
Privately Issued [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	16	16
Investment securities available for sale, estimated fair value	16	16
Amortized cost for held to maturity	77,155	93,496
Gross unrealized gains for held to maturity	11,056	11,779
Gross unrealized losses for held to maturity	17,938	18,181
Estimated fair value for held to maturity	70,273	87,094
Other Debt Securities [Member]
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	136,451	133,829
Investment securities available for sale, gross unrealized gains	1,664	2,046
Investment securities available for sale, gross unrealized losses	8,301	8,597
Investment securities available for sale, estimated fair value	129,814	127,278
Amortized cost for held to maturity	2,861	3,239
Estimated fair value for held to maturity	$ 2,861	$ 3,239

Investment Securities - Investm

Investment Securities - Investment Ratings of All Privately Issued Mortgage-Backed Securities and Other Debt Securities (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	$ 218,014
Total securities with disclosed rating, Estimated Fair Value	204,504
A or Better [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	10,375
BBB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	62,016
BB [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	31,303
B or Less [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	490
Not Rated [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Estimated Fair Value	100,320
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	1,531
Total securities with disclosed rating, Estimated Fair Value	1,540
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	1,540
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	77,171
Total securities with disclosed rating, Estimated Fair Value	70,289
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	1,533
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	490
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	68,266
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Total securities with disclosed rating, Amortized Cost	139,312
Total securities with disclosed rating, Estimated Fair Value	132,675
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	7,302
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	62,016
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	31,303
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	$ 32,054

Investment Securities - Amort_2

Investment Securities - Amortized Cost and Estimated Fair Value of Collateralized Mortgage Obligations (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized Cost And Fair Value Debt Securities [Abstract]
Collateralized mortgage obligations, Amortized cost	$ 77,964	$ 94,817
Collateralized mortgage obligations, Estimated fair value	$ 71,099	$ 88,410

Investment Securities - Amort_3

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt securities available for sale:
Due in one year or less	$ 4,950
Due after one year through five years	12,051
Due after five years through ten years	98,604
Due after ten years	30,000
Total available for sale (amortized cost)	145,605
Mortgage-backed securities available for sale	4,475,422
Investment securities available for sale, amortized cost	4,621,027	$ 6,258,276
Debt securities held to maturity:
Due in one year or less	4,355
Due after one year through five years	175
Due after ten years	2,861
Total available for held to maturity (amortized cost)	7,391
Mortgage-backed securities held to maturity	1,741,598
Amortized cost for held to maturity	1,748,989	2,656,917
Debt securities available for sale:
Due in one year or less	4,945
Due after one year through five years	12,585
Due after five years through ten years	97,301
Due after ten years	24,321
Total available for sale (fair value)	139,152
Mortgage-backed securities available for sale	4,683,454
Total	4,822,606	6,318,776
Debt securities held to maturity:
Due in one year or less	4,361
Due after one year through five years	178
Due after ten years	2,861
Total available for held to maturity (fair value)	7,400
Mortgage-backed securities held to maturity	1,834,881
Total	$ 1,842,281	$ 2,699,206

Investment Securities - Inves_2

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 35,727	$ 125,305
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(551)	(583)
Estimated fair value, 12 months or more	80,018	2,061,847
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(8,519)	(29,640)
Held to maturity, Estimated fair value, Less than 12 months	2,039	2,727
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(11)	(5)
Held to maturity, Estimated fair value, 12 months or more	52,418	194,891
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(17,938)	(20,168)
Total investment securities, fair value less than 12 months	37,766	128,032
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(562)	(588)
Total of investment securities, fair value, 12 Months or More	132,436	2,256,738
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(26,457)	(49,808)
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	985	1,406
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(14)	(7)
Estimated fair value, 12 months or more		2,893
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses		(9)
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	18,687	117,299
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(356)	(222)
Estimated fair value, 12 months or more	16,556	2,002,364
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(399)	(21,385)
Held to maturity, Estimated fair value, Less than 12 months	2,039	2,727
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(11)	(5)
Held to maturity, Estimated fair value, 12 months or more		145,235
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses		(1,987)
Other Debt Securities [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	16,055	6,600
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(181)	(354)
Estimated fair value, 12 months or more	63,462	56,313
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(8,120)	(8,243)
Obligations of States and Political Subdivisions [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, 12 months or more		277
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses		(3)
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Held to maturity, Estimated fair value, 12 months or more	52,418	49,656
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	$ (17,938)	$ (18,181)

Loans and Leases - Total Loans

Loans and Leases - Total Loans and Leases Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Loans
Total loans	$ 97,628,892	$ 89,776,328
Leases
Total loans and leases	98,875,788	91,188,525
Unearned discount	(339,921)	(265,656)
Loans and leases, net of unearned discount	98,535,867	90,922,869
Commercial Financial Loan [Member]
Loans
Total loans	26,554,486	22,575,700
Residential Real Estate [Member]
Loans
Total loans	16,708,644	16,098,125
Commercial Real Estate [Member]
Loans
Total loans	27,738,732	26,718,325
Construction Real Estate [Member]
Loans
Total loans	10,068,141	9,010,297
Consumer Real Estate [Member]
Loans
Total loans	16,558,889	15,373,881
Commercial Lease [Member]
Loans
Total loans	$ 1,246,896	$ 1,412,197

Loans and Leases - Additional I

Loans and Leases - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loans And Leases Receivable [Line Items]
Charges incurred for reimbursement of loan	$ 0	$ 0	$ 0
Amount of foreclosed residential real estate property held	28,000,000	76,000,000
Loans secured by residential real estate that were in the process of foreclosure	$ 214,000,000	402,000,000
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed	41.00%
Interest income that would have been recognized on nonaccrual and renegotiated loans if those loans were accruing interest at their originally contracted terms	$ 96,000,000	68,000,000	69,000,000
Interest on nonaccrual and renegotiated loans included in interest income	44,000,000	33,000,000	33,000,000
Contractual principal and interest payments		228,000,000	$ 228,000,000
Guaranteed amount included in the estimated residual value of leased assets associated with direct financing leases	$ 34,000,000	$ 37,000,000
Maximum [Member]
Loans And Leases Receivable [Line Items]
Purchased impaired loans as a percentage of total assets		1.00%	1.00%
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	$ 72,000,000	$ 28,000,000
New borrowings by directors, certain officers and their associates	46,000,000
Repayments and other reductions of borrowings by directors, certain officers and their associates	2,000,000
Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Loans serviced for others sold with credit recourse	4,000,000,000
Loans pledged to secure outstanding borrowings from the FHLB of New York	13,700,000,000
Residential Mortgage Loans [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	12,900,000,000
Residential Mortgage Loans [Member] | One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	777,000,000	414,000,000
Commercial Real Estate Loans [Member] | One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale	278,000,000	$ 28,000,000
Commercial Loans and Leases [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	10,200,000,000
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	2,100,000,000
Other Consumer Loans [Member]
Loans And Leases Receivable [Line Items]
Loans pledged to secure outstanding borrowings from the FHLB of New York	$ 8,500,000,000

Loans and Leases - Summary of C

Loans and Leases - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 95,120,921	$ 87,999,720
30-89 Days Past Due	662,439	1,174,132
Accruing Loans Past Due 90 Days or More	859,208	518,728
Purchased Impaired		227,545
Nonaccrual	1,893,299	963,112
Loans and leases, net of unearned discount	98,535,867	90,922,869
Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More		39,632
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	27,196,862	23,290,797
30-89 Days Past Due	60,822	184,011
Accruing Loans Past Due 90 Days or More	10,053	16,776
Nonaccrual	306,827	346,557
Loans and leases, net of unearned discount	27,574,564	23,838,168
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		27
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	26,688,515	26,311,414
30-89 Days Past Due	168,917	165,579
Accruing Loans Past Due 90 Days or More	47,014	6,740
Purchased Impaired		15,601
Nonaccrual	775,894	158,474
Loans and leases, net of unearned discount	27,680,340	26,657,808
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,246,095	1,521,315
30-89 Days Past Due	1,693	21,195
Accruing Loans Past Due 90 Days or More	856
Purchased Impaired		753
Nonaccrual	1,094	3,982
Loans and leases, net of unearned discount	1,249,738	1,547,245
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	8,523,591	7,204,148
30-89 Days Past Due	66,365	95,346
Accruing Loans Past Due 90 Days or More	3,816	3,360
Purchased Impaired		1,237
Nonaccrual	114,039	32,770
Loans and leases, net of unearned discount	8,707,811	7,336,861
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	13,764,836	12,760,040
30-89 Days Past Due	200,406	451,274
Accruing Loans Past Due 90 Days or More	792,888	486,515
Purchased Impaired		143,145
Nonaccrual	365,729	235,663
Loans and leases, net of unearned discount	15,123,859	14,082,425
Residential [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More		5,788
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,462,277	1,858,037
30-89 Days Past Due	19,687	65,215
Accruing Loans Past Due 90 Days or More		181
Purchased Impaired		66,809
Nonaccrual	147,170	83,427
Loans and leases, net of unearned discount	1,629,134	2,073,669
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	3,881,885	4,386,511
30-89 Days Past Due	24,329	30,229
Nonaccrual	79,392	63,215
Loans and leases, net of unearned discount	3,985,606	4,481,617
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		1,662
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	7,002,643	5,484,997
30-89 Days Past Due	47,161	36,827
Nonaccrual	25,519	14,219
Loans and leases, net of unearned discount	7,075,323	5,536,142
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		99
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,007,349	3,787,221
30-89 Days Past Due	55,498	78,478
Nonaccrual	39,404	21,293
Loans and leases, net of unearned discount	4,102,251	3,886,992
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,346,868	1,395,240
30-89 Days Past Due	17,561	45,978
Accruing Loans Past Due 90 Days or More	4,581	5,156
Nonaccrual	38,231	3,512
Loans and leases, net of unearned discount	$ 1,407,241	1,481,942
Other [Member] | Accruing Loans Acquired at Discount [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Loans Past Due 90 Days or More		$ 32,056

Loans and Leases - Summary of O

Loans and Leases - Summary of Outstanding Loan Balances Related to COVID-19 Modifications Granted (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		$ 806,046	$ 127,024	$ 180,224
Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		545,415	29,481	90,639
COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		4,579,759
COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	3,767,523
COVID-19 [Member] | Other Forbearances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[2]	812,236
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		199,918	63,356	102,914
Commercial, Financial, Leasing, etc. [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		70,671	10,485	50,490
Commercial, Financial, Leasing, etc. [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		387,780
Commercial, Financial, Leasing, etc. [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	95,823
Commercial, Financial, Leasing, etc. [Member] | COVID-19 [Member] | Other Forbearances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[2]	291,957
Commercial [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		1,103,020
Commercial [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	728,511
Commercial [Member] | COVID-19 [Member] | Other Forbearances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[2]	374,509
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		90	1,068
Residential Builder and Developer [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount			1,068
Residential Builder and Developer [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		653
Residential Builder and Developer [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	653
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		13,573	1,500	746
Other Commercial Construction [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		13,573		746
Other Commercial Construction [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		207,005
Other Commercial Construction [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	61,235
Other Commercial Construction [Member] | COVID-19 [Member] | Other Forbearances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[2]	145,770
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		207,517	22,726	38,072
Residential [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		183,878	10,819	19,962
Residential [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		2,447,422
Residential [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1],[3]	2,447,422
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		8,332	1,443	2,250
Residential Limited Documentation [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		7,100	399	827
Residential Limited Documentation [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		337,108
Residential Limited Documentation [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	337,108
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		17,254	4,180	3,979
Home Equity Lines and Loans [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		5,882	176	224
Home Equity Lines and Loans [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		18,440
Home Equity Lines and Loans [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	18,440
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		16,392	265	202
Recreational Finance [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		16,388	265	202
Recreational Finance [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		24,428
Recreational Finance [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	24,428
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		39,951	1,141	1,330
Automobile [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		39,949	$ 1,076	$ 1,318
Automobile [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		51,550
Automobile [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	51,550
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		7,788
Other [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		3,383
Other [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount		2,353
Other [Member] | COVID-19 [Member] | Payment Deferral [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	[1]	$ 2,353
[1]
[2]
[3]	Includes $1.7 billion of government-guaranteed loans.

Loans and Leases - Summary of_2

Loans and Leases - Summary of Outstanding Loan Balances Related to COVID-19 Modifications Granted - (Parenthetical) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Loans and leases, net of unearned discount		$ 806,046	$ 127,024	$ 180,224
Payment Deferral [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans and leases, net of unearned discount		545,415	$ 29,481	$ 90,639
COVID-19 [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans and leases, net of unearned discount		4,579,759
COVID-19 [Member] | Payment Deferral [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans and leases, net of unearned discount	[1]	3,767,523
COVID-19 [Member] | Payment Deferral [Member] | Government-Guaranteed Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans and leases, net of unearned discount		$ 1,700,000
[1]

Loans and Leases - Outstanding

Loans and Leases - Outstanding Principal Balance and Carrying Amount of Loans and Included in Consolidated Balance Sheet (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Outstanding principal and carrying value of acquired loans recorded at fair value
Outstanding principal balance	$ 769,414
Carrying amount	535,596
Commercial, Financial, Leasing, etc. [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	21,114
Commercial Real Estate [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	94,890
One-to-Four Family Residential [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	341,807
Consumer [Member]
Outstanding principal and carrying value of acquired loans recorded at fair value
Carrying amount	$ 77,785

Loans and Leases - Summary of_3

Loans and Leases - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 147,210	$ 157,918
Interest income	(49,017)	(37,819)
Reclassifications from nonaccretable balance	36,718	27,111
Balance at end of period	134,911	147,210
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	96,907	133,162
Interest income	(36,452)	(63,856)
Reclassifications from nonaccretable balance	15,534	22,849
Other	(3,909)	4,752
Balance at end of period	$ 72,080	$ 96,907

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, 2020USD ($)Modification	Dec. 31, 2019USD ($)Modification	Dec. 31, 2018USD ($)Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	5,250	412	557
Pre-modification Recorded Investment	$ 862,507	$ 143,556	$ 175,583
Loans and leases, net of unearned discount	$ 806,046	$ 127,024	$ 180,224
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			83
Pre-modification Recorded Investment			$ 30,217
Loans and leases, net of unearned discount			$ 30,731
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	394	150	203
Pre-modification Recorded Investment	$ 246,479	$ 63,715	$ 102,445
Loans and leases, net of unearned discount	$ 199,918	$ 63,356	$ 102,914
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	161	51
Pre-modification Recorded Investment	$ 310,578	$ 48,315
Loans and leases, net of unearned discount	$ 295,231	$ 31,345
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2	3	1
Pre-modification Recorded Investment	$ 13,602	$ 1,559	$ 752
Loans and leases, net of unearned discount	$ 13,573	$ 1,500	$ 746
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	631	83	134
Pre-modification Recorded Investment	$ 202,985	$ 21,695	$ 34,798
Loans and leases, net of unearned discount	$ 207,517	$ 22,726	$ 38,072
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	30	6	9
Pre-modification Recorded Investment	$ 7,413	$ 1,409	$ 1,887
Loans and leases, net of unearned discount	$ 8,332	$ 1,443	$ 2,250
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	259	41	47
Pre-modification Recorded Investment	$ 17,228	$ 4,127	$ 3,952
Loans and leases, net of unearned discount	$ 17,254	$ 4,180	$ 3,979
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	428	10	7
Pre-modification Recorded Investment	$ 16,392	$ 265	$ 202
Loans and leases, net of unearned discount	$ 16,392	$ 265	$ 202
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	2,249	66	73
Pre-modification Recorded Investment	$ 39,951	$ 1,141	$ 1,330
Loans and leases, net of unearned discount	$ 39,951	$ 1,141	1,330
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1,095
Pre-modification Recorded Investment	$ 7,788
Loans and leases, net of unearned discount	$ 7,788
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1	2
Pre-modification Recorded Investment	$ 91	$ 1,330
Loans and leases, net of unearned discount	90	1,068
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	545,415	29,481	90,639
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount			16,870
Principal Deferral [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	70,671	10,485	50,490
Principal Deferral [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	204,591	5,193
Principal Deferral [Member] | Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	13,573		746
Principal Deferral [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	183,878	10,819	19,962
Principal Deferral [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	7,100	399	827
Principal Deferral [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	5,882	176	224
Principal Deferral [Member] | Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	16,388	265	202
Principal Deferral [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	39,949	1,076	1,318
Principal Deferral [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	3,383
Principal Deferral [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount		1,068
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	803		978
Interest Rate Reduction [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount			175
Interest Rate Reduction [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	298		803
Interest Rate Reduction [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	505
Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	36,479		10,896
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount			4,686
Other [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	31,605		6,210
Other [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	4,874
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	223,349	97,543	77,711
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount			9,000
Combination of Concession Types [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	97,344	52,871	45,411
Combination of Concession Types [Member] | Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	85,261	26,152
Combination of Concession Types [Member] | Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount		1,500
Combination of Concession Types [Member] | Residential [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	23,639	11,907	18,110
Combination of Concession Types [Member] | Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	1,232	1,044	1,423
Combination of Concession Types [Member] | Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	11,372	4,004	3,755
Combination of Concession Types [Member] | Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	4
Combination of Concession Types [Member] | Automobile [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	2	$ 65	$ 12
Combination of Concession Types [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	4,405
Combination of Concession Types [Member] | Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Loans and leases, net of unearned discount	$ 90

Loans and Leases - Summary of L

Loans and Leases - Summary of Lease Financing Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Direct financings:
Lease payments receivable	$ 1,017,222	$ 1,164,567
Estimated residual value of leased assets	79,621	84,540
Unearned income	(83,673)	(106,780)
Investment in direct financings	1,013,170	1,142,327
Leveraged leases:
Lease payments receivable	76,453	82,065
Estimated residual value of leased assets	73,600	81,025
Unearned income	(28,388)	(31,596)
Investment in leveraged leases	121,665	131,494
Total investment in leases	1,134,835	1,273,821
Deferred taxes payable arising from leveraged leases	$ 61,905	$ 70,245

Loans and Leases - Minimum Futu

Loans and Leases - Minimum Future Lease Payments to be Received from Lease Financings (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Receivables [Abstract]
2021	$ 320,428
2022	288,322
2023	187,740
2024	122,735
2025	70,400
Later years	104,050
Total	$ 1,093,675

Allowance for Credit Losses - C

Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	$ 1,051,071	$ 1,019,444	$ 1,017,198
Provision for credit losses	800,000	176,000	132,000
Net charge-offs
Charge-offs	(333,507)	(237,708)	(231,241)
Recoveries	86,366	93,335	101,487
Net (charge-offs) recoveries	(247,141)	(144,373)	(129,754)
Ending balance	1,736,387	1,051,071	1,019,444
Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Adoption of new accounting standard	132,457
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	366,094	330,055	328,599
Provision for credit losses	220,544	69,702	33,967
Net charge-offs
Charge-offs	(135,083)	(58,244)	(60,414)
Recoveries	15,765	24,581	27,903
Net (charge-offs) recoveries	(119,318)	(33,663)	(32,511)
Ending balance	405,846	366,094	330,055
Commercial, Financial, Leasing, etc. [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Adoption of new accounting standard	(61,474)
Commercial Real Estate [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	322,201	341,655	374,085
Provision for credit losses	356,203	(10,726)	(41,181)
Net charge-offs
Charge-offs	(35,891)	(12,664)	(12,286)
Recoveries	4,550	3,936	21,037
Net (charge-offs) recoveries	(31,341)	(8,728)	8,751
Ending balance	670,719	322,201	341,655
Commercial Real Estate [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Adoption of new accounting standard	23,656
One-to-Four Family Residential [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	56,033	69,125	65,405
Provision for credit losses	(3,172)	(8,585)	12,401
Net charge-offs
Charge-offs	(10,283)	(12,711)	(15,345)
Recoveries	7,116	8,204	6,664
Net (charge-offs) recoveries	(3,167)	(4,507)	(8,681)
Ending balance	103,590	56,033	69,125
One-to-Four Family Residential [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Adoption of new accounting standard	53,896
Consumer [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	229,118	200,564	170,809
Provision for credit losses	226,425	126,029	127,068
Net charge-offs
Charge-offs	(152,250)	(154,089)	(143,196)
Recoveries	58,935	56,614	45,883
Net (charge-offs) recoveries	(93,315)	(97,475)	(97,313)
Ending balance	556,232	229,118	200,564
Consumer [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Adoption of new accounting standard	194,004
Unallocated [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	77,625	78,045	78,300
Provision for credit losses		(420)	(255)
Net charge-offs
Ending balance		$ 77,625	$ 78,045
Unallocated [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Adoption of new accounting standard	$ (77,625)

Allowance for Credit Losses - A

Allowance for Credit Losses - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Maximum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	150 days
Minimum [Member]
Loans And Leases Receivable [Line Items]
Loan delinquent period	90 days
Minimum [Member] | Commercial Loans and Commercial Real Estate [Member]
Loans And Leases Receivable [Line Items]
Amount of real estate loan as reported as accruing or nonaccruing	$ 1

Allowance for Credit Losses - L

Allowance for Credit Losses - Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020	Jan. 01, 2019	Jan. 01, 2018
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	$ 974,782	$ 399,274	$ 375,709
Amortized Cost without Allowance	918,517	563,838	517,899
Total	1,893,299	963,112	893,608
Amortized Cost				$ 1,134,333	$ 893,608	$ 882,598
Interest Income Recognized	54,217	36,807	46,838
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	226,897	206,644	126,753
Amortized Cost without Allowance	79,930	139,913	107,670
Total	306,827	346,557	234,423
Amortized Cost				346,743	234,423	240,991
Interest Income Recognized	11,269	8,960	7,873
Commercial [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	364,110	40,847	90,296
Amortized Cost without Allowance	411,784	117,627	113,376
Total	775,894	158,474	203,672
Amortized Cost				173,796	203,672	184,982
Interest Income Recognized	7,821	5,850	10,880
Residential Builder and Developer [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	1,094	604	2,205
Amortized Cost without Allowance		3,378	2,593
Total	1,094	3,982	4,798
Amortized Cost				4,708	4,798	6,451
Interest Income Recognized	1,694	357	1,779
Other Commercial Construction [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	20,992	12,425	14,604
Amortized Cost without Allowance	93,047	20,345	7,601
Total	114,039	32,770	22,205
Amortized Cost				35,881	22,205	10,088
Interest Income Recognized	8,457	634	3,474
Residential [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	159,006	59,982	57,346
Amortized Cost without Allowance	206,723	175,681	176,006
Total	365,729	235,663	233,352
Amortized Cost				322,504	233,352	235,834
Interest Income Recognized	18,069	12,630	14,065
Residential Limited Documentation [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	84,568	26,710	26,808
Amortized Cost without Allowance	62,602	56,717	57,877
Total	147,170	83,427	84,685
Amortized Cost				114,667	84,685	96,105
Interest Income Recognized	634	1,092	1,980
Home Equity Lines and Loans [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	61,031	24,812	30,819
Amortized Cost without Allowance	18,361	38,403	40,473
Total	79,392	63,215	71,292
Amortized Cost				65,039	71,292	74,500
Interest Income Recognized	4,092	5,987	5,535
Recreational Finance [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	19,434	9,054	6,016
Amortized Cost without Allowance	6,085	5,165	5,183
Total	25,519	14,219	11,199
Amortized Cost				14,308	11,199	6,509
Interest Income Recognized	626	575	333
Automobile [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	34,044	14,805	16,271
Amortized Cost without Allowance	5,360	6,488	7,088
Total	39,404	21,293	23,359
Amortized Cost				21,293	23,359	23,781
Interest Income Recognized	186	214	689
Other [Member]
Financing Receivable Impaired [Line Items]
Amortized Cost with Allowance	3,606	3,391	4,591
Amortized Cost without Allowance	34,625	121	32
Total	38,231	3,512	4,623
Amortized Cost				$ 35,394	$ 4,623	$ 3,357
Interest Income Recognized	$ 1,369	$ 508	$ 230

Allowance for Credit Losses - S

Allowance for Credit Losses - Summary of Loan grades applied various classes of Commercial and Real Estate Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 98,535,867	$ 90,922,869
Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,963,561
Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,387,378
Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	20,949,019	15,628,942	$ 10,466,749	$ 7,893,838	$ 6,013,013
Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	19,233,367
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,574,564	23,838,168
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	12,063,060
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	42,974
Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	25,927,474	22,595,821
Commercial, Financial, Leasing, etc. [Member] | Pass [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	11,352,416
Commercial, Financial, Leasing, etc. [Member] | Pass [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	21,286
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,340,263	895,790
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	584,751
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	13,970
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	306,827	346,557
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	125,893
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,718
Commercial, Financial, Leasing, etc. [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,128,774	2,388,900	1,675,653	989,229	779,407
Commercial, Financial, Leasing, etc. [Member] | Term Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,732,728	2,277,233	1,505,486	930,834	719,796
Commercial, Financial, Leasing, etc. [Member] | Term Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	388,326	84,358	113,940	41,587	39,930
Commercial, Financial, Leasing, etc. [Member] | Term Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,720	27,309	56,227	16,808	19,681
Commercial, Financial, Leasing, etc. [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,506,567
Commercial, Financial, Leasing, etc. [Member] | Term Loans Prior Period [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,387,695
Commercial, Financial, Leasing, etc. [Member] | Term Loans Prior Period [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	73,401
Commercial, Financial, Leasing, etc. [Member] | Term Loans Prior Period [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	45,471
Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,680,340	26,657,808
Commercial [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	954,022
Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,282,787	25,728,725
Commercial [Member] | Pass [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	875,348
Commercial [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,621,659	770,609
Commercial [Member] | Criticized Accrual [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	44,260
Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	775,894	158,474
Commercial [Member] | Criticized Nonaccrual [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	34,414
Commercial [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,906,363	5,203,887	3,925,746	3,018,239	3,511,628
Commercial [Member] | Term Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,353,450	4,681,834	3,299,095	2,628,061	2,746,165
Commercial [Member] | Term Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	526,037	400,154	579,507	290,885	568,144
Commercial [Member] | Term Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,876	121,899	47,144	99,293	197,319
Commercial [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,160,455
Commercial [Member] | Term Loans Prior Period [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	5,698,834
Commercial [Member] | Term Loans Prior Period [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,212,672
Commercial [Member] | Term Loans Prior Period [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	248,949
Residential Builder and Developer [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,249,738	1,547,245
Residential Builder and Developer [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	240,993
Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,113,915	1,419,162
Residential Builder and Developer [Member] | Pass [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	236,943
Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	134,729	124,101
Residential Builder and Developer [Member] | Criticized Accrual [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	4,050
Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,094	3,982
Residential Builder and Developer [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	509,985	331,245	124,289	18,469	10,976
Residential Builder and Developer [Member] | Term Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	506,295	223,880	109,453	15,048	10,976
Residential Builder and Developer [Member] | Term Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,690	106,847	14,836	3,421
Residential Builder and Developer [Member] | Term Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		518
Residential Builder and Developer [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	13,781
Residential Builder and Developer [Member] | Term Loans Prior Period [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	11,320
Residential Builder and Developer [Member] | Term Loans Prior Period [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,885
Residential Builder and Developer [Member] | Term Loans Prior Period [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	576
Other Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,707,811	7,336,861
Other Commercial Construction [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	80,018
Other Commercial Construction [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,644,349	7,092,799
Other Commercial Construction [Member] | Pass [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	74,611
Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	949,423	211,292
Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	114,039	32,770
Other Commercial Construction [Member] | Criticized Nonaccrual [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	5,407
Other Commercial Construction [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,087,785	3,213,005	2,442,676	1,175,501	389,889
Other Commercial Construction [Member] | Term Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,050,258	2,998,921	2,048,063	945,339	233,127
Other Commercial Construction [Member] | Term Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	37,192	148,492	381,091	225,949	144,665
Other Commercial Construction [Member] | Term Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	335	$ 65,592	$ 13,522	$ 4,213	$ 12,097
Other Commercial Construction [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	318,937
Other Commercial Construction [Member] | Term Loans Prior Period [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	294,030
Other Commercial Construction [Member] | Term Loans Prior Period [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	12,034
Other Commercial Construction [Member] | Term Loans Prior Period [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 12,873

Allowance for Credit Losses -_2

Allowance for Credit Losses - Summary of loans in Accrual and Nonaccrual Status (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Current	$ 95,120,921	$ 87,999,720
30-89 Days Past Due	662,439	1,174,132
Accruing Loans Past Due 90 Days or More	859,208	518,728
Nonaccrual	1,893,299	963,112
Loans and leases, net of unearned discount	98,535,867	90,922,869
Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,963,561
Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,387,378
Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	20,949,019	15,628,942	$ 10,466,749	$ 7,893,838	$ 6,013,013
Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	19,233,367
Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Current	13,764,836	12,760,040
30-89 Days Past Due	200,406	451,274
Accruing Loans Past Due 90 Days or More	792,888	486,515
Nonaccrual	365,729	235,663
Loans and leases, net of unearned discount	15,123,859	14,082,425
Residential [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	71,894
Nonaccrual	200
Loans and leases, net of unearned discount	72,094
Residential [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	2,722,862	1,416,259	618,736	1,318,094	718,235
30-89 Days Past Due	13,496	7,781	7,258	13,477	7,947
Accruing Loans Past Due 90 Days or More	579	15,234	38,145	212,818	45,804
Nonaccrual	3,133	14,439	5,183	6,408	2,900
Loans and leases, net of unearned discount	2,740,070	1,453,713	669,322	1,550,797	774,886
Residential [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Current	6,898,756
30-89 Days Past Due	150,447
Accruing Loans Past Due 90 Days or More	480,308
Nonaccrual	333,466
Loans and leases, net of unearned discount	7,862,977
Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,462,277	1,858,037
30-89 Days Past Due	19,687	65,215
Accruing Loans Past Due 90 Days or More		181
Nonaccrual	147,170	83,427
Loans and leases, net of unearned discount	1,629,134	2,073,669
Residential Limited Documentation [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,462,277
30-89 Days Past Due	19,687
Nonaccrual	147,170
Loans and leases, net of unearned discount	1,629,134
Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	3,881,885	4,386,511
30-89 Days Past Due	24,329	30,229
Nonaccrual	79,392	63,215
Loans and leases, net of unearned discount	3,985,606	4,481,617
Home Equity Lines and Loans [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	2,569,621
30-89 Days Past Due	939
Nonaccrual	5,752
Loans and leases, net of unearned discount	2,576,312
Home Equity Lines and Loans [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,252,185
30-89 Days Past Due	22,242
Nonaccrual	67,492
Loans and leases, net of unearned discount	1,341,919
Home Equity Lines and Loans [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	773	3,983	1,591	2,016	162
Loans and leases, net of unearned discount	773	3,983	1,591	2,016	162
Home Equity Lines and Loans [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Current	51,554
30-89 Days Past Due	1,148
Nonaccrual	6,148
Loans and leases, net of unearned discount	58,850
Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Current	7,002,643	5,484,997
30-89 Days Past Due	47,161	36,827
Nonaccrual	25,519	14,219
Loans and leases, net of unearned discount	7,075,323	5,536,142
Recreational Finance [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	2,796,359	1,751,766	907,595	630,151	352,414
30-89 Days Past Due	9,548	11,255	8,519	6,638	2,938
Nonaccrual	1,854	3,883	4,072	4,194	2,733
Loans and leases, net of unearned discount	2,807,761	1,766,904	920,186	640,983	358,085
Recreational Finance [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Current	564,358
30-89 Days Past Due	8,263
Nonaccrual	8,783
Loans and leases, net of unearned discount	581,404
Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Current	4,007,349	3,787,221
30-89 Days Past Due	55,498	78,478
Nonaccrual	39,404	21,293
Loans and leases, net of unearned discount	4,102,251	3,886,992
Automobile [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,595,636	1,106,782	629,338	440,604	171,017
30-89 Days Past Due	6,461	14,140	12,542	12,899	6,373
Nonaccrual	1,615	7,144	10,788	10,061	5,991
Loans and leases, net of unearned discount	1,603,712	1,128,066	652,668	463,564	183,381
Automobile [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Current	63,972
30-89 Days Past Due	3,083
Nonaccrual	3,805
Loans and leases, net of unearned discount	70,860
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,346,868	1,395,240
30-89 Days Past Due	17,561	45,978
Accruing Loans Past Due 90 Days or More	4,581	5,156
Nonaccrual	38,231	3,512
Loans and leases, net of unearned discount	1,407,241	1,481,942
Other [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	927,217
30-89 Days Past Due	10,594
Accruing Loans Past Due 90 Days or More	4,207
Nonaccrual	35,044
Loans and leases, net of unearned discount	977,062
Other [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,856
30-89 Days Past Due	481
Nonaccrual	148
Loans and leases, net of unearned discount	2,485
Other [Member] | Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	160,424	137,617	53,702	32,556	4,526
30-89 Days Past Due	1,879	1,130	577	2,301	42
Nonaccrual	1,493	492	339	183	31
Loans and leases, net of unearned discount	163,796	$ 139,239	$ 54,618	$ 35,040	$ 4,599
Other [Member] | Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Current	28,970
30-89 Days Past Due	557
Accruing Loans Past Due 90 Days or More	374
Nonaccrual	501
Loans and leases, net of unearned discount	$ 30,402

Allowance for Credit Losses -_3

Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 98,535,867	$ 90,922,869
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,574,564	23,838,168
Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	25,927,474	22,595,821
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,340,263	895,790
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	306,827	346,557
Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,680,340	26,657,808
Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,282,787	25,728,725
Commercial [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,621,659	770,609
Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	775,894	158,474
Residential Builder and Developer [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,249,738	1,547,245
Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,113,915	1,419,162
Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	134,729	124,101
Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,094	3,982
Other Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,707,811	7,336,861
Other Commercial Construction [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,644,349	7,092,799
Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	949,423	211,292
Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 114,039	$ 32,770

Premises and Equipment - Summar

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Land	$ 94,929	$ 96,118
Buildings	513,290	482,182
Leasehold improvements	302,246	262,438
Premises and equipment, gross	1,726,796	1,594,694
Less: accumulated depreciation and amortization	977,912	890,697
Right of use assets — operating leases	412,674	436,927
Premises and equipment, net	1,161,558	1,140,924
Owned Assets [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	807,701	739,724
Less: accumulated depreciation and amortization	971,979	882,272
Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Furniture and equipment	8,630	14,232
Less: accumulated depreciation and amortization	$ 5,933	$ 8,425

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Property Plant And Equipment Capitalized Interest Costs [Abstract]
Operating lease liabilities	$ 467,320		$ 488,000
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesMember		us-gaap:OtherLiabilitiesMember
Period of noncancelable operating lease in years	21 years
Net lease expense		$ 111,000

Premises and Equipment - Summ_2

Premises and Equipment - Summary of Lease Costs for Operating Leases, Cash Paid Toward Lease Liabilities, and Weighted-Average Remaining Term and Discount Rates of Operating Leases (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease cost
Operating lease cost	$ 104,158	$ 100,669
Short-term lease cost	198	105
Variable lease cost	1,565	2,332
Total lease cost	105,921	103,106
Other information
Right-of-use assets obtained in exchange for new operating lease liabilities	70,754	132,219
Cash paid toward lease liabilities	$ 104,396	$ 101,869
Weighted-average remaining lease term	7 years	7 years
Weighted-average discount rate	2.74%	3.01%

Premises and Equipment - Summ_3

Premises and Equipment - Summary of Minimum Lease Payments Under Noncancelable Operating Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment Capitalized Interest Costs [Abstract]
2021	$ 105,445
2022	93,621
2023	75,698
2024	61,412
2025	46,023
Later years	130,475
Total lease payments	512,674
Less: imputed interest	45,354
Operating lease liabilities	$ 467,320	$ 488,000

Capitalized Servicing Assets -

Capitalized Servicing Assets - Changes in Capitalized Servicing Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Residential Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	$ 244,411	$ 120,509	$ 114,978
Originations	45,101	26,067	28,985
Purchases		144,326	454
Amortization	(58,308)	(46,491)	(23,908)
Amortized value, ending balance	231,204	244,411	120,509
Valuation allowance	(30,000)	(7,000)
Ending balance, net	201,204	237,411	120,509
Commercial Mortgage Loans [Member]
Servicing Asset at Amortized Cost [Line Items]
Amortized value, Beginning balance	130,636	114,663	114,076
Originations	29,306	41,370	26,298
Amortization	(26,513)	(25,397)	(25,711)
Amortized value, ending balance	133,429	130,636	114,663
Ending balance, net	$ 133,429	$ 130,636	$ 114,663

Capitalized Servicing Assets _2

Capitalized Servicing Assets - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Residential Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	$ 26,300	$ 32,300		$ 26,300	$ 32,300	$ 22,200
Fair value of residential loan servicing assets	$ 240	$ 297		$ 240	$ 297
Weighted average discount rates used to estimate fair value of capitalized mortgaged loan servicing assets	9.40%	10.60%
Residential Mortgage Loans [Member] | LIBOR [Member]
Servicing Assets at Fair Value [Line Items]
Discounted rate represented weighted-average option-adjusted basis spread point percentage				9.18%	9.28%
Residential Mortgage Sub Servicing Loan [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	$ 68,100	$ 62,800		$ 68,100	$ 62,800	56,800
Residential Real Estate [Member]
Servicing Assets at Fair Value [Line Items]
Fair value of residential loan servicing assets			$ 13,300
Purchase price of servicing rights			$ 144
Commercial Mortgage Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced for others	18,900	17,600		18,900	17,600	15,500
Fair value of residential loan servicing assets	$ 160	$ 153		$ 160	153
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	$ 3,300	$ 3,400		$ 3,300	$ 3,400	$ 2,700

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, 2020	Dec. 31, 2019	Dec. 31, 2020
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			14.50%
Impact on fair value of 10% adverse change	$ (15,279)		$ (15,279)
Impact on fair value of 20% adverse change	$ (29,189)		$ (29,189)
Weighted-average OAS	9.18%		9.18%
Impact on fair value of 10% adverse change	$ (7,230)		$ (7,230)
Impact on fair value of 20% adverse change	$ (14,020)		$ (14,020)
Weighted-average discount rate	9.40%	10.60%
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	$ (7,024)		$ (7,024)
Impact on fair value of 20% adverse change	$ (13,556)		$ (13,556)

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Total Amortizing Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 138,421	$ 138,421
Accumulated Amortization	124,256	109,387
Net Carrying Amount	14,165	29,034
Core Deposit [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	131,664	131,664
Accumulated Amortization	119,125	105,802
Net Carrying Amount	12,539	25,862
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,757	6,757
Accumulated Amortization	5,131	3,585
Net Carrying Amount	$ 1,626	$ 3,172

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill And Other Intangible Assets [Line Items]
Amortization of core deposit and other intangible assets	$ 14,869	$ 19,490	$ 24,522
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	7 years
Amortization of core deposit and other intangible assets	$ 15,000	$ 19,000	$ 25,000
Core Deposit and Other Intangible Assets [Member] | Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	3 years
Core Deposit and Other Intangible Assets [Member] | Maximum [Member]
Goodwill And Other Intangible Assets [Line Items]
Estimated useful lives	7 years

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Estimated Amortization Expense in Future Years (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
2021	$ 10,167
2022	3,998
Net Carrying Amount	$ 14,165	$ 29,034

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, 2020	Dec. 31, 2019
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, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	0.01%	0.14%	2.58%
Daily-average amount outstanding	$ 61,551,000	$ 1,059,390,000	$ 330,665,000
Weighted-average interest rate	0.05%	2.34%	1.63%
Federal funds purchased and short term borrowings	$ 59,482,000	$ 62,363,000	$ 4,398,378,000
Federal Funds Purchased and Repurchase Agreements [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate	0.01%	0.14%	1.68%
Highest amount at a month-end	$ 82,893,000	$ 3,402,566,000	$ 2,654,416,000
Daily-average amount outstanding	$ 61,551,000	$ 260,322,000	$ 261,200,000
Weighted-average interest rate	0.05%	1.86%	1.49%
Federal Funds Purchased and Repurchase Agreements	$ 59,482,000	$ 62,363,000	$ 198,378,000
Other Short-term Borrowings [Member]
Schedule Of Borrowings [Line Items]
Weighted-average interest rate			2.63%
Highest amount at a month-end		5,000,000,000	$ 4,200,000,000
Daily-average amount outstanding		$ 799,068,000	$ 69,465,000
Weighted-average interest rate		2.49%	2.16%
Other Short-term Borrowings			$ 4,200,000,000

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Contractual interest rates of long-term agreements to repurchase securities		4.29%
Collateral posted		$ 108,000,000
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	1.06%	2.76%
Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	3.59%	5.34%
FHLBs Facility [Member]
Debt Instrument [Line Items]
Borrowing facilities available with FHLB's amount	$ 19,000,000,000
Federal Reserve Bank of New York [Member]
Debt Instrument [Line Items]
Line of credit facility	$ 13,000,000,000
Senior Notes Issued in July 2018 [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	0.90%	2.62%
Variable Rate Senior Notes [Member]
Debt Instrument [Line Items]
Weighted-average variable rates payable	0.63%	2.34%
Variable Rate Senior Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	0.49%	2.21%
Variable Rate Senior Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Variable interest rate of Senior Notes /Junior Subordinated Debentures	0.83%	2.54%
Long Term Fixed Rate Advances From Fhlb
Debt Instrument [Line Items]
Advances from the FHLB earliest maturity date	2029
Advances from the FHLB latest maturity date,	2035
Long Term Fixed Rate Advances From Fhlb | Weighted Average [Member]
Debt Instrument [Line Items]
Variable contractual interest rate of long-term debt	5.82%	5.82%
Subordinated Capital Notes [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument		3.02%
Subordinated Variable Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Interest rate of debt instrument	0.87%	2.55%
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Weighted-average variable rates payable	1.65%	3.37%
Short-term Borrowings [Member]
Debt Instrument [Line Items]
Stated maturity	1 year

Borrowings - Lines of Credit Un

Borrowings - Lines of Credit Under Formal Agreements (Detail) - M&T Bank [Member] $ in Thousands	Dec. 31, 2020USD ($)
Schedule Of Borrowings [Line Items]
Outstanding borrowings	$ 1,727
Unused	$ 32,010,950

Borrowings - Long-term Borrowin

Borrowings - Long-term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020
Schedule Of Borrowings [Line Items]
Fixed rates advances from FHLB	$ 1,815	$ 1,683
Agreements to repurchase securities	101,679
Other	8,533	2,997
Long-term borrowings	6,986,186	4,382,193
Variable Rate Term Loans Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	249,756	249,824
Variable Rate Term Loans Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	349,893	349,992
3.55% Fixed Rate Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	520,454	533,369
Variable Rate Term Loans Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	249,758	249,858
Fixed Rate Term Loans 2.25% Due 2019 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,254
Fixed Rate Term Loans 2.05% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,864
Fixed Rate Term Loans 2.10% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	654,136
Fixed Rate Term Loans 2.625% Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	652,714	664,400
Fixed Rate Term Loans 2.50% Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Variable\fixed rates term loan amount	749,572	749,656
Variable Rate Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Subordinated notes	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	514,353	552,194
BSB Capital Trust I - 8.125%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	15,728	15,752
Provident Trust I - 8.29%, due 2028 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	28,235	29,099
Southern Financial Statutory Trust I - 10.60%, due 2030 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	6,770	6,836
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	147,871	148,409
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	149,943	150,606
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	96,930	97,075
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	55,867	56,641
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Junior subordinated debentures associated with preferred capital securities	$ 8,236	$ 8,338

Borrowings - Long-term Borrow_2

Borrowings - Long-term Borrowings (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Variable Rate Term Loans Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2023	2023
Variable Rate Term Loans Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2021	2021
3.55% Fixed Rate Due 2023 [Member] | M&T Bank Corporation [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2023	2023
Interest rate of debt instrument	3.55%	3.55%
Variable Rate Term Loans Due 2022 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2022	2022
Fixed Rate Term Loans 2.10% Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2020	2020
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	2020	2020
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	2021	2021
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	2025	2025
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	2022	2022
Interest rate of debt instrument	2.50%	2.50%
Variable Rate Due 2020 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2020	2020
Variable Rate Due 2021 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2021	2021
3.40% due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2027	2027
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	2028	2028
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	2028	2028
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	2030	2030
Interest rate of debt instrument	10.60%	10.60%
First Maryland Capital I - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2027	2027
First Maryland Capital II - due 2027 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2027	2027
Allfirst Asset Trust - due 2029 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2029	2029
BSB Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2033	2033
Provident Statutory Trust III - Due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2033	2033
Southern Financial Capital Trust III - due 2033 [Member]
Schedule Of Borrowings [Line Items]
Debt maturity date	2033	2033

Borrowings - Maturity of Long-t

Borrowings - Maturity of Long-term Borrowings (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2021	$ 849,976
2022	917,270
2023	783,193
2025	749,656
Later years	1,082,098
Long-term borrowings	$ 4,382,193	$ 6,986,186

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
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, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Carrying Value	$ 1,250,000	$ 1,250,000
Series E Fixed-To-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	350,000	350,000
Preferred stock, Shares Outstanding	350,000	350,000
Carrying Value	$ 350,000	$ 350,000
Series F Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	50,000	50,000
Preferred stock, Shares Outstanding	50,000	50,000
Carrying Value	$ 500,000	$ 500,000
Series G Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, Shares Issued	40,000	40,000
Preferred stock, Shares Outstanding	40,000	40,000
Carrying Value	$ 400,000	$ 400,000

Shareholders' Equity - Issued_2

Shareholders' Equity - Issued and Outstanding Preferred Stock (Parenthetical) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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
Preferred stock, dividend declared per share	$ 64.50	$ 64.50	$ 64.50
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
Preferred stock, dividend declared per share	$ 512.50	$ 512.50	$ 512.50
Series G Fixed-Rate Reset Non-cumulative Perpetual Preferred Stock [Member]
Class Of Stock [Line Items]
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000
Preferred stock dividend rate	5.00%	5.00%
Date of change in the dividend rate	Jul. 31, 2024	Jul. 31, 2024
Preferred shares redemption date	Aug. 1, 2024	Aug. 1, 2024
Preferred Stock, Redemption Feature, Redemption Term	90 days	90 days
Preferred stock, dividend declared per share	$ 500.694	$ 125.694
U S treasury rate plus additional rate	3.174%	3.174%
Dividend payment terms	five-year	five-year

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Additional Information (Detail1)	Dec. 31, 2020
Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Disaggregation Of Revenue [Line Items]
Period of satisfaction of contract with customer	1 year

Revenue from Contracts with C_4

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Uncollected amounts receivable	$ 67	$ 62
Accrued interest and other liabilities [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue	$ 42	$ 43

Revenue from Contracts with C_5

Revenue from Contracts with Customers - Summary of Sources of Noninterest Income that are Subject to Noted Accounting Guidance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 47,428	$ 48,922	$ 51,069
Other revenues from operations:
Total other income	2,088,444	2,061,679	1,856,000
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	370,788	432,978	429,337
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	601,884	572,608	537,585
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	47,428	48,922	51,069
Other revenues from operations:
Merchant discount and credit card fees	102,472	107,042	105,953
Other	84,611	91,613	90,369
Total other income	1,207,183	1,253,163	1,214,313
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	370,788	432,978	429,337
ASU 2014-09 [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	601,884	572,608	537,585
ASU 2014-09 [Member] | Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	40,475	36,844	34,557
Total other income	90,612	97,565	96,889
ASU 2014-09 [Member] | Business Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	50,119	60,690	62,323
ASU 2014-09 [Member] | Business Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	18	31	9
ASU 2014-09 [Member] | Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	45,528	52,161	52,051
Other	9,408	7,498	8,796
Total other income	148,098	153,666	158,171
ASU 2014-09 [Member] | Commercial Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	92,720	93,044	96,407
ASU 2014-09 [Member] | Commercial Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	442	963	917
ASU 2014-09 [Member] | Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	2,221	2,516	2,213
Other	6,218	8,615	7,259
Total other income	18,691	20,959	19,342
ASU 2014-09 [Member] | Commercial Real Estate [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	10,252	9,828	9,870
ASU 2014-09 [Member] | Discretionary Portfolio [Member]
Other revenues from operations:
Other	1,625	1,776	1,738
Total other income	1,625	1,776	1,738
ASU 2014-09 [Member] | Residential Mortgage Banking [Member]
Other revenues from operations:
Other	4,732	3,492	3,814
Total other income	4,732	3,496	3,824
ASU 2014-09 [Member] | Residential Mortgage Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer		4	10
ASU 2014-09 [Member] | Retail Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	13,481	12,140	14,924
Other	20,813	36,144	38,529
Total other income	246,152	311,943	308,043
ASU 2014-09 [Member] | Retail Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	211,858	263,659	254,590
ASU 2014-09 [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	47,428	48,922	51,069
Other revenues from operations:
Merchant discount and credit card fees	767	3,381	2,208
Other	41,815	34,088	30,233
Total other income	697,273	663,758	626,306
ASU 2014-09 [Member] | All Other [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	5,839	5,753	6,137
ASU 2014-09 [Member] | All Other [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 601,424	$ 571,614	$ 536,659

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 80	$ 76	$ 66
Recognized income tax benefits related to stock-based compensation	$ 17	$ 19	$ 24
Shares under equity incentive compensation plan for future grant	3,100,665	3,742,478
Stock Options Outstanding, Granted	187,088	164,244	116,852
Directors Stock Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	3,809	5,043
Shares issued in connection with deferred compensation plans	295,182
Deferred Bonus Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issuable under deferred compensation plans	14,304	16,491
Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares under equity incentive compensation plan for future grant	2,233,581
Shares issued	77,170	71,676	58,167
Cash received from exercise of stock options	$ 12	$ 11	$ 10
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years	3 years	3 years	4 years
Shares issued	0	0	0
Unrecognized compensation cost expected to be recognized over a weighted-average period (in years)	1 year
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued	480,949	448,487	348,512
Weighted-average grant date fair value	$ 81	$ 74	$ 66
Unrecognized compensation cost related to non-vested awards	$ 29
Stock Option Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Stock options exercisable period, maximum	10 years 1 day
Cash realized from exercise of stock options	$ 3	9	60
Intrinsic value of stock options exercised	$ 1	$ 3	$ 16

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans - Summary of Restricted Stock and Restricted Stock Unit Activity (Detail)	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance | shares	691,227
Restricted Stock Outstanding, Granted | shares	480,949
Restricted Stock Outstanding, Vested | shares	(334,795)
Restricted Stock Outstanding, Cancelled | shares	(20,431)
Restricted Stock Outstanding, Unvested, Ending balance | shares	816,950
Weighted-Average Grant Price, Unvested, Beginning balance | $ / shares	$ 171.72
Weighted-Average Grant Price, Granted | $ / shares	168.71
Weighted-Average Grant Price, Vested | $ / shares	172.56
Weighted-Average Grant Price, Cancelled | $ / shares	171.91
Weighted-Average Grant Price, Unvested, Ending balance | $ / shares	$ 169.60
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted Stock Outstanding, Unvested, Beginning balance | shares	63,591
Restricted Stock Outstanding, Vested | shares	(49,468)
Restricted Stock Outstanding, Cancelled | shares	(573)
Restricted Stock Outstanding, Unvested, Ending balance | shares	13,550
Weighted-Average Grant Price, Unvested, Beginning balance | $ / shares	$ 162.45
Weighted-Average Grant Price, Vested | $ / shares	162.48
Weighted-Average Grant Price, Cancelled | $ / shares	158.02
Weighted-Average Grant Price, Unvested, Ending balance | $ / shares	$ 162.50

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Options Outstanding, Beginning balance	305,452
Stock Options Outstanding, Granted	187,088	164,244	116,852
Stock Options Outstanding, Exercised	(25,047)
Stock Options Outstanding, Expired	(2,070)
Stock Options Outstanding, Ending balance	465,423	305,452
Stock Options Outstanding, Exercisable	133,098
Weighted-Average Exercise Price, Outstanding, Beginning balance	$ 170.15
Weighted-Average Exercise Price, Granted	173.04
Weighted-Average Exercise Price, Exercised	117.81
Weighted-Average Exercise Price, Expired	174.09
Weighted-Average Exercise Price, Outstanding, Ending balance	174.11	$ 170.15
Weighted-Average Exercise Price, Exercisable	$ 178.58
Weighted-Average Life (In Years), Outstanding, Ending balance	8 years 2 months 12 days
Weighted-Average Life (In Years), Exercisable	7 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding, Ending balance	$ 38
Aggregate Intrinsic Value, Exercisable	$ 38

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 19,944	$ 17,294	$ 20,346
Interest cost on benefit obligation	71,421	81,579	74,704
Expected return on plan assets	(125,512)	(122,139)	(123,127)
Amortization of prior service cost	557	557	557
Recognized net actuarial (gain) loss	58,096	21,992	43,793
Net periodic pension cost (benefit)	24,506	(717)	16,273
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	970	859	938
Interest cost on benefit obligation	1,741	2,344	2,293
Amortization of prior service cost	(4,738)	(4,730)	(4,729)
Recognized net actuarial (gain) loss	(1,236)	(1,247)	(826)
Net periodic pension cost (benefit)	$ (3,263)	$ (2,774)	$ (2,324)

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in plan assets:
Fair value of plan assets at beginning of year	$ 2,035,878,000
Employer contributions	300,000,000	$ 0
Fair value of plan assets at end of year	2,418,702,000	2,035,878,000
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	2,247,329,000	1,949,613,000
Service cost	19,944,000	17,294,000	$ 20,346,000
Interest cost	71,421,000	81,579,000	74,704,000
Actuarial (gain) loss	288,944,000	298,713,000
Benefits paid	(106,346,000)	(99,870,000)
Benefit obligation at end of year	2,521,292,000	2,247,329,000	1,949,613,000
Change in plan assets:
Fair value of plan assets at beginning of year	2,037,940,000	1,833,833,000
Actual return on plan assets	178,610,000	293,546,000
Employer contributions	310,378,000	10,431,000
Benefits paid	(106,346,000)	(99,870,000)
Fair value of plan assets at end of year	2,420,582,000	2,037,940,000	1,833,833,000
Funded status	(100,710,000)	(209,389,000)
Accrued liability recognized in the consolidated balance sheet	(165,380,000)	(209,389,000)
Net accrued liability recognized in the consolidated balance sheet	(100,710,000)	(209,389,000)
Net loss (gain)	684,780,000	507,029,000
Net prior service cost (credit)	1,277,000	1,834,000
Pre-tax adjustment to AOCI	686,057,000	508,863,000
Taxes	(178,375,000)	(133,779,000)
Net adjustment to AOCI	507,682,000	375,084,000
Prepaid asset recognized in the consolidated balance sheet	64,670,000
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	56,492,000	59,991,000
Service cost	970,000	859,000	938,000
Interest cost	1,741,000	2,344,000	2,293,000
Plan participants’ contributions	2,386,000	2,749,000
Actuarial (gain) loss	2,371,000	(687,000)
Medicare Part D reimbursement	574,000	370,000
Benefits paid	(9,253,000)	(9,134,000)
Benefit obligation at end of year	55,281,000	56,492,000	$ 59,991,000
Change in plan assets:
Employer contributions	6,293,000	6,015,000
Plan participants’ contributions	2,386,000	2,749,000
Medicare Part D reimbursement	574,000	370,000
Benefits paid	(9,253,000)	(9,134,000)
Funded status	(55,281,000)	(56,492,000)
Accrued liability recognized in the consolidated balance sheet	(55,281,000)	(56,492,000)
Net accrued liability recognized in the consolidated balance sheet	(55,281,000)	(56,492,000)
Net loss (gain)	(13,701,000)	(17,308,000)
Net prior service cost (credit)	(22,269,000)	(27,007,000)
Pre-tax adjustment to AOCI	(35,970,000)	(44,315,000)
Taxes	9,352,000	11,650,000
Net adjustment to AOCI	$ (26,618,000)	$ (32,665,000)

Pension Plans and Other Postr_5

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Minimum pension liability	$ 650,000,000
Minimum pension liability adjustment net of tax	$ 481,000,000
Increase in minimum liability adjustment		$ 186,000,000
Discount rate	2.50%	3.25%
Defined contribution pension and retirement savings plans total expense	$ 35,000,000	$ 32,000,000	$ 29,000,000
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	9,000,000
Effect of 25 basis point decrease in discount rate on benefit obligation	86,000,000
Effect of 25 basis point increase in discount rate on benefit obligation	$ 91,000,000
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 eight years
Defined benefit pension plans	$ 479,000,000
Percentage of total assets	20.00%
Defined benefit plan fair value of plan assets	$ 2,418,702,000	2,035,878,000
Qualified benefit pension plans		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 contribution	$ 300,000,000	$ 0
Percentage of eligible employees contribution for Retirement Savings Plan	50.00%
Percentage of employer matching contribution to employee's contribution	100.00%	75.00%
Maximum employer contribution on Employee's qualified contribution	5.00%	4.50%
Qualified defined contribution plans expense during the period	$ 62,000,000	$ 48,000,000	43,000,000
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	$ 479,393,000	439,185,000
Other Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	5.00%
Other Securities [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocations for plan assets	60.00%
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 111,441,000	$ 148,603,000
Percentage of common stock in total plan assets	5.00%	7.00%
Supplemental Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 165,000,000	$ 154,000,000
Accumulated benefit obligation	165,000,000	154,000,000
Employer contribution	10,000,000	10,000,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	2,521,292,000	2,247,329,000	1,949,613,000
Accumulated benefit obligation	2,500,000,000	$ 2,200,000,000
Minimum pension liability	$ 686,000,000
Discount rate	2.50%	3.25%
Defined benefit plan fair value of plan assets	$ 2,420,582,000	$ 2,037,940,000	1,833,833,000
Employer contribution	310,378,000	10,431,000
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	55,281,000	$ 56,492,000	$ 59,991,000
Minimum pension liability	$ 36,000,000
Discount rate	2.50%	3.25%
Employer contribution	$ 6,293,000	$ 6,015,000

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss	$ 238,218	$ 126,618
Amortization of prior service (cost) credit	4,181	4,173	$ 4,172
Amortization of actuarial (loss) gain	(56,860)	(20,745)	$ (42,967)
Total recognized in other comprehensive income, pre-tax	185,539	110,046
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss	235,847	127,305
Amortization of prior service (cost) credit	(557)	(557)
Amortization of actuarial (loss) gain	(58,096)	(21,992)
Total recognized in other comprehensive income, pre-tax	177,194	104,756
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net loss	2,371	(687)
Amortization of prior service (cost) credit	4,738	4,730
Amortization of actuarial (loss) gain	1,236	1,247
Total recognized in other comprehensive income, pre-tax	$ 8,345	$ 5,290

Pension Plans and Other Postr_7

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Benefit Obligations (Detail)	Dec. 31, 2020	Dec. 31, 2019
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	2.50%	3.25%
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	2.50%	3.25%
Rate of increase in future compensation levels	3.37%	4.29%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	2.50%	3.25%

Pension Plans and Other Postr_8

Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Net Benefit Expense (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.25%	4.25%	3.50%
Long-term rate of return on plan assets	6.50%	6.50%	6.50%
Rate of increase in future compensation levels	4.29%	4.31%	4.33%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.25%	4.25%	3.50%

Pension Plans and Other Postr_9

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 2,418,702	$ 2,035,878
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	1,704,600	1,488,940
Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	430,348	314,701
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	283,754	232,237
Money-Market Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	65,263	38,461
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	48,322	33,870
Money-Market Investments [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	16,941	4,591
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	1,158,004	999,047
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	1,158,004	999,047
M&T Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	111,441	148,603
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	111,441	148,603
Domestic Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	308,220	219,663
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	308,220	219,663
International Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	13,648	10,476
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	13,648	10,476
Domestic Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	302,094	238,872
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	302,094	238,872
International Mutual Fund Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	422,601	381,433
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	422,601	381,433
Total Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	716,042	559,185
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	302,635	249,075
Total Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	413,407	310,110
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	172,762	112,783
Corporate Debt Securities [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	172,762	112,783
Government Agency [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	234,232	190,679
Government Agency [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	234,232	190,679
Non-U.S. Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	6,413	6,648
Non-U.S. Government [Member] | Significant Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	6,413	6,648
Domestic Mutual Fund Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	302,635	249,075
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	302,635	249,075
Other Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	479,393	439,185
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	195,639	206,948
Other Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	283,754	232,237
Other Diversified Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	83,507	86,980
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	83,507	86,980
Other Real Estate Partnerships [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	26,847	21,905
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	3,616	3,939
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	23,231	17,966
Other Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	97,124	87,966
Other Private Equity [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	97,124	87,966
Other Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	261,417	231,807
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	108,516	116,029
Other Hedge Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	152,901	115,778
Guaranteed Deposit Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	10,498	10,527
Guaranteed Deposit Fund [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan fair value of plan assets	$ 10,498	$ 10,527

Pension Plans and Other Post_10

Pension Plans and Other Postretirement Benefits - Fair Values of Company's Pension Plan Assets by Asset Category (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest and dividend receivable on plan assets	$ 2	$ 2
High-Yielding Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in mutual funds	22.00%	20.00%
Investment Grade Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Investment in mutual funds	78.00%	80.00%

Pension Plans and Other Post_11

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, 2020USD ($)
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	$ 2,035,878
Fair value of plan assets at end of year	2,418,702
Significant Unobservable Inputs (Level 3) [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	232,237
Fair value of plan assets at end of year	283,754
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	17,966
Purchase(Sales)	3,581
Total Realized/Unrealized Gains (Losses)	1,684
Fair value of plan assets at end of year	23,231
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	87,966
Purchase(Sales)	7,206
Total Realized/Unrealized Gains (Losses)	1,952
Fair value of plan assets at end of year	97,124
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	115,778
Purchase(Sales)	30,000
Total Realized/Unrealized Gains (Losses)	7,123
Fair value of plan assets at end of year	152,901
Guaranteed Deposit Fund [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	10,527
Fair value of plan assets at end of year	10,498
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	10,527
Total Realized/Unrealized Gains (Losses)	(29)
Fair value of plan assets at end of year	10,498
Other Securities [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Fair value of plan assets at beginning of year	439,185
Fair value of plan assets at end of year	479,393
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	232,237
Purchase(Sales)	40,787
Total Realized/Unrealized Gains (Losses)	10,730
Fair value of plan assets at end of year	$ 283,754

Pension Plans and Other Post_12

Pension Plans and Other Postretirement Benefits - Defined Benefit Plan Estimated Future Benefit Payments (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2021	$ 106,285
2022	109,880
2023	114,938
2024	119,402
2025	121,456
2026 through 2030	645,515
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
2021	3,238
2022	3,269
2023	3,131
2024	2,974
2025	2,789
2026 through 2030	$ 10,656

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Federal	$ 267,550	$ 359,668	$ 408,428
State and local	98,431	132,696	113,706
Total current	365,981	492,364	522,134
Deferred
Federal	(22,894)	40,769	(12,780)
State and local	(8,397)	16,779	28,637
Total deferred	(31,291)	57,548	15,857
Amortization of investments in qualified affordable housing projects	81,679	68,200	52,169
Income taxes	$ 416,369	$ 618,112	$ 590,160

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)State	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Income Tax Disclosure [Abstract]
Tax bad debt reserve	$ 137
Income taxes attributable to gains or losses on bank investment securities	$ 2	$ 5	$ (2)
Number of state and local jurisdictions where company files income tax returns | State	40

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income Taxes Expenses Benefit Reconciliation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income taxes at statutory federal income tax rate	$ 371,599	$ 534,925	$ 526,730
Increase (decrease) in taxes:
Tax-exempt income	(22,806)	(27,319)	(26,186)
State and local income taxes, net of federal income tax effect	71,127	118,085	112,451
Qualified affordable housing project federal tax credits, net	(14,826)	(15,324)	(12,240)
Other	11,275	7,745	(10,595)
Income taxes	$ 416,369	$ 618,112	$ 590,160

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Losses on loans and other assets	$ 471,767	$ 309,523	$ 322,818
Operating lease liabilities	121,216	128,178
Retirement benefits	26,185	55,048	30,057
Postretirement and other employee benefits	28,004	24,023	23,563
Incentive and other compensation plans	18,984	26,861	24,796
Stock-based compensation	29,507	27,912	26,759
Unrealized losses			52,580
Losses on cash flow hedges			1,861
Other	66,763	69,863	43,880
Gross deferred tax assets	762,426	641,408	526,314
Right of use assets and other leasing transactions	(285,311)	(326,626)	(186,787)
Unrealized gains	(50,785)	(13,322)
Capitalized servicing rights	(50,235)	(56,649)	(54,894)
Depreciation and amortization	(95,684)	(66,925)	(61,881)
Interest on loans	(8,113)	(23,552)	(18,920)
Gains on cash flow hedges	(97,004)	(36,845)
Other	(62,581)	(40,472)	(30,211)
Gross deferred tax liabilities	(649,713)	(564,391)	(352,693)
Net deferred tax asset	$ 112,713	$ 77,017	$ 173,621

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal, State and Local Tax [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 58,969	$ 56,274	$ 45,432
Increases as a result of tax positions taken during the period		6,996	13,426
Increases as a result of tax positions taken in prior years		3,265
Decreases as a result of settlements with taxing authorities			(664)
Decreases as a result of tax positions taken in prior years	(10,107)	(7,566)	(1,920)
Ending Balance	48,862	58,969	56,274
Accrued Interest [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	7,199	6,629	5,651
Increases as a result of tax positions taken in prior years	2,800	3,255	1,969
Decreases as a result of settlements with taxing authorities			(289)
Decreases as a result of tax positions taken in prior years	(2,384)	(2,685)	(702)
Ending Balance	7,615	7,199	6,629
Unrecognized Income Tax Benefits [Member]
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	66,168	62,903	51,083
Increases as a result of tax positions taken during the period		6,996	13,426
Increases as a result of tax positions taken in prior years	2,800	6,520	1,969
Decreases as a result of settlements with taxing authorities			(953)
Decreases as a result of tax positions taken in prior years	(12,491)	(10,251)	(2,622)
Ending Balance	56,477	$ 66,168	$ 62,903
Less: Federal, state and local income tax benefits	(11,174)
Net unrecognized tax benefits that, if recognized, would impact the effective income tax rate	$ 45,303

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Income available to common shareholders:
Net income	$ 1,353,152	$ 1,929,149	$ 1,918,080
Less: Preferred stock dividends	(68,228)	(69,441)	(72,521)
Net income available to common equity	1,284,924	1,859,708	1,845,559
Less: Income attributable to unvested stock-based compensation awards	(5,858)	(10,199)	(9,531)
Net income available to common shareholders	$ 1,279,066	$ 1,849,509	$ 1,836,028
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	129,404	135,169	144,740
Less: Unvested stock-based compensation awards	(766)	(741)	(748)
Weighted-average shares outstanding	128,638	134,428	143,992
Basic earnings per common share	$ 9.94	$ 13.76	$ 12.75

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income available to common equity	$ 1,284,924	$ 1,859,708	$ 1,845,559
Less: Income attributable to unvested stock-based compensation awards	(5,856)	(10,197)	(9,524)
Net income available to common shareholders	$ 1,279,068	$ 1,849,511	$ 1,836,035
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	129,404	135,169	144,740
Less: Unvested stock-based compensation awards	(766)	(741)	(748)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	66	34	159
Adjusted weighted-average shares outstanding	128,704	134,462	144,151
Diluted earnings per common share	$ 9.94	$ 13.75	$ 12.74

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	474,000	238,000	194,000

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (279,959)	$ (569,328)	$ (493,290)
Cumulative effect of change in accounting principle —equity securities			(22,795)
Unrealized holding losses, net, before tax	141,081	247,411	(121,589)
Foreign currency translation adjustment, before tax	2,724	1,381	(2,817)
Unrealized losses on cash flow hedges, before tax	505,042	160,373	(4,965)
Current year benefit plans gains, before tax	(238,218)	(126,618)	19,871
Total other comprehensive income (loss) before reclassifications, before tax	410,629	282,547	(109,500)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax	3,606	3,394	4,252
Gains (Loss) realized in net income	(2)	3	(18)
Accretion of net gain (losses) on terminated cash flow hedges, before tax	(125)	(136)	(111)
Net yield adjustment from cash flow hedges currently in effect, before tax	(271,971)	(13,011)	13,339
Amortization of prior service credit, before tax	(4,181)	(4,173)	(4,172)
Amortization of actuarial losses, before tax	56,860	20,745	42,967
Total other comprehensive income (loss), before tax	194,816	289,369	(53,243)
Ending balance, before tax	(85,143)	(279,959)	(569,328)
Beginning balance, tax	73,279	149,247	129,476
Cumulative effect of change in accounting principle —equity securities			5,942
Unrealized holding gains (losses), net, tax	(36,498)	(65,009)	31,946
Foreign currency translation adjustment, tax	(440)	(290)	592
Unrealized losses on cash flow hedges, tax	(130,432)	(42,163)	1,306
Current year benefit plans gains, tax	60,208	33,287	(5,224)
Total other comprehensive income (loss), tax	(107,162)	(74,175)	28,620
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, tax	(966)	(892)	(1,118)
Gains realized in net income, tax	1	(1)	4
Accretion of net gain on terminated cash flow hedges, tax	34	36	29
Net yield adjustment from cash flow hedges currently in effect, tax	70,239	3,421	(3,507)
Amortization of prior service credit, tax	1,057	1,097	1,097
Amortization of actuarial losses, tax	(14,371)	(5,454)	(11,296)
Total other comprehensive income (loss), tax	(51,168)	(75,968)	13,829
Ending balance, tax	22,111	73,279	149,247
Beginning balance, net of tax	(206,680)	(420,081)	(363,814)
Cumulative effect of change in accounting principle — equity securities			(16,853)
Unrealized holding gains (losses), net of tax	104,583	182,402	(89,643)
Foreign currency translation adjustments	2,284	1,091	(2,225)
Unrealized losses on cash flow hedges, net of tax	374,610	118,210	(3,659)
Current year benefit plans gains, net of tax	(178,010)	(93,331)	14,647
Total other comprehensive income (loss) before reclassifications, net of tax	303,467	208,372	(80,880)
Amortization of unrealized holding losses on held-to-maturity ('HTM') securities, net of tax	2,640	2,502	3,134
Gains realized in net income, net of tax	(1)	2	(14)
Accretion of net gain on terminated cash flow hedges, net of tax	(91)	(100)	(82)
Net yield adjustment from cash flow hedges currently in effect, net of tax	(201,732)	(9,590)	9,832
Amortization of prior service credit, net of tax	(3,124)	(3,076)	(3,075)
Amortization of actuarial losses, net of tax	42,489	15,291	31,671
Total other comprehensive income (loss)	143,648	213,401	(39,414)
Ending balance, net of tax	(63,032)	(206,680)	(420,081)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	50,701	(200,107)
Unrealized holding losses, net, before tax	141,081	247,411
Total other comprehensive income (loss) before reclassifications, before tax	141,081	247,411
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax	3,606	3,394
Gains (Loss) realized in net income	(2)	3
Total other comprehensive income (loss), before tax	144,685	250,808
Ending balance, before tax	195,386	50,701	(200,107)
Cumulative effect of change in accounting principle — equity securities			(16,853)
Total other comprehensive income (loss)	107,222	184,906	(86,523)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(464,548)	(354,502)	(413,168)
Current year benefit plans gains, before tax	(238,218)	(126,618)	19,871
Total other comprehensive income (loss) before reclassifications, before tax	(238,218)	(126,618)	19,871
Amortization of prior service credit, before tax	(4,181)	(4,173)	(4,172)
Amortization of actuarial losses, before tax	56,860	20,745	42,967
Total other comprehensive income (loss), before tax	(185,539)	(110,046)	58,666
Ending balance, before tax	(650,087)	(464,548)	(354,502)
Total other comprehensive income (loss)	(138,645)	(81,116)	43,243
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	133,888	(14,719)	(20,165)
Foreign currency translation adjustment, before tax	2,724	1,381	(2,817)
Unrealized losses on cash flow hedges, before tax	505,042	160,373	(4,965)
Total other comprehensive income (loss) before reclassifications, before tax	507,766	161,754	(7,782)
Accretion of net gain (losses) on terminated cash flow hedges, before tax	(125)	(136)	(111)
Net yield adjustment from cash flow hedges currently in effect, before tax	(271,971)	(13,011)	13,339
Total other comprehensive income (loss), before tax	235,670	148,607	5,446
Ending balance, before tax	$ 369,558	133,888	(14,719)
Accumulated Net Unrealized Investment Gain Loss All Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax		$ (200,107)	(59,957)
Cumulative effect of change in accounting principle —equity securities			(22,795)
Unrealized holding 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 (Loss) realized in net income			(18)
Total other comprehensive income (loss), before tax			(117,355)
Ending balance, before tax			$ (200,107)

Comprehensive Income - Accumula

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 15,716,649	$ 15,460,191	$ 16,250,819
Cumulative effect of change in accounting principle — equity securities			(16,853)
Net gain (loss) during period	143,648	213,401	(39,414)
Ending balance	16,187,283	15,716,649	15,460,191
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	37,380	(147,526)	(44,150)
Cumulative effect of change in accounting principle — equity securities			(16,853)
Net gain (loss) during period	107,222	184,906	(86,523)
Ending balance	144,602	37,380	(147,526)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(342,419)	(261,303)	(304,546)
Net gain (loss) during period	(138,645)	(81,116)	43,243
Ending balance	(481,064)	(342,419)	(261,303)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	98,359	(11,252)	(15,118)
Net gain (loss) during period	175,071	109,611	3,866
Ending balance	273,430	98,359	(11,252)
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(206,680)	(420,081)	(363,814)
Cumulative effect of change in accounting principle — equity securities			(16,853)
Net gain (loss) during period	143,648	213,401	(39,414)
Ending balance	$ (63,032)	$ (206,680)	$ (420,081)

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Other income:
Credit-related fee income	$ 70,387	$ 86,792	$ 82,614
Other expense:
Professional services	240,047	330,900	312,998
Amortization of capitalized mortgage servicing rights	$ 84,821	$ 71,888	49,619
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, 2020	Dec. 31, 2019	Dec. 31, 2017
International Activities [Line Items]
Revenues from international trust-related services	$ 36,000	$ 32,000	$ 29,000
Loans to foreign borrowers	96,799,480	89,871,798
Deposits at foreign office	652,104	1,684,044
Cayman Islands [Member]
International Activities [Line Items]
Deposits at foreign office	652,000	1,680,000
Canada [Member]
International Activities [Line Items]
Deposits at foreign office	32,000	23,000
Geographic Distribution, Foreign [Member]
International Activities [Line Items]
Loans to foreign borrowers	$ 170,000	$ 186,000
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, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 51,050,000,000	$ 57,550,000,000
Net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans	64,000,000	18,000,000
Unrealized gain recognized in other comprehensive income related to cash flow hedges	373,000,000
Aggregate fair value of derivative financial instruments in a liability position	114,000,000	51,000,000
Aggregate fair value of derivative financial instruments in asset position	3,000,000	6,000,000
Collateral relating to net asset positions	3,000,000	5,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	103,000,000	50,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	135,000,000	84,000,000
Interest Income [Member]
Derivative [Line Items]
Cash flow hedges drerivative instruments income	272,000,000	13,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	312,000,000	(2,000,000)	$ (25,000,000)
Notional amounts of derivative contracts entered into for trading account purposes	51,050,000,000
Interest Rate Swap Agreements [Member] | Maturity Period 2021 [Member]
Derivative [Line Items]
Unrealized gain recognized in other comprehensive income related to cash flow hedges	156,000,000
Interest Rate Swap Agreements [Member] | Maturity Period 2022 [Member]
Derivative [Line Items]
Unrealized gain recognized in other comprehensive income related to cash flow hedges	170,000,000
Interest Rate Swap Agreements [Member] | Maturity Period 2023 [Member]
Derivative [Line Items]
Unrealized gain recognized in other comprehensive income related to cash flow hedges	47,000,000
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	37,800,000,000	48,600,000,000
Foreign Currency and Other Option and Futures Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 776,000,000	$ 1,200,000,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount	$ 51,050,000,000	$ 57,550,000,000
Average Maturity (in years)	1 year	1 year 6 months
Estimated Fair Value Gain (Loss)	$ 1,076,000	$ (1,762,000)
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 49,400,000,000	$ 53,750,000,000
Average Maturity (in years)	10 months 24 days	1 year 4 months 24 days
Weighted-Average Rate, Fixed	2.22%	2.44%
Weighted-Average Rate, Variable	0.15%	1.73%
Estimated Fair Value Gain (Loss)	$ 425,000	$ (1,195,000)
Fixed Rate Long-Term Borrowings [Member] | Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 1,650,000,000	$ 3,800,000,000
Average Maturity (in years)	3 years 3 months 18 days	2 years 2 months 12 days
Weighted-Average Rate, Fixed	2.86%	2.51%
Weighted-Average Rate, Variable	0.79%	2.27%
Estimated Fair Value Gain (Loss)	$ 651,000	$ (567,000)

Derivative Financial Instrume_5

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount	$ 51,050,000,000	$ 57,550,000,000
Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	40,400,000,000
Fair Value Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value losses on hedging instruments	101,500,000	45,100,000
Cash Flow Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value losses on hedging instruments	372,200,000	$ 140,700,000
Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	$ 32,100,000,000

Derivative Financial Instrume_6

Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Outstanding Maturity (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Total	$ 51,050,000,000	$ 57,550,000,000
Interest Rate Swap Agreements [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
2021	27,700,000,000
2022	16,500,000,000
2023	6,350,000,000
2027	500,000,000
Total	$ 51,050,000,000

Derivative Financial Instrume_7

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 1,067,985	$ 427,267
Liability Derivatives, Fair Value	140,485	87,091
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,064,529	425,840
Liability Derivatives, Fair Value	131,135	84,676
Fair Value Hedges [Member] | Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	3,456	1,427
Liability Derivatives, Fair Value	9,350	2,415
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	1,968	232
Liability Derivatives, Fair Value	892	1,994
Commitments to Sell Real Estate Loans [Member] | Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	2,409	3,074
Liability Derivatives, Fair Value	13,868	3,548
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	1,488	1,195
Liability Derivatives, Fair Value	8,458	421
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	43,599	11,965
Liability Derivatives, Fair Value	365	1,225
Interest Rate Contracts [Member] | Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,008,913	398,295
Liability Derivatives, Fair Value	105,768	68,103
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	9,608	12,506
Liability Derivatives, Fair Value	$ 11,134	$ 11,800

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, 2020	Dec. 31, 2019
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ (5.6)	$ (43.3)
Reduction in estimated fair value of interest rate contracts in liability position	$ (806.5)	$ (281.3)

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 13,707	$ 33,212	$ 13,922
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	57,611	95,006	(10,006)
Derivatives in fair value hedging relationships, Hedged item	(57,686)	(94,742)	10,969
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	6,344	24,701	4,506
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 7,363	$ 8,511	$ 9,416

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 1,750,048	$ 3,840,775
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 101,326		$ 43,640

Variable Interest Entities an_2

Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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	142,601,105,000	119,872,757,000
Investment in partnership carrying amount	861,000,000	748,000,000
Unfunded commitments includes carrrying amount of its investments	406,000,000	414,000,000
Maximum exposure to loss of investments in real estate partnerships	1,200,000
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested	$ 2,300,000,000	$ 1,500,000,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 4,822,606	$ 6,318,776
U.S. Treasury and Federal Agencies [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	9,338	9,767
Obligations of States and Political Subdivisions [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities		775
Government Issued or Guaranteed [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	4,683,438	6,180,940
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	129,814	127,278
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	1,068,581	470,129
Investment securities	4,822,606	6,318,776
Equity securities	92,985	140,041
Real estate loans held for sale	1,054,676	442,079
Other assets	49,464	16,466
Total assets	7,088,312	7,387,491
Trading account liabilities	116,902	79,903
Other liabilities	23,583	7,188
Total liabilities	140,485	87,091
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	50,060	49,040
Equity securities	63,129	100,637
Total assets	113,189	149,677
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	1,018,521	421,089
Investment securities	4,822,590	6,318,760
Equity securities	29,856	39,404
Real estate loans held for sale	1,054,676	442,079
Other assets	5,865	4,501
Total assets	6,931,508	7,225,833
Trading account liabilities	116,902	79,903
Other liabilities	23,218	5,963
Total liabilities	140,120	85,866
Fair Value Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	16
Other assets	43,599	11,965
Total assets	43,615	11,981
Other liabilities	365	1,225
Total liabilities	365	1,225
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	9,338	9,767
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	9,338	9,767
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		775
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		775
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	4,683,438	6,180,940
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	4,683,438	6,180,940
Fair Value Measurements, Recurring [Member] | Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	16
Fair Value Measurements, Recurring [Member] | Privately Issued Mortgage-Backed Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	16	16
Fair Value Measurements, Recurring [Member] | Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	129,814	127,278
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	$ 129,814	$ 127,278

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 16	$ 22	$ 28
Total gains realized/unrealized:
Settlements		(6)	(6)
Ending Balance	16	16	22
Other Assets and Other Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	10,740	7,712	8,303
Total gains realized/unrealized:
Included in earnings	194,469	129,398	58,740
Transfers out of Level 3	(161,975)	(126,370)	(59,331)
Ending Balance	43,234	10,740	7,712
Changes in unrealized gains included in earnings related to assets still held at end of period	$ 42,597	$ 11,146	$ 7,386

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input [Extensible List]	us-gaap:MeasurementInputComparabilityAdjustmentMember
Residential Mortgage Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Capitalized servicing rights	$ 231,204	$ 244,411	$ 120,509	$ 114,978
Capitalized servicing rights, valuation allowance	$ (30,000)	(7,000)
Weighted-average prepayment speeds	14.50%
Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations	15.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations	90.00%
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	$ 222,000	110,000	83,000
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Capitalized servicing rights	159,000	188,000
Capitalized servicing rights, valuation allowance	30,000	7,000
Changes in fair value recognized for impairment of capitalized servicing rights	$ 23,000	$ 7,000
Weighted-average prepayment speeds	16.01%	18.50%
Discounted rate represented weighted-average option-adjusted basis spread point percentage	900.00%	900.00%
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	$ 652,000	$ 305,000	268,000
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	22,000	21,000
Fair Value, Measurements, Nonrecurring [Member] | Significant Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	339,000	115,000	120,000
Fair Value, Measurements, Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loans measured at fair value on nonrecurring basis	$ 313,000	$ 190,000	$ 148,000

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, 2020	Dec. 31, 2019
Privately Issued Mortgage-Backed Securities [Member] | Two Independent Pricing Quotes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements for certain Level 3 Assets and Liabilities	$ 16	$ 16
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	$ 43,234	$ 10,740
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	98.00%	99.00%
Other Assets and Other Liabilities [Member] | Discounted Cash Flows [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	16.00%	13.00%

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financial assets:
Interest-bearing deposits at banks	$ 23,663,810	$ 7,190,154
Federal funds sold		3,500
Investment securities	7,045,697	9,497,251
Loans and leases:
Loans and leases	98,875,788	91,188,525
Allowance for credit losses	(1,736,387)	(1,051,071)	$ (1,019,444)	$ (1,017,198)
Loans and leases, net	96,799,480	89,871,798
Financial liabilities:
Noninterest-bearing deposits	(47,572,884)	(32,396,407)
Savings and interest-checking deposits	(67,680,840)	(54,932,162)
Time deposits	(3,899,910)	(5,757,456)
Deposits at Cayman Islands office	(652,104)	(1,684,044)
Long-term borrowings	(4,382,193)	(6,986,186)
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,552,743	1,432,805
Interest-bearing deposits at banks	23,663,810	7,190,154
Federal funds sold		3,500
Trading account assets	1,068,581	470,129
Investment securities	7,045,697	9,497,251
Loans and leases:
Consumer loans	16,570,421	15,386,693
Allowance for credit losses	(1,736,387)	(1,051,071)
Loans and leases, net	96,799,480	89,871,798
Accrued interest receivable	419,936	333,142
Financial liabilities:
Noninterest-bearing deposits	(47,572,884)	(32,396,407)
Savings and interest-checking deposits	(67,680,840)	(54,932,162)
Time deposits	(3,899,910)	(5,757,456)
Deposits at Cayman Islands office	(652,104)	(1,684,044)
Short-term borrowings	(59,482)	(62,363)
Long-term borrowings	(4,382,193)	(6,986,186)
Accrued interest payable	(59,916)	(105,374)
Trading account liabilities	(116,902)	(79,903)
Other financial instruments:
Commitments to originate real estate loans for sale	43,234	10,740
Commitments to sell real estate loans	(18,429)	300
Other credit-related commitments	(133,354)	(136,470)
Interest rate swap agreements used for interest rate risk management	1,076	(1,762)
Estimate Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,552,743	1,432,805
Interest-bearing deposits at banks	23,663,810	7,190,154
Federal funds sold		3,500
Trading account assets	1,068,581	470,129
Investment securities	7,138,989	9,539,540
Loans and leases:
Consumer loans	16,554,050	15,413,262
Loans and leases, net	97,680,470	90,668,624
Accrued interest receivable	419,936	333,142
Financial liabilities:
Noninterest-bearing deposits	(47,572,884)	(32,396,407)
Savings and interest-checking deposits	(67,680,840)	(54,932,162)
Time deposits	(3,919,367)	(5,829,347)
Deposits at Cayman Islands office	(652,104)	(1,684,044)
Short-term borrowings	(59,482)	(62,363)
Long-term borrowings	(4,490,433)	(7,063,165)
Accrued interest payable	(59,916)	(105,374)
Trading account liabilities	(116,902)	(79,903)
Other financial instruments:
Commitments to originate real estate loans for sale	43,234	10,740
Commitments to sell real estate loans	(18,429)	300
Other credit-related commitments	(133,354)	(136,470)
Interest rate swap agreements used for interest rate risk management	1,076	(1,762)
Estimate Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,497,457	1,394,984
Trading account assets	50,060	49,040
Investment securities	63,129	100,637
Estimate Fair Value [Member] | Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	55,286	37,821
Interest-bearing deposits at banks	23,663,810	7,190,154
Federal funds sold		3,500
Trading account assets	1,018,521	421,089
Investment securities	7,005,571	9,351,793
Loans and leases:
Loans and leases, net	4,413,566	4,019,186
Accrued interest receivable	419,936	333,142
Financial liabilities:
Noninterest-bearing deposits	(47,572,884)	(32,396,407)
Savings and interest-checking deposits	(67,680,840)	(54,932,162)
Time deposits	(3,919,367)	(5,829,347)
Deposits at Cayman Islands office	(652,104)	(1,684,044)
Short-term borrowings	(59,482)	(62,363)
Long-term borrowings	(4,490,433)	(7,063,165)
Accrued interest payable	(59,916)	(105,374)
Trading account liabilities	(116,902)	(79,903)
Other financial instruments:
Commitments to sell real estate loans	(18,429)	300
Interest rate swap agreements used for interest rate risk management	1,076	(1,762)
Estimate Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	70,289	87,110
Loans and leases:
Consumer loans	16,554,050	15,413,262
Loans and leases, net	93,266,904	86,649,438
Other financial instruments:
Commitments to originate real estate loans for sale	43,234	10,740
Other credit-related commitments	(133,354)	(136,470)
Commercial Loans and Leases [Member] | Carrying Amount [Member]
Loans and leases:
Loans and leases	27,574,564	23,838,168
Commercial Loans and Leases [Member] | Estimate Fair Value [Member]
Loans and leases:
Loans and leases	27,220,699	23,510,908
Commercial Loans and Leases [Member] | Estimate Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Loans and leases	27,220,699	23,510,908
Commercial [Member] | Carrying Amount [Member]
Loans and leases:
Loans and leases	37,637,889	35,541,914
Commercial [Member] | Estimate Fair Value [Member]
Loans and leases:
Loans and leases	36,816,580	35,517,180
Commercial [Member] | Estimate Fair Value [Member] | Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Loans and leases	277,911	28,338
Commercial [Member] | Estimate Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Loans and leases	36,538,669	35,488,842
Residential Real Estate Loans | Carrying Amount [Member]
Loans and leases:
Loans and leases	16,752,993	16,156,094
Residential Real Estate Loans | Estimate Fair Value [Member]
Loans and leases:
Loans and leases	17,089,141	16,227,274
Residential Real Estate Loans | Estimate Fair Value [Member] | Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Loans and leases	4,135,655	3,990,848
Residential Real Estate Loans | Estimate Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Loans and leases	$ 12,953,486	$ 12,236,426

Commitments and Contingencies -

Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commitments to extend credit
Home equity lines of credit	$ 5,563,854	$ 5,442,160
Commercial real estate loans to be sold	363,735	164,076
Other commercial real estate	7,237,367	9,029,608
Residential real estate loans to be sold	1,026,118	423,056
Other residential real estate	665,259	448,375
Commercial and other	19,427,886	16,170,731
Standby letters of credit	2,241,417	2,441,432
Commercial letters of credit	27,332	41,059
Financial guarantees and indemnification contracts	4,220,531	4,108,572
Commitments to sell real estate loans	$ 2,108,823	$ 906,037

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers	$ 10,400,000,000	$ 9,100,000,000
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program	4,000,000,000	$ 3,900,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	0
Maximum [Member]
Loss Contingencies [Line Items]
Range of reasonably possible losses	$ 25,000,000

Segment Information - Informati

Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 3,866,317	$ 4,130,264	$ 4,072,302
Noninterest income	2,088,444	2,061,679	1,856,000
Total income	5,954,761	6,191,943	5,928,302
Provision for credit losses	800,000	176,000	132,000
Amortization of core deposit and other intangible assets	14,869	19,490	24,522
Depreciation and other amortization	305,419	281,825	154,483
Other noninterest expense	3,064,952	3,167,367	3,109,057
Income before taxes	1,769,521	2,547,261	2,508,240
Income tax expense (benefit)	416,369	618,112	590,160
Net income	1,353,152	1,929,149	1,918,080
Average total assets	135,480,000	119,584,000	116,959,000
Capital expenditures	172,000	178,000	98,000
All Other [Member]
Segment Reporting Information [Line Items]
Net interest income	121,808	537,940	557,542
Noninterest income	725,472	695,443	651,439
Total income	847,280	1,233,383	1,208,981
Provision for credit losses	482,202	6,257	(8,128)
Amortization of core deposit and other intangible assets	13,809	18,430	23,462
Depreciation and other amortization	116,979	108,604	68,004
Other noninterest expense	959,258	1,117,668	1,125,428
Income before taxes	(724,968)	(17,576)	215
Income tax expense (benefit)	(202,396)	(28,625)	(54,766)
Net income	(522,572)	11,049	54,981
Average total assets	22,996,000	14,953,000	13,877,000
Capital expenditures	138,000	98,000	65,000
Business Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	462,614	451,307	434,579
Noninterest income	103,837	113,855	111,600
Total income	566,451	565,162	546,179
Provision for credit losses	25,928	16,501	10,916
Depreciation and other amortization	1,482	2,066	382
Other noninterest expense	322,868	317,482	305,340
Income before taxes	216,173	229,113	229,541
Income tax expense (benefit)	56,953	60,617	61,279
Net income	159,220	168,496	168,262
Average total assets	8,152,000	5,793,000	5,631,000
Capital expenditures		1,000
Commercial Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	864,149	828,888	821,812
Noninterest income	276,791	289,558	288,908
Total income	1,140,940	1,118,446	1,110,720
Provision for credit losses	73,099	25,580	8,976
Depreciation and other amortization	2,421	2,353	496
Other noninterest expense	375,769	382,214	364,102
Income before taxes	689,651	708,299	737,146
Income tax expense (benefit)	181,179	187,835	198,229
Net income	508,472	520,464	538,917
Average total assets	30,338,000	28,142,000	26,626,000
Capital expenditures		2,000
Commercial Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	673,894	692,526	665,220
Noninterest income	208,367	214,970	183,955
Total income	882,261	907,496	849,175
Provision for credit losses	107,210	1,537	3,159
Amortization of core deposit and other intangible assets	1,060	1,060	1,060
Depreciation and other amortization	28,187	26,963	25,852
Other noninterest expense	256,428	239,333	217,387
Income before taxes	489,376	638,603	601,717
Income tax expense (benefit)	107,548	152,977	148,807
Net income	381,828	485,626	452,910
Average total assets	25,792,000	23,921,000	22,885,000
Discretionary Portfolio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	486,831	209,807	228,051
Noninterest income	(1,735)	26,919	(9,690)
Total income	485,096	236,726	218,361
Provision for credit losses	1,508	3,608	6,683
Depreciation and other amortization	285	279	187
Other noninterest expense	54,339	52,885	65,393
Income before taxes	428,964	179,954	146,098
Income tax expense (benefit)	101,673	36,342	29,872
Net income	327,291	143,612	116,226
Average total assets	27,726,000	29,081,000	32,123,000
Capital expenditures			1,000
Residential Mortgage Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	52,712	20,008	13,933
Noninterest income	515,549	393,372	305,560
Total income	568,261	413,380	319,493
Provision for credit losses	1,785	382	(2,178)
Depreciation and other amortization	60,129	48,248	24,288
Other noninterest expense	332,028	273,067	241,624
Income before taxes	174,319	91,683	55,759
Income tax expense (benefit)	40,667	19,355	10,272
Net income	133,652	72,328	45,487
Average total assets	4,038,000	2,611,000	2,161,000
Capital expenditures		1,000	1,000
Retail Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income	1,204,309	1,389,788	1,351,165
Noninterest income	260,163	327,562	324,228
Total income	1,464,472	1,717,350	1,675,393
Provision for credit losses	108,268	122,135	112,572
Depreciation and other amortization	95,936	93,312	35,274
Other noninterest expense	764,262	784,718	789,783
Income before taxes	496,006	717,185	737,764
Income tax expense (benefit)	130,745	189,611	196,467
Net income	365,261	527,574	541,297
Average total assets	16,438,000	15,083,000	13,656,000
Capital expenditures	$ 34,000	$ 76,000	$ 31,000

Segment Information - Informa_2

Segment Information - Information about Company's Segments (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting [Abstract]
Taxable-equivalent adjustment	$ 17,288,000	$ 22,863,000	$ 21,897,000

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 5,954,761	$ 6,191,943	$ 5,928,302
Income taxes	416,369	618,112	590,160
Net income	1,353,152	1,929,149	1,918,080
Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Revenues	(47,604)	(48,559)	(41,285)
Expenses	(14,038)	(18,218)	(24,660)
Income taxes	(8,824)	(7,976)	(4,371)
Net income	$ (24,742)	$ (22,365)	$ (12,254)

Segment Information - Additiona

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Percent of maximum revenue from single customer on total revenues	10.00%

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Regulatory Capital Requirements [Abstract]
Funds available for payment of dividends to M&T from banking subsidiaries	$ 1,300
Required subsidiary noninterest-earning reserves against certain deposit liabilities			$ 666
Capital conservation buffer		2.50%

Regulatory Matters - Summary of

Regulatory Matters - Summary of Required Minimum and Well Capitalized Capital Ratios (Detail)	Dec. 31, 2020
Regulatory Capital Requirements [Abstract]
Common equity Tier 1 ("CET1") to risk-weighted assets, Minimum	4.50%
Tier 1 capital to risk-weighted assets, Minimum	0.060
Total capital to risk-weighted assets, Minimum	0.080
Leverage — Tier 1 capital to average total assets, as defined	0.040
Common equity Tier 1 ("CET1") to risk-weighted assets, Well Capitalized	6.50%
Tier 1 capital to risk-weighted assets, Well capitalized	0.080
Total capital to risk-weighted assets, Well capitalized	0.100
Leverage — Tier 1 capital to average total assets, as defined	0.050

Regulatory Matters - Capital Ra

Regulatory Matters - Capital Ratios and Amounts of Company and its Banking Subsidiaries (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Ratio	4.50%
Ratio	0.060
Ratio	0.080
M&T Bank Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 10,623,368	$ 10,053,887
Ratio	10.00%	9.73%
Amount	$ 11,873,317	$ 11,303,836
Ratio	0.1117	0.1094
Amount	$ 14,207,937	$ 13,480,612
Ratio	0.1337	0.1305
Amount	$ 11,873,317	$ 11,303,836
Ratio	0.0848	0.0959
M&T Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 11,550,462	$ 10,649,953
Ratio	10.90%	10.34%
Amount	$ 11,550,462	$ 10,649,953
Ratio	0.1090	0.1034
Amount	$ 13,373,416	$ 12,342,834
Ratio	0.1262	0.1199
Amount	$ 11,550,462	$ 10,649,953
Ratio	0.0827	0.0908
Wilmington Trust, N.A. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Amount	$ 630,574	$ 606,538
Ratio	46.57%	56.35%
Amount	$ 630,574	$ 606,538
Ratio	0.4657	0.5635
Amount	$ 632,506	$ 608,130
Ratio	0.4672	0.5650
Amount	$ 630,574	$ 606,538
Ratio	0.1073	0.1312

Relationship with Bayview Len_2

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 4,382,193,000	$ 6,986,186,000
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	53,000,000	37,000,000	$ 24,000,000
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	1,900,000,000	2,200,000,000
Revenue from contract with customer	10,000,000	12,000,000	14,000,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	68,100,000,000	62,800,000,000
Revenues from sub-servicing	129,000,000	125,000,000	$ 114,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	77,000,000	$ 93,000,000
Secured loan facilities carrying amount				$ 100,000,000
Outstanding balance of secured debt				$ 60,000,000
Bayview Financial [Member] | FHA Guaranteed Mortgage Loans [Member]
Schedule of Equity Method Investments [Line Items]
FHA gauranteed mortgage loan	965,000,000
FHA gauranteed purchase amount of deliquent loan	1,000,000,000
Bayview Financial [Member] | Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	1,200,000,000
Bayview Financial [Member] | Syndicated Loan Facility [Member] | M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 210,000,000

Parent Company Financial Stat_3

Parent Company Financial Statements - Condensed Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments in consolidated subsidiaries
Total assets	$ 142,601,105	$ 119,872,757
Liabilities
Long-term borrowings	4,382,193	6,986,186
Total liabilities	126,413,822	104,156,108
Shareholders’ equity	16,187,283	15,716,649	$ 15,460,191	$ 16,250,819
Total liabilities and shareholders’ equity	142,601,105	119,872,757
Parent Company [Member]
Assets
Cash in subsidiary bank	100,593	83,531
Due from consolidated bank subsidiaries
Money-market savings	699,476	876,819
Current income tax receivable		1,261
Total due from consolidated bank subsidiaries	699,476	878,080
Investments in consolidated subsidiaries
Banks	16,554,287	15,732,008
Other	125,988	301,765
Investments in trust preferred entities (note 19)	22,846	23,022
Other assets	92,170	67,732
Total assets	17,595,360	17,086,138
Liabilities
Accrued expenses and other liabilities	96,664	74,235
Long-term borrowings	1,311,413	1,295,254
Total liabilities	1,408,077	1,369,489
Shareholders’ equity	16,187,283	15,716,649
Total liabilities and shareholders’ equity	$ 17,595,360	$ 17,086,138

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, 2020	Dec. 31, 2019	Dec. 31, 2018
Expense
Interest on long-term borrowings	$ 109,332	$ 239,242	$ 248,556
Other expense	3,385,240	3,468,682	3,288,062
Income tax credits	(416,369)	(618,112)	(590,160)
Equity in undistributed income of subsidiaries
Net income	$ 1,353,152	$ 1,929,149	$ 1,918,080
Net income per common share
Basic	$ 9.94	$ 13.76	$ 12.75
Diluted	$ 9.94	$ 13.75	$ 12.74
Parent Company [Member]
Income
Dividends from consolidated subsidiaries	$ 708,500	$ 2,025,000	$ 1,250,000
Income from Bayview Lending Group LLC	52,940	36,740	23,500
Other income	5,110	7,216	2,417
Total income	766,550	2,068,956	1,275,917
Expense
Interest on long-term borrowings	31,924	51,938	36,354
Other expense	33,704	25,236	23,894
Total expense	65,628	77,174	60,248
Income before income taxes and equity in undistributed income of subsidiaries	700,922	1,991,782	1,215,669
Income tax credits	1,984	8,313	8,446
Income before equity in undistributed income of subsidiaries	702,906	2,000,095	1,224,115
Equity in undistributed income of subsidiaries
Net income of subsidiaries	1,358,746	1,954,054	1,943,965
Less: dividends received	(708,500)	(2,025,000)	(1,250,000)
Equity in undistributed income of subsidiaries	650,246	(70,946)	693,965
Net income	$ 1,353,152	$ 1,929,149	$ 1,918,080
Net income per common share
Basic	$ 9.94	$ 13.76	$ 12.75
Diluted	$ 9.94	$ 13.75	$ 12.74

Parent Company Financial Stat_5

Parent Company Financial Statements - Condensed Statement of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income	$ 1,353,152	$ 1,929,149	$ 1,918,080
Adjustments to reconcile net income to net cash provided by operating activities
Provision for deferred income taxes	(31,291)	57,548	15,857
Net cash provided by operating activities	789,187	2,357,555	2,089,852
Cash flows from investing activities
Other, net	67,411	(195,921)	47,904
Cash flows from financing activities
Purchases of treasury stock	(373,750)	(1,349,785)	(2,194,396)
Dividends paid — common	(568,112)	(552,138)	(510,382)
Dividends paid — preferred	(68,256)	(67,454)	(72,521)
Proceeds from long-term borrowings			1,773,189
Redemption of Series A and Series C preferred stock		(381,500)
Other, net	(11,413)	(25,393)	17,167
Supplemental disclosure of cash flow information
Interest received during the year	4,135,990	4,892,301	4,568,991
Income taxes received during the year	275,558	320,513	375,116
Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock		396,000
Parent Company [Member]
Cash flows from operating activities
Net income	1,353,152	1,929,149	1,918,080
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed income of subsidiaries	(650,246)	70,946	(693,965)
Provision for deferred income taxes	1,079	5,263	4,949
Net change in accrued income and expense	(24,206)	(34,525)	(8,242)
Net cash provided by operating activities	679,779	1,970,833	1,220,822
Cash flows from investing activities
Proceeds from sales or maturities of investment securities		100
Other, net	176,050	51,235	29,933
Net cash provided by investing activities	176,050	51,335	29,933
Cash flows from financing activities
Purchases of treasury stock	(373,750)	(1,349,785)	(2,194,396)
Dividends paid — common	(568,112)	(552,138)	(510,382)
Dividends paid — preferred	(68,256)	(67,454)	(72,521)
Proceeds from long-term borrowings			748,595
Redemption of Series A and Series C preferred stock		(381,500)
Other, net	(5,992)	(4,431)	45,913
Net cash used by financing activities	(1,016,110)	(1,959,308)	(1,982,791)
Net increase (decrease) in cash and cash equivalents	(160,281)	62,860	(732,036)
Cash and cash equivalents at beginning of year	960,350	897,490	1,629,526
Cash and cash equivalents at end of year	800,069	960,350	897,490
Supplemental disclosure of cash flow information
Interest received during the year	1,493	1,752	2,219
Interest paid during the year	30,913	49,451	17,482
Income taxes received during the year	$ 11,528	6,251	$ 6,362
Parent Company [Member] | Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock		$ 396,000

Recent Accounting Developments

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses	$ 1,736,387		$ 1,051,071	$ 1,019,444	$ 1,017,198
Cumulative effect adjustment to retained earnings	$ 13,444,428		$ 12,820,916
ASU 2016-13 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses		$ 132,000
ASU 2016-13 [Member] | Cumulative Effect Period of Adoption Adjustment [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect adjustment to retained earnings		$ 132,000

Subsequent event - Additional I

Subsequent event - Additional Information (Details) - Subsequent Event [Member] - People’s United [Member] - USD ($)	Feb. 22, 2021	Jan. 21, 2021
Subsequent Event [Line Items]
Date of acquisition	Feb. 22, 2021
Business combination, market value	$ 7,600
Common stock, price per share	$ 0.118
Assets		$ 63,000
Loans		44,000
Deposits		$ 52,000