M&T Bank (MTB) 10-Q 4 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	MTB
Entity Registrant Name	M&T BANK CORPORATION
Entity Central Index Key	0000036270
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		128,292,616
Entity File Number	1-9861
Entity Tax Identification Number	16-0968385
Entity Incorporation, State or Country Code	NY
Title of 12(b) Security	Common Stock, $.50 par value
Security Exchange Name	NYSE
Entity Address, Address Line One	One M & T Plaza
Entity Address, Postal Zip Code	14203
Entity Address, City or Town	Buffalo
Entity Address, State or Province	NY
City Area Code	716
Local Phone Number	635-4000
Document Quarterly Report	true
Document Transition Report	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false

Consolidated Balance Sheet (Una

Consolidated Balance Sheet (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Cash and due from banks	$ 1,489,232	$ 1,432,805
Interest-bearing deposits at banks	20,197,937	7,190,154
Federal funds sold		3,500
Trading account	1,215,573	470,129
Investment securities (includes pledged securities that can be sold or repledged of $89,351 at September 30, 2020; $200,339 at December 31, 2019)
Available for sale (cost: $5,090,064 at September 30, 2020; $6,258,276 at December 31, 2019)	5,302,338	6,318,776
Held to maturity (fair value: $2,031,926 at September 30, 2020; $2,699,206 at December 31, 2019)	1,938,694	2,656,917
Equity and other securities (cost: $458,498 at September 30, 2020; $487,041 at December 31, 2019)	481,972	521,558
Total investment securities	7,723,004	9,497,251
Loans and leases	98,849,533	91,188,525
Unearned discount	(402,485)	(265,656)
Loans and leases, net of unearned discount	98,447,048	90,922,869
Allowance for credit losses	(1,758,505)	(1,051,071)
Loans and leases, net	96,688,543	89,871,798
Premises and equipment	1,146,681	1,140,924
Goodwill	4,593,112	4,593,112
Core deposit and other intangible assets	17,294	29,034
Accrued interest and other assets	5,555,367	5,644,050
Total assets	138,626,743	119,872,757
Liabilities
Noninterest-bearing deposits	44,201,670	32,396,407
Savings and interest-checking deposits	65,732,130	54,932,162
Time deposits	4,329,550	5,757,456
Deposits at Cayman Islands office	899,989	1,684,044
Total deposits	115,163,339	94,770,069
Short-term borrowings	46,123	62,363
Accrued interest and other liabilities	1,857,383	2,337,490
Long-term borrowings	5,458,885	6,986,186
Total liabilities	122,525,730	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 September 30, 2020 and December 31, 2019; Liquidation preference of $10,000 per share: 90,000 shares at September 30, 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 September 30, 2020 and December 31, 2019	79,871	79,871
Common stock issuable, 17,999 shares at September 30, 2020; 21,534 shares at December 31, 2019	1,327	1,566
Additional paid-in capital	6,609,573	6,593,539
Retained earnings	13,132,374	12,820,916
Accumulated other comprehensive income (loss), net	175,503	(206,680)
Treasury stock — common, at cost — 31,456,705 shares at September 30, 2020; 29,174,402 shares at December 31, 2019	(5,147,635)	(4,822,563)
Total shareholders’ equity	16,101,013	15,716,649
Total liabilities and shareholders’ equity	$ 138,626,743	$ 119,872,757

Consolidated Balance Sheet (U_2

Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Pledged securities that can be sold or repledged	$ 89,351	$ 200,339
Investment securities, available for sale, amortized cost	5,090,064	6,258,276
Investment securities, held to maturity, fair value	2,031,926	2,699,206
Equity and other securities, cost	$ 458,498	$ 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	17,999	21,534
Treasury stock, common shares	31,456,705	31,456,705
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 (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest income
Loans and leases, including fees	$ 956,594	$ 1,119,662	$ 2,983,787	$ 3,363,152
Investment securities
Fully taxable	38,529	69,059	135,858	225,048
Exempt from federal taxes	59	98	163	270
Deposits at banks	4,163	40,388	27,308	104,120
Other	1,816	262	6,706	1,101
Total interest income	1,001,161	1,229,469	3,153,822	3,693,691
Interest expense
Savings and interest-checking deposits	22,403	104,724	126,859	272,419
Time deposits	14,519	25,456	56,274	71,468
Deposits at Cayman Islands office	241	6,218	3,821	16,995
Short-term borrowings	1	6,967	26	21,573
Long-term borrowings	20,902	56,214	89,805	189,805
Total interest expense	58,066	199,579	276,785	572,260
Net interest income	943,095	1,029,890	2,877,037	3,121,431
Provision for credit losses	150,000	45,000	725,000	122,000
Net interest income after provision for credit losses	793,095	984,890	2,152,037	2,999,431
Other income
Brokerage services income	11,602	12,077	35,194	37,031
Trading account and foreign exchange gains	4,026	16,072	33,332	45,327
Gain (loss) on bank investment securities	2,773	3,737	(11,040)	24,489
Other revenues from operations	107,601	103,882	327,967	351,082
Total other income	520,561	527,779	1,537,194	1,540,639
Other expense
Salaries and employee benefits	478,897	476,780	1,474,582	1,431,717
Equipment and net occupancy	81,080	82,690	237,809	241,187
Outside data processing and software	64,660	60,360	190,446	168,011
FDIC assessments	12,121	9,906	38,599	29,104
Advertising and marketing	11,855	22,088	44,072	66,409
Printing, postage and supplies	9,422	10,201	31,534	30,380
Amortization of core deposit and other intangible assets	3,914	5,088	11,740	15,185
Other costs of operations	164,825	210,506	511,450	663,006
Total other expense	826,774	877,619	2,540,232	2,644,999
Income before taxes	486,882	635,050	1,148,999	1,895,071
Income taxes	114,746	154,969	266,987	458,988
Net income	372,136	480,081	882,012	1,436,083
Net income available to common shareholders
Basic	353,399	461,410	827,203	1,376,128
Diluted	$ 353,400	$ 461,410	$ 827,204	$ 1,376,129
Net income per common share
Basic	$ 2.75	$ 3.47	$ 6.42	$ 10.16
Diluted	$ 2.75	$ 3.47	$ 6.42	$ 10.16
Average common shares outstanding
Basic	128,285	132,965	128,750	135,411
Diluted	128,355	132,999	128,813	135,443
Mortgage Banking Revenues [Member]
Other income
Revenue from contract with customer	$ 153,267	$ 137,004	$ 426,200	$ 339,636
Service Charges on Deposit Accounts [Member]
Other income
Revenue from contract with customer	91,355	111,092	274,971	321,991
Trust Income [Member]
Other income
Revenue from contract with customer	$ 149,937	$ 143,915	$ 450,570	$ 421,083

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Partners Capital [Abstract]
Net income	$ 372,136	$ 480,081	$ 882,012	$ 1,436,083
Other comprehensive income (loss), net of tax and reclassification adjustments:
Net unrealized gains (losses) on investment securities	(17,948)	22,605	114,451	177,049
Cash flow hedges adjustments	(63,199)	8,695	240,562	155,666
Foreign currency translation adjustments	2,733	(1,704)	(261)	(2,104)
Defined benefit plans liability adjustments	9,287	3,054	27,431	9,162
Total other comprehensive income (loss)	(69,127)	32,650	382,183	339,773
Total comprehensive income	$ 303,009	$ 512,731	$ 1,264,195	$ 1,775,856

Consolidated Statement of Cash

Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net income	$ 882,012	$ 1,436,083
Adjustments to reconcile net income to net cash provided by operating activities
Provision for credit losses	725,000	122,000
Depreciation and amortization of premises and equipment	164,323	155,721
Amortization of capitalized servicing rights	63,992	53,137
Amortization of core deposit and other intangible assets	11,740	15,185
Provision for deferred income taxes	(119,913)	16,683
Asset write-downs	17,692	53,850
Net gain on sales of assets	(14,736)	(13,938)
Net change in accrued interest receivable, payable	(135,825)	8,771
Net change in other accrued income and expense	(344,085)	(75,564)
Net change in loans originated for sale	(422,773)	(20,325)
Net change in trading account assets and liabilities	(702,362)	(524,755)
Net cash provided by operating activities	125,065	1,226,848
Cash flows from investing activities
Proceeds from sales of investment securities equity and other	55,499	878,405
Proceeds from maturities of investment securities Available for sale	1,149,281	1,932,168
Proceeds from maturities of investment securities Held to maturity	719,379	787,655
Purchases of investment securities Available for sale	(5,860)	(9,791)
Purchases of investment securities Held to maturity	(8,995)	(495,277)
Purchases of investment securities equity and other	(26,955)	(821,120)
Net increase in loans and leases	(7,227,304)	(1,484,135)
Net increase in interest-bearing deposits at banks	(13,007,783)	(4,390,327)
Capital expenditures, net	(125,370)	(119,522)
Net (increase) decrease in loan servicing advances	149,838	(333,079)
Other, net	351,278	55,356
Net cash used by investing activities	(17,976,992)	(3,999,667)
Cash flows from financing activities
Net increase in deposits	20,394,732	4,959,327
Net increase (decrease) in short-term borrowings	(16,240)	1,115,518
Payments on long-term borrowings	(1,605,041)	(1,552,533)
Purchases of treasury stock	(373,750)	(1,067,575)
Dividends paid — common	(426,204)	(406,967)
Dividends paid — preferred	(55,444)	(54,642)
Redemption of Series A and Series C preferred stock		(381,500)
Other, net	(13,199)	(21,187)
Net cash provided by financing activities	17,904,854	2,986,441
Net increase in cash, cash equivalents and restricted cash	52,927	213,622
Cash, cash equivalents and restricted cash at beginning of period	1,436,305	1,605,439
Cash, cash equivalents and restricted cash at end of period	1,489,232	1,819,061
Supplemental disclosure of cash flow information
Interest received during the period	3,121,917	3,700,206
Interest paid during the period	319,079	577,291
Income taxes paid during the period	254,471	302,441
Supplemental schedule of noncash investing and financing activities
Real estate acquired in settlement of loans	20,047	66,018
Securitization of residential mortgage loans allocated to Available-for-sale investment securities		5,379
Securitization of residential mortgage loans allocated to capitalized servicing rights		83
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	$ 45,888	69,305
Series G Preferred Stock [Member]
Cash flows from financing activities
Proceeds from issuance of Series G preferred stock		$ 396,000

Consolidated Statement of Chang

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands		Total	ASU 2016-13 [Member]	Preferred Stock [Member]	Common Stock [Member]	Common Stock Issuable [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]ASU 2016-13 [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2018		$ 15,460,191		$ 1,231,500	$ 79,883	$ 1,726	$ 6,579,342	$ 11,516,672		$ (420,081)	$ (3,528,851)
Total comprehensive income		1,775,856						1,436,083		339,773
Preferred stock cash dividends	[1]	(55,404)						(55,404)
Redemption of Series A and Series C preferred stock		(381,500)		(381,500)
Issuance of Series G preferred stock		396,000		400,000			(4,000)
Purchases of treasury stock		(1,067,575)									(1,067,575)
Stock-based compensation transactions, net		59,210			(12)	(179)	9,363	(151)			50,189
Common stock cash dividends		(406,967)						(406,967)
Ending balance at Sep. 30, 2019		15,779,811		1,250,000	79,871	1,547	6,584,705	12,490,233		(80,308)	(4,546,237)
Beginning balance at Jun. 30, 2019		15,691,827		1,231,500	79,871	1,526	6,577,603	12,162,278		(112,958)	(4,247,993)
Total comprehensive income		512,731						480,081		32,650
Preferred stock cash dividends	[1]	(19,144)						(19,144)
Redemption of Series A and Series C preferred stock		(381,500)		(381,500)
Issuance of Series G preferred stock		396,000		400,000			(4,000)
Purchases of treasury stock		(299,963)									(299,963)
Stock-based compensation transactions, net		12,792				21	11,102	(50)			1,719
Common stock cash dividends		(132,932)						(132,932)
Ending balance at Sep. 30, 2019		15,779,811		1,250,000	79,871	1,547	6,584,705	12,490,233		(80,308)	(4,546,237)
Beginning 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)
Adoption of new accounting standard for credit losses			$ (91,925)						$ (91,925)
Total comprehensive income		1,264,195						882,012		382,183
Preferred stock cash dividends	[1]	(51,178)						(51,178)
Purchases of treasury stock		(373,750)									(373,750)
Stock-based compensation transactions, net		64,163				(239)	16,034	(310)			48,678
Common stock cash dividends		(427,141)						(427,141)
Ending balance at Sep. 30, 2020		16,101,013		1,250,000	79,871	1,327	6,609,573	13,132,374		175,503	(5,147,635)
Beginning balance at Jun. 30, 2020		15,945,105		1,250,000	79,871	1,308	6,599,069	12,919,345		244,630	(5,149,118)
Total comprehensive income		303,009						372,136		(69,127)
Preferred stock cash dividends	[1]	(17,050)						(17,050)
Stock-based compensation transactions, net		11,902				19	10,504	(104)			1,483
Common stock cash dividends		(141,953)						(141,953)
Ending balance at Sep. 30, 2020		$ 16,101,013		$ 1,250,000	$ 79,871	$ 1,327	$ 6,609,573	$ 13,132,374		$ 175,503	$ (5,147,635)
[1]	For the three-month and nine-month periods ended September 30, 2020, dividends per preferred share were: Preferred Series E - $16.125 and $48.375, respectively; Preferred Series F - $128.125 and $384.375, respectively; and Preferred Series G - $125.00 and $375.694, respectively. Dividends per preferred share for the three-month and nine-month periods ended September 30, 2019 were: Preferred Series A - $15.9375 and $47.8125, respectively; Preferred Series C - $15.9375 and $47.8125, respectively; Preferred Series E - $16.125 and $48.375, respectively; and Preferred Series F - $128.125 and $384.375, respectively.

Consolidated Statement of Cha_2

Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Retained Earnings [Member]
Common stock per share dividend amount	$ 1.10	$ 1	$ 3.30	$ 3
Preferred Series A [Member]
Preferred stock per share dividend amount		15.9375		47.8125
Preferred Series C [Member]
Preferred stock per share dividend amount		15.9375		47.8125
Preferred Series E [Member]
Preferred stock per share dividend amount	16.125	16.125	48.375	48.375
Preferred Series F [Member]
Preferred stock per share dividend amount	128.125	$ 128.125	384.375	$ 384.375
Series G Preferred Stock [Member]
Preferred stock per share dividend amount	$ 125		$ 375.694

Significant accounting policies

Significant accounting policies and current environment	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Significant accounting policies and current environment	1. Significant accounting policies and current environment The consolidated interim financial statements of M&T Bank Corporation (“M&T”) and subsidiaries (“the Company”) were compiled in accordance with generally accepted accounting principles (“GAAP”) using the accounting policies set forth in note 1 of Notes to Financial Statements included in Form 10-K for the year ended December 31, 2019 (“2019 Annual Report”), except that effective January 1, 2020 the Company adopted accounting guidance related to the recognition of expected credit losses that is discussed in notes 2, 3 and 15 herein. The financial statements contain all adjustments which are, in the opinion of management, necessary for a fair statement of the Company’s financial position, results of operations and cash flows for the interim periods presented. 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 economic activity that severely hampered the ability for businesses and consumers to meet their repayment obligations. The effects of the pandemic contributed to a significant increase in the provision for credit losses during the first nine months of 2020. The Coronavirus Aid, Relief, and Economic Security Act (“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. That 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 generally 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, fee waivers, extensions of repayment term, or other delays in payment. 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 previously described, the modified loans have not been classified as troubled debt restructurings nor reported as past due.

Investment securities

Investment securities	9 Months Ended
	Sep. 30, 2020
Investments Debt And Equity Securities [Abstract]
Investment securities	2. Investment securities The amortized cost and estimated fair value of investment securities were as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In thousands) September 30, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 9,154 $ 226 $ 10 $ 9,370 Mortgage-backed securities: Government issued or guaranteed 4,944,979 221,561 839 5,165,701 Privately issued 16 — — 16 Other debt securities 135,915 1,328 9,992 127,251 5,090,064 223,115 10,841 5,302,338 Investment securities held to maturity: U.S. Treasury and federal agencies 3,000 — — 3,000 Obligations of states and political subdivisions 1,855 10 — 1,865 Mortgage-backed securities: Government issued or guaranteed 1,850,864 100,104 92 1,950,876 Privately issued 80,013 11,010 17,800 73,223 Other debt securities 2,962 — — 2,962 1,938,694 111,124 17,892 2,031,926 Total debt securities $ 7,028,758 $ 334,239 $ 28,733 $ 7,334,264 Equity and other securities: Readily marketable equity — at fair value $ 77,708 $ 23,474 $ — $ 101,182 Other — at cost 380,790 — — 380,790 Total equity and other securities $ 458,498 $ 23,474 $ — $ 481,972 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 2. Investment securities, continued There were no significant gross realized gains or losses from sales of investment securities for the three-month and nine-month periods ended September 30, 2020 and 2019. Unrealized gains on equity securities during the three months ended September 30, 2020 were $3 million and unrealized losses during the nine months ended September 30, 2020 were $11 million, compared with unrealized gains of $4 million and $24 million during the three months and nine months ended September 30, 2019, respectively. At September 30, 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 $ 5,197 5,207 Due after one year through five years 11,446 12,009 Due after five years through ten years 98,426 95,033 Due after ten years 30,000 24,372 145,069 136,621 Mortgage-backed securities available for sale 4,944,995 5,165,717 $ 5,090,064 5,302,338 Debt securities held to maturity: Due in one year or less $ 4,680 4,688 Due after one year through five years 175 177 Due after ten years 2,962 2,962 7,817 7,827 Mortgage-backed securities held to maturity 1,930,877 2,024,099 $ 1,938,694 2,031,926 2. Investment securities, continued A summary of investment securities that as of September 30, 2020 and December 31, 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) September 30, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 985 (10 ) — — Mortgage-backed securities: Government issued or guaranteed 20,313 (364 ) 21,735 (475 ) Other debt securities 42,385 (1,087 ) 62,659 (8,905 ) 63,683 (1,461 ) 84,394 (9,380 ) Investment securities held to maturity: Mortgage-backed securities: Government issued or guaranteed 11,357 (92 ) — — Privately issued 7,476 (32 ) 46,048 (17,768 ) 18,833 (124 ) 46,048 (17,768 ) Total $ 82,516 (1,585 ) 130,442 (27,148 ) 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 290 individual debt securities with aggregate gross unrealized losses of $29 million at September 30, 2020. Based on a review of each of the securities in the investment securities portfolio at September 30, 2020, the Company concluded that it expected to recover the amortized cost basis of its investment. As of September 30, 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 September 30, 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 equity securities. 2. Investment securities, continued As described in notes 3 and 15, 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 their contractual term. The Company estimated no material allowance for credit losses for its investment securities classified as held-to-maturity at January 1, 2020 or September 30, 2020, as the substantial majority of such investment securities are obligations backed by the U.S. government or its agencies.

Loans and leases and the allowa

Loans and leases and the allowance for credit losses	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Loans and leases and the allowance for credit losses	3. Loans and leases and the 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 their contractual term considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The amended guidance also requires recording an allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination. The initial allowance for these assets will be added to the purchase price at acquisition rather than being reported as an expense. Subsequent changes in the allowance will be recorded in the income statement as an adjustment to the provision for credit losses. The new guidance replaced the previous incurred loss model for determining the allowance for credit losses. The adoption resulted in a $132 million increase in the allowance for credit losses at January 1, 2020. Prior to January 1, 2020, 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 borrowers’ repayment status. Effective with the adoption of the new accounting standard, the Company’s nonaccrual loan policy now applies to loans acquired at a discount. That change added $171 million to nonaccrual loans as of the January 1, 2020 adoption date. Past due and nonaccrual loans A summary of current, past due and nonaccrual loans as of September 30, 2020 and December 31, 2019 follows: Current 30-89 Days Past Due Accruing Loans Due 90 Days or More Nonaccrual Total (In thousands) September 30, 2020 Commercial, financial, leasing, etc. $ 27,249,552 282,917 8,551 350,628 $ 27,891,648 Real estate: Commercial 27,250,676 197,881 8,189 252,515 27,709,261 Residential builder and developer 1,353,863 7,282 — 1,833 1,362,978 Other commercial construction 8,405,525 66,599 94 37,627 8,509,845 Residential 13,934,309 185,420 503,450 297,636 14,920,815 Residential — limited documentation 1,606,130 20,980 — 115,783 1,742,893 Consumer: Home equity lines and loans 4,000,829 22,209 — 78,820 4,101,858 Recreational finance 6,838,126 36,003 — 24,191 6,898,320 Automobile 3,829,968 42,906 — 42,374 3,915,248 Other 1,337,042 11,601 6,974 38,565 1,394,182 Total $ 95,806,020 873,798 527,258 1,239,972 $ 98,447,048 3. Loans and leases and the allowance for credit losses, continued 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) Excludes loans acquired at a discount. (b) Loans acquired at a discount that were recorded at fair value at acquisition date. This category does not include purchased impaired loans that are presented separately. (c) Accruing loans acquired at a discount that were impaired at acquisition date and recorded at fair value. A summary of outstanding loan balances for which COVID-19 related modifications were granted as of September 30, 2020 and June 30, 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. September June 30, 2020 (In thousands) Commercial, financial, leasing, etc. $ 815,186 $ 5,302,196 Real estate: Commercial 4,452,846 7,802,006 Residential builder and developer 1,473 18,253 Other commercial construction 671,378 861,536 Residential 2,852,740 1,737,483 Residential — limited documentation 454,378 538,671 Consumer: Home equity lines and loans 25,658 88,162 Recreational finance 39,754 254,205 Automobile 62,871 326,113 Other 2,336 16,611 Total $ 9,378,620 $ 16,945,236 Substantially all of the loan modifications outstanding at September 30, 2020 are scheduled to expire in the fourth quarter of 2020. Should borrowers request further forbearance, the credit quality of the loans and the ability and willingness of borrowers to repay such loans will be re-assessed to determine whether the Company expects to receive all principal and interest payments due. 3. Loans and leases and the allowance for credit losses, continued One-to-four family residential mortgage loans held for sale were $571 million and $414 million at September 30, 2020 and December 31, 2019, respectively. Commercial real estate loans held for sale were $336 million at September 30, 2020 and $28 million at December 31, 2019. 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 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Purchased Other Purchased Other Impaired Acquired Impaired Acquired (In thousands) Balance at beginning of period $ 147,104 $ 90,911 $ 147,210 $ 96,907 Interest income (9,564 ) (9,238 ) (37,278 ) (28,621 ) Reclassifications from nonaccretable balance 9,079 3,990 36,687 12,312 Other (a) — 41 — 5,106 Balance at end of period $ 146,619 $ 85,704 $ 146,619 $ 85,704 (a) Other changes in expected cash flows included changes in interest rates and prepayment assumptions. Credit quality indicators 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 3. Loans and leases and the allowance for credit losses, continued 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 September 30, 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 $ 8,209,336 2,387,719 1,638,389 1,001,452 816,518 1,488,463 10,444,292 27,536 $ 26,013,705 Criticized accrual 389,682 75,106 141,774 50,144 45,345 57,137 758,594 9,533 1,527,315 Criticized nonaccrual 2,793 23,546 49,840 16,456 18,790 66,410 165,625 7,168 350,628 Total commercial, financial, leasing, etc. $ 8,601,811 2,486,371 1,830,003 1,068,052 880,653 1,612,010 11,368,511 44,237 $ 27,891,648 Real estate: Commercial: Loan grades: Pass $ 2,773,454 4,911,992 3,458,071 2,851,599 2,823,120 6,188,879 810,180 — $ 23,817,295 Criticized accrual 343,722 436,191 531,848 294,994 728,208 1,252,953 51,535 — 3,639,451 Criticized nonaccrual 242 43,342 5,168 31,506 21,507 149,629 1,121 — 252,515 Total commercial real estate $ 3,117,418 5,391,525 3,995,087 3,178,099 3,572,835 7,591,461 862,836 — $ 27,709,261 Residential builder and developer: Loan grades: Pass $ 399,778 399,923 207,188 26,378 11,668 14,190 233,182 — $ 1,292,307 Criticized accrual 32,441 12,744 15,255 3,421 — 1,410 3,567 — 68,838 Criticized nonaccrual — 518 — — — 1,315 — — 1,833 Total residential builder and developer $ 432,219 413,185 222,443 29,799 11,668 16,915 236,749 — $ 1,362,978 Other commercial construction: Loan grades: Pass $ 721,942 2,613,554 2,229,748 1,137,823 352,930 299,184 77,873 — $ 7,433,054 Criticized accrual 26,338 223,956 365,284 243,108 166,048 14,430 — — 1,039,164 Criticized nonaccrual — — — 4,340 3,254 24,913 5,120 — 37,627 Total other commercial construction $ 748,280 2,837,510 2,595,032 1,385,271 522,232 338,527 82,993 — $ 8,509,845 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 September 30, 2020 for the various classes of the Company’s residential real estate loans and consumer loans by origination year is as follows. 3. Loans and leases and the allowance for credit losses, continued Term Loans by Origination Year Revolving Revolving Loans Converted to Term 2020 2019 2018 2017 2016 Prior Loans Loans Total (In thousands) Residential: Current $ 2,089,095 1,489,244 664,588 1,282,631 756,137 7,583,780 68,834 — $ 13,934,309 30-89 days past due 4,319 8,534 5,234 17,517 6,758 143,058 — — 185,420 Accruing loans past due 90 days or more 387 9,213 26,596 124,510 30,048 312,696 — — 503,450 Nonaccrual 761 4,590 1,653 5,257 1,002 284,167 206 — 297,636 Total residential $ 2,094,562 1,511,581 698,071 1,429,915 793,945 8,323,701 69,040 — $ 14,920,815 Residential - limited documentation: Current $ — — — — — 1,606,130 — — $ 1,606,130 30-89 days past due — — — — — 20,980 — — 20,980 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — — — — — 115,783 — — 115,783 Total residential - limited documentation $ — — — — — 1,742,893 — — $ 1,742,893 Consumer: Home equity lines and loans: Current $ 668 4,357 1,961 2,155 163 57,998 2,622,825 1,310,702 $ 4,000,829 30-89 days past due — — 72 — — 1,809 1,374 18,954 22,209 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — 20 — 52 — 5,018 6,988 66,742 78,820 Total home equity lines and loans $ 668 4,377 2,033 2,207 163 64,825 2,631,187 1,396,398 $ 4,101,858 3. Loans and leases and the allowance for credit losses, continued 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 $ 2,323,314 1,881,732 969,243 674,896 379,441 609,500 — — $ 6,838,126 30-89 days past due 5,130 9,073 6,755 5,091 3,168 6,786 — — 36,003 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,314 3,961 3,790 4,175 2,379 8,572 — — 24,191 Total recreational finance $ 2,329,758 1,894,766 979,788 684,162 384,988 624,858 — — $ 6,898,320 Automobile: Current $ 1,084,223 1,223,790 711,515 513,607 208,741 88,092 — — $ 3,829,968 30-89 days past due 2,884 10,573 11,193 10,126 5,170 2,960 — — 42,906 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,244 7,754 11,224 11,010 6,461 4,681 — — 42,374 Total automobile $ 1,088,351 1,242,117 733,932 534,743 220,372 95,733 — — $ 3,915,248 Other: Current $ 132,769 154,094 62,966 39,231 6,252 31,356 908,567 1,807 $ 1,337,042 30-89 days past due 1,874 890 537 243 29 570 6,954 504 11,601 Accruing loans past due 90 days or more — — — — — 287 6,687 — 6,974 Nonaccrual 1,540 446 442 226 43 383 35,186 299 38,565 Total other $ 136,183 155,430 63,945 39,700 6,324 32,596 957,394 2,610 $ 1,394,182 Total loans and leases at September 30, 2020 $ 18,549,250 15,936,862 11,120,334 8,351,948 6,393,180 20,443,519 16,208,710 1,443,245 $ 98,447,048 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 3. Loans and leases and the allowance for credit losses, continued Allowance for credit losses For purposes of determining the level of the allowance for credit losses, the Company evaluates its loan and lease portfolio by loan type. Changes in the allowance for credit losses for the three months ended September 30, 2020 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Total (In thousands) Beginning balance $ 398,257 576,321 118,921 544,737 $ 1,638,236 Provision for credit losses 25,450 87,403 (683 ) 37,830 150,000 Net charge-offs Charge-offs (14,434 ) (4,522 ) (1,516 ) (31,754 ) (52,226 ) Recoveries 4,475 2,578 960 14,482 22,495 Net charge-offs (9,959 ) (1,944 ) (556 ) (17,272 ) (29,731 ) Ending balance $ 413,748 661,780 117,682 565,295 $ 1,758,505 Changes in the allowance for credit losses for the three months ended September 30, 2019 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) Beginning balance $ 335,855 343,296 61,011 211,220 78,485 $ 1,029,867 Provision for credit losses 24,538 (16,713 ) (309 ) 37,735 (251 ) 45,000 Net charge-offs Charge-offs (15,678 ) (1,107 ) (2,721 ) (40,735 ) — (60,241 ) Recoveries 6,730 1,656 1,511 13,914 — 23,811 Net (charge-offs) recoveries (8,948 ) 549 (1,210 ) (26,821 ) — (36,430 ) Ending balance $ 351,445 327,132 59,492 222,134 78,234 $ 1,038,437 Changes in the allowance for credit losses for the nine months ended September 30, 2020 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) 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 161,444 335,159 11,458 216,939 — 725,000 Net charge-offs Charge-offs (63,425 ) (23,266 ) (8,227 ) (116,409 ) — (211,327 ) Recoveries 11,109 4,030 4,522 41,643 — 61,304 Net charge-offs (52,316 ) (19,236 ) (3,705 ) (74,766 ) — (150,023 ) Ending balance $ 413,748 661,780 117,682 565,295 — $ 1,758,505 3. Loans and leases and the allowance for credit losses, continued Changes in the allowance for credit losses for the nine months ended September 30, 2019 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) Beginning balance $ 330,055 341,655 69,125 200,564 78,045 $ 1,019,444 Provision for credit losses 41,146 (6,415 ) (5,132 ) 92,212 189 122,000 Net charge-offs Charge-offs (40,786 ) (11,555 ) (9,356 ) (113,050 ) — (174,747 ) Recoveries 21,030 3,447 4,855 42,408 — 71,740 Net charge-offs (19,756 ) (8,108 ) (4,501 ) (70,642 ) — (103,007 ) Ending balance $ 351,445 327,132 59,492 222,134 78,234 $ 1,038,437 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. A description of the methodologies used by the Company to estimate its allowance for credit losses prior to January 1, 2020 is included in note 4 of Notes to Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. 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. 3. Loans and leases and the allowance for credit losses, continued 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 three-month and nine-month periods ended September 30, 2020 and 2019 follows. September 30, 2020 June 30, 2020 January 1, 2020 Three Months Ended September 2020 Nine Months Ended September 2020 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Amortized Cost Interest Income Recognized Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 264,515 86,113 350,628 284,654 346,743 5,999 9,035 Real estate: Commercial 86,199 166,316 252,515 172,488 173,796 993 6,782 Residential builder and developer 1,833 — 1,833 1,748 4,708 114 173 Other commercial construction 15,441 22,186 37,627 85,426 35,881 232 6,809 Residential 66,302 231,334 297,636 306,907 322,504 3,410 15,258 Residential — limited documentation 29,824 85,959 115,783 118,695 114,667 114 571 Consumer: Home equity lines and loans 36,134 42,686 78,820 77,094 65,039 1,017 3,236 Recreational finance 17,637 6,554 24,191 24,152 14,308 155 461 Automobile 37,355 5,019 42,374 42,736 21,293 47 139 Other 3,567 34,998 38,565 42,750 35,394 174 489 Total $ 558,807 681,165 1,239,972 1,156,650 1,134,333 12,255 42,953 3. Loans and leases and the allowance for credit losses, continued September 30, 2019 June 30, 2019 January 1, 2019 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Amortized Cost Interest Income Recognized Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 223,183 159,626 382,809 223,733 234,423 836 7,552 Real estate: Commercial 40,203 144,429 184,632 203,116 203,672 1,802 5,212 Residential builder and developer 1,596 3,379 4,975 5,985 4,798 89 308 Other commercial construction 15,501 15,940 31,441 32,769 22,205 488 1,669 Residential 57,070 166,496 223,566 210,922 233,352 3,425 10,014 Residential — limited documentation 27,803 53,876 81,679 87,551 84,685 269 795 Consumer: Home equity lines and loans 23,908 36,007 59,915 66,927 71,292 1,846 4,617 Recreational finance 6,577 5,275 11,852 11,153 11,199 147 431 Automobile 14,596 6,443 21,039 20,170 23,359 54 161 Other 3,066 275 3,341 3,058 4,623 145 392 Total $ 413,503 591,746 1,005,249 865,384 893,608 9,101 31,151 In determining the allowance for credit losses, 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 September 30, 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. The Company’s reserve for off-balance sheet credit exposures was not material at September 30, 2020 and December 31, 2019. Loan modifications During the normal course of business, the Company modifies loans to maximize recovery efforts. If the borrower is experiencing financial difficulty and a concession is granted, the Company considers such modifications as troubled debt restructurings and classifies those loans as either nonaccrual loans or renegotiated loans. The types of concessions that the Company grants typically include principal deferrals and interest rate concessions, but may also include other types of concessions. 3. Loans and leases and the allowance for credit losses, continued The table that follows summarizes the Company’s loan modification activities that were considered troubled debt restructurings for the three-month and nine-month periods ended September 30, 2020 and 2019: Post-modification (a) Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total Three Months Ended September 30, 2020 (Dollars in thousands) Commercial, financial, leasing, etc. 112 $ 35,037 $ 7,145 $ 298 $ — $ 27,512 $ 34,955 Real estate: Commercial 50 13,293 12,506 172 30 600 13,308 Residential 30 8,544 5,517 — — 3,616 9,133 Consumer: Home equity lines and loans 33 3,410 129 — — 3,286 3,415 Recreational finance 74 2,734 2,734 — — — 2,734 Automobile 403 7,007 7,005 — — 2 7,007 Other 383 3,046 142 — — 2,904 3,046 Total 1,085 $ 73,071 $ 35,178 $ 470 $ 30 $ 37,920 $ 73,598 Three Months Ended September 30, 2019 Commercial, financial, leasing, etc. 26 $ 6,145 $ 1,441 $ — $ — $ 4,666 $ 6,107 Real estate: Commercial 9 2,986 383 — — 2,589 2,972 Residential 20 5,161 3,046 — — 2,535 5,581 Residential — limited documentation 1 236 — — — 240 240 Consumer: Home equity lines and loans 12 1,392 — — — 1,399 1,399 Recreational finance 3 61 61 — — — 61 Automobile 26 485 457 — — 28 485 Total 97 $ 16,466 $ 5,388 $ — $ — $ 11,457 $ 16,845 3. Loans and leases and the allowance for credit losses, continued Post-modification (a) Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total Nine Months Ended September 30, 2020 (Dollars in thousands) Commercial, financial, leasing, etc. 279 $ 102,865 $ 29,762 $ 298 $ 31,605 $ 40,013 $ 101,678 Real estate: Commercial 106 94,807 24,372 505 4,830 52,916 82,623 Residential builder and developer 1 91 — — — 90 90 Residential 82 27,594 11,865 — — 19,126 30,991 Residential — limited documentation 9 2,980 2,667 — — 1,232 3,899 Consumer: Home equity lines and loans 159 11,719 688 — — 11,057 11,745 Recreational finance 348 13,619 13,619 — — — 13,619 Automobile 1,873 33,541 33,539 — — 2 33,541 Other 718 5,229 824 — — 4,405 5,229 Total 3,575 $ 292,445 $ 117,336 $ 803 $ 36,435 $ 128,841 $ 283,415 Nine Months Ended September 30, 2019 Commercial, financial, leasing, etc. 115 $ 39,357 $ 8,582 $ — $ — $ 30,827 $ 39,409 Real estate: Commercial 38 22,567 3,947 — — 18,197 22,144 Residential builder and developer 2 1,330 1,068 — — — 1,068 Other commercial construction 2 1,456 — — 1,399 1,399 Residential 63 16,490 8,805 — — 8,842 17,647 Residential — limited documentation 4 1,084 399 — — 705 1,104 Consumer: Home equity lines and loans 32 3,141 90 — — 3,078 3,168 Recreational finance 8 164 164 — — — 164 Automobile 58 991 926 — — 65 991 Total 322 $ 86,580 $ 23,981 $ — $ — $ 63,113 $ 87,094 (a) Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages. The present value of interest rate concessions, discounted at the effective rate of the original loan, was not material. Troubled debt restructurings are evaluated for impairment giving consideration to the impact of the modified loan terms on the present value of the loan’s expected cash flows. Impairment of troubled debt restructurings that have subsequently defaulted may also be measured based on the loan’s observable market price or the fair value of collateral if the loan is collateral-dependent. Charge-offs may also be recognized on troubled debt restructurings that have subsequently defaulted. Loans that were modified as troubled debt restructurings during the twelve months ended September 30, 2020 and 2019 and for which there was a subsequent payment default during the nine-month periods ended September 30, 2020 and 2019, respectively, were not material. The amount of foreclosed residential real estate property held by the Company was $43 million and $76 million at September 30, 2020 and December 31, 2019, respectively. There were $231 million and $402 million at September 30, 2020 and December 31, 2019, respectively, of loans secured by residential real estate that were in the process of foreclosure. Of all loans in the process of foreclosure at September 30, 2020, approximately 42% were government guaranteed.

Borrowings

Borrowings	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Borrowings	4. Borrowings M&T had $527 million of fixed and variable rate junior subordinated deferrable interest debentures ("Junior Subordinated Debentures") outstanding at September 30, 2020 that are held by various trusts that were issued in connection with the issuance by those trusts of preferred capital securities ("Capital Securities") and common securities ("Common Securities"). The proceeds from the issuances of the Capital Securities and the Common Securities were used by the trusts to purchase the Junior Subordinated Debentures. The Common Securities of each of those trusts are wholly owned by M&T and are the only class of each trust's securities possessing general voting powers. The Capital Securities represent preferred undivided interests in the assets of the corresponding trust. Under the Federal Reserve Board’s risk-based capital guidelines, the securities are includable in M&T’s Tier 2 regulatory capital. Holders of the Capital Securities receive preferential cumulative cash distributions unless M&T exercises its right to extend the payment of interest on the Junior Subordinated Debentures as allowed by the terms of each such debenture, in which case payment of distributions on the respective Capital Securities will be deferred for comparable periods. During an extended interest period, M&T may not pay dividends or distributions on, or repurchase, redeem or acquire any shares of its capital stock. In general, the agreements governing the Capital Securities, in the aggregate, provide a full, irrevocable and unconditional guarantee by M&T of the payment of distributions on, the redemption of, and any liquidation distribution with respect to the Capital Securities. The obligations under such guarantee and the Capital Securities are subordinate and junior in right of payment to all senior indebtedness of M&T. The Capital Securities will remain outstanding until the Junior Subordinated Debentures are repaid at maturity, are redeemed prior to maturity or are distributed in liquidation to the trusts. The Capital Securities are mandatorily redeemable in whole, but not in part, upon repayment at the stated maturity dates (ranging from 2027 to 2033) of the Junior Subordinated Debentures or the earlier redemption of the Junior Subordinated Debentures in whole upon the occurrence of one or more events set forth in the indentures relating to the Capital Securities, and in whole or in part at any time after an optional redemption prior to contractual maturity contemporaneously with the optional redemption of the related Junior Subordinated Debentures in whole or in part, subject to possible regulatory approval. On January 7, 2020, M&T Bank, the principal bank subsidiary of M&T, redeemed $750 million of fixed rate senior notes that were due to mature on February 6, 2020. In addition, M&T Bank redeemed $750 million of fixed rate senior notes on July 17, 2020 that were due to mature on August 17, 2020. Also included in long-term borrowings was an agreement to repurchase securities that totaled $102 million at December 31, 2019. The outstanding agreement matured in July 2020. The agreement was subject to legally enforceable master netting arrangements, however, the Company did not offset any amounts related to the agreement in its consolidated financial statements. The Company posted collateral consisting primarily of government guaranteed mortgage-backed securities of $108 million at December 31, 2019 .

Revenue from contracts with cus

Revenue from contracts with customers	9 Months Ended
	Sep. 30, 2020
Revenue From Contract With Customer [Abstract]
Revenue from contracts with customers	5. 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. 5. Revenue from contracts with customers, continued The Company generally charges customer accounts or otherwise bills customers upon completion of its services. Typically the Company’s contracts with customers have a duration of one year or less and payment for services is received at least annually, but oftentimes more frequently as services are provided. At September 30, 2020 and December 31, 2019, the Company had $61 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 Company’s consolidated balance sheet. In certain situations the Company is paid in advance of providing services and defers the recognition of revenue until its service obligation is satisfied. At September 30, 2020 and December 31, 2019, the Company had deferred revenue of $41 million and $43 million, respectively, related to the sources in the accompanying tables recorded in accrued interest and other liabilities in the consolidated balance sheet. The following tables summarize sources of the Company’s noninterest income during the three-month and nine-month periods ended September 30, 2020 and 2019 that are subject to the noted accounting guidance. Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total Three Months Ended September 30, 2020 (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 11,527 22,816 2,347 — — 53,379 1,286 $ 91,355 Trust income — 1 — — — — 149,936 149,937 Brokerage services income — — — — — — 11,602 11,602 Other revenues from operations: Merchant discount and credit card fees 10,533 10,785 492 — — 4,159 (315 ) 25,654 Other — 2,940 929 205 1,127 5,994 10,212 21,407 $ 22,060 36,542 3,768 205 1,127 63,532 172,721 $ 299,955 Three Months Ended September 30, 2019 Classification in consolidated statement of income Service charges on deposit accounts $ 15,131 23,427 2,415 — — 68,455 1,664 $ 111,092 Trust income 9 242 — — — — 143,664 143,915 Brokerage services income — — — — — — 12,077 12,077 Other revenues from operations: Merchant discount and credit card fees 9,692 13,409 670 — — 4,150 269 28,190 Other — 1,239 1,372 503 816 9,347 7,076 20,353 $ 24,832 38,317 4,457 503 816 81,952 164,750 $ 315,627 5. Revenue from contracts with customers, continued Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total Nine Months Ended September 30, 2020 (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 38,048 69,487 7,724 — — 155,073 4,639 $ 274,971 Trust income 18 442 — — — — 450,110 450,570 Brokerage services income — — — — — — 35,194 35,194 Other revenues from operations: Merchant discount and credit card fees 29,023 32,992 1,720 — — 9,880 261 73,876 Other — 5,913 2,960 1,212 3,101 15,142 32,149 60,477 $ 67,089 108,834 12,404 1,212 3,101 180,095 522,353 $ 895,088 Nine Months Ended September 30, 2019 Classification in consolidated statement of income Service charges on deposit accounts $ 45,415 69,731 7,303 — 4 195,267 4,271 $ 321,991 Trust income 21 680 — — — — 420,382 421,083 Brokerage services income — — — — — — 37,031 37,031 Other revenues from operations: Merchant discount and credit card fees 28,469 38,630 1,772 — — 11,854 1,291 82,016 Other — 5,386 5,840 1,545 2,913 27,170 26,159 69,013 $ 73,905 114,427 14,915 1,545 2,917 234,291 489,134 $ 931,134

Pension plans and other postret

Pension plans and other postretirement benefits	9 Months Ended
	Sep. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Pension plans and other postretirement benefits	6. Pension plans and other postretirement benefits The Company provides defined benefit pension and other postretirement benefits (including health care and life insurance benefits) to qualified retired employees. Net periodic defined benefit cost for defined benefit plans consisted of the following: Pension Benefits Other Postretirement Benefits Three Months Ended September 30 2020 2019 2020 2019 (In thousands) Service cost $ 4,986 4,324 242 215 Interest cost on projected benefit obligation 17,855 20,394 436 586 Expected return on plan assets (31,378 ) (30,534 ) — — Amortization of prior service cost (credit) 125 139 (1,175 ) (1,182 ) Amortization of net actuarial loss (gain) 13,950 5,498 (300 ) (312 ) Net periodic cost (benefit) $ 5,538 (179 ) (797 ) (693 ) Pension Benefits Other Postretirement Benefits Nine Months Ended September 30 2020 2019 2020 2019 (In thousands) Service cost $ 14,958 12,970 727 644 Interest cost on projected benefit obligation 53,565 61,184 1,306 1,758 Expected return on plan assets (94,134 ) (91,604 ) — — Amortization of prior service cost (credit) 404 418 (3,544 ) (3,547 ) Amortization of net actuarial loss (gain) 42,998 16,494 (918 ) (935 ) Net periodic cost (benefit) $ 17,791 (538 ) (2,429 ) (2,080 ) Service cost is reflected in salaries and employee benefits expense in the consolidated statement of income. The other components of net periodic benefit cost are reflected in other costs of operations. Expenses incurred in connection with the Company's defined contribution pension and retirement savings plans totaled $23 million and $21 million for the three months ended September 30, 2020 and 2019, respectively, and $73 million and $61 million for the nine months ended September 30, 2020 and 2019, respectively, and are included in salaries and employee benefits expense.

Earnings per common share

Earnings per common share	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Earnings per common share	7. Earnings per common share The computations of basic earnings per common share follow: Three Months Ended September 30 Nine Months Ended September 30 2020 2019 2020 2019 (In thousands, except per share) Income available to common shareholders: Net income $ 372,136 480,081 882,012 1,436,083 Less: Preferred stock dividends (17,050 ) (16,103 ) (51,178 ) (52,364 ) Net income available to common equity 355,086 463,978 830,834 1,383,719 Less: Income attributable to unvested stock-based compensation awards (1,687 ) (2,568 ) (3,631 ) (7,591 ) Net income available to common shareholders $ 353,399 461,410 827,203 1,376,128 Weighted-average shares outstanding: Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards 129,061 133,703 129,518 136,156 Less: Unvested stock-based compensation awards (776 ) (738 ) (768 ) (745 ) Weighted-average shares outstanding 128,285 132,965 128,750 135,411 Basic earnings per common share $ 2.75 3.47 6.42 10.16 The computations of diluted earnings per common share follow: Three Months Ended September 30 Nine Months Ended September 30 2020 2019 2020 2019 (In thousands, except per share) Net income available to common equity $ 355,086 463,978 830,834 1,383,719 Less: Income attributable to unvested stock-based compensation awards (1,686 ) (2,568 ) (3,630 ) (7,590 ) Net income available to common shareholders $ 353,400 461,410 827,204 1,376,129 Adjusted weighted-average shares outstanding: Common and unvested stock-based compensation awards 129,061 133,703 129,518 136,156 Less: Unvested stock-based compensation awards (776 ) (738 ) (768 ) (745 ) Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock 70 34 63 32 Adjusted weighted-average shares outstanding 128,355 132,999 128,813 135,443 Diluted earnings per common share $ 2.75 3.47 6.42 10.16 GAAP defines unvested share-based awards that contain nonforfeitable rights to dividends or dividend equivalents (whether paid or unpaid) as participating securities that shall be included in the computation of earnings per common share pursuant to the two-class method. The Company has issued stock-based compensation awards in the form of restricted stock and restricted stock units which, in accordance with GAAP, are considered participating securities. Stock-based compensation awards and warrants to purchase common stock of M&T representing 483,182 and 277,840 common shares during the three-month periods ended September 30, 2020 and 2019, respectively, and 477,144 and 224,639 common shares during the nine-month periods ended September 30, 2020 and 2019, respectively, were not included in the computations of diluted earnings per common share because the effect on those periods would have been antidilutive.

Comprehensive income

Comprehensive income	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Comprehensive income	8. Comprehensive income The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other comprehensive income (loss) to net income: Investment Defined Benefit Total Amount Income Securities Plans Other Before Tax Tax Net (In thousands) Balance — January 1, 2020 $ 50,701 (464,548 ) 133,888 $ (279,959 ) 73,279 $ (206,680 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 151,777 — — 151,777 (39,277 ) 112,500 Foreign currency translation adjustment — — (222 ) (222 ) (39 ) (261 ) Unrealized gains on cash flow hedges — — 508,226 508,226 (131,504 ) 376,722 Total other comprehensive income before reclassifications 151,777 — 508,004 659,781 (170,820 ) 488,961 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities 2,678 — — 2,678 (a) (725 ) 1,953 Gains realized in net income (3 ) — — (3 ) (b) 1 (2 ) Accretion of net gain on terminated cash flow hedges — (94 ) (94 ) (c) 26 (68 ) Net yield adjustment from cash flow hedges currently in effect — — (183,598 ) (183,598 ) (a) 47,506 (136,092 ) Amortization of prior service credit — (3,140 ) — (3,140 ) (d) 927 (2,213 ) Amortization of actuarial losses — 42,080 — 42,080 (d) (12,436 ) 29,644 Total other comprehensive income 154,452 38,940 324,312 517,704 (135,521 ) 382,183 Balance — September 30, 2020 $ 205,153 (425,608 ) 458,200 $ 237,745 (62,242 ) $ 175,503 Balance — January 1, 2019 $ (200,107 ) (354,502 ) (14,719 ) $ (569,328 ) 149,247 $ (420,081 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 237,615 — — 237,615 (62,432 ) 175,183 Foreign currency translation adjustment — — (2,663 ) (2,663 ) 559 (2,104 ) Unrealized gains on cash flow hedges — — 204,587 204,587 (53,786 ) 150,801 Total other comprehensive income before reclassifications 237,615 — 201,924 439,539 (115,659 ) 323,880 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities 2,524 — — 2,524 (a) (663 ) 1,861 Losses realized in net income 7 — — 7 (b) (2 ) 5 Accretion of net gain on terminated cash flow hedges — — (93 ) (93 ) (c) 25 (68 ) Net yield adjustment from cash flow hedges currently in effect — — 6,693 6,693 (a) (1,760 ) 4,933 Amortization of prior service credit — (3,129 ) — (3,129 ) (d) 823 (2,306 ) Amortization of actuarial losses — 15,559 — 15,559 (d) (4,091 ) 11,468 Total other comprehensive income 240,146 12,430 208,524 461,100 (121,327 ) 339,773 Balance — September 30, 2019 $ 40,039 (342,072 ) 193,805 $ (108,228 ) 27,920 $ (80,308 ) (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. 8. Comprehensive income, continued Accumulated other comprehensive income (loss), net consisted of the following: Defined Cash Flow Investment Benefit Hedges Securities Plans and Total (In thousands) Balance — December 31, 2019 $ 37,380 (342,419 ) 98,359 $ (206,680 ) Net gain during period 114,451 27,431 240,301 382,183 Balance — September 30, 2020 $ 151,831 (314,988 ) 338,660 $ 175,503

Derivative financial instrument

Derivative financial instruments	9 Months Ended
	Sep. 30, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative financial instruments	9. Derivative financial instruments As part of managing interest rate risk, the Company enters into interest rate swap agreements to modify the repricing characteristics of certain portions of the Company’s portfolios of earning assets and interest-bearing liabilities. The Company designates interest rate swap agreements utilized in the management of interest rate risk as either fair value hedges or cash flow hedges. Interest rate swap agreements are generally entered into with counterparties that meet established credit standards and most contain master netting, collateral and/or settlement provisions protecting the at-risk party. Based on adherence to the Company’s credit standards and the presence of the netting, collateral or settlement provisions, the Company believes that the credit risk inherent in these contracts was not material as of September 30, 2020. The net effect of interest rate swap agreements was to increase net interest income by $95 million and $212 million during the three-month and nine-month periods ended September 30, 2020, respectively, and to increase net interest income by $1 million during the three-month period ended September 30, 2019 and decrease net interest income by $23 million during the nine-month period ended September 30, 2019. 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 September 30, 2020 Fair value hedges: Fixed rate long-term borrowings (b) $ 2,300,000 2.7 2.80 % 0.69 % $ (513 ) Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(c) 52,250,000 1.1 2.40 % 0.15 % 890 Total $ 54,550,000 1.1 $ 377 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) Certain clearinghouse exchanges consider payments by counterparties for variation margin on derivative instruments to be settlements of those positions. The impact of such treatment at September 30, 2020 and December 31, 2019 was a reduction of the estimated fair value gains on interest rate swap agreements designated as fair value hedges of $120.8 million and $45.1 million, respectively, and on interest rate swap agreements designated as cash flow hedges of $463.3 million and $140.7 million, respectively. (b) Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate. (c) (d) . 9. Derivative financial instruments, continued 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 $36.6 billion and $48.6 billion at September 30, 2020 and December 31, 2019, respectively. The notional amounts of foreign currency and other option and futures contracts entered into for trading account purposes aggregated $877 million and $1.2 billion at September 30, 2020 and December 31, 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 September 30, December 31, September 30, December 31, 2020 2019 2020 2019 (In thousands) Derivatives designated and qualifying as hedging instruments Interest rate swap agreements (a) $ 1,710 $ 232 $ 1,333 $ 1,994 Commitments to sell real estate loans (a) 1,525 1,195 2,264 421 3,235 1,427 3,597 2,415 Derivatives not designated and qualifying as hedging instruments Mortgage-related commitments to originate real estate loans for sale (a) 51,786 11,965 283 1,225 Commitments to sell real estate loans (a) 1,795 3,074 11,066 3,548 Trading: Interest rate contracts (b) 1,157,856 398,295 115,361 68,103 Foreign exchange and other option and futures contracts (b) 7,694 12,506 7,624 11,800 1,219,131 425,840 134,334 84,676 Total derivatives $ 1,222,366 $ 427,267 $ 137,931 $ 87,091 (a) Asset derivatives are reported in other assets and liability derivatives are reported in other liabilities. (b) Asset derivatives are reported in trading account assets and liability derivatives are reported in other liabilities. The impact of variation margin payments at September 30, 2020 and December 31, 2019 was a reduction of the estimated fair value of interest rate contracts in the trading account in an asset position of $2.9 million and $43.3 million, respectively, and in a liability position of $944.9 million and $281.3 million, respectively. Amount of Gain (Loss) Recognized Three Months Ended September 30, 2020 Three Months Ended September 30, 2019 Derivative Hedged Item Derivative Hedged Item (In thousands) Derivatives in fair value hedging relationships Interest rate swap agreements: Fixed rate long-term borrowings (a) $ (13,067 ) 12,822 $ 22,582 (22,412 ) Derivatives not designated as hedging instruments Trading: Interest rate contracts (b) $ (4,776 ) $ 6,435 Foreign exchange and other option and futures contracts (b) 1,486 2,598 Total $ (3,290 ) $ 9,033 9. Derivative financial instruments, continued Amount of Gain (Loss) Recognized Nine Months Ended September 30, 2020 Nine Months Ended September 30, 2019 Derivative Hedged Item Derivative Hedged Item (In thousands) Derivatives in fair value hedging relationships Interest rate swap agreements: Fixed rate long-term borrowings (a) $ 75,760 (75,607 ) $ 113,441 (112,884 ) Derivatives not designated as hedging instruments Trading: Interest rate contracts (b) $ 8,988 $ 17,639 Foreign exchange and other option and futures contracts (b) 6,555 6,690 Total $ 15,543 $ 24,329 (a) Reported as an adjustment to interest expense. (b) Reported as trading account and foreign exchange gains. Carrying Amount of the Hedged Item Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item September 30, 2020 December 31, 2019 September 30, 2020 December 31, 2019 (In thousands) Location in the of the Hedged Items in Fair Value Long-term debt $ 2,417,559 $ 3,840,775 $ 119,247 $ 43,640 The amount of gain (loss) recognized in the consolidated statement of income associated with derivatives designated as cash flow hedges was not material. The Company also has commitments to sell and commitments to originate residential and commercial real estate loans that are considered derivatives. The Company designates certain of the commitments to sell real estate loans as fair value hedges of real estate loans held for sale. The Company also utilizes commitments to sell real estate loans to offset the exposure to changes in the fair value of certain commitments to originate real estate loans for sale. As a result of these activities, net unrealized pre-tax gains related to hedged loans held for sale, commitments to originate loans for sale and commitments to sell loans were approximately $66 million and $18 million at September 30, 2020 and December 31, 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. 9. Derivative financial instruments, continued The aggregate fair value of derivative financial instruments in a liability position and the net liability positions with counterparties, which are subject to master netting arrangements, was $127 million and $51 million at September 30, 2020 and December 31, 2019, respectively. The Company was required to post collateral relating to those positions of $123 million and $50 million at September 30, 2020 and December 31, 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 rating were to fall below specified ratings, the counterparties of the derivative financial instruments could demand immediate incremental collateralization on those instruments in a net liability position. The aggregate fair value of all derivative financial instruments with such credit risk-related contingent features in a net liability position on September 30, 2020 was not significant. 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 nil at September 30, 2020 and $6 million at December 31, 2019. Counterparties posted collateral relating to those positions of $5 million at December 31, 2019. 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 $125 million and $84 million at September 30, 2020 and December 31, 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.

Variable interest entities and

Variable interest entities and asset securitizations	9 Months Ended
	Sep. 30, 2020
Text Block [Abstract]
Variable interest entities and asset securitizations	10. 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 during the nine-month periods ended September 30, 2020 and 2019 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 4, M&T has issued junior subordinated debentures payable to various trusts that have issued Capital Securities. M&T owns the common securities of those trust entities. The Company is not considered to be the primary beneficiary of those entities and, accordingly, the trusts are not included in the Company’s consolidated financial statements. At each of September 30, 2020 and December 31, 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 4. 10. Variable interest entities and asset securitizations, continued The Company has invested as a limited partner in various partnerships that collectively had total assets of approximately $2.1 billion at September 30, 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 $791 million, including $380 million of unfunded commitments, at September 30, 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 September 30, 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 September 30, 2020 was $978 million, including possible recapture of certain tax credits. Management currently estimates that no material losses are probable as a result of the Company’s involvement with such entities. The Company, in its position as limited partner, does not direct the activities that most significantly impact the economic performance of the partnerships and, therefore, in accordance with the accounting provisions for variable interest entities, the partnership entities are not included in the Company’s consolidated financial statements. The Company’s investment in qualified affordable housing projects is amortized to income taxes in the consolidated statement of income as tax credits and other tax benefits resulting from deductible losses associated with the projects are received. The Company 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	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair value measurements	11. Fair value measurements GAAP permits an entity to choose to measure eligible financial instruments and other items at fair value. The Company has not made any fair value elections at September 30, 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, 11. Fair value measurements, continued prepayment speeds and credit losses. Assets and liabilities valued using model-based techniques are classified as either Level 2 or Level 3, depending on the lowest level classification of an input that is considered significant to the overall valuation. The following is a description of the valuation methodologies used for the Company's assets and liabilities that are measured on a recurring basis at estimated fair value. Trading account assets and liabilities Trading account assets and liabilities consist primarily of interest rate contracts and foreign exchange contracts with customers who require such services with offsetting positions with third parties to minimize the Company's risk with respect to such transactions. The Company generally determines the fair value of its derivative trading account assets and liabilities using externally developed pricing models based on market observable inputs and, therefore, classifies such valuations as Level 2. Mutual funds held in connection with deferred compensation and other arrangements have been classified as Level 1 valuations. Valuations of investments in municipal and other bonds can generally be obtained through reference to quoted prices in less active markets for the same or similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2. Investment securities available for sale and equity securities The majority of the Company's available-for-sale investment securities have been valued by reference to prices for similar securities or through model-based techniques in which all significant inputs are observable and, therefore, such valuations have been classified as Level 2. Certain investments in mutual funds and equity securities are actively traded and, therefore, have been classified as Level 1 valuations. Real estate loans held for sale The Company utilizes commitments to sell real estate loans to hedge the exposure to changes in fair value of real estate loans held for sale. The carrying value of hedged real estate loans held for sale includes changes in estimated fair value during the hedge period. Typically, the Company attempts to hedge real estate loans held for sale from the date of close through the sale date. The fair value of hedged real estate loans held for sale is generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans with similar characteristics and, accordingly, such loans have been classified as a Level 2 valuation. Commitments to originate real estate loans for sale and commitments to sell real estate loans The Company enters into various commitments to originate real estate loans for sale and commitments to sell real estate loans. Such commitments are considered to be derivative financial instruments and, therefore, are carried at estimated fair value on the consolidated balance sheet. The estimated fair values of such commitments were generally calculated by reference to quoted prices in secondary markets for commitments to sell real estate loans to certain government-sponsored entities and other parties. The fair valuations of commitments to sell real estate loans generally result in a Level 2 classification. The estimated fair value of commitments to originate real estate loans for sale are adjusted to reflect the Company's anticipated commitment expirations. The estimated commitment expirations are considered significant unobservable inputs contributing to the Level 3 classification of commitments to originate real estate loans for sale. Significant unobservable inputs used in the determination of estimated fair value of commitments to originate real estate loans for sale are included in the accompanying table of significant unobservable inputs to Level 3 measurements. Interest rate swap agreements used for interest rate risk management The Company utilizes interest rate swap agreements as part of the management of interest rate risk to modify the repricing characteristics of certain portions of its portfolios of earning assets and interest-bearing liabilities. The Company generally determines the fair value of its interest rate swap agreements using externally developed pricing 11. Fair value measurements, continued 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 September 30, 2020 and December 31, 2019 measured at estimated fair value on a recurring basis: Fair Value Measurements Level 1 Level 2 Level 3 (In thousands) September 30, 2020 Trading account assets $ 1,215,573 $ 50,023 $ 1,165,550 $ — Investment securities available for sale: U.S. Treasury and federal agencies 9,370 — 9,370 — Mortgage-backed securities: Government issued or guaranteed 5,165,701 — 5,165,701 — Privately issued 16 — — 16 Other debt securities 127,251 — 127,251 — 5,302,338 — 5,302,322 16 Equity securities 101,182 72,856 28,326 — Real estate loans held for sale 909,335 — 909,335 — Other assets (a) 56,816 — 5,030 51,786 Total assets $ 7,585,244 $ 122,879 $ 7,410,563 $ 51,802 Trading account liabilities $ 122,985 $ — $ 122,985 $ — Other liabilities (a) 14,946 — 14,663 283 Total liabilities $ 137,931 $ — $ 137,648 $ 283 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) Comprised predominantly of interest rate swap agreements used for interest rate risk management (Level 2), commitments to sell real estate loans (Level 2) and commitments to originate real estate loans to be held for sale (Level 3). 11. Fair value measurements, continued The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the three months ended September 30, 2020 and 2019 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets 2020 (In thousands) Balance — June 30, 2020 $ 16 40,106 Total gains realized/unrealized: Included in earnings — 57,819 (a) Settlements — — Transfers out of Level 3 — (46,422 ) (b) Balance — September 30, 2020 $ 16 51,503 Changes in unrealized gains included in earnings related to assets still held at September 30, 2020 $ — 44,127 (a) 2019 Balance — June 30, 2019 $ 16 17,200 Total gains realized/unrealized: Included in earnings — 62,178 (a) Settlements — — Transfers out of Level 3 — (55,104 ) (b) Balance — September 30, 2019 $ 16 24,274 Changes in unrealized gains included in earnings related to assets still held at September 30, 2019 $ — 19,350 (a) 11. Fair value measurements, continued The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the nine months ended September 30, 2020 and 2019 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets 2020 (In thousands) Balance — January 1, 2020 $ 16 10,740 Total gains realized/unrealized: Included in earnings — 150,632 (a) Settlements — — Transfers out of Level 3 — (109,869 ) (b) Balance — September 30, 2020 $ 16 51,503 Changes in unrealized gains included in earnings related to assets still held at September 30, 2020 $ — 50,411 (a) 2019 Balance — January 1, 2019 $ 22 7,712 Total gains realized/unrealized: Included in earnings — 115,187 (a) Settlements (6 ) — Transfers out of Level 3 — (98,625 ) (b) Balance — September 30, 2019 $ 16 24,274 Changes in unrealized gains included in earnings related to assets still held at September 30, 2019 $ — 24,981 (a) (a) Reported as mortgage banking revenues in the consolidated statement of income and includes the fair value of commitment issuances and expirations. (b) Transfers out of Level 3 consist of interest rate locks transferred to closed loans. The Company is required, on a nonrecurring basis, to adjust the carrying value of certain assets or provide valuation allowances related to certain assets using fair value measurements. The more significant of those assets follow. Loans Loans are generally not recorded at fair value on a recurring basis. Periodically, the Company records nonrecurring adjustments to the carrying value of loans based on fair value measurements for partial charge-offs of the uncollectible portions of those loans. Nonrecurring adjustments also include certain impairment amounts for collateral-dependent loans when establishing the allowance for credit losses. Such amounts are generally based on the fair value of the underlying collateral supporting the loan and, as a result, the carrying value of the loan less the calculated valuation amount does not necessarily represent the fair value of the loan. Real estate collateral is typically valued using appraisals or other indications of value based on recent comparable sales of similar properties or assumptions generally observable in the marketplace and the related nonrecurring fair value measurement adjustments have 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 11. Fair value measurements, continued specific borrower facts and circumstances and the experience of credit personnel in their dealings with similar borrower collateral liquidations. Such discounts were in the range of 15% to 90% with a weighted-average of 59% at September 30, 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 nonrecurring fair value measurement adjustments have been classified as Level 2. Collateral values for other consumer installment loans are generally estimated based on historical recovery rates for similar types of loans, which at September 30, 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 $387 million at September 30, 2020 ($159 million and $228 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 $302 million at September 30, 2019 ($122 million and $180 million of which were classified as Level 2 and Level 3, respectively). Changes in fair value recognized for partial charge-offs of loans and loan impairment reserves on loans held by the Company on September 30, 2020 were decreases of $82 million and $153 million for the three-month and nine-month periods ended September 30, 2020, respectively. Changes in fair value recognized for partial charge-offs of loans and loan impairment reserves on loans held by the Company on September 30, 2019 were decreases of $51 million and $85 million for the three-month and nine-month periods ended September 30, 2019, respectively. 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 $27 million and $17 million at September 30, 2020 and 2019, respectively. Changes in fair value recognized for those foreclosed assets held by the Company were not material during the three-month and nine-month periods ended September 30, 2020 and 2019. 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 $165 million and $188 million at September 30, 2020 and December 31, 2019, respectively, required a valuation allowance of $27 million and $7 million, respectively. Significant unobservable inputs used in this Level 3 valuation included weighted-average prepayment speeds of 17.19% and 18.50% at September 30, 2020 and December 31, 2019, respectively, and a weighted-average option-adjusted spread of 900 basis points at each date. There was no impairment charge for 11. Fair value measurements, continued capitalized servicing rights during the three months ended September 30, 2020, but a $20 million valuation charge was recognized during the nine months ended September 30, 2020. Changes recognized for impairment of capitalized servicing rights were $14 million and $23 million for the three months and nine months ended September 30, 2019, respectively. Significant unobservable inputs to Level 3 measurements The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for certain Level 3 assets and liabilities at September 30, 2020 and December 31, 2019: Fair Value Valuation Technique Unobservable Inputs/Assumptions Range (Weighted- Average) (In September 30, 2020 Recurring fair value measurements Privately issued mortgage- backed securities $ 16 Two independent pricing quotes — — Net other assets (liabilities) (a) 51,503 Discounted cash flow Commitment expirations 0% - 90%(18%) 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) Other Level 3 assets (liabilities) consist of commitments to originate real estate loans. Sensitivity of fair value measurements to changes in unobservable inputs An increase (decrease) in the estimate of expirations for commitments to originate real estate loans would generally result in a lower (higher) 11. Fair value measurements, continued Disclosures of fair value of financial instruments The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following table: September 30, 2020 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,489,232 1,489,232 1,437,569 51,663 — Interest-bearing deposits at banks 20,197,937 20,197,937 — 20,197,937 — Trading account assets 1,215,573 1,215,573 50,023 1,165,550 — Investment securities 7,723,004 7,816,236 72,856 7,670,141 73,239 Loans and leases: Commercial loans and leases 27,891,648 27,422,525 — — 27,422,525 Commercial real estate loans 37,582,084 36,343,024 — 336,039 36,006,985 Residential real estate loans 16,663,708 16,935,950 — 4,070,917 12,865,033 Consumer loans 16,309,608 16,149,710 — — 16,149,710 Allowance for credit losses (1,758,505 ) — — — — Loans and leases, net 96,688,543 96,851,209 — 4,406,956 92,444,253 Accrued interest receivable 429,751 429,751 — 429,751 — Financial liabilities: Noninterest-bearing deposits $ (44,201,670 ) (44,201,670 ) — (44,201,670 ) — Savings and interest-checking deposits (65,732,130 ) (65,732,130 ) — (65,732,130 ) — Time deposits (4,329,550 ) (4,357,963 ) — (4,357,963 ) — Deposits at Cayman Islands office (899,989 ) (899,989 ) — (899,989 ) — Short-term borrowings (46,123 ) (46,123 ) — (46,123 ) — Long-term borrowings (5,458,885 ) (5,540,675 ) — (5,540,675 ) — Accrued interest payable (66,158 ) (66,158 ) — (66,158 ) — Trading account liabilities (122,985 ) (122,985 ) — (122,985 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 51,503 51,503 — — 51,503 Commitments to sell real estate loans (10,010 ) (10,010 ) — (10,010 ) — Other credit-related commitments (135,416 ) (135,416 ) — — (135,416 ) Interest rate swap agreements used for interest rate risk management 377 377 — 377 — 11. Fair value measurements, continued 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,

Commitments and contingencies

Commitments and contingencies	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and contingencies	12. 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. September 30, December 31, 2020 2019 (In thousands) Commitments to extend credit Home equity lines of credit $ 5,557,722 $ 5,442,160 Commercial real estate loans to be sold 216,353 164,076 Other commercial real estate 8,031,403 9,029,608 Residential real estate loans to be sold 1,134,097 423,056 Other residential real estate 712,964 448,375 Commercial and other 19,921,166 16,170,731 Standby letters of credit 2,354,799 2,441,432 Commercial letters of credit 32,422 41,059 Financial guarantees and indemnification contracts 4,250,654 4,108,572 Commitments to sell real estate loans 1,895,436 906,037 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 in the preceding table, the Company had discretionary funding commitments to commercial customers of $10.1 billion and $9.1 billion at September 30, 2020 and December 31, 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 oftentimes similar to standby letters of credit and include mandatory purchase agreements issued to ensure that customer obligations are fulfilled, recourse obligations associated with sold loans, and other guarantees of customer performance or compliance with designated rules and regulations. Included in financial guarantees and indemnification contracts are loan principal amounts sold with recourse in conjunction with the Company's involvement in the Fannie Mae Delegated Underwriting and Servicing program. The Company's maximum credit risk for recourse associated with loans sold under this program totaled approximately $3.9 billion at each of September 30, 2020 and December 31, 2019. Since many loan commitments, standby letters of credit, and guarantees and indemnification contracts expire without being funded in whole or in part, the contract amounts are not necessarily indicative of future cash flows. The Company utilizes commitments to sell real estate loans to hedge exposure to changes in the fair value of real estate loans held for sale. Such commitments are considered derivatives and along with commitments to originate real estate loans to be held for sale are generally recorded in the consolidated balance sheet at estimated fair market value. The Company 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. 12. Commitments and contingencies, continued The amount of those charges is based on the volume of loans sold, the level of reimbursement requests received from loan purchasers and estimates of losses that may be associated with previously sold loans. At September 30, 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 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 pending or threatened litigation could result in exposure in excess of the recorded liability, the amount of such excess is not currently estimable. Although not considered probable, the range of reasonably possible losses for such matters in the aggregate, beyond the existing recorded liability, was estimated to be between $0 and $25 million as of September 30, 2020. Although the Company does not believe that the outcome of pending legal matters will be material to the Company’s consolidated financial position, it cannot rule out the possibility that such outcomes will be material to the consolidated results of operations for a particular reporting period in the future.

Segment information

Segment information	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment information	13. Segment information Reportable segments have been determined based upon the Company's internal profitability reporting system, which is organized by strategic business unit. Certain strategic business units have been combined for segment information reporting purposes where the nature of the products and services, the type of customer and the distribution of those products and services are similar. The reportable segments are Business Banking, Commercial Banking, Commercial Real Estate, Discretionary Portfolio, Residential Mortgage Banking and Retail Banking. The financial information of the Company's segments was compiled utilizing the accounting policies described in note 22 of Notes to Financial Statements in the 2019 Annual Report. The management accounting policies and processes utilized in compiling segment financial information are highly subjective and, unlike financial accounting, are not based on authoritative guidance similar to GAAP. As a result, the financial information of the reported segments is not necessarily comparable with similar information reported by other financial institutions. Furthermore, changes in management structure or allocation methodologies and procedures may result in changes in reported segment financial data. 13. Segment information, continued Information about the Company's segments is presented in the following table: Three Months Ended September 30 2020 2019 Total Revenues(a) Inter- segment Revenues Net Income (Loss) Total Revenues(a) Inter- segment Revenues Net Income (Loss) (In thousands) Business Banking $ 131,566 (1 ) 35,614 $ 143,741 912 46,147 Commercial Banking 276,125 117 131,414 282,757 980 132,668 Commercial Real Estate 202,987 (17 ) 87,095 238,364 458 131,161 Discretionary Portfolio 140,135 (10,748 ) 97,399 50,871 (10,550 ) 29,604 Residential 161,151 22,190 45,318 115,239 19,363 15,846 Retail Banking 351,312 268 85,229 432,339 1,808 131,638 All Other 200,380 (11,809 ) (109,933 ) 294,358 (12,971 ) (6,983 ) Total $ 1,463,656 — 372,136 $ 1,557,669 — 480,081 Nine Months Ended September 30 2020 2019 Total Revenues(a) Inter- segment Revenues Net Income (Loss) Total Revenues(a) Inter- segment Revenues Net Income (Loss) (In thousands) Business Banking $ 407,485 1,028 106,103 $ 423,830 2,772 131,668 Commercial Banking 855,426 1,419 386,176 828,357 2,707 388,393 Commercial Real Estate 653,405 452 311,586 682,979 1,218 370,288 Discretionary Portfolio 328,181 (33,646 ) 218,758 175,764 (29,140 ) 106,816 Residential Mortgage Banking 428,757 64,623 107,334 295,449 51,027 36,429 Retail Banking 1,107,516 802 281,973 1,299,823 7,106 417,198 All Other 633,461 (34,678 ) (529,918 ) 955,868 (35,690 ) (14,709 ) Total $ 4,414,231 — 882,012 $ 4,662,070 — 1,436,083 13. Segment information, continued Average Total Assets Nine Months Ended September 30 Year Ended December 2020 2019 2019 (In millions) Business Banking $ 7,902 5,758 5,793 Commercial Banking 30,450 28,089 28,142 Commercial Real Estate 25,594 23,893 23,921 Discretionary Portfolio 27,878 29,355 29,081 Residential Mortgage Banking 3,530 2,444 2,611 Retail Banking 16,231 14,839 15,083 All Other 20,845 14,206 14,953 Total $ 132,430 118,584 119,584 (a) Total revenues are comprised of net interest income and other income. Net interest income is the difference between taxable-equivalent interest earned on assets and interest paid on liabilities owed by a segment and a funding charge (credit) based on the Company's internal funds transfer and allocation methodology. Segments are charged a cost to fund any assets (e.g. loans) and are paid a funding credit for any funds provided (e.g. deposits). The taxable-equivalent adjustment aggregated $4,019,000 and $5,579,000 for the three-month periods ended September 30, 2020 and 2019, respectively, and $13,316,000 and $17,471,000 for the nine-month periods ended September 30, 2020 and 2019, respectively, and is eliminated in "All Other" total revenues. Intersegment revenues are included in total revenues of the reportable segments. The elimination of intersegment revenues is included in the determination of "All Other" total revenues

Relationship with Bayview Lendi

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.	9 Months Ended
	Sep. 30, 2020
Text Block [Abstract]
Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P.	14. Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. M&T holds a minority interest in Bayview Lending Group LLC ("BLG"), a privately-held commercial mortgage company. That investment had no remaining carrying value Bayview Financial Holdings, L.P. (together with its affiliates, "Bayview Financial"), a privately-held specialty finance company, is BLG's majority investor. In addition to their common investment in BLG, the Company and Bayview Financial conduct other business activities with each other. The Company has obtained loan servicing rights for mortgage loans from BLG and Bayview Financial having outstanding principal balances of $2.0 billion and $2.2 billion at September 30, 2020 and December 31, 2019, respectively. Revenues from those servicing rights were $2 million and $3 million for the three-month periods ended September 30, 2020 and 2019, respectively, and $7 million and $9 million for the nine-month periods ended September 30, 2020 and 2019, respectively. The Company sub-services residential mortgage loans for Bayview Financial having outstanding principal balances of $67.0 billion and $62.8 billion at September 30, 2020 and December 31, 2019, respectively. Revenues earned for sub-servicing loans for Bayview Financial were $30 million and $33 million for the three-month periods ended September 30, 2020 and 2019, respectively and $101 million and $90 million for the nine-month periods ended September 30, 2020 and 2019, respectively. In addition, the Company held $80 million and $93 million of mortgage-backed securities in its held-to-maturity portfolio at September 30, 2020 and December 31, 2019, respectively, that were securitized by Bayview Financial. At September 30, 2020, the Company held $164 million of Bayview Financial’s $1.0 billion syndicated loan facility. Also, in the second quarter 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 September 30, 2020 with a remaining balance of $87 million.

Recent accounting developments

Recent accounting developments	9 Months Ended
	Sep. 30, 2020
Accounting Changes And Error Corrections [Abstract]
Recent accounting developments	15. 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 replaces 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 will represent a valuation account that is deducted from the amortized cost basis of the financial assets to present their net carrying value at the amount expected to be collected. The income statement will reflect the measurement of credit losses for newly recognized financial assets as well as expected increases or decreases of expected credit losses that have taken place during the period. When determining the allowance, expected credit losses over the contractual term of the financial asset(s) (taking into account prepayments) will be estimated considering relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. The amended guidance also requires recording an allowance for credit losses for purchased financial assets with a more-than-insignificant amount of credit deterioration since origination. The initial allowance for these assets will be added to the purchase price at acquisition rather than being reported as an expense. Subsequent changes in the allowance will be recorded 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 two-year reasonable and supportable forecast period. Subsequent to the forecast period, the Company reverts to longer term historical loss experience to estimate expected credit losses over the remaining contractual life. 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 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. 15. Recent accounting developments, continued 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 amended guidance modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurements. The amendments are a result of the disclosure framework project that focuses on improvements to the effectiveness of disclosures in the notes to financial statements. The amendments remove, modify, and add certain disclosure requirements. The disclosure requirements 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 guidance effective January 1, 2020. A prospective transition method is being used for the amendments relating to disclosures being added under the guidance. 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. All other amendments relating to removing or modifying certain disclosures are applied retrospectively. 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 Subtopic 350-40 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 nine months ended September 30,2020. 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. 15. Recent accounting developments, continued Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of September 30, 2020 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, 2021 Early adoption permitted The amendments should be applied retrospectively. The Company does not expect the guidance to have a material impact on its consolidated financial statements. 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 amendments should be applied on a prospective basis. The Company does not expect the guidance will have a material impact on its consolidated financial statements. 15. Recent accounting developments, continued Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of September 30, 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 amendments related to separate financial statements of legal entities that are not subject to tax should be applied on a retrospective basis for all periods presented. The amendments related to changes in ownership of foreign equity method investments or foreign subsidiaries should be applied on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. The amendments related to franchise taxes that are partially based on income should be applied on either a retrospective basis for all periods presented or a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption. All other amendments should be applied on a prospective basis. Early adoption of the amendments in an interim period would require recognition of any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an early adoption election would require adoption of all the amendments in the same period. The Company does not expect the guidance to have a material impact on its consolidated financial statements. 15. Recent accounting developments, continued Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of September 30, 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 The amendments for contract modifications can be elected to be applied as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from a date within an interim period that includes or is subsequent to March 12, 2020. The amendments for existing hedging relationships can be elected to be applied as of the beginning of the interim period that includes March 12, 2020 and to new eligible hedging relationships entered into after the beginning of the interim period that includes March 12, 2020. The Company does not expect the guidance to have a material impact on its consolidated financial statements. 15. Recent accounting developments, continued Standard Description Required date of adoption Effect on consolidated financial statements Standards Not Yet Adopted as of September 30, 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. Clarifiy 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.

Significant accounting polici_2

Significant accounting policies and current environment (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Accounting	The consolidated interim financial statements of M&T Bank Corporation (“M&T”) and subsidiaries (“the Company”) were compiled in accordance with generally accepted accounting principles (“GAAP”) using the accounting policies set forth in note 1 of Notes to Financial Statements included in Form 10-K for the year ended December 31, 2019 (“2019 Annual Report”), except that effective January 1, 2020 the Company adopted accounting guidance related to the recognition of expected credit losses that is discussed in notes 2, 3 and 15 herein. The financial statements contain all adjustments which are, in the opinion of management, necessary for a fair statement of the Company’s financial position, results of operations and cash flows for the interim periods presented.
Risk and Uncertainty	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 economic activity that severely hampered the ability for businesses and consumers to meet their repayment obligations. The effects of the pandemic contributed to a significant increase in the provision for credit losses during the first nine months of 2020. The Coronavirus Aid, Relief, and Economic Security Act (“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. That 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 generally 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, fee waivers, extensions of repayment term, or other delays in payment. 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 previously described, the modified loans have not been classified as troubled debt restructurings nor reported as past due.

Investment securities (Tables)

Investment securities (Tables)	9 Months Ended
	Sep. 30, 2020
Investments Debt And Equity Securities [Abstract]
Amortized Cost and Estimated Fair Value of Investment Securities	The amortized cost and estimated fair value of investment securities were as follows: Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value (In thousands) September 30, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 9,154 $ 226 $ 10 $ 9,370 Mortgage-backed securities: Government issued or guaranteed 4,944,979 221,561 839 5,165,701 Privately issued 16 — — 16 Other debt securities 135,915 1,328 9,992 127,251 5,090,064 223,115 10,841 5,302,338 Investment securities held to maturity: U.S. Treasury and federal agencies 3,000 — — 3,000 Obligations of states and political subdivisions 1,855 10 — 1,865 Mortgage-backed securities: Government issued or guaranteed 1,850,864 100,104 92 1,950,876 Privately issued 80,013 11,010 17,800 73,223 Other debt securities 2,962 — — 2,962 1,938,694 111,124 17,892 2,031,926 Total debt securities $ 7,028,758 $ 334,239 $ 28,733 $ 7,334,264 Equity and other securities: Readily marketable equity — at fair value $ 77,708 $ 23,474 $ — $ 101,182 Other — at cost 380,790 — — 380,790 Total equity and other securities $ 458,498 $ 23,474 $ — $ 481,972 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
Amortized Cost And Estimated Fair Value Of Debt Securities By Contractual Maturity Table Text Block	At September 30, 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 $ 5,197 5,207 Due after one year through five years 11,446 12,009 Due after five years through ten years 98,426 95,033 Due after ten years 30,000 24,372 145,069 136,621 Mortgage-backed securities available for sale 4,944,995 5,165,717 $ 5,090,064 5,302,338 Debt securities held to maturity: Due in one year or less $ 4,680 4,688 Due after one year through five years 175 177 Due after ten years 2,962 2,962 7,817 7,827 Mortgage-backed securities held to maturity 1,930,877 2,024,099 $ 1,938,694 2,031,926
Investment Securities in Continuous Unrealized Loss Position	A summary of investment securities that as of September 30, 2020 and December 31, 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) September 30, 2020 Investment securities available for sale: U.S. Treasury and federal agencies $ 985 (10 ) — — Mortgage-backed securities: Government issued or guaranteed 20,313 (364 ) 21,735 (475 ) Other debt securities 42,385 (1,087 ) 62,659 (8,905 ) 63,683 (1,461 ) 84,394 (9,380 ) Investment securities held to maturity: Mortgage-backed securities: Government issued or guaranteed 11,357 (92 ) — — Privately issued 7,476 (32 ) 46,048 (17,768 ) 18,833 (124 ) 46,048 (17,768 ) Total $ 82,516 (1,585 ) 130,442 (27,148 ) 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 and the allo_2

Loans and leases and the allowance for credit losses (Tables)	9 Months Ended
	Sep. 30, 2020
Receivables [Abstract]
Summary of Current, Past Due and Nonaccrual Loans	A summary of current, past due and nonaccrual loans as of September 30, 2020 and December 31, 2019 follows: Current 30-89 Days Past Due Accruing Loans Due 90 Days or More Nonaccrual Total (In thousands) September 30, 2020 Commercial, financial, leasing, etc. $ 27,249,552 282,917 8,551 350,628 $ 27,891,648 Real estate: Commercial 27,250,676 197,881 8,189 252,515 27,709,261 Residential builder and developer 1,353,863 7,282 — 1,833 1,362,978 Other commercial construction 8,405,525 66,599 94 37,627 8,509,845 Residential 13,934,309 185,420 503,450 297,636 14,920,815 Residential — limited documentation 1,606,130 20,980 — 115,783 1,742,893 Consumer: Home equity lines and loans 4,000,829 22,209 — 78,820 4,101,858 Recreational finance 6,838,126 36,003 — 24,191 6,898,320 Automobile 3,829,968 42,906 — 42,374 3,915,248 Other 1,337,042 11,601 6,974 38,565 1,394,182 Total $ 95,806,020 873,798 527,258 1,239,972 $ 98,447,048 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) Excludes loans acquired at a discount. (b) Loans acquired at a discount that were recorded at fair value at acquisition date. This category does not include purchased impaired loans that are presented separately. (c) Accruing loans acquired at a discount that were impaired at acquisition date and recorded at fair value.
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 September 30, 2020 and June 30, 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. September June 30, 2020 (In thousands) Commercial, financial, leasing, etc. $ 815,186 $ 5,302,196 Real estate: Commercial 4,452,846 7,802,006 Residential builder and developer 1,473 18,253 Other commercial construction 671,378 861,536 Residential 2,852,740 1,737,483 Residential — limited documentation 454,378 538,671 Consumer: Home equity lines and loans 25,658 88,162 Recreational finance 39,754 254,205 Automobile 62,871 326,113 Other 2,336 16,611 Total $ 9,378,620 $ 16,945,236
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 three months and nine months ended September 30, 2019 follows: Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Purchased Other Purchased Other Impaired Acquired Impaired Acquired (In thousands) Balance at beginning of period $ 147,104 $ 90,911 $ 147,210 $ 96,907 Interest income (9,564 ) (9,238 ) (37,278 ) (28,621 ) Reclassifications from nonaccretable balance 9,079 3,990 36,687 12,312 Other (a) — 41 — 5,106 Balance at end of period $ 146,619 $ 85,704 $ 146,619 $ 85,704 (a) Other changes in expected cash flows included changes in interest rates and prepayment assumptions.
Summary of Loan grades applied various classes of Commercial and Real Estate Loans	The following table summarizes the loan grades applied at September 30, 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 $ 8,209,336 2,387,719 1,638,389 1,001,452 816,518 1,488,463 10,444,292 27,536 $ 26,013,705 Criticized accrual 389,682 75,106 141,774 50,144 45,345 57,137 758,594 9,533 1,527,315 Criticized nonaccrual 2,793 23,546 49,840 16,456 18,790 66,410 165,625 7,168 350,628 Total commercial, financial, leasing, etc. $ 8,601,811 2,486,371 1,830,003 1,068,052 880,653 1,612,010 11,368,511 44,237 $ 27,891,648 Real estate: Commercial: Loan grades: Pass $ 2,773,454 4,911,992 3,458,071 2,851,599 2,823,120 6,188,879 810,180 — $ 23,817,295 Criticized accrual 343,722 436,191 531,848 294,994 728,208 1,252,953 51,535 — 3,639,451 Criticized nonaccrual 242 43,342 5,168 31,506 21,507 149,629 1,121 — 252,515 Total commercial real estate $ 3,117,418 5,391,525 3,995,087 3,178,099 3,572,835 7,591,461 862,836 — $ 27,709,261 Residential builder and developer: Loan grades: Pass $ 399,778 399,923 207,188 26,378 11,668 14,190 233,182 — $ 1,292,307 Criticized accrual 32,441 12,744 15,255 3,421 — 1,410 3,567 — 68,838 Criticized nonaccrual — 518 — — — 1,315 — — 1,833 Total residential builder and developer $ 432,219 413,185 222,443 29,799 11,668 16,915 236,749 — $ 1,362,978 Other commercial construction: Loan grades: Pass $ 721,942 2,613,554 2,229,748 1,137,823 352,930 299,184 77,873 — $ 7,433,054 Criticized accrual 26,338 223,956 365,284 243,108 166,048 14,430 — — 1,039,164 Criticized nonaccrual — — — 4,340 3,254 24,913 5,120 — 37,627 Total other commercial construction $ 748,280 2,837,510 2,595,032 1,385,271 522,232 338,527 82,993 — $ 8,509,845
Summary of loans in Accrual and Nonaccrual Status	. A summary of loans in accrual and nonaccrual status at September 30, 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 $ 2,089,095 1,489,244 664,588 1,282,631 756,137 7,583,780 68,834 — $ 13,934,309 30-89 days past due 4,319 8,534 5,234 17,517 6,758 143,058 — — 185,420 Accruing loans past due 90 days or more 387 9,213 26,596 124,510 30,048 312,696 — — 503,450 Nonaccrual 761 4,590 1,653 5,257 1,002 284,167 206 — 297,636 Total residential $ 2,094,562 1,511,581 698,071 1,429,915 793,945 8,323,701 69,040 — $ 14,920,815 Residential - limited documentation: Current $ — — — — — 1,606,130 — — $ 1,606,130 30-89 days past due — — — — — 20,980 — — 20,980 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — — — — — 115,783 — — 115,783 Total residential - limited documentation $ — — — — — 1,742,893 — — $ 1,742,893 Consumer: Home equity lines and loans: Current $ 668 4,357 1,961 2,155 163 57,998 2,622,825 1,310,702 $ 4,000,829 30-89 days past due — — 72 — — 1,809 1,374 18,954 22,209 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual — 20 — 52 — 5,018 6,988 66,742 78,820 Total home equity lines and loans $ 668 4,377 2,033 2,207 163 64,825 2,631,187 1,396,398 $ 4,101,858 3. Loans and leases and the allowance for credit losses, continued 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 $ 2,323,314 1,881,732 969,243 674,896 379,441 609,500 — — $ 6,838,126 30-89 days past due 5,130 9,073 6,755 5,091 3,168 6,786 — — 36,003 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,314 3,961 3,790 4,175 2,379 8,572 — — 24,191 Total recreational finance $ 2,329,758 1,894,766 979,788 684,162 384,988 624,858 — — $ 6,898,320 Automobile: Current $ 1,084,223 1,223,790 711,515 513,607 208,741 88,092 — — $ 3,829,968 30-89 days past due 2,884 10,573 11,193 10,126 5,170 2,960 — — 42,906 Accruing loans past due 90 days or more — — — — — — — — — Nonaccrual 1,244 7,754 11,224 11,010 6,461 4,681 — — 42,374 Total automobile $ 1,088,351 1,242,117 733,932 534,743 220,372 95,733 — — $ 3,915,248 Other: Current $ 132,769 154,094 62,966 39,231 6,252 31,356 908,567 1,807 $ 1,337,042 30-89 days past due 1,874 890 537 243 29 570 6,954 504 11,601 Accruing loans past due 90 days or more — — — — — 287 6,687 — 6,974 Nonaccrual 1,540 446 442 226 43 383 35,186 299 38,565 Total other $ 136,183 155,430 63,945 39,700 6,324 32,596 957,394 2,610 $ 1,394,182 Total loans and leases at September 30, 2020 $ 18,549,250 15,936,862 11,120,334 8,351,948 6,393,180 20,443,519 16,208,710 1,443,245 $ 98,447,048
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
Changes in Allowance for Credit Losses	Changes in the allowance for credit losses for the three months ended September 30, 2020 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Total (In thousands) Beginning balance $ 398,257 576,321 118,921 544,737 $ 1,638,236 Provision for credit losses 25,450 87,403 (683 ) 37,830 150,000 Net charge-offs Charge-offs (14,434 ) (4,522 ) (1,516 ) (31,754 ) (52,226 ) Recoveries 4,475 2,578 960 14,482 22,495 Net charge-offs (9,959 ) (1,944 ) (556 ) (17,272 ) (29,731 ) Ending balance $ 413,748 661,780 117,682 565,295 $ 1,758,505 Changes in the allowance for credit losses for the three months ended September 30, 2019 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) Beginning balance $ 335,855 343,296 61,011 211,220 78,485 $ 1,029,867 Provision for credit losses 24,538 (16,713 ) (309 ) 37,735 (251 ) 45,000 Net charge-offs Charge-offs (15,678 ) (1,107 ) (2,721 ) (40,735 ) — (60,241 ) Recoveries 6,730 1,656 1,511 13,914 — 23,811 Net (charge-offs) recoveries (8,948 ) 549 (1,210 ) (26,821 ) — (36,430 ) Ending balance $ 351,445 327,132 59,492 222,134 78,234 $ 1,038,437 Changes in the allowance for credit losses for the nine months ended September 30, 2020 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) 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 161,444 335,159 11,458 216,939 — 725,000 Net charge-offs Charge-offs (63,425 ) (23,266 ) (8,227 ) (116,409 ) — (211,327 ) Recoveries 11,109 4,030 4,522 41,643 — 61,304 Net charge-offs (52,316 ) (19,236 ) (3,705 ) (74,766 ) — (150,023 ) Ending balance $ 413,748 661,780 117,682 565,295 — $ 1,758,505 Changes in the allowance for credit losses for the nine months ended September 30, 2019 were as follows: Commercial, Financial, Real Estate Leasing, etc. Commercial Residential Consumer Unallocated Total (In thousands) Beginning balance $ 330,055 341,655 69,125 200,564 78,045 $ 1,019,444 Provision for credit losses 41,146 (6,415 ) (5,132 ) 92,212 189 122,000 Net charge-offs Charge-offs (40,786 ) (11,555 ) (9,356 ) (113,050 ) — (174,747 ) Recoveries 21,030 3,447 4,855 42,408 — 71,740 Net charge-offs (19,756 ) (8,108 ) (4,501 ) (70,642 ) — (103,007 ) Ending balance $ 351,445 327,132 59,492 222,134 78,234 $ 1,038,437
Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans	3. Loans and leases and the allowance for credit losses, continued 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 three-month and nine-month periods ended September 30, 2020 and 2019 follows. September 30, 2020 June 30, 2020 January 1, 2020 Three Months Ended September 2020 Nine Months Ended September 2020 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Amortized Cost Interest Income Recognized Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 264,515 86,113 350,628 284,654 346,743 5,999 9,035 Real estate: Commercial 86,199 166,316 252,515 172,488 173,796 993 6,782 Residential builder and developer 1,833 — 1,833 1,748 4,708 114 173 Other commercial construction 15,441 22,186 37,627 85,426 35,881 232 6,809 Residential 66,302 231,334 297,636 306,907 322,504 3,410 15,258 Residential — limited documentation 29,824 85,959 115,783 118,695 114,667 114 571 Consumer: Home equity lines and loans 36,134 42,686 78,820 77,094 65,039 1,017 3,236 Recreational finance 17,637 6,554 24,191 24,152 14,308 155 461 Automobile 37,355 5,019 42,374 42,736 21,293 47 139 Other 3,567 34,998 38,565 42,750 35,394 174 489 Total $ 558,807 681,165 1,239,972 1,156,650 1,134,333 12,255 42,953 3. Loans and leases and the allowance for credit losses, continued September 30, 2019 June 30, 2019 January 1, 2019 Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 Amortized Cost with Allowance Amortized Cost Total Amortized Cost Amortized Cost Interest Income Recognized Interest Income Recognized (In thousands) Commercial, financial, leasing, etc. $ 223,183 159,626 382,809 223,733 234,423 836 7,552 Real estate: Commercial 40,203 144,429 184,632 203,116 203,672 1,802 5,212 Residential builder and developer 1,596 3,379 4,975 5,985 4,798 89 308 Other commercial construction 15,501 15,940 31,441 32,769 22,205 488 1,669 Residential 57,070 166,496 223,566 210,922 233,352 3,425 10,014 Residential — limited documentation 27,803 53,876 81,679 87,551 84,685 269 795 Consumer: Home equity lines and loans 23,908 36,007 59,915 66,927 71,292 1,846 4,617 Recreational finance 6,577 5,275 11,852 11,153 11,199 147 431 Automobile 14,596 6,443 21,039 20,170 23,359 54 161 Other 3,066 275 3,341 3,058 4,623 145 392 Total $ 413,503 591,746 1,005,249 865,384 893,608 9,101 31,151
Loan Modification Activities that were Considered Troubled Debt Restructurings	The table that follows summarizes the Company’s loan modification activities that were considered troubled debt restructurings for the three-month and nine-month periods ended September 30, 2020 and 2019: Post-modification (a) Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total Three Months Ended September 30, 2020 (Dollars in thousands) Commercial, financial, leasing, etc. 112 $ 35,037 $ 7,145 $ 298 $ — $ 27,512 $ 34,955 Real estate: Commercial 50 13,293 12,506 172 30 600 13,308 Residential 30 8,544 5,517 — — 3,616 9,133 Consumer: Home equity lines and loans 33 3,410 129 — — 3,286 3,415 Recreational finance 74 2,734 2,734 — — — 2,734 Automobile 403 7,007 7,005 — — 2 7,007 Other 383 3,046 142 — — 2,904 3,046 Total 1,085 $ 73,071 $ 35,178 $ 470 $ 30 $ 37,920 $ 73,598 Three Months Ended September 30, 2019 Commercial, financial, leasing, etc. 26 $ 6,145 $ 1,441 $ — $ — $ 4,666 $ 6,107 Real estate: Commercial 9 2,986 383 — — 2,589 2,972 Residential 20 5,161 3,046 — — 2,535 5,581 Residential — limited documentation 1 236 — — — 240 240 Consumer: Home equity lines and loans 12 1,392 — — — 1,399 1,399 Recreational finance 3 61 61 — — — 61 Automobile 26 485 457 — — 28 485 Total 97 $ 16,466 $ 5,388 $ — $ — $ 11,457 $ 16,845 3. Loans and leases and the allowance for credit losses, continued Post-modification (a) Number Pre- modification Recorded Investment Principal Deferral Interest Rate Reduction Other Combination of Concession Types Total Nine Months Ended September 30, 2020 (Dollars in thousands) Commercial, financial, leasing, etc. 279 $ 102,865 $ 29,762 $ 298 $ 31,605 $ 40,013 $ 101,678 Real estate: Commercial 106 94,807 24,372 505 4,830 52,916 82,623 Residential builder and developer 1 91 — — — 90 90 Residential 82 27,594 11,865 — — 19,126 30,991 Residential — limited documentation 9 2,980 2,667 — — 1,232 3,899 Consumer: Home equity lines and loans 159 11,719 688 — — 11,057 11,745 Recreational finance 348 13,619 13,619 — — — 13,619 Automobile 1,873 33,541 33,539 — — 2 33,541 Other 718 5,229 824 — — 4,405 5,229 Total 3,575 $ 292,445 $ 117,336 $ 803 $ 36,435 $ 128,841 $ 283,415 Nine Months Ended September 30, 2019 Commercial, financial, leasing, etc. 115 $ 39,357 $ 8,582 $ — $ — $ 30,827 $ 39,409 Real estate: Commercial 38 22,567 3,947 — — 18,197 22,144 Residential builder and developer 2 1,330 1,068 — — — 1,068 Other commercial construction 2 1,456 — — 1,399 1,399 Residential 63 16,490 8,805 — — 8,842 17,647 Residential — limited documentation 4 1,084 399 — — 705 1,104 Consumer: Home equity lines and loans 32 3,141 90 — — 3,078 3,168 Recreational finance 8 164 164 — — — 164 Automobile 58 991 926 — — 65 991 Total 322 $ 86,580 $ 23,981 $ — $ — $ 63,113 $ 87,094 (a) Financial effects impacting the recorded investment included principal payments or advances, charge-offs and capitalized escrow arrearages. The present value of interest rate concessions, discounted at the effective rate of the original loan, was not material.

Revenue from contracts with c_2

Revenue from contracts with customers (Tables)	9 Months Ended
	Sep. 30, 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 the three-month and nine-month periods ended September 30, 2020 and 2019 that are subject to the noted accounting guidance. Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total Three Months Ended September 30, 2020 (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 11,527 22,816 2,347 — — 53,379 1,286 $ 91,355 Trust income — 1 — — — — 149,936 149,937 Brokerage services income — — — — — — 11,602 11,602 Other revenues from operations: Merchant discount and credit card fees 10,533 10,785 492 — — 4,159 (315 ) 25,654 Other — 2,940 929 205 1,127 5,994 10,212 21,407 $ 22,060 36,542 3,768 205 1,127 63,532 172,721 $ 299,955 Three Months Ended September 30, 2019 Classification in consolidated statement of income Service charges on deposit accounts $ 15,131 23,427 2,415 — — 68,455 1,664 $ 111,092 Trust income 9 242 — — — — 143,664 143,915 Brokerage services income — — — — — — 12,077 12,077 Other revenues from operations: Merchant discount and credit card fees 9,692 13,409 670 — — 4,150 269 28,190 Other — 1,239 1,372 503 816 9,347 7,076 20,353 $ 24,832 38,317 4,457 503 816 81,952 164,750 $ 315,627 5. Revenue from contracts with customers, continued Business Banking Commercial Banking Commercial Real Estate Discretionary Portfolio Residential Mortgage Banking Retail Banking All Other Total Nine Months Ended September 30, 2020 (In thousands) Classification in consolidated statement of income Service charges on deposit accounts $ 38,048 69,487 7,724 — — 155,073 4,639 $ 274,971 Trust income 18 442 — — — — 450,110 450,570 Brokerage services income — — — — — — 35,194 35,194 Other revenues from operations: Merchant discount and credit card fees 29,023 32,992 1,720 — — 9,880 261 73,876 Other — 5,913 2,960 1,212 3,101 15,142 32,149 60,477 $ 67,089 108,834 12,404 1,212 3,101 180,095 522,353 $ 895,088 Nine Months Ended September 30, 2019 Classification in consolidated statement of income Service charges on deposit accounts $ 45,415 69,731 7,303 — 4 195,267 4,271 $ 321,991 Trust income 21 680 — — — — 420,382 421,083 Brokerage services income — — — — — — 37,031 37,031 Other revenues from operations: Merchant discount and credit card fees 28,469 38,630 1,772 — — 11,854 1,291 82,016 Other — 5,386 5,840 1,545 2,913 27,170 26,159 69,013 $ 73,905 114,427 14,915 1,545 2,917 234,291 489,134 $ 931,134

Pension plans and other postr_2

Pension plans and other postretirement benefits (Tables)	9 Months Ended
	Sep. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Net Periodic Defined Benefit Cost for Defined Benefit Plans	Net periodic defined benefit cost for defined benefit plans consisted of the following: Pension Benefits Other Postretirement Benefits Three Months Ended September 30 2020 2019 2020 2019 (In thousands) Service cost $ 4,986 4,324 242 215 Interest cost on projected benefit obligation 17,855 20,394 436 586 Expected return on plan assets (31,378 ) (30,534 ) — — Amortization of prior service cost (credit) 125 139 (1,175 ) (1,182 ) Amortization of net actuarial loss (gain) 13,950 5,498 (300 ) (312 ) Net periodic cost (benefit) $ 5,538 (179 ) (797 ) (693 ) Pension Benefits Other Postretirement Benefits Nine Months Ended September 30 2020 2019 2020 2019 (In thousands) Service cost $ 14,958 12,970 727 644 Interest cost on projected benefit obligation 53,565 61,184 1,306 1,758 Expected return on plan assets (94,134 ) (91,604 ) — — Amortization of prior service cost (credit) 404 418 (3,544 ) (3,547 ) Amortization of net actuarial loss (gain) 42,998 16,494 (918 ) (935 ) Net periodic cost (benefit) $ 17,791 (538 ) (2,429 ) (2,080 )

Earnings per common share (Tabl

Earnings per common share (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Computations of Basic Earnings Per Common Share	The computations of basic earnings per common share follow: Three Months Ended September 30 Nine Months Ended September 30 2020 2019 2020 2019 (In thousands, except per share) Income available to common shareholders: Net income $ 372,136 480,081 882,012 1,436,083 Less: Preferred stock dividends (17,050 ) (16,103 ) (51,178 ) (52,364 ) Net income available to common equity 355,086 463,978 830,834 1,383,719 Less: Income attributable to unvested stock-based compensation awards (1,687 ) (2,568 ) (3,631 ) (7,591 ) Net income available to common shareholders $ 353,399 461,410 827,203 1,376,128 Weighted-average shares outstanding: Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards 129,061 133,703 129,518 136,156 Less: Unvested stock-based compensation awards (776 ) (738 ) (768 ) (745 ) Weighted-average shares outstanding 128,285 132,965 128,750 135,411 Basic earnings per common share $ 2.75 3.47 6.42 10.16
Computations of Diluted Earnings Per Common Share	The computations of diluted earnings per common share follow: Three Months Ended September 30 Nine Months Ended September 30 2020 2019 2020 2019 (In thousands, except per share) Net income available to common equity $ 355,086 463,978 830,834 1,383,719 Less: Income attributable to unvested stock-based compensation awards (1,686 ) (2,568 ) (3,630 ) (7,590 ) Net income available to common shareholders $ 353,400 461,410 827,204 1,376,129 Adjusted weighted-average shares outstanding: Common and unvested stock-based compensation awards 129,061 133,703 129,518 136,156 Less: Unvested stock-based compensation awards (776 ) (738 ) (768 ) (745 ) Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock 70 34 63 32 Adjusted weighted-average shares outstanding 128,355 132,999 128,813 135,443 Diluted earnings per common share $ 2.75 3.47 6.42 10.16

Comprehensive income (Tables)

Comprehensive income (Tables)	9 Months Ended
	Sep. 30, 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 comprehensive income (loss) to net income: 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 151,777 — — 151,777 (39,277 ) 112,500 Foreign currency translation adjustment — — (222 ) (222 ) (39 ) (261 ) Unrealized gains on cash flow hedges — — 508,226 508,226 (131,504 ) 376,722 Total other comprehensive income before reclassifications 151,777 — 508,004 659,781 (170,820 ) 488,961 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on held-to-maturity (“HTM”) securities 2,678 — — 2,678 (a) (725 ) 1,953 Gains realized in net income (3 ) — — (3 ) (b) 1 (2 ) Accretion of net gain on terminated cash flow hedges — (94 ) (94 ) (c) 26 (68 ) Net yield adjustment from cash flow hedges currently in effect — — (183,598 ) (183,598 ) (a) 47,506 (136,092 ) Amortization of prior service credit — (3,140 ) — (3,140 ) (d) 927 (2,213 ) Amortization of actuarial losses — 42,080 — 42,080 (d) (12,436 ) 29,644 Total other comprehensive income 154,452 38,940 324,312 517,704 (135,521 ) 382,183 Balance — September 30, 2020 $ 205,153 (425,608 ) 458,200 $ 237,745 (62,242 ) $ 175,503 Balance — January 1, 2019 $ (200,107 ) (354,502 ) (14,719 ) $ (569,328 ) 149,247 $ (420,081 ) Other comprehensive income before reclassifications: Unrealized holding gains, net 237,615 — — 237,615 (62,432 ) 175,183 Foreign currency translation adjustment — — (2,663 ) (2,663 ) 559 (2,104 ) Unrealized gains on cash flow hedges — — 204,587 204,587 (53,786 ) 150,801 Total other comprehensive income before reclassifications 237,615 — 201,924 439,539 (115,659 ) 323,880 Amounts reclassified from accumulated other comprehensive income that (increase) decrease net income: Amortization of unrealized holding losses on HTM securities 2,524 — — 2,524 (a) (663 ) 1,861 Losses realized in net income 7 — — 7 (b) (2 ) 5 Accretion of net gain on terminated cash flow hedges — — (93 ) (93 ) (c) 25 (68 ) Net yield adjustment from cash flow hedges currently in effect — — 6,693 6,693 (a) (1,760 ) 4,933 Amortization of prior service credit — (3,129 ) — (3,129 ) (d) 823 (2,306 ) Amortization of actuarial losses — 15,559 — 15,559 (d) (4,091 ) 11,468 Total other comprehensive income 240,146 12,430 208,524 461,100 (121,327 ) 339,773 Balance — September 30, 2019 $ 40,039 (342,072 ) 193,805 $ (108,228 ) 27,920 $ (80,308 ) (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. 8. Comprehensive income, continued
Accumulated Other Comprehensive Income (Loss), Net	Accumulated other comprehensive income (loss), net consisted of the following: Defined Cash Flow Investment Benefit Hedges Securities Plans and Total (In thousands) Balance — December 31, 2019 $ 37,380 (342,419 ) 98,359 $ (206,680 ) Net gain during period 114,451 27,431 240,301 382,183 Balance — September 30, 2020 $ 151,831 (314,988 ) 338,660 $ 175,503

Derivative financial instrume_2

Derivative financial instruments (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2020 Fair value hedges: Fixed rate long-term borrowings (b) $ 2,300,000 2.7 2.80 % 0.69 % $ (513 ) Cash flow hedges: Interest payments on variable rate commercial real estate loans (b)(c) 52,250,000 1.1 2.40 % 0.15 % 890 Total $ 54,550,000 1.1 $ 377 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) Certain clearinghouse exchanges consider payments by counterparties for variation margin on derivative instruments to be settlements of those positions. The impact of such treatment at September 30, 2020 and December 31, 2019 was a reduction of the estimated fair value gains on interest rate swap agreements designated as fair value hedges of $120.8 million and $45.1 million, respectively, and on interest rate swap agreements designated as cash flow hedges of $463.3 million and $140.7 million, respectively. (b) Under the terms of these agreements, the Company receives settlement amounts at a fixed rate and pays at a variable rate. (c) (d) .
Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet	Information about the fair values of derivative instruments in the Company’s consolidated balance sheet and consolidated statement of income follows: Asset Derivatives Liability Derivatives Fair Value Fair Value September 30, December 31, September 30, December 31, 2020 2019 2020 2019 (In thousands) Derivatives designated and qualifying as hedging instruments Interest rate swap agreements (a) $ 1,710 $ 232 $ 1,333 $ 1,994 Commitments to sell real estate loans (a) 1,525 1,195 2,264 421 3,235 1,427 3,597 2,415 Derivatives not designated and qualifying as hedging instruments Mortgage-related commitments to originate real estate loans for sale (a) 51,786 11,965 283 1,225 Commitments to sell real estate loans (a) 1,795 3,074 11,066 3,548 Trading: Interest rate contracts (b) 1,157,856 398,295 115,361 68,103 Foreign exchange and other option and futures contracts (b) 7,694 12,506 7,624 11,800 1,219,131 425,840 134,334 84,676 Total derivatives $ 1,222,366 $ 427,267 $ 137,931 $ 87,091 (a) Asset derivatives are reported in other assets and liability derivatives are reported in other liabilities. (b) Asset derivatives are reported in trading account assets and liability derivatives are reported in other liabilities. The impact of variation margin payments at September 30, 2020 and December 31, 2019 was a reduction of the estimated fair value of interest rate contracts in the trading account in an asset position of $2.9 million and $43.3 million, respectively, and in a liability position of $944.9 million and $281.3 million, respectively. Carrying Amount of the Hedged Item Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount of the Hedged Item September 30, 2020 December 31, 2019 September 30, 2020 December 31, 2019 (In thousands) Location in the of the Hedged Items in Fair Value Long-term debt $ 2,417,559 $ 3,840,775 $ 119,247 $ 43,640
Information about Fair Values of Derivative Instruments in Consolidated Statement of Income	Amount of Gain (Loss) Recognized Three Months Ended September 30, 2020 Three Months Ended September 30, 2019 Derivative Hedged Item Derivative Hedged Item (In thousands) Derivatives in fair value hedging relationships Interest rate swap agreements: Fixed rate long-term borrowings (a) $ (13,067 ) 12,822 $ 22,582 (22,412 ) Derivatives not designated as hedging instruments Trading: Interest rate contracts (b) $ (4,776 ) $ 6,435 Foreign exchange and other option and futures contracts (b) 1,486 2,598 Total $ (3,290 ) $ 9,033 9. Derivative financial instruments, continued Amount of Gain (Loss) Recognized Nine Months Ended September 30, 2020 Nine Months Ended September 30, 2019 Derivative Hedged Item Derivative Hedged Item (In thousands) Derivatives in fair value hedging relationships Interest rate swap agreements: Fixed rate long-term borrowings (a) $ 75,760 (75,607 ) $ 113,441 (112,884 ) Derivatives not designated as hedging instruments Trading: Interest rate contracts (b) $ 8,988 $ 17,639 Foreign exchange and other option and futures contracts (b) 6,555 6,690 Total $ 15,543 $ 24,329 (a) Reported as an adjustment to interest expense. (b) Reported as trading account and foreign exchange gains.

Fair value measurements (Tables

Fair value measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis	The following tables present assets and liabilities at September 30, 2020 and December 31, 2019 measured at estimated fair value on a recurring basis: Fair Value Measurements Level 1 Level 2 Level 3 (In thousands) September 30, 2020 Trading account assets $ 1,215,573 $ 50,023 $ 1,165,550 $ — Investment securities available for sale: U.S. Treasury and federal agencies 9,370 — 9,370 — Mortgage-backed securities: Government issued or guaranteed 5,165,701 — 5,165,701 — Privately issued 16 — — 16 Other debt securities 127,251 — 127,251 — 5,302,338 — 5,302,322 16 Equity securities 101,182 72,856 28,326 — Real estate loans held for sale 909,335 — 909,335 — Other assets (a) 56,816 — 5,030 51,786 Total assets $ 7,585,244 $ 122,879 $ 7,410,563 $ 51,802 Trading account liabilities $ 122,985 $ — $ 122,985 $ — Other liabilities (a) 14,946 — 14,663 283 Total liabilities $ 137,931 $ — $ 137,648 $ 283 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) Comprised predominantly of interest rate swap agreements used for interest rate risk management (Level 2), commitments to sell real estate loans (Level 2) and commitments to originate real estate loans to be held for sale (Level 3).
Changes in Level 3 Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis	The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the three months ended September 30, 2020 and 2019 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets 2020 (In thousands) Balance — June 30, 2020 $ 16 40,106 Total gains realized/unrealized: Included in earnings — 57,819 (a) Settlements — — Transfers out of Level 3 — (46,422 ) (b) Balance — September 30, 2020 $ 16 51,503 Changes in unrealized gains included in earnings related to assets still held at September 30, 2020 $ — 44,127 (a) 2019 Balance — June 30, 2019 $ 16 17,200 Total gains realized/unrealized: Included in earnings — 62,178 (a) Settlements — — Transfers out of Level 3 — (55,104 ) (b) Balance — September 30, 2019 $ 16 24,274 Changes in unrealized gains included in earnings related to assets still held at September 30, 2019 $ — 19,350 (a) 11. Fair value measurements, continued The changes in Level 3 assets and liabilities measured at estimated fair value on a recurring basis during the nine months ended September 30, 2020 and 2019 were as follows: Investment Securities Available for Sale Privately Issued Mortgage-Backed Other Assets 2020 (In thousands) Balance — January 1, 2020 $ 16 10,740 Total gains realized/unrealized: Included in earnings — 150,632 (a) Settlements — — Transfers out of Level 3 — (109,869 ) (b) Balance — September 30, 2020 $ 16 51,503 Changes in unrealized gains included in earnings related to assets still held at September 30, 2020 $ — 50,411 (a) 2019 Balance — January 1, 2019 $ 22 7,712 Total gains realized/unrealized: Included in earnings — 115,187 (a) Settlements (6 ) — Transfers out of Level 3 — (98,625 ) (b) Balance — September 30, 2019 $ 16 24,274 Changes in unrealized gains included in earnings related to assets still held at September 30, 2019 $ — 24,981 (a) (a) Reported as mortgage banking revenues in the consolidated statement of income and includes the fair value of commitment issuances and expirations. (b) Transfers out of Level 3 consist of interest rate locks transferred to closed loans.
Quantitative Information Related to Significant Unobservable Inputs	The following tables present quantitative information about significant unobservable inputs used in the fair value measurements for certain Level 3 assets and liabilities at September 30, 2020 and December 31, 2019: Fair Value Valuation Technique Unobservable Inputs/Assumptions Range (Weighted- Average) (In September 30, 2020 Recurring fair value measurements Privately issued mortgage- backed securities $ 16 Two independent pricing quotes — — Net other assets (liabilities) (a) 51,503 Discounted cash flow Commitment expirations 0% - 90%(18%) 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) Other Level 3 assets (liabilities) consist of commitments to originate real estate loans.
Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities)	The carrying amounts and estimated fair value for financial instrument assets (liabilities) are presented in the following table: September 30, 2020 Carrying Amount Estimated Fair Value Level 1 Level 2 Level 3 (In thousands) Financial assets: Cash and cash equivalents $ 1,489,232 1,489,232 1,437,569 51,663 — Interest-bearing deposits at banks 20,197,937 20,197,937 — 20,197,937 — Trading account assets 1,215,573 1,215,573 50,023 1,165,550 — Investment securities 7,723,004 7,816,236 72,856 7,670,141 73,239 Loans and leases: Commercial loans and leases 27,891,648 27,422,525 — — 27,422,525 Commercial real estate loans 37,582,084 36,343,024 — 336,039 36,006,985 Residential real estate loans 16,663,708 16,935,950 — 4,070,917 12,865,033 Consumer loans 16,309,608 16,149,710 — — 16,149,710 Allowance for credit losses (1,758,505 ) — — — — Loans and leases, net 96,688,543 96,851,209 — 4,406,956 92,444,253 Accrued interest receivable 429,751 429,751 — 429,751 — Financial liabilities: Noninterest-bearing deposits $ (44,201,670 ) (44,201,670 ) — (44,201,670 ) — Savings and interest-checking deposits (65,732,130 ) (65,732,130 ) — (65,732,130 ) — Time deposits (4,329,550 ) (4,357,963 ) — (4,357,963 ) — Deposits at Cayman Islands office (899,989 ) (899,989 ) — (899,989 ) — Short-term borrowings (46,123 ) (46,123 ) — (46,123 ) — Long-term borrowings (5,458,885 ) (5,540,675 ) — (5,540,675 ) — Accrued interest payable (66,158 ) (66,158 ) — (66,158 ) — Trading account liabilities (122,985 ) (122,985 ) — (122,985 ) — Other financial instruments: Commitments to originate real estate loans for sale $ 51,503 51,503 — — 51,503 Commitments to sell real estate loans (10,010 ) (10,010 ) — (10,010 ) — Other credit-related commitments (135,416 ) (135,416 ) — — (135,416 ) Interest rate swap agreements used for interest rate risk management 377 377 — 377 — 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)	9 Months Ended
	Sep. 30, 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. September 30, December 31, 2020 2019 (In thousands) Commitments to extend credit Home equity lines of credit $ 5,557,722 $ 5,442,160 Commercial real estate loans to be sold 216,353 164,076 Other commercial real estate 8,031,403 9,029,608 Residential real estate loans to be sold 1,134,097 423,056 Other residential real estate 712,964 448,375 Commercial and other 19,921,166 16,170,731 Standby letters of credit 2,354,799 2,441,432 Commercial letters of credit 32,422 41,059 Financial guarantees and indemnification contracts 4,250,654 4,108,572 Commitments to sell real estate loans 1,895,436 906,037

Segment information (Tables)

Segment information (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Information about Company's Segments	Information about the Company's segments is presented in the following table: Three Months Ended September 30 2020 2019 Total Revenues(a) Inter- segment Revenues Net Income (Loss) Total Revenues(a) Inter- segment Revenues Net Income (Loss) (In thousands) Business Banking $ 131,566 (1 ) 35,614 $ 143,741 912 46,147 Commercial Banking 276,125 117 131,414 282,757 980 132,668 Commercial Real Estate 202,987 (17 ) 87,095 238,364 458 131,161 Discretionary Portfolio 140,135 (10,748 ) 97,399 50,871 (10,550 ) 29,604 Residential 161,151 22,190 45,318 115,239 19,363 15,846 Retail Banking 351,312 268 85,229 432,339 1,808 131,638 All Other 200,380 (11,809 ) (109,933 ) 294,358 (12,971 ) (6,983 ) Total $ 1,463,656 — 372,136 $ 1,557,669 — 480,081 Nine Months Ended September 30 2020 2019 Total Revenues(a) Inter- segment Revenues Net Income (Loss) Total Revenues(a) Inter- segment Revenues Net Income (Loss) (In thousands) Business Banking $ 407,485 1,028 106,103 $ 423,830 2,772 131,668 Commercial Banking 855,426 1,419 386,176 828,357 2,707 388,393 Commercial Real Estate 653,405 452 311,586 682,979 1,218 370,288 Discretionary Portfolio 328,181 (33,646 ) 218,758 175,764 (29,140 ) 106,816 Residential Mortgage Banking 428,757 64,623 107,334 295,449 51,027 36,429 Retail Banking 1,107,516 802 281,973 1,299,823 7,106 417,198 All Other 633,461 (34,678 ) (529,918 ) 955,868 (35,690 ) (14,709 ) Total $ 4,414,231 — 882,012 $ 4,662,070 — 1,436,083 13. Segment information, continued Average Total Assets Nine Months Ended September 30 Year Ended December 2020 2019 2019 (In millions) Business Banking $ 7,902 5,758 5,793 Commercial Banking 30,450 28,089 28,142 Commercial Real Estate 25,594 23,893 23,921 Discretionary Portfolio 27,878 29,355 29,081 Residential Mortgage Banking 3,530 2,444 2,611 Retail Banking 16,231 14,839 15,083 All Other 20,845 14,206 14,953 Total $ 132,430 118,584 119,584 (a) Total revenues are comprised of net interest income and other income. Net interest income is the difference between taxable-equivalent interest earned on assets and interest paid on liabilities owed by a segment and a funding charge (credit) based on the Company's internal funds transfer and allocation methodology. Segments are charged a cost to fund any assets (e.g. loans) and are paid a funding credit for any funds provided (e.g. deposits). The taxable-equivalent adjustment aggregated $4,019,000 and $5,579,000 for the three-month periods ended September 30, 2020 and 2019, respectively, and $13,316,000 and $17,471,000 for the nine-month periods ended September 30, 2020 and 2019, respectively, and is eliminated in "All Other" total revenues. Intersegment revenues are included in total revenues of the reportable segments. The elimination of intersegment revenues is included in the determination of "All Other" total revenues

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Estimated Fair Value of Investment Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule Of Amortized Cost And Estimated Fair Value Of Investment Securities [Line Items]
Investment securities available for sale, amortized cost	$ 5,090,064	$ 6,258,276
Investment securities available for sale, gross unrealized gains	223,115	90,723
Investment securities available for sale, gross unrealized losses	10,841	30,223
Investment securities available for sale, estimated fair value	5,302,338	6,318,776
Amortized cost for held to maturity	1,938,694	2,656,917
Gross unrealized gains for held to maturity	111,124	62,462
Gross unrealized losses for held to maturity	17,892	20,173
Estimated fair value for held to maturity	2,031,926	2,699,206
Equity and other securities, Amortized Cost	458,498	487,041
Equity securities, Gross Unrealized Gains	23,474	34,786
Equity securities, Gross Unrealized Losses		269
Equity and other securities, Estimated Fair Value	481,972	521,558
Other securities, Amortized cost	380,790	381,517
Other securities, Estimated fair value	380,790	381,517
Total debt securities Amortized cost	7,028,758	8,915,193
Total debt securities Gross unrealized gains	334,239	153,185
Total debt securities Gross unrealized losses	28,733	50,396
Total debt securities Estimated fair value	7,334,264	9,017,982
Readily marketable securities Amortized cost	77,708	105,524
Readily marketable securities Gross unrealized gains	23,474	34,786
Readily marketable securities Gross unrealized losses		269
Readily marketable securities Estimated fair value	101,182	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	226	41
Investment securities available for sale, gross unrealized losses	10	16
Investment securities available for sale, estimated fair value	9,370	9,767
Amortized cost for held to maturity	3,000	249,862
Gross unrealized gains for held to maturity		286
Estimated fair value for held to maturity	3,000	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	1,855	4,140
Gross unrealized gains for held to maturity	10	16
Estimated fair value for held to maturity	1,865	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	4,944,979	6,113,913
Investment securities available for sale, gross unrealized gains	221,561	88,634
Investment securities available for sale, gross unrealized losses	839	21,607
Investment securities available for sale, estimated fair value	5,165,701	6,180,940
Amortized cost for held to maturity	1,850,864	2,306,180
Gross unrealized gains for held to maturity	100,104	50,381
Gross unrealized losses for held to maturity	92	1,992
Estimated fair value for held to maturity	1,950,876	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	80,013	93,496
Gross unrealized gains for held to maturity	11,010	11,779
Gross unrealized losses for held to maturity	17,800	18,181
Estimated fair value for held to maturity	73,223	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	135,915	133,829
Investment securities available for sale, gross unrealized gains	1,328	2,046
Investment securities available for sale, gross unrealized losses	9,992	8,597
Investment securities available for sale, estimated fair value	127,251	127,278
Amortized cost for held to maturity	2,962	3,239
Estimated fair value for held to maturity	$ 2,962	$ 3,239

Investment Securities - Additio

Investment Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)Security	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)Security	Sep. 30, 2019USD ($)
Amortized Cost And Fair Value Debt Securities [Abstract]
Gross realized gains(loss) on sale of investment securities	$ 0	$ 0	$ 0	$ 0
Gains (losses) on equity securities	$ 2,773,000	$ 3,737,000	$ (11,040,000)	$ 24,489,000
Number of debt securities with aggregate gross unrealized losses | Security	290		290
Unrealized losses on individual debt securities			$ (29,000,000)
Cost method equity securities	$ 381,000,000		$ 381,000,000

Investment Securities - Amort_2

Investment Securities - Amortized Cost and Estimated Fair Value of Debt Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt securities available for sale:
Due in one year or less	$ 5,197
Due after one year through five years	11,446
Due after five years through ten years	98,426
Due after ten years	30,000
Total available for sale (amortized cost)	145,069
Mortgage-backed securities available for sale	4,944,995
Investment securities available for sale, amortized cost	5,090,064	$ 6,258,276
Debt securities held to maturity:
Due in one year or less	4,680
Due after one year through five years	175
Due after ten years	2,962
Total available for held to maturity (amortized cost)	7,817
Mortgage-backed securities held to maturity	1,930,877
Amortized cost for held to maturity	1,938,694	2,656,917
Debt securities available for sale:
Due in one year or less	5,207
Due after one year through five years	12,009
Due after five years through ten years	95,033
Due after ten years	24,372
Total available for sale (fair value)	136,621
Mortgage-backed securities available for sale	5,165,717
Total	5,302,338	6,318,776
Debt securities held to maturity:
Due in one year or less	4,688
Due after one year through five years	177
Due after ten years	2,962
Total available for held to maturity (fair value)	7,827
Mortgage-backed securities held to maturity	2,024,099
Total	$ 2,031,926	$ 2,699,206

Investment Securities - Investm

Investment Securities - Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	$ 63,683	$ 125,305
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(1,461)	(583)
Estimated fair value, 12 months or more	84,394	2,061,847
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(9,380)	(29,640)
Held to maturity, Estimated fair value, Less than 12 months	18,833	2,727
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(124)	(5)
Held to maturity, Estimated fair value, 12 months or more	46,048	194,891
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	(17,768)	(20,168)
Total investment securities, fair value less than 12 months	82,516	128,032
Investment Securities Continuous Unrealized Loss Position Less Than Twelve Months Aggregate Losses	(1,585)	(588)
Total of investment securities, fair value, 12 Months or More	130,442	2,256,738
Investment Securities Continuous Unrealized Loss Position Twelve Months or Longer Aggregate Losses	(27,148)	(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	(10)	(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)
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)
Government Issued or Guaranteed [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Estimated fair value, Less than 12 months	20,313	117,299
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(364)	(222)
Estimated fair value, 12 months or more	21,735	2,002,364
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(475)	(21,385)
Held to maturity, Estimated fair value, Less than 12 months	11,357	2,727
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(92)	(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	42,385	6,600
Available For Sale Securities Continuous Unrealized Losses Position Less Than Twelve Months Aggregate Losses	(1,087)	(354)
Estimated fair value, 12 months or more	62,659	56,313
Available For Sale Securities Continuous Unrealized Loss Position Twelve Months Or More Aggregate Losses	(8,905)	(8,243)
Privately Issued [Member]
Schedule Of Available For Sale Securities And Held To Maturity [Line Items]
Held to maturity, Estimated fair value, Less than 12 months	7,476
Held To Maturity Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses	(32)
Held to maturity, Estimated fair value, 12 months or more	46,048	49,656
Held To Maturity Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses	$ (17,768)	$ (18,181)

Loans and Leases and the Allo_3

Loans and Leases and the Allowance for Credit Losses - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended
	Jan. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Loans And Leases Receivable [Line Items]
Increase in allowance for credit loss	$ 132
Effect of change in allowance for credit loss to non accrual loan	$ 171
Contractual principal and interest payments			$ 228
Amount of foreclosed residential real estate property held		$ 43	76
Loans secured by residential real estate that were in the process of foreclosure		$ 231	$ 402
Percentage loans in the process of foreclosure, serviced by other entities, classified as government guaranteed		42.00%
Maximum [Member]
Loans And Leases Receivable [Line Items]
Purchased impaired loans as a percentage of total assets			1.00%
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
Residential Mortgage Loans [Member] | One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale		571	$ 414
Commercial Real Estate Loans [Member] | One-to-Four Family Residential [Member]
Loans And Leases Receivable [Line Items]
Mortgage loans held for sale		$ 336	$ 28

Loans and Leases and the Allo_4

Loans and Leases and the Allowance for Credit Losses - Summary of Current, Past Due and Nonaccrual Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	$ 95,806,020	$ 87,999,720
30-89 Days Past Due	873,798	1,174,132
Accruing Loans Past Due 90 Days or More	527,258	518,728
Nonaccrual	1,239,972	963,112
Loans and leases, net of unearned discount	98,447,048	90,922,869
Purchased Impaired		227,545
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	27,249,552	23,290,797
30-89 Days Past Due	282,917	184,011
Accruing Loans Past Due 90 Days or More	8,551	16,776
Nonaccrual	350,628	346,557
Loans and leases, net of unearned discount	27,891,648	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	27,250,676	26,311,414
30-89 Days Past Due	197,881	165,579
Accruing Loans Past Due 90 Days or More	8,189	6,740
Nonaccrual	252,515	158,474
Loans and leases, net of unearned discount	27,709,261	26,657,808
Purchased Impaired		15,601
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,353,863	1,521,315
30-89 Days Past Due	7,282	21,195
Nonaccrual	1,833	3,982
Loans and leases, net of unearned discount	1,362,978	1,547,245
Purchased Impaired		753
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	8,405,525	7,204,148
30-89 Days Past Due	66,599	95,346
Accruing Loans Past Due 90 Days or More	94	3,360
Nonaccrual	37,627	32,770
Loans and leases, net of unearned discount	8,509,845	7,336,861
Purchased Impaired		1,237
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	13,934,309	12,760,040
30-89 Days Past Due	185,420	451,274
Accruing Loans Past Due 90 Days or More	503,450	486,515
Nonaccrual	297,636	235,663
Loans and leases, net of unearned discount	14,920,815	14,082,425
Purchased Impaired		143,145
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	1,606,130	1,858,037
30-89 Days Past Due	20,980	65,215
Accruing Loans Past Due 90 Days or More		181
Nonaccrual	115,783	83,427
Loans and leases, net of unearned discount	1,742,893	2,073,669
Purchased Impaired		66,809
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	4,000,829	4,386,511
30-89 Days Past Due	22,209	30,229
Nonaccrual	78,820	63,215
Loans and leases, net of unearned discount	4,101,858	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	6,838,126	5,484,997
30-89 Days Past Due	36,003	36,827
Nonaccrual	24,191	14,219
Loans and leases, net of unearned discount	6,898,320	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	3,829,968	3,787,221
30-89 Days Past Due	42,906	78,478
Nonaccrual	42,374	21,293
Loans and leases, net of unearned discount	3,915,248	3,886,992
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current	1,337,042	1,395,240
30-89 Days Past Due	11,601	45,978
Accruing Loans Past Due 90 Days or More	6,974	5,156
Nonaccrual	38,565	3,512
Loans and leases, net of unearned discount	$ 1,394,182	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 and the Allo_5

Loans and Leases and the Allowance for Credit Losses - Summary of Outstanding Loan Balances Related to COVID-19 Modifications Granted (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	$ 98,447,048		$ 90,922,869
COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	9,378,620	$ 16,945,236
Commercial, Financial, Leasing, etc. [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	27,891,648		23,838,168
Commercial, Financial, Leasing, etc. [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	815,186	5,302,196
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	27,709,261		26,657,808
Commercial [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	4,452,846	7,802,006
Residential Builder and Developer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	1,362,978		1,547,245
Residential Builder and Developer [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	1,473	18,253
Other Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	8,509,845		7,336,861
Other Commercial Construction [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	671,378	861,536
Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	14,920,815		14,082,425
Residential [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	2,852,740	1,737,483
Residential Limited Documentation [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	1,742,893		2,073,669
Residential Limited Documentation [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	454,378	538,671
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	4,101,858		4,481,617
Home Equity Lines and Loans [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	25,658	88,162
Recreational Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	6,898,320		5,536,142
Recreational Finance [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	39,754	254,205
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	3,915,248		3,886,992
Automobile [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	62,871	326,113
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	1,394,182		$ 1,481,942
Other [Member] | COVID-19 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases, net of unearned discount	$ 2,336	$ 16,611

Loans and Leases and the Allo_6

Loans and Leases and the Allowance for Credit Losses - 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 and the Allo_7

Loans and Leases and the Allowance for Credit Losses - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 147,104	$ 147,210
Interest income	(9,564)	(37,278)
Reclassifications from nonaccretable balance	9,079	36,687
Balance at end of period	146,619	146,619
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	90,911	96,907
Interest income	(9,238)	(28,621)
Reclassifications from nonaccretable balance	3,990	12,312
Other	41	5,106
Balance at end of period	$ 85,704	$ 85,704

Loans and Leases and the Allo_8

Loans and Leases and the Allowance for Credit Losses - Summary of Loan grades applied various classes of Commercial and Real Estate Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 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	$ 98,447,048	$ 90,922,869
Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,208,710
Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,443,245
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,891,648	23,838,168
Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,013,705	22,595,821
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,527,315	895,790
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	350,628	346,557
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	11,368,511
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	10,444,292
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	758,594
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	165,625
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	44,237
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans Converted to Term Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,536
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans Converted to Term Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	9,533
Commercial, Financial, Leasing, etc. [Member] | Revolving Loans Converted to Term Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,168
Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,709,261	26,657,808
Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,817,295	25,728,725
Commercial [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,639,451	770,609
Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	252,515	158,474
Commercial [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	862,836
Commercial [Member] | Revolving Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	810,180
Commercial [Member] | Revolving Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	51,535
Commercial [Member] | Revolving Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,121
Residential Builder and Developer [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,362,978	1,547,245
Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,292,307	1,419,162
Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	68,838	124,101
Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,833	3,982
Residential Builder and Developer [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	236,749
Residential Builder and Developer [Member] | Revolving Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	233,182
Residential Builder and Developer [Member] | Revolving Loans [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,567
Other Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,509,845	7,336,861
Other Commercial Construction [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,433,054	7,092,799
Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,039,164	211,292
Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	37,627	32,770
Other Commercial Construction [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	82,993
Other Commercial Construction [Member] | Revolving Loans [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	77,873
Other Commercial Construction [Member] | Revolving Loans [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	5,120
Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	18,549,250	15,936,862	$ 11,120,334	$ 8,351,948	$ 6,393,180
Term Loans [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,601,811	2,486,371	1,830,003	1,068,052	880,653
Term Loans [Member] | Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,209,336	2,387,719	1,638,389	1,001,452	816,518
Term Loans [Member] | Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	389,682	75,106	141,774	50,144	45,345
Term Loans [Member] | Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	2,793	23,546	49,840	16,456	18,790
Term Loans [Member] | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,117,418	5,391,525	3,995,087	3,178,099	3,572,835
Term Loans [Member] | Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	2,773,454	4,911,992	3,458,071	2,851,599	2,823,120
Term Loans [Member] | Commercial [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	343,722	436,191	531,848	294,994	728,208
Term Loans [Member] | Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	242	43,342	5,168	31,506	21,507
Term Loans [Member] | Residential Builder and Developer [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	432,219	413,185	222,443	29,799	11,668
Term Loans [Member] | Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	399,778	399,923	207,188	26,378	11,668
Term Loans [Member] | Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	32,441	12,744	15,255	3,421
Term Loans [Member] | Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		518
Term Loans [Member] | Other Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	748,280	2,837,510	2,595,032	1,385,271	522,232
Term Loans [Member] | Other Commercial Construction [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	721,942	2,613,554	2,229,748	1,137,823	352,930
Term Loans [Member] | Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,338	$ 223,956	$ 365,284	243,108	166,048
Term Loans [Member] | Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount				$ 4,340	$ 3,254
Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	20,443,519
Term Loans Prior Period [Member] | Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,612,010
Term Loans Prior Period [Member] | Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,488,463
Term Loans Prior Period [Member] | Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	57,137
Term Loans Prior Period [Member] | Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	66,410
Term Loans Prior Period [Member] | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,591,461
Term Loans Prior Period [Member] | Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	6,188,879
Term Loans Prior Period [Member] | Commercial [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,252,953
Term Loans Prior Period [Member] | Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	149,629
Term Loans Prior Period [Member] | Residential Builder and Developer [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,915
Term Loans Prior Period [Member] | Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	14,190
Term Loans Prior Period [Member] | Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,410
Term Loans Prior Period [Member] | Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,315
Term Loans Prior Period [Member] | Other Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	338,527
Term Loans Prior Period [Member] | Other Commercial Construction [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	299,184
Term Loans Prior Period [Member] | Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	14,430
Term Loans Prior Period [Member] | Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 24,913

Loans and Leases and the Allo_9

Loans and Leases and the Allowance for Credit Losses - Summary of loans in Accrual and Nonaccrual Status (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Current	$ 95,806,020	$ 87,999,720
30-89 Days Past Due	873,798	1,174,132
Accruing Loans Past Due 90 Days or More	527,258	518,728
Nonaccrual	1,239,972	963,112
Loans and leases, net of unearned discount	98,447,048	90,922,869
Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,208,710
Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,443,245
Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Current	13,934,309	12,760,040
30-89 Days Past Due	185,420	451,274
Accruing Loans Past Due 90 Days or More	503,450	486,515
Nonaccrual	297,636	235,663
Loans and leases, net of unearned discount	14,920,815	14,082,425
Residential [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	68,834
Nonaccrual	206
Loans and leases, net of unearned discount	69,040
Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,606,130	1,858,037
30-89 Days Past Due	20,980	65,215
Accruing Loans Past Due 90 Days or More		181
Nonaccrual	115,783	83,427
Loans and leases, net of unearned discount	1,742,893	2,073,669
Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	4,000,829	4,386,511
30-89 Days Past Due	22,209	30,229
Nonaccrual	78,820	63,215
Loans and leases, net of unearned discount	4,101,858	4,481,617
Home Equity Lines and Loans [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	2,622,825
30-89 Days Past Due	1,374
Nonaccrual	6,988
Loans and leases, net of unearned discount	2,631,187
Home Equity Lines and Loans [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,310,702
30-89 Days Past Due	18,954
Nonaccrual	66,742
Loans and leases, net of unearned discount	1,396,398
Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Current	6,838,126	5,484,997
30-89 Days Past Due	36,003	36,827
Nonaccrual	24,191	14,219
Loans and leases, net of unearned discount	6,898,320	5,536,142
Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Current	3,829,968	3,787,221
30-89 Days Past Due	42,906	78,478
Nonaccrual	42,374	21,293
Loans and leases, net of unearned discount	3,915,248	3,886,992
Other [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,337,042	1,395,240
30-89 Days Past Due	11,601	45,978
Accruing Loans Past Due 90 Days or More	6,974	5,156
Nonaccrual	38,565	3,512
Loans and leases, net of unearned discount	1,394,182	1,481,942
Other [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	908,567
30-89 Days Past Due	6,954
Accruing Loans Past Due 90 Days or More	6,687
Nonaccrual	35,186
Loans and leases, net of unearned discount	957,394
Other [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,807
30-89 Days Past Due	504
Nonaccrual	299
Loans and leases, net of unearned discount	2,610
Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	18,549,250	15,936,862	$ 11,120,334	$ 8,351,948	$ 6,393,180
Term Loans [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Current	2,089,095	1,489,244	664,588	1,282,631	756,137
30-89 Days Past Due	4,319	8,534	5,234	17,517	6,758
Accruing Loans Past Due 90 Days or More	387	9,213	26,596	124,510	30,048
Nonaccrual	761	4,590	1,653	5,257	1,002
Loans and leases, net of unearned discount	2,094,562	1,511,581	698,071	1,429,915	793,945
Term Loans [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	668	4,357	1,961	2,155	163
30-89 Days Past Due			72
Nonaccrual		20		52
Loans and leases, net of unearned discount	668	4,377	2,033	2,207	163
Term Loans [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Current	2,323,314	1,881,732	969,243	674,896	379,441
30-89 Days Past Due	5,130	9,073	6,755	5,091	3,168
Nonaccrual	1,314	3,961	3,790	4,175	2,379
Loans and leases, net of unearned discount	2,329,758	1,894,766	979,788	684,162	384,988
Term Loans [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,084,223	1,223,790	711,515	513,607	208,741
30-89 Days Past Due	2,884	10,573	11,193	10,126	5,170
Nonaccrual	1,244	7,754	11,224	11,010	6,461
Loans and leases, net of unearned discount	1,088,351	1,242,117	733,932	534,743	220,372
Term Loans [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Current	132,769	154,094	62,966	39,231	6,252
30-89 Days Past Due	1,874	890	537	243	29
Nonaccrual	1,540	446	442	226	43
Loans and leases, net of unearned discount	136,183	$ 155,430	$ 63,945	$ 39,700	$ 6,324
Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	20,443,519
Term Loans Prior Period [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Current	7,583,780
30-89 Days Past Due	143,058
Accruing Loans Past Due 90 Days or More	312,696
Nonaccrual	284,167
Loans and leases, net of unearned discount	8,323,701
Term Loans Prior Period [Member] | Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Current	1,606,130
30-89 Days Past Due	20,980
Nonaccrual	115,783
Loans and leases, net of unearned discount	1,742,893
Term Loans Prior Period [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Current	57,998
30-89 Days Past Due	1,809
Nonaccrual	5,018
Loans and leases, net of unearned discount	64,825
Term Loans Prior Period [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Current	609,500
30-89 Days Past Due	6,786
Nonaccrual	8,572
Loans and leases, net of unearned discount	624,858
Term Loans Prior Period [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Current	88,092
30-89 Days Past Due	2,960
Nonaccrual	4,681
Loans and leases, net of unearned discount	95,733
Term Loans Prior Period [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Current	31,356
30-89 Days Past Due	570
Accruing Loans Past Due 90 Days or More	287
Nonaccrual	383
Loans and leases, net of unearned discount	$ 32,596

Loans and Leases and the All_10

Loans and Leases and the Allowance for Credit Losses - Summary of Loan Grades (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 98,447,048	$ 90,922,869
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,891,648	23,838,168
Commercial, Financial, Leasing, etc. [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	26,013,705	22,595,821
Commercial, Financial, Leasing, etc. [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,527,315	895,790
Commercial, Financial, Leasing, etc. [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	350,628	346,557
Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	27,709,261	26,657,808
Commercial [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	23,817,295	25,728,725
Commercial [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	3,639,451	770,609
Commercial [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	252,515	158,474
Residential Builder and Developer [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,362,978	1,547,245
Residential Builder and Developer [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,292,307	1,419,162
Residential Builder and Developer [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	68,838	124,101
Residential Builder and Developer [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,833	3,982
Other Commercial Construction [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	8,509,845	7,336,861
Other Commercial Construction [Member] | Pass [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,433,054	7,092,799
Other Commercial Construction [Member] | Criticized Accrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,039,164	211,292
Other Commercial Construction [Member] | Criticized Nonaccrual [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	$ 37,627	$ 32,770

Loans and Leases and the All_11

Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 1,638,236	$ 1,029,867	$ 1,051,071	$ 1,019,444
Provision for credit losses	150,000	45,000	725,000	122,000
Net charge-offs
Charge-offs	(52,226)	(60,241)	(211,327)	(174,747)
Recoveries	22,495	23,811	61,304	71,740
Net (charge-offs) recoveries	(29,731)	(36,430)	(150,023)	(103,007)
Ending balance	1,758,505	1,038,437	1,758,505	1,038,437
Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Net charge-offs
Adoption of new accounting standard			132,457
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	398,257	335,855	366,094	330,055
Provision for credit losses	25,450	24,538	161,444	41,146
Net charge-offs
Charge-offs	(14,434)	(15,678)	(63,425)	(40,786)
Recoveries	4,475	6,730	11,109	21,030
Net (charge-offs) recoveries	(9,959)	(8,948)	(52,316)	(19,756)
Ending balance	413,748	351,445	413,748	351,445
Commercial, Financial, Leasing, etc. [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Net charge-offs
Adoption of new accounting standard			(61,474)
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	576,321	343,296	322,201	341,655
Provision for credit losses	87,403	(16,713)	335,159	(6,415)
Net charge-offs
Charge-offs	(4,522)	(1,107)	(23,266)	(11,555)
Recoveries	2,578	1,656	4,030	3,447
Net (charge-offs) recoveries	(1,944)	549	(19,236)	(8,108)
Ending balance	661,780	327,132	661,780	327,132
Commercial Real Estate [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Net charge-offs
Adoption of new accounting standard			23,656
One-to-Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	118,921	61,011	56,033	69,125
Provision for credit losses	(683)	(309)	11,458	(5,132)
Net charge-offs
Charge-offs	(1,516)	(2,721)	(8,227)	(9,356)
Recoveries	960	1,511	4,522	4,855
Net (charge-offs) recoveries	(556)	(1,210)	(3,705)	(4,501)
Ending balance	117,682	59,492	117,682	59,492
One-to-Four Family Residential [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Net charge-offs
Adoption of new accounting standard			53,896
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	544,737	211,220	229,118	200,564
Provision for credit losses	37,830	37,735	216,939	92,212
Net charge-offs
Charge-offs	(31,754)	(40,735)	(116,409)	(113,050)
Recoveries	14,482	13,914	41,643	42,408
Net (charge-offs) recoveries	(17,272)	(26,821)	(74,766)	(70,642)
Ending balance	$ 565,295	222,134	565,295	222,134
Consumer [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Net charge-offs
Adoption of new accounting standard			194,004
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance		78,485	77,625	78,045
Provision for credit losses		(251)		189
Net charge-offs
Ending balance		$ 78,234		$ 78,234
Unallocated [Member] | Revision of Prior Period, Accounting Standards Update, Adjustment [Member]
Net charge-offs
Adoption of new accounting standard			$ (77,625)

Loans and Leases and the All_12

Loans and Leases and the Allowance for Credit Losses - Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Jan. 01, 2020	Jun. 30, 2019	Jan. 01, 2019
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	$ 558,807	$ 413,503	$ 558,807	$ 413,503
Amortized Cost without Allowance	681,165	591,746	681,165	591,746
Total	1,239,972	1,005,249	1,239,972	1,005,249
Amortized Cost					$ 1,156,650	$ 1,134,333	$ 865,384	$ 893,608
Interest Income Recognized	12,255	9,101	42,953	31,151
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	264,515	223,183	264,515	223,183
Amortized Cost without Allowance	86,113	159,626	86,113	159,626
Total	350,628	382,809	350,628	382,809
Amortized Cost					284,654	346,743	223,733	234,423
Interest Income Recognized	5,999	836	9,035	7,552
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	86,199	40,203	86,199	40,203
Amortized Cost without Allowance	166,316	144,429	166,316	144,429
Total	252,515	184,632	252,515	184,632
Amortized Cost					172,488	173,796	203,116	203,672
Interest Income Recognized	993	1,802	6,782	5,212
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	1,833	1,596	1,833	1,596
Amortized Cost without Allowance		3,379		3,379
Total	1,833	4,975	1,833	4,975
Amortized Cost					1,748	4,708	5,985	4,798
Interest Income Recognized	114	89	173	308
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	15,441	15,501	15,441	15,501
Amortized Cost without Allowance	22,186	15,940	22,186	15,940
Total	37,627	31,441	37,627	31,441
Amortized Cost					85,426	35,881	32,769	22,205
Interest Income Recognized	232	488	6,809	1,669
Residential [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	66,302	57,070	66,302	57,070
Amortized Cost without Allowance	231,334	166,496	231,334	166,496
Total	297,636	223,566	297,636	223,566
Amortized Cost					306,907	322,504	210,922	233,352
Interest Income Recognized	3,410	3,425	15,258	10,014
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	29,824	27,803	29,824	27,803
Amortized Cost without Allowance	85,959	53,876	85,959	53,876
Total	115,783	81,679	115,783	81,679
Amortized Cost					118,695	114,667	87,551	84,685
Interest Income Recognized	114	269	571	795
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	36,134	23,908	36,134	23,908
Amortized Cost without Allowance	42,686	36,007	42,686	36,007
Total	78,820	59,915	78,820	59,915
Amortized Cost					77,094	65,039	66,927	71,292
Interest Income Recognized	1,017	1,846	3,236	4,617
Recreational Finance [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	17,637	6,577	17,637	6,577
Amortized Cost without Allowance	6,554	5,275	6,554	5,275
Total	24,191	11,852	24,191	11,852
Amortized Cost					24,152	14,308	11,153	11,199
Interest Income Recognized	155	147	461	431
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	37,355	14,596	37,355	14,596
Amortized Cost without Allowance	5,019	6,443	5,019	6,443
Total	42,374	21,039	42,374	21,039
Amortized Cost					42,736	21,293	20,170	23,359
Interest Income Recognized	47	54	139	161
Other [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	3,567	3,066	3,567	3,066
Amortized Cost without Allowance	34,998	275	34,998	275
Total	38,565	3,341	38,565	3,341
Amortized Cost					$ 42,750	$ 35,394	$ 3,058	$ 4,623
Interest Income Recognized	$ 174	$ 145	$ 489	$ 392

Loans and Leases and the All_13

Loans and Leases and the Allowance for Credit Losses - Loan Modification Activities that were Considered Troubled Debt Restructurings (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)Modification	Sep. 30, 2019USD ($)Modification	Sep. 30, 2020USD ($)Modification	Sep. 30, 2019USD ($)Modification
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	1,085	97	3,575	322
Pre-modification Recorded Investment	$ 73,071	$ 16,466	$ 292,445	$ 86,580
Post- modification	73,598	16,845	283,415	87,094
Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	35,178	5,388	117,336	23,981
Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	470		803
Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	30		36,435
Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 37,920	$ 11,457	$ 128,841	$ 63,113
Commercial, Financial, Leasing, etc. [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	112	26	279	115
Pre-modification Recorded Investment	$ 35,037	$ 6,145	$ 102,865	$ 39,357
Post- modification	34,955	6,107	101,678	39,409
Commercial, Financial, Leasing, etc. [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	7,145	1,441	29,762	8,582
Commercial, Financial, Leasing, etc. [Member] | Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	298		298
Commercial, Financial, Leasing, etc. [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			31,605
Commercial, Financial, Leasing, etc. [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 27,512	$ 4,666	$ 40,013	$ 30,827
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	50	9	106	38
Pre-modification Recorded Investment	$ 13,293	$ 2,986	$ 94,807	$ 22,567
Post- modification	13,308	2,972	82,623	22,144
Commercial Real Estate [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	12,506	383	24,372	3,947
Commercial Real Estate [Member] | Interest Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	172		505
Commercial Real Estate [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	30		4,830
Commercial Real Estate [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 600	$ 2,589	$ 52,916	$ 18,197
Residential Builder and Developer [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification			1	2
Pre-modification Recorded Investment			$ 91	$ 1,330
Post- modification			90	1,068
Residential Builder and Developer [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification				$ 1,068
Residential Builder and Developer [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			$ 90
Other Commercial Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification				2
Pre-modification Recorded Investment				$ 1,456
Post- modification				1,399
Other Commercial Construction [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification				$ 1,399
Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	30	20	82	63
Pre-modification Recorded Investment	$ 8,544	$ 5,161	$ 27,594	$ 16,490
Post- modification	9,133	5,581	30,991	17,647
Residential [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	5,517	3,046	11,865	8,805
Residential [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 3,616	$ 2,535	$ 19,126	$ 8,842
Home Equity Lines and Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	33	12	159	32
Pre-modification Recorded Investment	$ 3,410	$ 1,392	$ 11,719	$ 3,141
Post- modification	3,415	1,399	11,745	3,168
Home Equity Lines and Loans [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	129		688	90
Home Equity Lines and Loans [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 3,286	$ 1,399	$ 11,057	$ 3,078
Recreational Finance [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	74	3	348	8
Pre-modification Recorded Investment	$ 2,734	$ 61	$ 13,619	$ 164
Post- modification	2,734	61	13,619	164
Recreational Finance [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 2,734	$ 61	$ 13,619	$ 164
Automobile [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	403	26	1,873	58
Pre-modification Recorded Investment	$ 7,007	$ 485	$ 33,541	$ 991
Post- modification	7,007	485	33,541	991
Automobile [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	7,005	457	33,539	926
Automobile [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 2	$ 28	$ 2	$ 65
Other [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification	383		718
Pre-modification Recorded Investment	$ 3,046		$ 5,229
Post- modification	3,046		5,229
Other [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	142		824
Other [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification	$ 2,904		$ 4,405
Residential Limited Documentation [Member]
Financing Receivable, Modifications [Line Items]
Number of modifications | Modification		1	9	4
Pre-modification Recorded Investment		$ 236	$ 2,980	$ 1,084
Post- modification		240	3,899	1,104
Residential Limited Documentation [Member] | Principal Deferral [Member]
Financing Receivable, Modifications [Line Items]
Post- modification			2,667	399
Residential Limited Documentation [Member] | Combination of Concession Types [Member]
Financing Receivable, Modifications [Line Items]
Post- modification		$ 240	$ 1,232	$ 705

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($) $ in Millions	Jul. 17, 2020	Jan. 07, 2020	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Junior subordinated debentures			$ 527
Debt Maturity, Start Year			Jan. 1, 2027
Debt Maturity, End Year			Dec. 31, 2033
Agreements to repurchase securities				$ 102
Collateral posted				$ 108
Fixed Rate Senior Notes Due On February 6, 2020 [Member]
Debt Instrument [Line Items]
Redeemed senior notes		$ 750
Maturity Date		Aug. 17, 2020
Fixed Rate Senior Notes Due On July 17, 2020 [Member]
Debt Instrument [Line Items]
Redeemed senior notes	$ 750
Maturity Date	Aug. 17, 2020

Revenue from Contracts with C_3

Revenue from Contracts with Customers - Additional Information (Detail1)	Sep. 30, 2020
Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-07-01
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	Sep. 30, 2020	Dec. 31, 2019
Disaggregation Of Revenue [Line Items]
Uncollected amounts receivable	$ 61	$ 62
Accrued interest and other liabilities [Member]
Disaggregation Of Revenue [Line Items]
Deferred revenue	$ 41	$ 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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation Of Revenue [Line Items]
Brokerage services income	$ 11,602	$ 12,077	$ 35,194	$ 37,031
Other revenues from operations:
Total other income	520,561	527,779	1,537,194	1,540,639
Total other income	520,561	527,779	1,537,194	1,540,639
Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	91,355	111,092	274,971	321,991
Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	149,937	143,915	450,570	421,083
ASU 2014-09 [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	11,602	12,077	35,194	37,031
Other revenues from operations:
Merchant discount and credit card fees	25,654	28,190	73,876	82,016
Other	21,407	20,353	60,477	69,013
Total other income	299,955	315,627	895,088	931,134
Merchant discount and credit card fees	25,654	28,190	73,876	82,016
Other	21,407	20,353	60,477	69,013
Total other income	299,955	315,627	895,088	931,134
ASU 2014-09 [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	91,355	111,092	274,971	321,991
ASU 2014-09 [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	149,937	143,915	450,570	421,083
ASU 2014-09 [Member] | Business Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	10,533	9,692	29,023	28,469
Total other income	22,060	24,832	67,089	73,905
Merchant discount and credit card fees	10,533	9,692	29,023	28,469
Total other income	22,060	24,832	67,089	73,905
ASU 2014-09 [Member] | Business Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	11,527	15,131	38,048	45,415
ASU 2014-09 [Member] | Business Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer		9	18	21
ASU 2014-09 [Member] | Commercial Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	10,785	13,409	32,992	38,630
Other	2,940	1,239	5,913	5,386
Total other income	36,542	38,317	108,834	114,427
Merchant discount and credit card fees	10,785	13,409	32,992	38,630
Other	2,940	1,239	5,913	5,386
Total other income	36,542	38,317	108,834	114,427
ASU 2014-09 [Member] | Commercial Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	22,816	23,427	69,487	69,731
ASU 2014-09 [Member] | Commercial Banking [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1	242	442	680
ASU 2014-09 [Member] | Commercial Real Estate [Member]
Other revenues from operations:
Merchant discount and credit card fees	492	670	1,720	1,772
Other	929	1,372	2,960	5,840
Total other income	3,768	4,457	12,404	14,915
Merchant discount and credit card fees	492	670	1,720	1,772
Other	929	1,372	2,960	5,840
Total other income	3,768	4,457	12,404	14,915
ASU 2014-09 [Member] | Commercial Real Estate [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	2,347	2,415	7,724	7,303
ASU 2014-09 [Member] | Discretionary Portfolio [Member]
Other revenues from operations:
Other	205	503	1,212	1,545
Total other income	205	503	1,212	1,545
Other	205	503	1,212	1,545
Total other income	205	503	1,212	1,545
ASU 2014-09 [Member] | Residential Mortgage Banking [Member]
Other revenues from operations:
Other	1,127	816	3,101	2,913
Total other income	1,127	816	3,101	2,917
Other	1,127	816	3,101	2,913
Total other income	1,127	816	3,101	2,917
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
ASU 2014-09 [Member] | Retail Banking [Member]
Other revenues from operations:
Merchant discount and credit card fees	4,159	4,150	9,880	11,854
Other	5,994	9,347	15,142	27,170
Total other income	63,532	81,952	180,095	234,291
Merchant discount and credit card fees	4,159	4,150	9,880	11,854
Other	5,994	9,347	15,142	27,170
Total other income	63,532	81,952	180,095	234,291
ASU 2014-09 [Member] | Retail Banking [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	53,379	68,455	155,073	195,267
ASU 2014-09 [Member] | All Other [Member]
Disaggregation Of Revenue [Line Items]
Brokerage services income	11,602	12,077	35,194	37,031
Other revenues from operations:
Merchant discount and credit card fees	(315)	269	261	1,291
Other	10,212	7,076	32,149	26,159
Total other income	172,721	164,750	522,353	489,134
Merchant discount and credit card fees	(315)	269	261	1,291
Other	10,212	7,076	32,149	26,159
Total other income	172,721	164,750	522,353	489,134
ASU 2014-09 [Member] | All Other [Member] | Service Charges on Deposit Accounts [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	1,286	1,664	4,639	4,271
ASU 2014-09 [Member] | All Other [Member] | Trust Income [Member]
Disaggregation Of Revenue [Line Items]
Revenue from contract with customer	$ 149,936	$ 143,664	$ 450,110	$ 420,382

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefits - Net Periodic Defined Benefit Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,986	$ 4,324	$ 14,958	$ 12,970
Interest cost on projected benefit obligation	17,855	20,394	53,565	61,184
Expected return on plan assets	(31,378)	(30,534)	(94,134)	(91,604)
Amortization of prior service cost (credit)	125	139	404	418
Amortization of net actuarial loss (gain)	13,950	5,498	42,998	16,494
Net periodic cost (benefit)	5,538	(179)	17,791	(538)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	242	215	727	644
Interest cost on projected benefit obligation	436	586	1,306	1,758
Amortization of prior service cost (credit)	(1,175)	(1,182)	(3,544)	(3,547)
Amortization of net actuarial loss (gain)	(300)	(312)	(918)	(935)
Net periodic cost (benefit)	$ (797)	$ (693)	$ (2,429)	$ (2,080)

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefits - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Compensation And Retirement Disclosure [Abstract]
Defined contribution pension and retirement savings plans total expense	$ 23	$ 21	$ 73	$ 61

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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income available to common shareholders:
Net income	$ 372,136	$ 480,081	$ 882,012	$ 1,436,083
Less: Preferred stock dividends	(17,050)	(16,103)	(51,178)	(52,364)
Net income available to common equity	355,086	463,978	830,834	1,383,719
Less: Income attributable to unvested stock-based compensation awards	(1,687)	(2,568)	(3,631)	(7,591)
Net income available to common shareholders	$ 353,399	$ 461,410	$ 827,203	$ 1,376,128
Weighted-average shares outstanding:
Common shares outstanding (including common stock issuable) and unvested stock-based compensation awards	129,061	133,703	129,518	136,156
Less: Unvested stock-based compensation awards	(776)	(738)	(768)	(745)
Weighted-average shares outstanding	128,285	132,965	128,750	135,411
Basic earnings per common share	$ 2.75	$ 3.47	$ 6.42	$ 10.16

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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net income available to common equity	$ 355,086	$ 463,978	$ 830,834	$ 1,383,719
Less: Income attributable to unvested stock-based compensation awards	(1,686)	(2,568)	(3,630)	(7,590)
Net income available to common shareholders	$ 353,400	$ 461,410	$ 827,204	$ 1,376,129
Adjusted weighted-average shares outstanding:
Common and unvested stock-based compensation awards	129,061	133,703	129,518	136,156
Less: Unvested stock-based compensation awards	(776)	(738)	(768)	(745)
Plus: Incremental shares from assumed conversion of stock-based compensation awards and warrants to purchase common stock	70	34	63	32
Adjusted weighted-average shares outstanding	128,355	132,999	128,813	135,443
Diluted earnings per common share	$ 2.75	$ 3.47	$ 6.42	$ 10.16

Earnings Per Common Share - Add

Earnings Per Common Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share	483,182	277,840	477,144	224,639

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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			$ (279,959)	$ (569,328)
Unrealized holding gains (losses), net, before tax			151,777	237,615
Foreign currency translation adjustment, before tax			(222)	(2,663)
Unrealized gains (losses) on cash flow hedges, before tax			508,226	204,587
Total other comprehensive income (loss) before reclassifications, before tax			659,781	439,539
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			2,678	2,524
Gains (Loss) realized in net income			(3)	7
Accretion of net gain on terminated cash flow hedges, before tax			(94)	(93)
Net yield adjustment from cash flow hedges currently in effect, before tax			(183,598)	6,693
Amortization of prior service credit, before tax			(3,140)	(3,129)
Amortization of actuarial losses, before tax			42,080	15,559
Total other comprehensive income (loss), before tax			517,704	461,100
Ending balance, before tax	$ 237,745	$ (108,228)	237,745	(108,228)
Beginning balance, before tax			73,279	149,247
Unrealized holding gains (losses), net, before tax			(39,277)	(62,432)
Foreign currency translation adjustment, before tax			(39)	559
Unrealized gains (losses) on cash flow hedges, before tax			(131,504)	(53,786)
Total other comprehensive income (loss) before reclassifications, before tax			(170,820)	(115,659)
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			(725)	(663)
Gains (Loss) realized in net income			1	(2)
Accretion of net gain on terminated cash flow hedges, before tax			26	25
Net yield adjustment from cash flow hedges currently in effect, before tax			47,506	(1,760)
Amortization of prior service credit, before tax			927	823
Amortization of actuarial losses, before tax			(12,436)	(4,091)
Total other comprehensive income (loss), before tax			(135,521)	(121,327)
Ending balance, before tax	(62,242)	27,920	(62,242)	27,920
Unrealized holding gains (losses), net, before tax			(39,277)	(62,432)
Beginning balance, before tax			(206,680)	(420,081)
Unrealized holding gains (losses), net, before tax			112,500	175,183
Foreign currency translation adjustments	2,733	(1,704)	(261)	(2,104)
Unrealized gains (losses) on cash flow hedges, before tax			376,722	150,801
Total other comprehensive income (loss) before reclassifications, before tax			488,961	323,880
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			1,953	1,861
Gains (Loss) realized in net income			(2)	(5)
Accretion of net gain on terminated cash flow hedges, before tax			(68)	(68)
Net yield adjustment from cash flow hedges currently in effect, before tax			(136,092)	4,933
Amortization of prior service credit, before tax			(2,213)	(2,306)
Amortization of actuarial losses, before tax			29,644	(11,468)
Total other comprehensive income (loss)	(69,127)	32,650	382,183	339,773
Ending balance, before tax	175,503	(80,308)	175,503	(80,308)
Losses realized in net income, net of tax			2	5
Amortization of actuarial losses, net of tax			(29,644)	11,468
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			50,701	(200,107)
Unrealized holding gains (losses), net, before tax			151,777	237,615
Total other comprehensive income (loss) before reclassifications, before tax			151,777	237,615
Amortization of unrealized holding losses on held-to-maturity ("HTM") securities, before tax			2,678	2,524
Gains (Loss) realized in net income			(3)	7
Total other comprehensive income (loss), before tax			154,452	240,146
Ending balance, before tax	205,153	40,039	205,153	40,039
Total other comprehensive income (loss)			114,451
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(464,548)	(354,502)
Amortization of prior service credit, before tax			(3,140)	(3,129)
Amortization of actuarial losses, before tax			42,080	15,559
Total other comprehensive income (loss), before tax			38,940	12,430
Ending balance, before tax	(425,608)	(342,072)	(425,608)	(342,072)
Total other comprehensive income (loss)			27,431
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			133,888	(14,719)
Foreign currency translation adjustment, before tax			(222)	(2,663)
Unrealized gains (losses) on cash flow hedges, before tax			508,226	204,587
Total other comprehensive income (loss) before reclassifications, before tax			508,004	201,924
Accretion of net gain on terminated cash flow hedges, before tax			(94)	(93)
Net yield adjustment from cash flow hedges currently in effect, before tax			(183,598)	6,693
Total other comprehensive income (loss), before tax			324,312	208,524
Ending balance, before tax	$ 458,200	$ 193,805	$ 458,200	$ 193,805

Comprehensive Income - Accumula

Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 15,945,105	$ 15,691,827	$ 15,716,649	$ 15,460,191
Net gain during period	(69,127)	32,650	382,183	339,773
Ending balance	16,101,013	15,779,811	16,101,013	15,779,811
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			37,380
Net gain during period			114,451
Ending balance	151,831		151,831
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(342,419)
Net gain during period			27,431
Ending balance	(314,988)		(314,988)
Cash Flow Hedges and Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			98,359
Net gain during period			240,301
Ending balance	338,660		338,660
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	244,630	(112,958)	(206,680)	(420,081)
Net gain during period			382,183
Ending balance	$ 175,503	$ (80,308)	$ 175,503	$ (80,308)

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	$ 54,550,000,000		$ 54,550,000,000		$ 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	66,000,000		66,000,000		18,000,000
Aggregate fair value of derivative financial instruments in a liability position	127,000,000		127,000,000		51,000,000
Aggregate fair value of derivative financial instruments in asset position					6,000,000
Net fair value of derivative financial instruments in a net asset position					6,000,000
Collateral relating to net asset positions					5,000,000
Counterparties [Member]
Derivative [Line Items]
Post collateral requirements relating to positions	123,000,000		123,000,000		50,000,000
Clearinghouse Credit Facilities [Member]
Derivative [Line Items]
Amount of initial margin posted	125,000,000		125,000,000		84,000,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Increase decrease in net interest income due to interest rate swap agreements	95,000,000	$ 1,000,000	212,000,000	$ (23,000,000)
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amounts of derivative contracts entered into for trading account purposes	36,600,000,000		36,600,000,000		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	$ 877,000,000		$ 877,000,000		$ 1,200,000,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount	$ 54,550,000,000	$ 57,550,000,000
Average Maturity (in years)	1 year 1 month 6 days	1 year 6 months
Estimated Fair Value Gain (Loss)	$ 377,000	$ (1,762,000)
Interest Payments On Variable Rate Commercial Real Estate Loans [Member] | Cash Flow Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 52,250,000,000	$ 53,750,000,000
Average Maturity (in years)	1 year 1 month 6 days	1 year 4 months 24 days
Weighted-Average Rate, Fixed	2.40%	2.44%
Weighted-Average Rate, Variable	0.15%	1.73%
Estimated Fair Value Gain (Loss)	$ 890,000	$ (1,195,000)
Fixed Rate Long-Term Borrowings [Member] | Fair Value Hedges [Member]
Derivative [Line Items]
Notional Amount	$ 2,300,000,000	$ 3,800,000,000
Average Maturity (in years)	2 years 8 months 12 days	2 years 2 months 12 days
Weighted-Average Rate, Fixed	2.80%	2.51%
Weighted-Average Rate, Variable	0.69%	2.27%
Estimated Fair Value Gain (Loss)	$ (513,000)	$ (567,000)

Derivative Financial Instrume_5

Derivative Financial Instruments - Information about Interest Rate Swap Agreements (Parenthetical) (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional Amount	$ 54,550,000,000	$ 57,550,000,000
Forward-Starting Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Notional Amount	38,900,000,000	40,400,000,000
Fair Value Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value losses on hedging instruments	120,800,000	45,100,000
Cash Flow Hedges [Member]
Derivative [Line Items]
Reduction of estimated fair value losses on hedging instruments	$ 463,300,000	$ 140,700,000

Derivative Financial Instrume_6

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 1,222,366	$ 427,267
Liability Derivatives, Fair Value	137,931	87,091
Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,219,131	425,840
Liability Derivatives, Fair Value	134,334	84,676
Fair Value Hedges [Member] | Derivatives Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	3,235	1,427
Liability Derivatives, Fair Value	3,597	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	1,710	232
Liability Derivatives, Fair Value	1,333	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	1,795	3,074
Liability Derivatives, Fair Value	11,066	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	1,525	1,195
Liability Derivatives, Fair Value	2,264	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	51,786	11,965
Liability Derivatives, Fair Value	283	1,225
Interest Rate Contracts [Member] | Derivatives Not Designated and Qualifying as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	1,157,856	398,295
Liability Derivatives, Fair Value	115,361	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	7,694	12,506
Liability Derivatives, Fair Value	$ 7,624	$ 11,800

Derivative Financial Instrume_7

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Balance Sheet (Parenthetical) (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Offsetting [Abstract]
Reduction in estimated fair value of interest rate contracts in asset position	$ (2.9)	$ (43.3)
Reduction in estimated fair value of interest rate contracts in liability position	$ (944.9)	$ (281.3)

Derivative Financial Instrume_8

Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ (3,290)	$ 9,033	$ 15,543	$ 24,329
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	(13,067)	22,582	75,760	113,441
Derivatives in fair value hedging relationships, Hedged item	12,822	(22,412)	(75,607)	(112,884)
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	(4,776)	6,435	8,988	17,639
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 1,486	$ 2,598	$ 6,555	$ 6,690

Derivative Financial Instrume_9

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	Sep. 30, 2020	Dec. 31, 2019
Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 2,417,559	$ 3,840,775
Cumulative Amount of Fair Value Hedging Adjustment Increasing (Decreasing) the Carrying Amount [Member]
Derivatives, Fair Value [Line Items]
Hedged Item	$ 119,247	$ 43,640

Variable Interest Entities an_2

Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Loss on securitization of assets			$ 0	$ 0
Other assets for its "investment" in the common securities recognized by the company of various trusts	$ 23,000,000		23,000,000		$ 23,000,000
Total assets of partnerships in which the company invested	138,626,743,000		138,626,743,000		119,872,757,000
Investment in partnership carrying amount	791,000,000		791,000,000		748,000,000
Unfunded commitments includes carrrying amount of its investments	380,000,000		380,000,000		414,000,000
Maximum exposure to loss of investments in real estate partnerships	978,000,000		978,000,000
Investments amortized to income tax expense	22,000,000	$ 17,000,000	65,000,000	51,000,000
Federal tax credits and other federal tax benefits recognized	26,000,000	$ 21,000,000	78,000,000	$ 62,000,000
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested	$ 2,100,000,000		$ 2,100,000,000		$ 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	Sep. 30, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	$ 5,302,338	$ 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	9,370	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	5,165,701	6,180,940
Other Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investment securities	127,251	127,278
Fair Value Measurements, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading account assets	1,215,573	470,129
Investment securities	5,302,338	6,318,776
Equity securities	101,182	140,041
Real estate loans held for sale	909,335	442,079
Other assets	56,816	16,466
Total assets	7,585,244	7,387,491
Trading account liabilities	122,985	79,903
Other liabilities	14,946	7,188
Total liabilities	137,931	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	50,023	49,040
Equity securities	72,856	100,637
Total assets	122,879	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	1,165,550	421,089
Investment securities	5,302,322	6,318,760
Equity securities	28,326	39,404
Real estate loans held for sale	909,335	442,079
Other assets	5,030	4,501
Total assets	7,410,563	7,225,833
Trading account liabilities	122,985	79,903
Other liabilities	14,663	5,963
Total liabilities	137,648	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	51,786	11,965
Total assets	51,802	11,981
Other liabilities	283	1,225
Total liabilities	283	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	9,370	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	9,370	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	5,165,701	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	5,165,701	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	127,251	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	$ 127,251	$ 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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 16	$ 16	$ 16	$ 22
Total gains realized/unrealized:
Settlements				(6)
Ending Balance	16	16	16	16
Other Assets and Other Liabilities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	40,106	17,200	10,740	7,712
Total gains realized/unrealized:
Included in earnings	57,819	62,178	150,632	115,187
Transfers out of Level 3	(46,422)	(55,104)	(109,869)	(98,625)
Ending Balance	51,503	24,274	51,503	24,274
Changes in unrealized gains included in earnings related to assets still held at end of period	$ 44,127	$ 19,350	$ 50,411	$ 24,981

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Measurement Input [Extensible List]	us-gaap:MeasurementInputComparabilityAdjustmentMember		us-gaap:MeasurementInputComparabilityAdjustmentMember
Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations			15.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Discount rates for fair value estimations			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	$ 82	$ 51	$ 82	$ 85
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	165		165		$ 188
Capitalized servicing rights, valuation allowance			27		$ 7
Changes in fair value recognized for impairment of capitalized servicing rights	0	14		23
Valuation charge recognized			$ 20
Weighted-average prepayment speeds			17.19%		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	387	302	$ 387	302	$ 305
Assets taken in foreclosure of defaulted loans measured at fair value on a nonrecurring basis	27	17	27	17
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	159	122	159	122	115
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	$ 228	$ 180	$ 228	$ 180	$ 190

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information Related to Significant Unobservable Inputs (Detail) - Fair Value Measurements, Recurring [Member] - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Discounted Cash Flows | Other Assets and Other Liabilities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements	$ 51,503	$ 10,740
Discounted Cash Flows | Other Assets and Other Liabilities [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	0.00%	0.00%
Discounted Cash Flows | Other Assets and Other Liabilities [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	90.00%	99.00%
Discounted Cash Flows | Other Assets and Other Liabilities [Member] | Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Commitment expirations	18.00%	13.00%
Two Independent Pricing Quotes [Member] | Privately Issued Mortgage-Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Recurring fair value measurements	$ 16	$ 16

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Amounts and Estimated Fair Value for Financial Instrument Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Financial assets:
Interest-bearing deposits at banks	$ 20,197,937		$ 7,190,154
Investment securities	7,723,004		9,497,251
Federal funds sold			3,500
Loans and leases:
Allowance for credit losses	(1,758,505)	$ (1,638,236)	(1,051,071)	$ (1,038,437)	$ (1,029,867)	$ (1,019,444)
Loans and leases, net	96,688,543		89,871,798
Financial liabilities:
Noninterest-bearing deposits	(44,201,670)		(32,396,407)
Savings and interest-checking deposits	(65,732,130)		(54,932,162)
Time deposits	(4,329,550)		(5,757,456)
Deposits at Cayman Islands office	(899,989)		(1,684,044)
Long-term borrowings	(5,458,885)		(6,986,186)
Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities	73,239
Loans and leases:
Consumer loans	16,149,710
Loans and leases, net	92,444,253
Other financial instruments:
Commitments to originate real estate loans for sale	51,503
Other credit-related commitments	(135,416)
Commercial Loans And Leases [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	27,422,525
Commercial [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	36,006,985
Residential Real Estate Loans [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases	12,865,033
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	1,489,232		1,432,805
Interest-bearing deposits at banks	20,197,937		7,190,154
Trading account assets	1,215,573		470,129
Investment securities	7,723,004		9,497,251
Federal funds sold			3,500
Loans and leases:
Consumer loans	16,309,608		15,386,693
Allowance for credit losses	(1,758,505)		(1,051,071)
Loans and leases, net	96,688,543		89,871,798
Accrued interest receivable	429,751		333,142
Financial liabilities:
Noninterest-bearing deposits	(44,201,670)		(32,396,407)
Savings and interest-checking deposits	(65,732,130)		(54,932,162)
Time deposits	(4,329,550)		(5,757,456)
Deposits at Cayman Islands office	(899,989)		(1,684,044)
Short-term borrowings	(46,123)		(62,363)
Long-term borrowings	(5,458,885)		(6,986,186)
Accrued interest payable	(66,158)		(105,374)
Trading account liabilities	(122,985)		(79,903)
Other financial instruments:
Commitments to originate real estate loans for sale	51,503		10,740
Commitments to sell real estate loans	(10,010)		300
Other credit-related commitments	(135,416)		(136,470)
Interest rate swap agreements used for interest rate risk management	377		(1,762)
Carrying Amount [Member] | Commercial Loans And Leases [Member]
Loans and leases:
Commercial loans and leases	27,891,648		23,838,168
Carrying Amount [Member] | Commercial [Member]
Loans and leases:
Commercial loans and leases	37,582,084		35,541,914
Carrying Amount [Member] | Residential Real Estate Loans [Member]
Loans and leases:
Commercial loans and leases	16,663,708		16,156,094
Estimate Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,489,232		1,432,805
Interest-bearing deposits at banks	20,197,937		7,190,154
Trading account assets	1,215,573		470,129
Investment securities	7,816,236		9,539,540
Federal funds sold			3,500
Loans and leases:
Consumer loans	16,149,710		15,413,262
Loans and leases, net	96,851,209		90,668,624
Accrued interest receivable	429,751		333,142
Financial liabilities:
Noninterest-bearing deposits	(44,201,670)		(32,396,407)
Savings and interest-checking deposits	(65,732,130)		(54,932,162)
Time deposits	(4,357,963)		(5,829,347)
Deposits at Cayman Islands office	(899,989)		(1,684,044)
Short-term borrowings	(46,123)		(62,363)
Long-term borrowings	(5,540,675)		(7,063,165)
Accrued interest payable	(66,158)		(105,374)
Trading account liabilities	(122,985)		(79,903)
Other financial instruments:
Commitments to originate real estate loans for sale	51,503		10,740
Commitments to sell real estate loans	(10,010)		300
Other credit-related commitments	(135,416)		(136,470)
Interest rate swap agreements used for interest rate risk management	377		(1,762)
Estimate Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets:
Cash and cash equivalents	1,437,569		1,394,984
Trading account assets	50,023		49,040
Investment securities	72,856		100,637
Estimate Fair Value [Member] | Significant Observable Inputs (Level 2) [Member]
Financial assets:
Cash and cash equivalents	51,663		37,821
Interest-bearing deposits at banks	20,197,937		7,190,154
Trading account assets	1,165,550		421,089
Investment securities	7,670,141		9,351,793
Federal funds sold			3,500
Loans and leases:
Loans and leases, net	4,406,956		4,019,186
Accrued interest receivable	429,751		333,142
Financial liabilities:
Noninterest-bearing deposits	(44,201,670)		(32,396,407)
Savings and interest-checking deposits	(65,732,130)		(54,932,162)
Time deposits	(4,357,963)		(5,829,347)
Deposits at Cayman Islands office	(899,989)		(1,684,044)
Short-term borrowings	(46,123)		(62,363)
Long-term borrowings	(5,540,675)		(7,063,165)
Accrued interest payable	(66,158)		(105,374)
Trading account liabilities	(122,985)		(79,903)
Other financial instruments:
Commitments to sell real estate loans	(10,010)		300
Interest rate swap agreements used for interest rate risk management	377		(1,762)
Estimate Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Investment securities			87,110
Loans and leases:
Consumer loans			15,413,262
Loans and leases, net			86,649,438
Other financial instruments:
Commitments to originate real estate loans for sale			10,740
Other credit-related commitments			(136,470)
Estimate Fair Value [Member] | Commercial Loans And Leases [Member]
Loans and leases:
Commercial loans and leases	27,422,525		23,510,908
Estimate Fair Value [Member] | Commercial Loans And Leases [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases			23,510,908
Estimate Fair Value [Member] | Commercial [Member]
Loans and leases:
Commercial loans and leases	36,343,024		35,517,180
Estimate Fair Value [Member] | Commercial [Member] | Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Commercial loans and leases	336,039		28,338
Estimate Fair Value [Member] | Commercial [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases			35,488,842
Estimate Fair Value [Member] | Residential Real Estate Loans [Member]
Loans and leases:
Commercial loans and leases	16,935,950		16,227,274
Estimate Fair Value [Member] | Residential Real Estate Loans [Member] | Significant Observable Inputs (Level 2) [Member]
Loans and leases:
Commercial loans and leases	$ 4,070,917		3,990,848
Estimate Fair Value [Member] | Residential Real Estate Loans [Member] | Significant Unobservable Inputs (Level 3) [Member]
Loans and leases:
Commercial loans and leases			$ 12,236,426

Commitments and Contingencies -

Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Commitments to extend credit
Home equity lines of credit	$ 5,557,722	$ 5,442,160
Commercial real estate loans to be sold	216,353	164,076
Other commercial real estate	8,031,403	9,029,608
Residential real estate loans to be sold	1,134,097	423,056
Other residential real estate	712,964	448,375
Commercial and other	19,921,166	16,170,731
Standby letters of credit	2,354,799	2,441,432
Commercial letters of credit	32,422	41,059
Financial guarantees and indemnification contracts	4,250,654	4,108,572
Commitments to sell real estate loans	$ 1,895,436	$ 906,037

Commitments and Contingencies_2

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Commitments to extend credit to commercial customers	$ 10,100,000,000	$ 9,100,000,000
Maximum credit risk for recourse associated with loans sold under Federal National Mortgage Association Delegated Underwriting and Servicing program	3,900,000,000	$ 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	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Net income	$ 372,136	$ 480,081	$ 882,012	$ 1,436,083
Net Income (Loss)	372,136	480,081	882,012	1,436,083
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,463,656	1,557,669	4,414,231	4,662,070
Business Banking [Member]
Segment Reporting Information [Line Items]
Net income	35,614	46,147	106,103	131,668
Net Income (Loss)	35,614	46,147	106,103	131,668
Business Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	131,566	143,741	407,485	423,830
Business Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(1)	912	1,028	2,772
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net income	131,414	132,668	386,176	388,393
Net Income (Loss)	131,414	132,668	386,176	388,393
Commercial Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	276,125	282,757	855,426	828,357
Commercial Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	117	980	1,419	2,707
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Net income	87,095	131,161	311,586	370,288
Net Income (Loss)	87,095	131,161	311,586	370,288
Commercial Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	202,987	238,364	653,405	682,979
Commercial Real Estate [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(17)	458	452	1,218
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Net income	97,399	29,604	218,758	106,816
Net Income (Loss)	97,399	29,604	218,758	106,816
Discretionary Portfolio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	140,135	50,871	328,181	175,764
Discretionary Portfolio [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(10,748)	(10,550)	(33,646)	(29,140)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Net income	45,318	15,846	107,334	36,429
Net Income (Loss)	45,318	15,846	107,334	36,429
Residential Mortgage Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	161,151	115,239	428,757	295,449
Residential Mortgage Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	22,190	19,363	64,623	51,027
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net income	85,229	131,638	281,973	417,198
Net Income (Loss)	85,229	131,638	281,973	417,198
Retail Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	351,312	432,339	1,107,516	1,299,823
Retail Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	268	1,808	802	7,106
All Other [Member]
Segment Reporting Information [Line Items]
Net income	(109,933)	(6,983)	(529,918)	(14,709)
Net Income (Loss)	(109,933)	(6,983)	(529,918)	(14,709)
All Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	200,380	294,358	633,461	955,868
All Other [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ (11,809)	$ (12,971)	$ (34,678)	$ (35,690)

Segment Information - Summary o

Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Segment Reporting Information [Line Items]
Average Total Assets	$ 132,430	$ 119,584	$ 118,584
Business Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	7,902	5,793	5,758
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	30,450	28,142	28,089
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average Total Assets	25,594	23,921	23,893
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Average Total Assets	27,878	29,081	29,355
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	3,530	2,611	2,444
Retail Banking [Member]
Segment Reporting Information [Line Items]
Average Total Assets	16,231	15,083	14,839
All Other [Member]
Segment Reporting Information [Line Items]
Average Total Assets	$ 20,845	$ 14,953	$ 14,206

Segment Information - Summary_2

Segment Information - Summary of Segment Information (Parenthetical) (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Taxable-equivalent adjustment	$ 4,019,000	$ 5,579,000	$ 13,316,000	$ 17,471,000

Relationship with Bayview Len_2

Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 5,458,885,000		$ 5,458,885,000			$ 6,986,186,000
Bayview Lending Group [Member]
Schedule of Equity Method Investments [Line Items]
Carrying value of minority interest investment in Bayview Lending Group LLC	0		0
Income (loss) from equity method investments	0	$ 0
Bayview Lending Group [Member] | Other Revenues From Operations [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments			23,000,000	$ 37,000,000
Bayview Lending Group and Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	2,000,000,000		2,000,000,000			2,200,000,000
Revenue from contract with customer	2,000,000	3,000,000	7,000,000	9,000,000
Bayview Financial [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	67,000,000,000		67,000,000,000			62,800,000,000
Revenues from sub-servicing	30,000,000	$ 33,000,000	101,000,000	$ 90,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	80,000,000		80,000,000			$ 93,000,000
Secured loan facilities carrying amount					$ 100,000,000
Outstanding balance of secured debt	87,000,000		87,000,000
Bayview Financial [Member] | Syndicated Loan Facility [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	1,000,000,000		1,000,000,000
Bayview Financial [Member] | Syndicated Loan Facility [Member] | M&T Bank [Member]
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 164,000,000		$ 164,000,000

Recent Accounting Developments

Recent Accounting Developments - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses	$ 1,758,505	$ 1,638,236		$ 1,051,071	$ 1,038,437	$ 1,029,867	$ 1,019,444
Cumulative effect adjustment to retained earnings	$ 13,132,374			$ 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