Wintrust Financial (WTFC) 10-Q 7 May 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-35077
Entity Registrant Name	WINTRUST FINANCIAL CORP
Entity Incorporation, State or Country Code	IL
Entity Tax Identification Number	36-3873352
Entity Address, Address Line One	9700 W. Higgins Road, Suite 800
Entity Address, City or Town	Rosemont
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60018
City Area Code	847
Local Phone Number	939-9000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,039,674
Entity Central Index Key	0001015328
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Stock, no par value
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, no par value
Trading Symbol	WTFC
Security Exchange Name	NASDAQ
Series D Preferred Stock, no par value
Entity Information [Line Items]
Title of 12(b) Security	Series D Preferred Stock, no par value
Trading Symbol	WTFCM
Security Exchange Name	NASDAQ
Depositary Shares
Entity Information [Line Items]
Title of 12(b) Security	6.875% Fixed-Rate Reset Non-Cumulative Perpetual Series EPreferred Stock, no par value
Trading Symbol	WTFCP
Security Exchange Name	NASDAQ

Consolidated Statements Of Cond

Consolidated Statements Of Condition - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Assets
Cash and due from banks	$ 426,325	$ 322,415	$ 349,118
Federal funds sold and securities purchased under resale agreements	52	59	309
Interest-bearing deposits with banks	3,348,794	4,802,527	1,943,743
Available-for-sale securities, at fair value	2,430,749	3,055,839	3,570,959
Held-to-maturity securities, at amortized cost, net of allowance for credit losses of $99, $59 and $70 at March 31, 2021, December 31, 2020 and March 31, 2020, respectively ($2.1 billion, $593.8 million and $879.2 million fair value at March 31, 2021, December 31, 2020 and March 31, 2020, respectively)	2,166,419	579,138	865,376
Trading account securities	951	671	2,257
Equity securities with readily determinable fair value	90,338	90,862	47,310
Federal Home Loan Bank and Federal Reserve Bank stock	135,881	135,588	134,546
Brokerage customer receivables	19,056	17,436	16,293
Mortgage loans held-for-sale, at fair value	1,260,193	1,272,090	656,934
Loans, net of unearned income	33,171,233	32,079,073	27,807,321
Allowance for loan losses	(321,209)	(379,910)	(253,412)
Net loans	32,893,524	31,759,699	27,591,271
Premises and equipment, net	760,522	768,808	764,583
Lease investments, net	238,984	242,434	207,147
Accrued interest receivable and other assets	1,230,362	1,351,455	1,460,168
Trade date securities receivable	0	0	502,207
Goodwill	646,017	645,707	643,441
Other intangible assets	34,035	36,040	44,185
Total assets	45,682,202	45,080,768	38,799,847
Deposits:
Non-interest-bearing	12,297,337	11,748,455	7,556,755
Interest-bearing	25,575,315	25,344,196	23,904,905
Total deposits	37,872,652	37,092,651	31,461,660
Federal Home Loan Bank advances	1,228,436	1,228,429	1,174,894
Other borrowings	516,877	518,928	487,503
Subordinated notes	436,595	436,506	436,179
Junior subordinated debentures	253,566	253,566	253,566
Trade date securities payable	995	200,907	0
Accrued interest payable and other liabilities	1,120,570	1,233,786	1,285,652
Total liabilities	41,429,691	40,964,773	35,099,454
Shareholders' Equity:
Common stock, no par value; $1.00 stated value; 100,000,000 shares authorized at March 31, 2021, December 31, 2020 and March 31, 2020; 58,726,900 shares issued at March 31, 2021, 58,473,252 shares issued at December 31, 2020 and 58,266,136 shares issued at March 31, 2020	58,727	58,473	58,266
Surplus	1,663,008	1,649,990	1,652,063
Treasury stock, at cost, 1,703,627 shares at March 31, 2021 and December 31, 2020, and 720,784 shares at March 31, 2020	(100,363)	(100,363)	(44,891)
Retained earnings	2,208,535	2,080,013	1,917,558
Accumulated other comprehensive income (loss)	10,104	15,382	(7,603)
Total shareholders’ equity	4,252,511	4,115,995	3,700,393
Total liabilities and shareholders’ equity	$ 45,682,202	$ 45,080,768	$ 38,799,847
Treasury stock (in shares)	1,703,627	1,703,627	720,784
Loans
Assets
Allowance for loan losses	$ (277,709)	$ (319,374)	$ (216,050)
Series D -$25 liquidation value; 5,000,000 shares issued and outstanding at March 31, 2021, December 31, 2020 and March 31, 2020
Shareholders' Equity:
Preferred stock, no par value; 20,000,000 shares authorized:	125,000	125,000	125,000
Series E - $25,000 liquidation value; 11,500 shares issued and outstanding at March 31, 2021 and December 31, 2020 and no shares issued at March 31, 2020
Shareholders' Equity:
Preferred stock, no par value; 20,000,000 shares authorized:	$ 287,500	$ 287,500	$ 0

Consolidated Statements Of Co_2

Consolidated Statements Of Condition (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Allowance for held-to-maturity securities losses	$ 99	$ 59	$ 70
Held-to-maturity securities, fair value	$ 2,121,065	$ 593,767	$ 879,192
Preferred stock, authorized (in shares)	20,000,000	20,000,000	20,000,000
Common stock, stated value (usd per share)	$ 1	$ 1	$ 1
Common stock, authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, issued (in shares)	58,726,900	58,473,252	58,266,136
Treasury stock (in shares)	1,703,627	1,703,627	720,784
Series D Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 25	$ 25	$ 25
Preferred stock, issued (in shares)	5,000,000	5,000,000	5,000,000
Preferred stock, outstanding (in shares)	5,000,000	5,000,000	5,000,000
Series E Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 25,000	$ 25,000	$ 25,000
Preferred stock, issued (in shares)	11,500	0	0
Preferred stock, outstanding (in shares)	11,500	0	0

Consolidated Statements Of Inco

Consolidated Statements Of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest income
Interest and fees on loans	$ 274,100	$ 301,839
Mortgage loans held-for-sale	9,036	3,165
Interest-bearing deposits with banks	1,199	4,768
Federal funds sold and securities purchased under resale agreements	0	86
Investment securities	19,264	32,467
Trading account securities	2	7
Federal Home Loan Bank and Federal Reserve Bank stock	1,745	1,577
Brokerage customer receivables	123	158
Total interest income	305,469	344,067
Interest expense
Interest on deposits	27,944	67,435
Interest on Federal Home Loan Bank advances	4,840	3,360
Interest on other borrowings	2,609	3,546
Interest on subordinated notes	5,477	5,472
Interest on junior subordinated debentures	2,704	2,811
Total interest expense	43,574	82,624
Net interest income	261,895	261,443
Provision for credit losses	(45,347)	52,961
Net interest income after provision for credit losses	307,242	208,482
Non-interest income
Revenue from contracts with customers	47,768	43,655
Mortgage banking	113,494	48,326
Gains (losses) on investment securities, net	1,154	(4,359)
Fees from covered call options	0	2,292
Trading gains (losses), net	419	(451)
Operating lease income, net	14,440	11,984
Other	15,654	18,244
Total non-interest income	186,506	113,242
Non-interest expense
Salaries and employee benefits	180,809	136,762
Equipment	20,912	14,834
Operating lease equipment depreciation	10,771	9,260
Occupancy, net	19,996	17,547
Data processing	6,048	8,373
Advertising and marketing	8,546	10,862
Professional fees	7,587	6,721
Amortization of other intangible assets	2,007	2,863
FDIC insurance	6,558	4,135
OREO expense, net	(251)	(876)
Other	23,906	24,160
Total non-interest expense	286,889	234,641
Income before taxes	206,859	87,083
Income tax expense	53,711	24,271
Net income	153,148	62,812
Preferred stock dividends	6,991	2,050
Net income applicable to common shares	$ 146,157	$ 60,762
Net income per common share-Basic (usd per share)	$ 2.57	$ 1.05
Net income per common share-Diluted (usd per share)	2.54	1.04
Cash dividends declared per common share (usd per share)	$ 0.31	$ 0.28
Weighted average common shares outstanding (in shares)	56,904	57,620
Dilutive potential common shares (in shares)	681	575
Average common shares and dilutive common shares (in shares)	57,585	58,195
Wealth management
Non-interest income
Revenue from contracts with customers	$ 29,309	$ 25,941
Service charges on deposit accounts
Non-interest income
Revenue from contracts with customers	$ 12,036	$ 11,265

Consolidated Statements Of Comp

Consolidated Statements Of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 153,148	$ 62,812
Unrealized (losses) gains on available-for-sale securities
Before tax	(60,726)	91,354
Tax effect	16,207	(24,347)
Net of tax	(44,519)	67,007
Reclassification of net gains on available-for-sale securities included in net income
Before tax	210	491
Tax effect	(56)	(132)
Net of tax	154	359
Reclassification of amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale
Before tax	57	78
Tax effect	(15)	(21)
Net of tax	42	57
Net unrealized (losses) gains on available-for-sale securities	(44,715)	66,591
Unrealized gains (losses) on derivative instruments
Before tax	50,792	(38,693)
Tax effect	(13,535)	10,322
Net unrealized gains (losses) on derivative instruments	37,257	(28,371)
Foreign currency adjustment
Before tax	2,734	(14,333)
Tax effect	(554)	3,188
Net foreign currency adjustment	2,180	(11,145)
Total other comprehensive (loss) income	(5,278)	27,075
Comprehensive income	$ 147,870	$ 89,887

Consolidated Statements Of Chan

Consolidated Statements Of Changes In Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred stock	Common stock	Surplus	Treasury stock	Retained earnings	Accumulated other comprehensive (loss) income	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, AdjustmentRetained earnings
Balance at Dec. 31, 2019	$ 3,691,250	$ 125,000	$ 57,951	$ 1,650,278	$ (6,931)	$ 1,899,630	$ (34,678)	$ (26,717)	$ (26,717)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	62,812					62,812
Other comprehensive income, net of tax	27,075						27,075
Cash dividends declared on common stock	(16,117)					(16,117)
Dividends on preferred stock	(2,050)					(2,050)
Common stock repurchases under authorized program	(37,116)				(37,116)
Stock-based compensation	(2,819)			(2,819)
Common stock issued for:
Exercise of stock options and warrants	3,546		95	3,543	(92)
Restricted stock awards	(752)		190	(190)	(752)
Employee stock purchase plan	709		10	699
Director compensation plan	572		20	552
Balance at Mar. 31, 2020	3,700,393	125,000	58,266	1,652,063	(44,891)	1,917,558	(7,603)
Balance at Dec. 31, 2020	4,115,995	412,500	58,473	1,649,990	(100,363)	2,080,013	15,382
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	153,148					153,148
Other comprehensive income, net of tax	(5,278)						(5,278)
Cash dividends declared on common stock	(17,635)					(17,635)
Dividends on preferred stock	(6,991)					(6,991)
Stock-based compensation	2,862			2,862
Common stock issued for:
Exercise of stock options and warrants	8,961		209	8,752
Restricted stock awards			7	(7)
Employee stock purchase plan	815		14	801
Director compensation plan	634		24	610
Balance at Mar. 31, 2021	$ 4,252,511	$ 412,500	$ 58,727	$ 1,663,008	$ (100,363)	$ 2,208,535	$ 10,104

Consolidated Statements Of Ch_2

Consolidated Statements Of Changes In Shareholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash dividends declared per common share (usd per share)	$ 0.31	$ 0.28
Series D Preferred Stock
Dividends on preferred stock (usd per share)	0.41	$ 0.41
Series E Preferred Stock
Dividends on preferred stock (usd per share)	$ 429.69

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities:
Net income	$ 153,148	$ 62,812
Adjustments to reconcile net income to net cash provided by (used for) operating activities
Provision for credit losses	(45,347)	52,961
Depreciation, amortization and accretion, net	25,561	23,376
Stock-based compensation expense (benefit)	2,862	(2,819)
Net amortization of premium on securities	2,000	1,762
Accretion of discount and deferred fees on loans, net	(21,335)	(10,730)
Mortgage servicing rights fair value changes, net	(7,877)	21,580
Non-designated derivatives fair value changes, net	(723)	(4,707)
Originations and purchases of mortgage loans held-for-sale	(2,221,967)	(1,216,101)
Early buy-out exercises of mortgage loans held-for-sale guaranteed by U.S. Government Agencies, net of subsequent paydown or payoff	(24,362)	0
Proceeds from sales of mortgage loans held-for-sale	2,336,246	961,842
Bank owned life insurance ("BOLI") income	(1,124)	1,284
Increase in trading securities, net	(280)	(1,189)
Net (increase) decrease in brokerage customer receivables	(1,620)	280
Gains on mortgage loans sold	(85,200)	(51,134)
(Gains) losses on investment securities, net	(1,154)	4,359
Losses (gains) on sales of premises and equipment, net	29	(4)
Net gains on sales and fair value adjustments of other real estate owned	(604)	(1,001)
Decrease (increase) in accrued interest receivable and other assets, net	109,554	(214,552)
Decrease in accrued interest payable and other liabilities, net	(1,026)	(7,829)
Net Cash Provided by (Used for) Operating Activities	216,781	(379,810)
Investing Activities:
Proceeds from maturities and calls of available-for-sale securities	595,248	162,824
Proceeds from maturities and calls of held-to-maturity securities	106,535	393,148
Proceeds from sales of available-for-sale securities	0	0
Proceeds from sales of equity securities with readily determinable fair value	1,509	30
Proceeds from sales and capital distributions of equity securities without readily determinable fair value	386	288
Purchases of available-for-sale securities	(31,524)	(1,039,817)
Purchases of held-to-maturity securities	(1,894,837)	(124,575)
Purchases of equity securities with readily determinable fair value	0	(46)
Purchases of equity securities without readily determinable fair value	(2,360)	(893)
Purchases of Federal Home Loan Bank and Federal Reserve Bank stock, net	(293)	(33,807)
Distributions from (contributions to) investments in partnerships, net	60	(355)
Proceeds from sales of other real estate owned	2,162	4,793
Net decrease in interest-bearing deposits with banks	1,454,501	216,944
Net increase in loans	(1,082,709)	(1,006,031)
Purchases of premises and equipment, net	(4,388)	(21,385)
Net Cash Used for Investing Activities	(855,710)	(1,448,882)
Financing Activities:
Increase in deposit accounts, net	780,009	1,354,778
(Decrease) increase in other borrowings, net	(6,378)	88,073
Increase in Federal Home Loan Bank advances, net	0	500,000
Cash payments to settle contingent consideration liabilities recognized in business combinations	(16,583)	0
Issuance of common shares resulting from the exercise of stock options, employee stock purchase plan and conversion of common stock warrants	10,410	4,919
Common stock repurchases under authorized program	0	(37,041)
Common stock repurchases for tax withholdings related to stock-based compensation	0	(919)
Dividends paid	(24,626)	(18,167)
Net Cash Provided by Financing Activities	742,832	1,891,643
Net Increase in Cash and Cash Equivalents	103,903	62,951
Cash and Cash Equivalents at Beginning of Period	322,474	286,476
Cash and Cash Equivalents at End of Period	$ 426,377	$ 349,427

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The interim consolidated financial statements of Wintrust Financial Corporation and its subsidiaries (collectively, “Wintrust” or the “Company”) presented herein are unaudited, but in the opinion of management, reflect all necessary adjustments of a normal or recurring nature for a fair presentation of results as of the dates and for the periods covered by the interim consolidated financial statements. The accompanying interim consolidated financial statements are unaudited and do not include information or footnotes necessary for a complete presentation of financial condition, results of operations or cash flows in accordance with U.S. generally accepted accounting principles (“GAAP”). The interim unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 (“2020 Form 10-K”). Operating results reported for the period are not necessarily indicative of the results which may be expected for the entire year. Reclassifications of certain prior period amounts have been made to conform to the current period presentation. The preparation of the financial statements requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities. Management believes that the estimates made are reasonable; however, changes in estimates may be required if economic or other conditions develop differently from management’s expectations. Certain policies and accounting principles inherently have a greater reliance on the use of estimates, assumptions and judgments and as such have a greater possibility of producing results that could be materially different than originally reported. Management views critical accounting policies to be those which are highly dependent on subjective or complex judgments, estimates and assumptions, and where changes in those estimates and assumptions could have a significant impact on the financial statements. Management currently views the determination of the allowance for credit losses, including the allowance for loan losses, the allowance for unfunded commitment losses and the allowance for held-to-maturity securities losses, estimations of fair value, the valuations required for impairment testing of goodwill, the valuation and accounting for derivative instruments and income taxes as the accounting areas that require the most subjective and complex judgments, and as such could be the most subject to revision as new information becomes available. Descriptions of the Company's significant accounting policies are included in Note 1 - “Summary of Significant Accounting Policies” of the 2020 Form 10-K.

Recent Accounting Developments

Recent Accounting Developments	3 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Developments	Recent Accounting Developments Legislation and Regulations Issued as a Result of the COVID-19 Pandemic On March 27, 2020, the President of the United States signed the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act" or the "Act"), which provides entities with optional temporary relief from certain accounting and financial reporting requirements under U.S. GAAP. Section 4013 of the CARES Act allows financial institutions to suspend application of certain current troubled debt restructuring ("TDR") accounting guidance under Accounting Standards Codification (“ASC”) 310-40 for loan modifications related to the COVID-19 pandemic made between March 1, 2020 and the earlier of December 31, 2020 or 60 days after the end of the COVID-19 national emergency, provided certain criteria are met. This relief can be applied to loan modifications for borrowers that were not more than 30 days past due as of December 31, 2019 and to loan modifications that defer or delay the payment of principal or interest, or change the interest rate on the loan. On December 27, 2020, the Consolidated Appropriations Act, 2021 (the "CAA"), which combined stimulus relief for the COVID-19 pandemic with an omnibus spending bill for the 2021 fiscal year, was signed by the President of the United States. The CAA included extension of TDR accounting relief provided under the CARES Act to January 1, 2022. The Company chose to apply this relief to eligible loan modifications. The business tax provisions of the Act include temporary changes to income and non-income based tax laws, including immediate recovery of qualified improvement property costs and acceleration of Alternative Minimum Tax (AMT) credits. These provisions did not have a material impact on the Company's deferred taxes. In April 2020, federal and state banking regulators issued the Interagency Statement on Loan Modifications and Reporting for Financial Institutions Working with Customers Affected by the Coronavirus to provide separate relief, specifically indicating that if a modification is either short-term (e.g., six months) or mandated by a federal or state government in response to the COVID-19 pandemic, the borrower is not considered to be experiencing financial difficulty and thus does not represent a TDR under ASC 310-40. Additionally, in August 2020, regulators issued the Joint Statement on Additional Loan Accommodations Related to the COVID-19 pandemic to provide prudent risk management and consumer protection principles for financial institutions to consider while working with borrowers as loans near the end of initial loan accommodation periods applicable during the COVID-19 pandemic. The Company continues to prudently work with borrowers negatively impacted by the COVID-19 pandemic while managing credit risks and recognizing appropriate allowance for credit losses on its loan portfolio. Reference Rate Reform In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848),” which provides temporary optional relief for contracts modified as a result of reference rate reform meeting certain modification criteria, generally allowing an entity to account for contract modifications occurring due to reference rate reform as an event that does not require contract remeasurement or reassessment of a previous accounting determination at the modification date. The guidance also includes temporary optional expedients intended to provide relief from various hedge effectiveness requirements for hedging relationships affected by reference rate reform, provided certain criteria are met, and allows a one-time election to sell or transfer to either available-for-sale or trading any held-to-maturity ("HTM") debt securities that refer to an interest rate affected by reference rate reform and were classified as HTM prior to January 1, 2020. Additionally, in January 2021, the FASB issued ASU No. 2021-01, “Reference Rate Reform (Topic 848): Scope,” which provided additional clarification that certain optional expedients and exceptions noted above apply to derivative instruments that use an interest rate for margining, discounting or contract price alignment that is modified as a result of reference rate reform. This guidance was effective upon issuance and can be applied prospectively, with certain exceptions, through December 31, 2022. In November 2020, federal and state banking regulators issued the “Interagency Policy Statement on Reference Rates for Loans" to reiterate that a specific replacement rate for loans impacted by reference rate reform has not been endorsed and entities may utilize any replacement reference rate determined to be appropriate based on its funding model and customer needs. As discussed in the “Interagency Policy Statement on Reference Rates for Loans," fallback language should be included in lending contracts to provide for use of a robust fallback rate if the initial reference rate is discontinued. Additionally, federal banking regulators issued the "Interagency Statement on LIBOR Transition" acknowledging that the administrator of USD LIBOR benchmarks has announced it will consult on its intention to cease the publication of the one week and two month USD LIBOR settings immediately following the LIBOR publication on December 31, 2021, and the remaining USD LIBOR settings immediately following the LIBOR publication on June 30, 2023. On March 5, 2021, the administrator of USD LIBOR benchmarks confirmed these dates and will cease publication of USD LIBOR tenors accordingly. As discussed in the "Interagency Statement on LIBOR Transition," regulators encouraged banks to cease entering into new contracts that use USD LIBOR as a reference rate as soon as practicable and in any event by December 31, 2021, in order to facilitate an orderly, safe and sound LIBOR transition. The Company continues to monitor efforts and evaluate the impact of reference rate reform on its consolidated financial statements. Income Taxes In December 2019, the FASB issued ASU No. 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes," to simplify the accounting for income taxes by removing certain exceptions to the general principles of ASC 740, "Income Taxes". The guidance also improved consistent application by clarifying and amending existing guidance from ASC 740. The Company adopted ASU No. 2019-12 as of January 1, 2021. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Investment Securities In January 2020, the FASB issued ASU No. 2020-01, “Clarifying the Interactions Between Investments-Equity Securities (ASC Topic 321), Investments-Equity Method and Joint Ventures (ASC Topic 323), and Derivatives and Hedging (ASC Topic 815),” which amended ASC 323, Investments-Equity Method & Joint Ventures to clarify that an entity should consider observable transactions that require it to either apply or discontinue using the equity method of accounting for purposes of applying the measurement alternative in accordance with ASC 321, Investments-Equity Securities, immediately before applying or discontinuing the equity method under ASC 323. The guidance also amended ASC 815, Derivatives & Hedging, to clarify that, when determining the accounting for certain nonderivative forward contracts and purchased options, an entity should not consider how to account for the resulting investments upon eventual settlement or exercise, and that an entity should evaluate the remaining characteristics in accordance with ASC 815 to determine the accounting for those forward contracts and purchased options. The Company adopted ASU No. 2020-01 as of January 1, 2021 under a prospective approach. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Codification Improvements In October 2020, the FASB issued ASU No. 2020-08, “Codification Improvements to Subtopic 310-20, Receivables — Nonrefundable Fees and Other Costs,” clarifying that, for each reporting period, an entity should reevaluate whether a callable debt security with multiple call dates is within the scope of ASC 310-20, which was amended to require amortization of any premium to the next call date. The next call date was defined as the first date when a call option at a specified price becomes exercisable. The Company adopted ASU No. 2020-08 as of January 1, 2021 under a prospective approach. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Additionally, the FASB issued ASU No. 2020-10, “Codification Improvements,” in October 2020 to improve the consistency of the Codification by adding or moving disclosure-specific guidance contained in the Other Presentation Matters section to the appropriate Disclosure Section for various Topics. The Company adopted ASU No. 2020-10 as of January 1, 2021 under a retrospective approach. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. SEC Amendments to Financial Disclosures about Acquired and Disposed Businesses In May 2020, the SEC issued a final rule on “Amendments to Financial Disclosures about Acquired and Disposed Businesses,” which provides for specific disclosure changes, including revising the investment and income significance tests, conforming the significance threshold and tests for a disposed business to those used for an acquired business, permitting abbreviated financial statements for certain acquisitions of a component of an entity, and reducing the maximum number of years for which financial statements are required for acquired businesses from three years to two years, among other amendments. This guidance was effective on January 1, 2021. Debt In August 2020, the FASB issued ASU No. 2020-06, “Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity,” which includes provisions for reducing the number of accounting models used in accounting for convertible debt instruments and convertible preferred stock, amending derivatives and earnings-per-share (EPS) guidance and expanding disclosures for convertible debt instruments and EPS. This guidance is effective for fiscal years beginning after December 15, 2021, including interim periods therein, and is to be applied under either a full or modified retrospective approach. Early adoption is permitted. The Company does not expect this guidance to have a material impact on the Company’s consolidated financial statements. SEC Update of Statistical Disclosures for Bank and Savings and Loan Registrants In September 2020, the SEC issued a final rule on the “Update of Statistical Disclosures for Bank and Savings and Loan Registrants,” which adopts rules to update statistical disclosure requirements for banking registrants. The amendments update and expand the disclosures that registrants are required to provide, codify certain Industry Guide 3 disclosure items and eliminate other Guide 3 disclosures that overlap with SEC rules, GAAP or IFRS standards. In addition, Guide 3 is being rescinded and replaced with a new subpart of Regulation S-K. The SEC ruling is applicable to fiscal years beginning after December 15, 2021 and early compliance is permitted. The Company does not expect this guidance to have a material impact on the Company’s consolidated financial statements.

Cash and Cash Equivalents

Cash and Cash Equivalents	3 Months Ended
	Mar. 31, 2021
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	Cash and Cash EquivalentsFor purposes of the Consolidated Statements of Cash Flows, the Company considers cash and cash equivalents to include cash on hand, cash items in the process of collection, non-interest bearing amounts due from correspondent banks, federal funds sold and securities purchased under resale agreements with original maturities of three months or less. These items are included within the Company’s Consolidated Statements of Condition as cash and due from banks, and federal funds sold and securities purchased under resale agreements.

Investment Securities

Investment Securities	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities The following tables are a summary of the investment securities portfolios as of the dates shown: March 31, 2021 (Dollars in thousands) Amortized Gross Gross Fair Available-for-sale securities U.S. Treasury $ 64,999 $ 2 $ — $ 65,001 U.S. Government agencies 77,908 3,618 — 81,526 Municipal 143,711 4,761 (172) 148,300 Corporate notes: Financial issuers 91,806 461 (935) 91,332 Other 1,000 17 — 1,017 Mortgage-backed: (1) Mortgage-backed securities 2,007,092 52,855 (26,038) 2,033,909 Collateralized mortgage obligations 9,411 253 — 9,664 Total available-for-sale securities $ 2,395,927 $ 61,967 $ (27,145) $ 2,430,749 Held-to-maturity securities U.S. Government agencies $ 176,160 $ 1,644 $ (7,230) $ 170,574 Municipal 197,865 10,713 (535) 208,043 Mortgage-backed securities 1,737,115 265 (49,114) 1,688,266 Corporate notes 55,378 — (1,196) 54,182 Total held-to-maturity securities $ 2,166,518 $ 12,622 $ (58,075) $ 2,121,065 Less: Allowance for credit losses (99) Held-to-maturity securities, net of allowance for credit losses $ 2,166,419 Equity securities with readily determinable fair value $ 86,121 $ 5,362 $ (1,145) $ 90,338 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. December 31, 2020 Amortized Gross Gross Fair (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 304,956 $ 15 $ — $ 304,971 U.S. Government agencies 80,074 4,439 — 84,513 Municipal 141,244 5,707 (41) 146,910 Corporate notes: Financial issuers 91,786 1,363 (2,764) 90,385 Other 1,000 20 — 1,020 Mortgage-backed: (1) Mortgage-backed securities 2,330,332 86,721 (15) 2,417,038 Collateralized mortgage obligations 10,689 313 — 11,002 Total available-for-sale securities $ 2,960,081 $ 98,578 $ (2,820) $ 3,055,839 Held-to-maturity securities U.S. Government agencies $ 177,959 $ 2,552 $ — $ 180,511 Municipal 200,707 12,232 (214) 212,725 Mortgage-backed securities 200,531 — — 200,531 Total held-to-maturity securities $ 579,197 $ 14,784 $ (214) $ 593,767 Less: Allowance for credit losses (59) Held-to-maturity securities, net of allowance for credit losses $ 579,138 Equity securities with readily determinable fair value $ 87,618 $ 3,674 $ (430) $ 90,862 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. March 31, 2020 Amortized Gross Gross Fair (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 120,404 $ 1,266 $ — $ 121,670 U.S. Government agencies 362,969 5,674 — 368,643 Municipal 143,273 3,571 (235) 146,609 Corporate notes: Financial issuers 111,718 90 (11,821) 99,987 Other 1,000 31 — 1,031 Mortgage-backed: (1) Mortgage-backed securities 2,697,264 111,275 (4) 2,808,535 Collateralized mortgage obligations 24,077 416 (9) 24,484 Total available-for-sale securities $ 3,460,705 $ 122,323 $ (12,069) $ 3,570,959 Held-to-maturity securities U.S. Government agencies $ 646,976 $ 5,996 $ (4) $ 652,968 Municipal $ 218,470 7,909 (155) 226,224 Total held-to-maturity securities $ 865,446 $ 13,905 $ (159) $ 879,192 Less: Allowance for credit losses (70) Held-to-maturity securities, net of allowance for credit losses $ 865,376 Equity securities with readily determinable fair value $ 48,060 $ 781 $ (1,531) $ 47,310 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. Equity securities without readily determinable fair values totaled $33.3 million as of March 31, 2021. Equity securities without readily determinable fair values are included as part of accrued interest receivable and other assets in the Company's Consolidated Statements of Condition. The Company monitors its equity investments without readily determinable fair values to identify potential transactions that may indicate an observable price change in orderly transactions for the identical or a similar investment of the same issuer, requiring adjustment to its carrying amount. The Company recorded no upward and no downward adjustments related to such observable price changes for the three months ended March 31, 2021. The Company conducts a quarterly assessment of its equity securities without readily determinable fair values to determine whether impairment exists in such securities, considering, among other factors, the nature of the securities, financial condition of the issuer and expected future cash flows. During the three months ended March 31, 2021, the Company recorded $30,000 of impairment of equity securities without readily determinable fair values. The following table presents the portion of the Company’s available-for-sale investment securities portfolios that have gross unrealized losses, reflecting the length of time that individual securities have been in a continuous unrealized loss position at March 31, 2021: Continuous unrealized Continuous unrealized Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale securities U.S. Treasury $ — $ — $ — $ — $ — $ — U.S. Government agencies — — — — — — Municipal 24,326 (168) 110 (4) 24,436 (172) Corporate notes: Financial issuers 14,850 (150) 48,196 (785) 63,046 (935) Other — — — — — — Mortgage-backed: Mortgage-backed securities 571,821 (26,037) 61 (1) 571,882 (26,038) Collateralized mortgage obligations — — — — — — Total available-for-sale securities $ 610,997 $ (26,355) $ 48,367 $ (790) $ 659,364 $ (27,145) The Company conducts a regular assessment of its investment securities to determine whether securities are experiencing credit losses. Factors for consideration include the nature of the securities, credit ratings or financial condition of the issuer, the extent of the unrealized loss, expected cash flows, market conditions and the Company’s ability to hold the securities through the anticipated recovery period. The Company does not consider available-for-sale securities with unrealized losses at March 31, 2021 to be experiencing credit losses and recognized no resulting allowance for credit losses for such individually assessed credit losses. The Company does not intend to sell these investments and it is more likely than not that the Company will not be required to sell these investments before recovery of the amortized cost bases, which may be the maturity dates of the securities. The unrealized losses within each category have occurred as a result of changes in interest rates, market spreads and market conditions subsequent to purchase. Available-for-sale securities with continuous unrealized losses existing for more than twelve months were primarily corporate notes. See Note 6—Allowance for Credit Losses for further discussion regarding any credit losses associated with held-to-maturity securities at March 31, 2021. The following table provides information as to the amount of gross gains and losses, adjustments and impairment on investment securities recognized in earnings and proceeds received through the sale or call of investment securities: Three months ended March 31, (Dollars in thousands) 2021 2020 Realized gains on investment securities $ 216 $ 496 Realized losses on investment securities (6) (5) Net realized gains on investment securities 210 491 Unrealized gains on equity securities with readily determinable fair value 1,875 — Unrealized losses on equity securities with readily determinable fair value (901) (3,546) Net unrealized gains (losses) on equity securities with readily determinable fair value 974 (3,546) Upward adjustments of equity securities without readily determinable fair values — 393 Downward adjustments of equity securities without readily determinable fair values — — Impairment of equity securities without readily determinable fair values (30) (1,697) Adjustment and impairment, net, of equity securities without readily determinable fair values (30) (1,304) Gains (losses) on investment securities, net $ 1,154 $ (4,359) Proceeds from sales of available-for-sale securities (1) $ — $ — Proceeds from sales of equity securities with readily determinable fair value 1,509 30 Proceeds from sales and capital distributions of equity securities without readily determinable fair value 386 288 (1) Includes proceeds from available-for-sale securities sold in accordance with written covered call options sold to a third party. The amortized cost and fair value of available-for-sale and held-to-maturity investment securities as of March 31, 2021, December 31, 2020 and March 31, 2020, by contractual maturity, are shown in the following table. Contractual maturities may differ from actual maturities as borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Mortgage-backed securities are not included in the maturity categories in the following maturity summary as actual maturities may differ from contractual maturities because the underlying mortgages may be called or prepaid without penalties: March 31, 2021 December 31, 2020 March 31, 2020 (Dollars in thousands) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Available-for-sale securities Due in one year or less $ 100,140 $ 100,361 $ 343,601 $ 343,846 $ 186,538 $ 187,789 Due in one to five years 76,104 78,291 67,901 70,334 70,812 71,825 Due in five to ten years 110,125 110,928 111,886 112,178 174,262 164,479 Due after ten years 93,055 97,596 95,672 101,441 307,752 313,847 Mortgage-backed 2,016,503 2,043,573 2,341,021 2,428,040 2,721,341 2,833,019 Total available-for-sale securities $ 2,395,927 $ 2,430,749 $ 2,960,081 $ 3,055,839 $ 3,460,705 $ 3,570,959 Held-to-maturity securities Due in one year or less $ 6,812 $ 6,863 $ 7,138 $ 7,186 $ 5,310 $ 5,333 Due in one to five years 50,318 50,734 22,217 23,068 23,801 24,158 Due in five to ten years 184,677 191,539 150,621 159,293 143,783 148,746 Due after ten years 187,596 183,663 198,690 203,689 692,552 700,955 Mortgage-backed 1,737,115 1,688,266 200,531 200,531 — — Total held-to-maturity securities $ 2,166,518 $ 2,121,065 $ 579,197 $ 593,767 $ 865,446 $ 879,192 Less: Allowance for credit losses (99) (59) (70) Held-to-maturity securities, net of allowance for credit losses $ 2,166,419 $ 579,138 $ 865,376 Securities having a carrying value of $2.1 billion at March 31, 2021 as well as securities having a carrying value of $2.4 billion and $1.5 billion at December 31, 2020 and March 31, 2020, respectively, were pledged as collateral for public deposits, trust deposits, Federal Home Loan Bank ("FHLB") advances and available lines of credit, securities sold under repurchase

Loans

Loans	3 Months Ended
	Mar. 31, 2021
Loans and Leases Receivable Disclosure [Abstract]
Loans	Loans The following table shows the Company’s loan portfolio by category as of the dates shown: March 31, December 31, March 31, (Dollars in thousands) 2021 2020 2020 Balance: Commercial $ 12,708,207 $ 11,955,967 $ 9,025,886 Commercial real estate 8,544,779 8,494,132 8,185,531 Home equity 390,253 425,263 494,655 Residential real estate 1,421,973 1,259,598 1,377,389 Premium finance receivables Commercial insurance 3,958,543 4,054,489 3,465,055 Life insurance 6,111,495 5,857,436 5,221,639 Consumer and other 35,983 32,188 37,166 Total loans, net of unearned income $ 33,171,233 $ 32,079,073 $ 27,807,321 Mix: Commercial 38 % 37 % 32 % Commercial real estate 26 26 29 Home equity 1 1 2 Residential real estate 4 5 5 Premium finance receivables Commercial insurance 12 13 13 Life insurance 19 18 19 Consumer and other 0 0 0 Total loans, net of unearned income 100 % 100 % 100 % The Company’s loan portfolio is generally comprised of loans to consumers and small to medium-sized businesses, which, for the commercial and commercial real estate portfolios, are located primarily within the geographic market areas that the banks serve. Various niche lending businesses, including lease finance and franchise lending, operate on a national level. Additionally, to provide short-term relief due to macroeconomic deterioration from the COVID-19 pandemic to small businesses within such market areas, the Company originated loans through the Paycheck Protection Program ("PPP"), an expansion of guaranteed lending under Section 7(a) of the Small Business Act within the CARES Act. As of March 31, 2021, the Company's commercial portfolio included approximately $3.3 billion of such PPP loans. The premium finance receivables portfolios are made to customers throughout the United States and Canada. The Company strives to maintain a loan portfolio that is diverse in terms of loan type, industry, borrower and geographic concentrations. Such diversification reduces the exposure to economic downturns that may occur in different segments of the economy or in different industries. Certain premium finance receivables are recorded net of unearned income. The unearned income portions of such premium finance receivables were $114.4 million at March 31, 2021, $113.1 million at December 31, 2020 and $115.2 million at March 31, 2020. Total loans, excluding PCD loans, include net deferred loan fees and costs and fair value purchase accounting adjustments totaling $(32.2) million at March 31, 2021, $(3.2) million at December 31, 2020 and $11.1 million at March 31, 2020. Net deferred fees as of March 31, 2021 includes $64.6 million of net deferred fees paid by the Small Business Administration ("SBA") for loans originated under the PPP. As PPP loans share similar characteristics (loan terms), and prepayments are considered probable and can reasonably be estimated due to terms of the program, the Company considers estimated future principal prepayments in recognizing such deferred fees for determining a constant effective yield on the portfolio of loans. It is the policy of the Company to review each prospective credit in order to determine the appropriateness and, when required, the adequacy of security or collateral necessary to obtain when making a loan. The type of collateral, when required, will vary from liquid assets to real estate. The Company seeks to ensure access to collateral, in the event of default, through adherence to state lending laws and the Company’s credit monitoring procedures.

Allowance for Credit Losses

Allowance for Credit Losses	3 Months Ended
	Mar. 31, 2021
Credit Loss [Abstract]
Allowance for Credit Losses	Allowance for Credit Losses In accordance with ASC 326, the Company is required to measure the allowance for credit losses of financial assets with similar risk characteristics on a collective or pooled basis. In considering the segmentation of financial assets measured at amortized cost into pools, the Company considered various risk characteristics in its analysis. Generally, the segmentation utilized represents the level at which the Company develops and documents its systematic methodology to determine the allowance for credit losses for the financial asset held at amortized cost, specifically the Company's loan portfolio and debt securities classified as held-to-maturity. Below is a summary of the Company's loan portfolio segments and major debt security types: Commercial loans, including PPP loans: The Company makes commercial loans for many purposes, including working capital lines and leasing arrangements, that are generally renewable annually and supported by business assets, personal guarantees and additional collateral. Underlying collateral includes receivables, inventory, enterprise value and the assets of the business. Commercial business lending is generally considered to involve a slightly higher degree of risk than traditional consumer bank lending. This portfolio includes a range of industries, including manufacturing, restaurants, franchise, professional services, equipment finance and leasing, mortgage warehouse lending and industrial. The Company also originates loans through the PPP. Administered by the SBA, the PPP provides short-term relief primarily related to the disruption from COVID-19 to companies and non-profits that meet the SBA’s definition of an eligible small business. Under the program, the SBA will forgive all or a portion of the loan if, during a certain period, loans are used for qualifying expenses. If all or a portion of the loan is not forgiven, the borrower is responsible for repayment. PPP loans are fully guaranteed by the SBA, including any portion not forgiven. The SBA guarantee exists at the inception of the loan and throughout its life and is not separated from the loan if the loan is subsequently sold or transferred. As it is not considered a freestanding contract, the Company considers the impact of the SBA guarantee when measuring the allowance for credit losses. Commercial real estate loans, including construction and development, and non-construction: The Company's commercial real estate loans are generally secured by a first mortgage lien and assignment of rents on the underlying property. Since most of the Company's bank branches are located in the Chicago metropolitan area and southern Wisconsin, a significant portion of the Company's commercial real estate loan portfolio is located in this region. As the risks and circumstances of such loans in construction phase vary from that of non-construction commercial real estate loans, the Company assessed the allowance for credit losses separately for these two segments. Home equity loans: The Company's home equity loans and lines of credit are primarily originated by each of the bank subsidiaries in their local markets where there is a strong understanding of the underlying real estate value. The Company's banks monitor and manage these loans, and conduct an automated review of all home equity loans and lines of credit at least twice per year. The banks subsidiaries use this information to manage loans that may be higher risk and to determine whether to obtain additional credit information or updated property valuations. In a limited number of cases, the Company may issue home equity credit together with first mortgage financing, and requests for such financing are evaluated on a combined basis. Residential real estate loans: The Company's residential real estate portfolio includes one- to four-family fixed and adjustable rate mortgages with repricing terms generally from one to three years, construction loans to individuals and bridge financing loans for qualifying customers. The Company's residential mortgages relate to properties located principally in the Chicago metropolitan area and southern Wisconsin or vacation homes owned by local residents. Due to interest rate risk considerations, the Company generally sells in the secondary market loans originated with long-term fixed rates, however, certain of these loans may be retained within the banks’ own portfolios where they are non-agency conforming, or where the terms of the loans make them favorable to retain. The Company believes that since this loan portfolio consists primarily of locally originated loans, and since the majority of the borrowers are longer-term customers with lower LTV ratios, the Company faces a relatively low risk of borrower default and delinquency. It is not the Company's current practice to underwrite, and there are no plans to underwrite subprime, Alt A, no or little documentation loans, or option ARM loans. Premium finance receivables: The Company makes loans to businesses to finance the insurance premiums they pay on their commercial insurance policies. The loans are indirectly originated by working through independent medium and large insurance agents and brokers located throughout the United States and Canada. The insurance premiums financed are primarily for commercial customers’ purchases of liability, property and casualty and other commercial insurance. This lending involves relatively rapid turnover of the loan portfolio and high volume of loan originations. The Company performs ongoing credit and other reviews of the agents and brokers to mitigate against the risk of fraud. The Company also originates life insurance premium finance receivables. These loans are originated directly with the borrowers with assistance from life insurance carriers, independent insurance agents, financial advisors and legal counsel. The life insurance policy is the primary form of collateral. In addition, these loans often are secured with a letter of credit, marketable securities or certificates of deposit. In some cases, the Company may make a loan that has a partially unsecured position. Consumer and other loans: Included in the consumer and other loan category is a wide variety of personal and consumer loans to individuals. The Company originates consumer loans in order to provide a wider range of financial services to their customers. Consumer loans generally have shorter terms and higher interest rates than mortgage loans but generally involve more credit risk than mortgage loans due to the type and nature of the collateral. U.S. government agency securities: This security type includes debt obligations of certain government-sponsored entities of the U.S. government such as the Federal Home Loan Bank, Federal Agricultural Mortgage Corporation, Federal Farm Credit Banks Funding Corporation and Fannie Mae. Such securities often contain an explicit or implicit guarantee of the U.S. government. Municipal securities: The Company's municipal securities portfolio include bond issues for various municipal government entities located throughout the United States, including the Chicago metropolitan area and southern Wisconsin, some of which are privately placed and non-rated. Though the risk of loss is typically low, including within the Company, default history exists on municipal securities within the United States. Mortgage-backed securities: This security type includes debt obligations supported by pools of individual mortgage loans and issued by certain government-sponsored entities of the U.S. government such as Freddie Mac and Fannie Mae. Such securities are considered to contain an implicit guarantee of the U.S. government. Corporate notes: The Company's corporate notes portfolio includes bond issues for various public companies representing a diversified population of industries. The risk of loss in this portfolio is considered low based on the characteristics of the investments, including the Company’s own past history with similar investments. In accordance with ASC 326, the Company elected to not measure an allowance for credit losses on accrued interest as such accrued interest is written off in a timely manner when deemed uncollectible. Any such write-off of accrued interest will reverse previously recognized interest income. In addition, the Company elected to not include accrued interest within presentation and disclosures of the carrying amount of financial assets held at amortized cost. This election is applicable to the various disclosures included within the Company's financial statements. Accrued interest related to financial assets held at amortized cost is included within accrued interest receivable and other assets within the Company's Consolidated Statements of Condition and totaled $128.8 million at March 31, 2021, $121.9 million at December 31, 2020 and $116.4 million at March 31, 2020. The tables below show the aging of the Company’s loan portfolio by the segmentation noted above at March 31, 2021, December 31, 2020 and March 31, 2020: As of March 31, 2021 90+ days and still accruing 60-89 days past due 30-59 days past due (In thousands) Nonaccrual Current Total Loans Loan Balances (includes PCD): Commercial Commercial, industrial and other, excluding PPP loans $ 22,459 $ — $ 13,292 $ 35,535 $ 9,343,939 $ 9,415,225 Commercial PPP loans — — — 6 3,292,976 3,292,982 Commercial real estate Construction and development 2,673 — 499 23,967 1,326,185 1,353,324 Non-construction 31,707 — 7,657 46,201 7,105,890 7,191,455 Home equity 5,536 — 492 780 383,445 390,253 Residential real estate 21,553 — 944 13,768 1,385,708 1,421,973 Premium finance receivables Commercial insurance loans 9,690 4,592 5,113 16,552 3,922,596 3,958,543 Life insurance loans — 191 — 14,821 6,096,483 6,111,495 Consumer and other 497 161 8 74 35,243 35,983 Total loans, net of unearned income $ 94,115 $ 4,944 $ 28,005 $ 151,704 $ 32,892,465 $ 33,171,233 As of December 31, 2020 90+ days and still accruing 60-89 days past due 30-59 days past due (In thousands) Nonaccrual Current Total Loans Loan Balances (includes PCD): Commercial Commercial, industrial and other, excluding PPP loans $ 21,743 $ 307 $ 6,900 $ 44,345 $ 9,166,751 $ 9,240,046 Commercial PPP loans — — — 36 2,715,885 2,715,921 Commercial real estate Construction and development 5,633 — — 5,344 1,360,825 1,371,802 Non-construction 40,474 — 5,178 26,772 7,049,906 7,122,330 Home equity 6,529 — 47 637 418,050 425,263 Residential real estate 26,071 — 1,635 12,584 1,219,308 1,259,598 Premium finance receivables Commercial insurance loans 13,264 12,792 6,798 18,809 4,002,826 4,054,489 Life insurance loans — — 21,003 30,465 5,805,968 5,857,436 Consumer and other 436 264 24 136 31,328 32,188 Total loans, net of unearned income $ 114,150 $ 13,363 $ 41,585 $ 139,128 $ 31,770,847 $ 32,079,073 As of March 31, 2020 90+ days and still accruing 60-89 days past due 30-59 days past due (In thousands) Nonaccrual Current Total Loans Loan Balances (includes PCD): Commercial Commercial, industrial and other, excluding PPP loans $ 49,916 $ 1,241 $ 8,873 $ 86,129 $ 8,879,727 $ 9,025,886 Commercial PPP loans — — — — — — Commercial real estate Construction and development 7,422 147 1,859 16,938 1,274,987 1,301,353 Non-construction 55,408 369 8,353 58,130 6,761,918 6,884,178 Home equity 7,243 — 214 2,096 485,102 494,655 Residential real estate 18,965 605 345 28,983 1,328,491 1,377,389 Premium finance receivables Commercial insurance loans 21,058 16,505 10,327 32,811 3,384,354 3,465,055 Life insurance loans — — 2,403 37,374 5,181,862 5,221,639 Consumer and other 403 78 625 207 35,853 37,166 Total loans, net of unearned income $ 160,415 $ 18,945 $ 32,999 $ 262,668 $ 27,332,294 $ 27,807,321 Credit Quality Indicators Credit quality indicators, specifically the Company's internal risk rating systems, reflect how the Company monitors credit losses and represents factors used by the Company when measuring the allowance for credit losses. The following discusses the Company's credit quality indicators by financial asset. Loan portfolios The Company's ability to manage credit risk depends in large part on our ability to properly identify and manage problem loans. To do so, the Company operates a credit risk rating system under which credit management personnel assign a credit risk rating (1 to 10 rating) to each loan at the time of origination and review loans on a regular basis. These credit risk ratings are also an important aspect of the Company's allowance for credit losses measurement methodology. The credit risk rating structure and classifications are shown below: Pass (risk rating 1 to 5): Based on various factors (liquidity, leverage, etc.), the Company believes asset quality is acceptable and is deemed to not require additional monitoring by the Company. Special mention (risk rating 6): Assets in this category are currently protected, potentially weak, but not to the point of substandard classification. Loss potential is moderate if corrective action is not taken. Substandard accrual (risk rating 7): Assets in this category have well defined weaknesses that jeopardize the liquidation of the debt. Loss potential is distinct but with no discernible impairment. Substandard nonaccrual/doubtful (risk rating 8 and 9): Assets have all the weaknesses in those classified “substandard accrual” with the added characteristic that the weaknesses make collection or liquidation in full, on the basis of current existing facts, conditions, and values, improbable. Loss/fully charged-off (risk rating 10): Assets in this category are considered fully uncollectible. As such, these assets have no carrying balance on the Company's Consolidated Statements of Condition. Each loan officer is responsible for monitoring his or her loan portfolio, recommending a credit risk rating for each loan in his or her portfolio and ensuring the credit risk ratings are appropriate. These credit risk ratings are then ratified by the bank’s chief credit officer and/or concurrence credit officer. Credit risk ratings are determined by evaluating a number of factors including: a borrower’s financial strength, cash flow coverage, collateral protection and guarantees. The Company’s Problem Loan Reporting system includes all loans with credit risk ratings of 6 through 9. This system is designed to provide an on-going detailed tracking mechanism for each problem loan. Once management determines that a loan has deteriorated to a point where it has a credit risk rating of 6 or worse, the Company’s Managed Asset Division performs an overall credit and collateral review. As part of this review, all underlying collateral is identified and the valuation methodology is analyzed and tracked. As a result of this initial review by the Company’s Managed Asset Division, the credit risk rating is reviewed and a portion of the outstanding loan balance may be deemed uncollectible and, as a result, no longer share similar risk characteristics as its related pool. If that is the case, the individual loan is considered collateral dependent and individually assessed for an allowance for credit loss. The Company’s individual assessment utilizes an independent re-appraisal of the collateral (unless such a third-party evaluation is not possible due to the unique nature of the collateral, such as a closely-held business or thinly traded securities). In the case of commercial real estate collateral, an independent third party appraisal is ordered by the Company’s Real Estate Services Group to determine if there has been any change in the underlying collateral value. These independent appraisals are reviewed by the Real Estate Services Group and sometimes by independent third party valuation experts and may be adjusted depending upon market conditions. Through the credit risk rating process, loans are reviewed to determine if they are performing in accordance with the original contractual terms. If the borrower has failed to comply with the original contractual terms, further action may be required by the Company, including a downgrade in the credit risk rating, movement to non-accrual status or a charge-off. If the Company determines that a loan amount or portion thereof is uncollectible, the loan’s credit risk rating is immediately downgraded to an 8 or 9 and the uncollectible amount is charged-off. Any loan that has a partial charge-off continues to be assigned a credit risk rating of an 8 or 9 for the duration of time that a balance remains outstanding. The Company undertakes a thorough and ongoing analysis to determine if additional impairment and/or charge-offs are appropriate and to begin a workout plan for the credit to minimize actual losses. In determining the appropriate charge-off for collateral-dependent loans, the Company considers the results of appraisals for the associated collateral. The table below shows the Company’s loan portfolio by credit quality indicator and year of origination at March 31, 2021: As of March 31, 2021 Year of Origination Revolving Total (In thousands) 2021 2020 2019 2018 2017 Prior Revolving to Term Loans Loan Balances: Commercial, industrial and other Pass $ 574,195 $ 1,951,426 $ 1,158,699 $ 840,181 $ 611,479 $ 742,116 $ 2,908,239 $ 4,925 $ 8,791,260 Special mention 965 27,786 83,315 38,930 33,116 24,760 86,729 36 295,637 Substandard accrual 22,738 19,675 65,902 71,312 25,052 61,313 39,766 111 305,869 Substandard nonaccrual/doubtful — 1,887 1,770 2,117 2,078 14,074 533 — 22,459 Total commercial, industrial and other $ 597,898 $ 2,000,774 $ 1,309,686 $ 952,540 $ 671,725 $ 842,263 $ 3,035,267 $ 5,072 $ 9,415,225 Commercial PPP Pass $ 1,242,766 $ 2,049,342 $ — $ — $ — $ — $ — $ — $ 3,292,108 Special mention 874 — — — — — — — 874 Substandard accrual — — — — — — — — — Substandard nonaccrual/doubtful — — — — — — — — — Total commercial PPP $ 1,243,640 $ 2,049,342 $ — $ — $ — $ — $ — $ — $ 3,292,982 Construction and development Pass $ 40,266 $ 346,452 $ 433,184 $ 196,502 $ 89,377 $ 109,596 $ 29,747 $ — $ 1,245,124 Special mention 282 11,935 16,864 21,075 24,465 4,068 — — 78,689 Substandard accrual — — 1,207 21,872 2,929 678 152 — 26,838 Substandard nonaccrual/doubtful — — — 1,571 — 1,102 — — 2,673 Total construction and development $ 40,548 $ 358,387 $ 451,255 $ 241,020 $ 116,771 $ 115,444 $ 29,899 $ — $ 1,353,324 Non-construction Pass $ 249,241 $ 1,295,535 $ 1,030,111 $ 816,725 $ 772,702 $ 2,189,960 $ 184,304 $ 244 $ 6,538,822 Special mention 3,875 9,905 65,413 66,860 69,759 220,549 — — 436,361 Substandard accrual — 2,023 42,238 9,358 21,352 109,584 10 — 184,565 Substandard nonaccrual/doubtful — — 266 1,221 2,131 28,089 — — 31,707 Total non-construction $ 253,116 $ 1,307,463 $ 1,138,028 $ 894,164 $ 865,944 $ 2,548,182 $ 184,314 $ 244 $ 7,191,455 Home equity Pass $ — $ 44 $ — $ 47 $ 28 $ 7,082 $ 356,197 $ — $ 363,398 Special mention — — — — — 2,103 4,905 245 7,253 Substandard accrual — — — 317 — 11,953 1,053 743 14,066 Substandard nonaccrual/doubtful — — — — 157 3,799 1,580 — 5,536 Total home equity $ — $ 44 $ — $ 364 $ 185 $ 24,937 $ 363,735 $ 988 $ 390,253 Residential real estate Pass $ 301,904 $ 346,823 $ 265,543 $ 100,023 $ 115,609 $ 240,205 $ — $ — $ 1,370,107 Special mention 80 302 237 2,017 2,163 8,467 — — 13,266 Substandard accrual 291 2,304 1,025 897 2,300 10,230 — — 17,047 Substandard nonaccrual/doubtful — 186 1,121 745 5,034 14,467 — — 21,553 Total residential real estate $ 302,275 $ 349,615 $ 267,926 $ 103,682 $ 125,106 $ 273,369 $ — $ — $ 1,421,973 Premium finance receivables - commercial Pass $ 2,001,412 $ 1,896,547 $ 27,366 $ 2,961 $ 54 $ — $ — $ — $ 3,928,340 Special mention 8,051 11,093 8 — — — — — 19,152 Substandard accrual 1 1,267 13 80 — — — — 1,361 Substandard nonaccrual/doubtful 512 7,898 1,252 28 — — — — 9,690 Total premium finance receivables - commercial $ 2,009,976 $ 1,916,805 $ 28,639 $ 3,069 $ 54 $ — $ — $ — $ 3,958,543 Premium finance receivables - life Pass $ 112,896 $ 636,815 $ 658,163 $ 620,034 $ 678,197 $ 3,404,823 $ — $ — $ 6,110,928 Special mention — — — — 567 — — — 567 Substandard accrual — — — — — — — — — Substandard nonaccrual/doubtful — — — — — — — — — Total premium finance receivables - life $ 112,896 $ 636,815 $ 658,163 $ 620,034 $ 678,764 $ 3,404,823 $ — $ — $ 6,111,495 Consumer and other Pass $ 1,204 $ 1,955 $ 1,749 $ 1,389 $ 179 $ 14,366 $ 14,206 $ — $ 35,048 Special mention 3 10 19 — 86 91 6 — 215 Substandard accrual — 4 1 — — 215 3 — 223 Substandard nonaccrual/doubtful — 1 — 104 — 392 — — 497 Total consumer and other $ 1,207 $ 1,970 $ 1,769 $ 1,493 $ 265 $ 15,064 $ 14,215 $ — $ 35,983 Total loans (1) Pass $ 4,523,884 $ 8,524,939 $ 3,574,815 $ 2,577,862 $ 2,267,625 $ 6,708,148 $ 3,492,693 $ 5,169 $ 31,675,135 Special mention 14,130 61,031 165,856 128,882 130,156 260,038 91,640 281 852,014 Substandard accrual 23,030 25,273 110,386 103,836 51,633 193,973 40,984 854 549,969 Substandard nonaccrual/doubtful 512 9,972 4,409 5,786 9,400 61,923 2,113 — 94,115 Total loans $ 4,561,556 $ 8,621,215 $ 3,855,466 $ 2,816,366 $ 2,458,814 $ 7,224,082 $ 3,627,430 $ 6,304 $ 33,171,233 (1) Includes $164.7 million of loans with COVID-19 related modifications that migrated from pass as of March 1, 2020 to special mention or substandard accrual as of March 31, 2021. These loans were further qualitatively evaluated as a part of the measurement of the allowance for credit losses as of March 31, 2021. Held-to-maturity debt securities The Company conducts an assessment of its investment securities, including those classified as held-to-maturity, at the time of purchase and on at least an annual basis to ensure such investment securities remain within appropriate levels of risk and continue to perform satisfactorily in fulfilling its obligations. The Company considers, among other factors, the nature of the securities and credit ratings or financial condition of the issuer. If available, the Company obtains a credit rating for issuers from a Nationally Recognized Statistical Rating Organization (“NRSRO”) for consideration. If no such rating is available for an issuer, the Company performs an internal rating based on the scale utilized within the loan portfolio as discussed above. For purposes of the table below, the Company has converted any issuer rating from an NRSRO into the Company’s internal ratings based on Investment Policy and review by the Company’s management. As of March 31, 2021 Year of Origination Total (In thousands) 2021 2020 2019 2018 2017 Prior Balance Amortized Cost Balances: U.S. government agencies 1-4 internal grade $ 97,786 $ 25,000 $ — $ 50,000 $ — $ 3,374 $ 176,160 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total U.S. government agencies $ 97,786 $ 25,000 $ — $ 50,000 $ — $ 3,374 $ 176,160 Municipal 1-4 internal grade $ 1,377 $ — $ 161 $ 7,549 $ 43,603 $ 145,175 $ 197,865 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total municipal $ 1,377 $ — $ 161 $ 7,549 $ 43,603 $ 145,175 $ 197,865 Mortgage-backed securities 1-4 internal grade $ 1,737,115 $ — $ — $ — $ — $ — $ 1,737,115 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total mortgage-backed securities $ 1,737,115 $ — $ — $ — $ — $ — $ 1,737,115 Corporate notes 1-4 internal grade $ — $ 13,661 $ 7,462 $ 3,325 $ 3,282 $ 27,648 $ 55,378 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total corporate notes $ — $ 13,661 $ 7,462 $ 3,325 $ 3,282 $ 27,648 $ 55,378 Total held-to-maturity securities $ 2,166,518 Less: Allowance for credit losses (99) Held-to-maturity securities, net of allowance for credit losses $ 2,166,419 Measurement of Allowance for Credit Losses The Company's allowance for credit losses consists of the allowance for loan losses, the allowance for unfunded commitment losses and the allowance for held-to-maturity debt security losses. In accordance with ASC 326, the Company measures the allowance for credit losses at the time of origination or purchase of a financial asset, representing an estimate of lifetime expected credit losses on the related asset. When developing its estimate, the Company considers available information relevant to assessing the collectability of cash flows, from both internal and external sources. Historical credit loss experience is one input in the estimation process as well as inputs relevant to current conditions and reasonable and supportable forecasts. In considering past events, the Company considers the relevance, or lack thereof, of historical information due to changes in such things as financial asset underwriting or collection practices, and changes in portfolio mix due to changing business plans and strategies. In considering current conditions and forecasts, the Company considers both the current economic environment and the forecasted direction of the economic environment with emphasis on those factors deemed relevant to or driving changes in expected credit losses. As significant judgment is required, the review of the appropriateness of the allowance for credit losses is performed quarterly by various committees with participation by the Company's executive management. March 31, December 31, March 31, (In thousands) 2021 2020 2020 Allowance for loan losses $ 277,709 $ 319,374 $ 216,050 Allowance for unfunded lending-related commitments losses 43,500 60,536 37,362 Allowance for loan losses and unfunded lending-related commitments losses 321,209 379,910 253,412 Allowance for held-to-maturity securities losses 99 59 70 Allowance for credit losses $ 321,308 $ 379,969 $ 253,482 The allowance for credit losses is measured on a collective or pooled basis when similar risk characteristics exist, based upon the segmentation discussed above. The Company utilizes modeling methodologies that estimate lifetime credit loss rates on each pool, including methodologies estimating the probability of default and loss given default on specific segments. Historical credit loss history is adjusted for reasonable and supportable forecasts developed by the Company on a quantitative or qualitative basis and incorporates third party economic forecasts. Reasonable and supportable forecasts consider the macroeconomic factors that are most relevant to evaluating and predicting expected credit losses in the Company's financial assets. Currently, the Company utilizes an eight quarter forecast period using a single macroeconomic scenario provided by a third-party and reviewed within the Company's governance structure. For periods beyond the ability to develop reasonable and supportable forecasts, the Company reverts to historical loss rates at an input level, straight-line over a four quarter reversion period. Expected credit losses are measured over the contractual term of the financial asset with consideration of expected prepayments. Expected extensions, renewals or modifications of the financial asset are only considered when either 1) the expected extension, renewal or modification is contained within the existing agreement and is not unconditionally cancelable, or 2) the expected extension, renewal or modification is reasonably expected to result in a TDR. The methodologies discussed above are applied to both current asset balances on the Company's Consolidated Statements of Condition and off-balance sheet commitments (i.e. unfunded lending-related commitments). Assets that do not share similar risk characteristics with a pool are assessed for the allowance for credit losses on an individual basis. These typically include assets experiencing financial difficulties, including assets rated as substandard nonaccrual and doubtful as well as assets currently classified or expected to be classified as TDRs. If foreclosure is probable or the asset is considered collateral-dependent, expected credit losses are measured based upon the fair value of the underlying collateral adjusted for selling costs, if appropriate. Underlying collateral across the Company's segments consist primarily of real estate, land and construction assets as well as general business assets of the borrower. As of March 31, 2021, substandard nonaccrual loans totaling $56.8 million in carrying balance had no related allowance for credit losses. For certain accruing current and expected TDRs, expected credit losses are measured based upon the present value of future cash flows of the modified asset terms compared to the amortized cost of the asset. Considering accounting relief provided under Section 4013 of the CARES Act, loans identified as being reasonably expected to be modified into TDRs in the future totaled $198,000 as of March 31, 2021. The Company does not measure an allowance for credit losses on accrued interest receivable balances because these balances are written off in a timely manner as a reduction to interest income when assets are placed on nonaccrual status. Loan portfolios A summary of activity in the allowance for credit losses, specifically for the loan portfolio (i.e. allowance for loan losses and allowance for unfunded commitment losses), for the three months ended March 31, 2021 and 2020 is as follows. Three months ended March 31, 2021 Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total Loans (In thousands) Commercial Allowance for credit losses at beginning of period $ 94,212 $ 243,603 $ 11,437 $ 12,459 $ 17,777 $ 422 $ 379,910 Other adjustments — — — — 30 — 30 Charge-offs (11,781) (980) — (2) (3,239) (114) (16,116) Recoveries 452 200 101 204 1,782 32 2,771 Provision for credit losses 12,757 (61,031) (156) 1,581 1,127 336 (45,386) Allowance for credit losses at period end $ 95,640 $ 181,792 $ 11,382 $ 14,242 $ 17,477 $ 676 $ 321,209 Individually measured $ 5,046 $ 2,042 $ 338 $ 822 $ — $ 81 $ 8,329 Collectively measured 90,594 179,750 11,044 13,420 17,477 595 312,880 Loans at period end Individually measured $ 30,144 $ 43,858 $ 21,167 $ 28,675 $ — $ 560 $ 124,404 Collectively measured 12,678,063 8,500,921 369,086 1,341,382 10,070,038 35,423 32,994,913 Loans held at fair value — — — 51,916 — — 51,916 Three months ended March 31, 2020 Commercial Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total Loans (In thousands) Allowance for credit losses at beginning of period $ 64,920 $ 68,511 $ 3,878 $ 9,800 $ 9,647 $ 1,705 $ 158,461 Cumulative effect adjustment from the adoption of ASU 2016-13 9,039 32,064 9,061 3,002 (4,959) (863) 47,344 Other adjustments — — — — (73) — (73) Charge-offs (2,153) (570) (1,001) (401) (3,184) (128) (7,437) Recoveries 384 263 294 60 1,110 41 2,152 Provision for credit losses 35,156 12,528 162 89 5,339 (309) 52,965 Allowance for credit losses at period end $ 107,346 $ 112,796 $ 12,394 $ 12,550 $ 7,880 $ 446 $ 253,412 Individually measured $ 12,524 $ 9,108 $ 290 $ 466 $ — $ 104 $ 22,492 Collectively measured 94,822 103,688 12,104 12,084 7,880 342 230,920 Loans at period end Individually measured $ 56,416 $ 80,873 $ 23,060 $ 27,854 $ — $ 537 $ 188,740 Collectively measured 8,969,470 8,104,658 471,595 1,207,268 8,686,694 36,629 27,476,314 Loans held at fair value — — — 142,267 — — 142,267 At January 1, 2020, the Company adopted ASU 2016-13, which replaced the previous incurred loss methodology for measuring the allowance for credit losses with a lifetime expected loss methodology. At adoption, the allowance for credit losses related to loans and lending agreements increased approximately $47.3 million, including an increase of approximately $33.2 million recorded to the allowance for unfunded commitment losses within accrued interest and other liabilities on the Company's Consolidated Statements of Condition, with an offsetting amount recorded directly to retained earnings, net of taxes. The remaining $14.2 million cumulative effect adjustment was recorded to the allowance for loan losses, presented separately on the Company's Consolidated Statements of Condition. Of the amount recorded to the allowance for loan losses, $11.0 million related to PCD loans with such offsetting amount added directly to the carrying balance of the loans and the remaining $3.2 million not related to PCD loans recorded directly to retained earnings, net of taxes, on the Company's Consolidated Statements of Condition. For the three months ended March 31, 2021 and 2020, the Company recognized approximately $(45.4) million and $53.0 million of provision for credit losses, respectively, related to loans and lending agreements. The decreased provision was primarily the result of improvements in the forecasted macroeconomic conditions created by the COVID-19 pandemic, and the resulting impact on the

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets A summary of the Company’s goodwill assets by reporting unit is presented in the following table: (In thousands) December 31, Goodwill Impairment Goodwill Adjustments March 31, Community banking $ 536,396 $ — $ — $ — $ 536,396 Specialty finance 39,938 — — 310 40,248 Wealth management 69,373 — — — 69,373 Total $ 645,707 $ — $ — $ 310 $ 646,017 The specialty finance unit’s goodwill increased $310,000 in the first three months of 2021 as a result of foreign currency translation adjustments related to the Canadian acquisitions. The Company assesses each reporting unit’s goodwill for impairment on at least an annual basis and considers potential indicators of impairment at each reporting date between annual goodwill impairment tests. At October 1, 2020, the Company utilized a quantitative approach for its annual goodwill impairment tests of the banking, specialty finance and wealth management reporting units and determined that no impairment existed at that time. At each reporting date between annual goodwill impairment tests, the Company considers potential indicators of impairment. Given the current economic uncertainty and volatility surrounding COVID-19, the Company assessed whether such events and circumstances resulted in it being more likely than not that the fair value of any reporting unit was less than its carrying value. Impairment indicators considered include the condition of the economy and banking industry; government intervention and regulatory updates; the impact of recent events to financial performance and cost factors of the reporting units; performance of the Company’s stock and other relevant events. The Company further considered the amount by which fair value exceeded book value for each reporting unit in its most recent quantitative analysis and sensitivities performed. At the conclusion of this assessment of all reporting units, the Company determined that as of March 31, 2021, it was more likely than not that the fair value of all reporting units exceeded the respective carrying value of such reporting unit. A summary of intangible assets as of the dates shown and the expected amortization of finite-lived intangible assets as of March 31, 2021 is as follows: (In thousands) March 31, December 31, March 31, Community banking segment: Core deposit intangibles with finite lives: Gross carrying amount $ 55,206 $ 55,206 $ 55,206 Accumulated amortization (34,099) (32,680) (28,024) Net carrying amount $ 21,107 $ 22,526 $ 27,182 Trademark with indefinite lives: Carrying amount 5,800 5,800 5,800 Total net carrying amount $ 26,907 $ 28,326 $ 32,982 Specialty finance segment: Customer list intangibles with finite lives: Gross carrying amount $ 1,968 $ 1,966 $ 1,956 Accumulated amortization (1,665) (1,644) (1,574) Net carrying amount $ 303 $ 322 $ 382 Wealth management segment: Customer list and other intangibles with finite lives: Gross carrying amount $ 20,430 $ 20,430 $ 20,430 Accumulated amortization (13,605) (13,038) (9,609) Net carrying amount $ 6,825 $ 7,392 $ 10,821 Total intangible assets: Gross carrying amount $ 83,404 $ 83,402 $ 83,392 Accumulated amortization (49,369) (47,362) (39,207) Total intangible assets, net $ 34,035 $ 36,040 $ 44,185 Estimated amortization Actual in three months ended March 31, 2021 $ 2,007 Estimated remaining in 2021 5,685 Estimated—2022 6,135 Estimated—2023 4,670 Estimated—2024 3,263 Estimated—2025 2,552 The core deposit intangibles recognized in connection with prior bank acquisitions are amortized over a ten-year period on an accelerated basis. The customer list intangibles recognized in connection with the purchase of life insurance premium finance assets in 2009 are being amortized over an 18-year period on an accelerated basis. The customer list and other intangibles recognized in connection with prior acquisitions within the wealth management segment are being amortized over a period of up to ten years on a straight-line basis. Indefinite-lived intangible assets consist of certain trade and domain names recognized in connection with the acquisition of Veterans First Mortgage in 2018. As indefinite-lived intangible assets are not amortized, the Company assesses impairment on at least an annual basis. Total amortization expense associated with finite-lived intangibles totaled approximately $2.0 million and $2.9 million for the three months ended March 31, 2021 and 2020, respectively.

Mortgage Servicing Rights ("MSR

Mortgage Servicing Rights ("MSRs")	3 Months Ended
	Mar. 31, 2021
Disclosures Pertaining to Servicing Assets and Servicing Liabilities [Abstract]
Mortgage Servicing Rights (MSRs)	Mortgage Servicing Rights (“MSRs”) The following is a summary of the changes in the carrying value of MSRs, accounted for at fair value, for the periods indicated: Three Months Ended March 31, March 31, (In thousands) 2021 2020 Balance at beginning of the period $ 92,081 $ 85,638 Additions from loans sold with servicing retained 24,616 9,447 Estimate of changes in fair value due to: Early buyout options (“EBO”) exercised (258) — Payoffs and paydowns (10,168) (7,024) Changes in valuation inputs or assumptions 18,045 (14,557) Fair value at end of the period $ 124,316 $ 73,504 Unpaid principal balance of mortgage loans serviced for others $ 11,530,676 $ 8,314,634 The Company recognizes MSR assets upon the sale of residential real estate loans to external third parties when it retains the obligation to service the loans and the servicing fee is more than adequate compensation. The initial recognition of MSR assets from loans sold with servicing retained and subsequent changes in fair value of all MSRs are recognized in mortgage banking revenue. MSRs are subject to changes in value from actual and expected prepayment of the underlying loans. The estimation of fair value related to MSRs is partly impacted by the Company exercising its EBO on eligible loans previously sold to the Government National Mortgage Association (“GNMA”). Under such optional repurchase program, financial institutions acting as servicers are allowed to buy back from the securitized loan pool individual delinquent mortgage loans meeting certain criteria for which the institution was the original transferor of such loans. At the option of the servicer and without prior authorization from GNMA, the servicer may repurchase such delinquent loans for an amount equal to the remaining principal balance of the loan. At the time of such repurchase, any MSR value related to such loans is derecognized. Starting in 2019, the Company periodically purchased options for the right to purchase securities not currently held within the banks’ investment portfolios and entered into interest rate swaps in which the Company elected to not designate such derivatives as hedging instruments. These option and swap transactions were designed primarily to economically hedge a portion of the fair value adjustments related to MSRs. During the second quarter of 2020, the Company terminated these interest rate swaps. There were no such options or interest rate swaps outstanding as of March 31, 2021. For more information regarding these hedges, see Note 14 - Derivative Financial Instruments in Item 1 of this report.

Deposits

Deposits	3 Months Ended
	Mar. 31, 2021
Deposits [Abstract]
Deposits	Deposits The following table is a summary of deposits as of the dates shown: (Dollars in thousands) March 31, December 31, March 31, Balance: Non-interest-bearing $ 12,297,337 $ 11,748,455 $ 7,556,755 NOW and interest-bearing demand deposits 3,562,312 3,349,021 3,181,159 Wealth management deposits 4,274,527 4,138,712 3,936,968 Money market 9,236,434 9,348,806 8,114,659 Savings 3,690,892 3,531,029 3,282,340 Time certificates of deposit 4,811,150 4,976,628 5,389,779 Total deposits $ 37,872,652 $ 37,092,651 $ 31,461,660 Mix: Non-interest-bearing 32 % 32 % 24 % NOW and interest-bearing demand deposits 9 9 10 Wealth management deposits 11 11 13 Money market 25 25 26 Savings 10 10 10 Time certificates of deposit 13 13 17 Total deposits 100 % 100 % 100 % Wealth management deposits represent deposit balances (primarily money market accounts) at the Company’s subsidiary banks from brokerage customers of Wintrust Investments, LLC (“Wintrust Investments”), Chicago Deferred Exchange Company (“CDEC”), trust and asset management customers of the Company and brokerage customers from unaffiliated companies.

FHLB Advances, Other Borrowings

FHLB Advances, Other Borrowings and Subordinated Notes	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
FHLB Advances, Other Borrowings and Subordinated Notes	FHLB Advances, Other Borrowings and Subordinated Notes The following table is a summary of FHLB advances, other borrowings and subordinated notes as of the dates shown: (In thousands) March 31, December 31, March 31, FHLB advances $ 1,228,436 $ 1,228,429 $ 1,174,894 Other borrowings: Notes payable 96,363 101,710 167,746 Short-term borrowings 12,416 11,366 12,127 Other 64,659 65,108 66,266 Secured borrowings 343,439 340,744 241,364 Total other borrowings 516,877 518,928 487,503 Subordinated notes 436,595 436,506 436,179 Total FHLB advances, other borrowings and subordinated notes $ 2,181,908 $ 2,183,863 $ 2,098,576 FHLB Advances FHLB advances consist of obligations of the banks and are collateralized by qualifying commercial and residential real estate and home equity loans and certain securities. FHLB advances are stated at par value of the debt adjusted for unamortized prepayment fees paid at the time of prior restructurings of FHLB advances, unamortized fair value adjustments recorded in connection with advances acquired through acquisitions and debt issuance costs. Notes Payable On September 18, 2018, the Company established a $150.0 million term facility ("Term Facility"), which is part of a $200.0 million loan agreement ("Credit Agreement") with unaffiliated banks. The Credit Agreement consists of the Term Facility with an original outstanding balance of $150.0 million and a $50.0 million revolving credit facility ("Revolving Credit Facility"). At March 31, 2021, the Company had a notes payable balance of $96.4 million under the Term Facility. The Term Facility is stated at par of the current outstanding balance of the debt adjusted for unamortized costs paid by the Company in relation to the debt issuance. The Company was contractually required to borrow the entire amount of the Term Facility on September 18, 2018 and all such borrowings must be repaid by September 18, 2023. Beginning December 31, 2018, the Company is required to make quarterly payments of principal plus interest on the Term Facility. At March 31, 2021, the Company had no outstanding balance under the Revolving Credit Facility. Unamortized costs paid by the Company in relation to the issuance of the Revolving Credit Facility are classified in other assets on the Consolidated Statements of Condition. An amendment to the Credit Agreement was executed on and effective as of September 15, 2020. The amendment provided for, among other things, extension of the maturity date under the Revolving Credit Facility to September 14, 2021, revision of certain financial covenants; and the addition of a mechanism to replace LIBOR with an alternate benchmark rate. Borrowings under the amended Credit Agreement that are considered “Base Rate Loans” bear interest at a rate equal to the sum of (1) 60 basis points (in the case of a borrowing under the Revolving Credit Facility) or 75 basis points (in the case of a borrowing under the Term Facility) plus (2) the highest of (a) the federal funds rate plus 50 basis points, (b) the lender's prime rate, or (c) the Eurodollar Rate (as defined below) that would be applicable for an interest period of one month plus 100 basis points. Borrowings under the agreement that are considered “Eurodollar Rate Loans” bear interest at a rate equal to the sum of (1) 135 basis points (in the case of a borrowing under the Revolving Credit Facility) or 125 basis points (in the case of a borrowing under the Term Facility) plus (2) the LIBOR rate for the applicable period, as adjusted for statutory reserve requirements for eurocurrency liabilities (the “Eurodollar Rate”). A commitment fee is payable quarterly equal to 0.30% of the actual daily amount by which the lenders' commitment under the Revolving Credit Facility exceeded the amount outstanding under such facility. Borrowings under the amended Credit Agreement are secured by pledges of and first priority perfected security interests in the Company's equity interest in its bank subsidiaries and contain several restrictive covenants, including the maintenance of various capital adequacy levels, asset quality and profitability ratios, and certain restrictions on dividends and other indebtedness. In September 2020, the required levels to maintain for certain restrictive covenants within the Credit Agreement were amended. At March 31, 2021, the Company was in compliance with all such covenants. The Revolving Credit Facility and the Term Facility are available to be utilized, as needed, to provide capital to fund continued growth at the Company’s banks and to serve as an interim source of funds for acquisitions, common stock repurchases or other general corporate purposes. Short-term Borrowings Short-term borrowings include securities sold under repurchase agreements and federal funds purchased. These borrowings totaled $12.4 million at March 31, 2021 compared to $11.4 million at December 31, 2020 and $12.1 million at March 31, 2020. At March 31, 2021, December 31, 2020 and March 31, 2020, securities sold under repurchase agreements represent $12.4 million, $11.4 million and $12.1 million, respectively, of customer sweep accounts in connection with master repurchase agreements at the banks. The Company records securities sold under repurchase agreements at their gross value and does not offset positions on the Consolidated Statements of Condition. As of March 31, 2021, the Company had pledged securities related to its customer balances in sweep accounts of $20.6 million. Securities pledged for customer balances in sweep accounts and short-term borrowings from brokers are maintained under the Company’s control and consist of mortgage-backed securities. These securities are included in the available-for-sale portfolio as reflected on the Company’s Consolidated Statements of Condition. The following is a summary of these securities pledged as of March 31, 2021 disaggregated by investment category and maturity of the related customer sweep account, and reconciled to the outstanding balance of securities sold under repurchase agreements: (In thousands) Overnight Sweep Collateral Available-for-sale securities pledged Mortgage-backed securities $ 20,580 Total collateral pledged 20,580 Excess collateral 8,164 Securities sold under repurchase agreements $ 12,416 Other Borrowings Other borrowings at March 31, 2021 represent a fixed-rate promissory note issued by the Company in June 2017 and amended in March 2020 ("Fixed-Rate Promissory Note") related to and secured by three office buildings owned by the Company. At March 31, 2021, the Fixed-Rate Promissory Note had a balance of $64.7 million compared to $65.1 million at December 31, 2020 and $66.3 million at March 31, 2020. Under the Fixed-Rate Promissory Note, during the three months ended March 31, 2020, the Company made monthly principal payments and paid interest at a fixed rate of 3.36%. An amendment to the Fixed-Rate Promissory Note was executed on and effective as of March 31, 2020. The amendment increased the principal amount to $66.4 million, reduced the interest rate to 3.00% and extended the maturity date to March 31, 2025. The Fixed-Rate Promissory Note contains several restrictive covenants, including the maintenance of various capital adequacy levels, asset quality and profitability ratios, and certain restrictions on dividends and indebtedness. At March 31, 2021, the Company was in compliance with all such covenants. Secured Borrowings Secured borrowings at March 31, 2021 primarily represents transactions to sell an undivided co-ownership interest in all receivables owed to the Company's subsidiary, First Insurance Funding of Canada ("FIFC Canada"). In December 2014, FIFC Canada sold such interest to an unrelated third party in exchange for a cash payment of approximately C$150 million pursuant to a receivables purchase agreement (“Receivables Purchase Agreement”). The Receivables Purchase Agreement was amended in December 2015, effectively extending the maturity date from December 15, 2015 to December 15, 2017. Additionally, at that time, the unrelated third party paid an additional C$10 million, which increased the total payments to C$160 million. The Receivables Purchase Agreement was again amended in December 2017, effectively extending the maturity date from December 15, 2017 to December 16, 2019. Additionally, in December 2017, the unrelated third party paid an additional C$10 million, which increased the total payments to C$170 million. In June 2018, the unrelated third party paid an additional C$20 million, which increased the total payments to C$190 million. The Receivables Purchase Agreement was again amended in February 2019, effectively extending the maturity date from December 16, 2019 to December 15, 2020. Additionally, in February 2019, the unrelated third party paid an additional C$20 million, which increased the total payments to C$210 million. In May 2019, the unrelated third party paid an additional C$70 million, which increased the total payments to C$280 million. In January 2020, the unrelated third party paid an additional C$40 million, which increased the total payments to C$320 million, and the Receivables Purchase Agreement was amended to effectively extend the maturity date from December 15, 2020 to December 15, 2021. In May 2020, the unrelated third party paid an additional C$100 million, which increased the total payments to C$420 million. In January 2021, the Receivables Purchase Agreement was amended to effectively extend the maturity date from December 15, 2021 to December 15, 2022. These transactions were not considered sales of receivables and, as such, related proceeds received are reflected on the Company’s Consolidated Statements of Condition as a secured borrowing owed to the unrelated third party, net of unamortized debt issuance costs, and translated to the Company’s reporting currency as of the respective date. At March 31, 2021, the translated balance of the secured borrowing totaled $334.1 million compared to $329.9 million at December 31, 2020 and $227.4 million at March 31, 2020. Additionally, the interest rate under the Receivables Purchase Agreement at March 31, 2021 was 1.1015%. The remaining $9.4 million within secured borrowings at March 31, 2021 represents other sold interests in certain loans by the Company that were not considered sales and, as such, related proceeds received are reflected on the Company’s Consolidated Statements of Condition as a secured borrowing owed to the various unrelated third parties. Subordinated Notes At March 31, 2021, the Company had outstanding subordinated notes totaling $436.6 million compared to $436.5 million and $436.2 million outstanding at December 31, 2020 and March 31, 2020, respectively. During the second quarter of 2019, the Company issued $300.0 million of subordinated notes, receiving $296.7 million in net proceeds. The subordinated notes have a stated interest rate of 4.85% and mature in June 2029. In 2014, the Company issued $140.0 million of subordinated notes receiving $139.1 million in net proceeds. The subordinated notes have a stated interest rate of 5.00% and mature in June 2024. Subordinated notes are stated at par adjusted for unamortized issuance costs paid related to such debt.

Junior Subordinated Debentures

Junior Subordinated Debentures	3 Months Ended
	Mar. 31, 2021
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Junior Subordinated Debentures	Junior Subordinated DebenturesAs of March 31, 2021, the Company owned 100% of the common securities of eleven trusts, Wintrust Capital Trust III, Wintrust Statutory Trust IV, Wintrust Statutory Trust V, Wintrust Capital Trust VII, Wintrust Capital Trust VIII, Wintrust Capital Trust IX, Northview Capital Trust I, Town Bankshares Capital Trust I, First Northwest Capital Trust I, Suburban Illinois Capital Trust II, and Community Financial Shares Statutory Trust II (the “Trusts”) set up to provide long-term financing. The Northview, Town, First Northwest, Suburban, and Community Financial Shares capital trusts were acquired as part of the acquisitions of Northview Financial Corporation, Town Bankshares, Ltd., First Northwest Bancorp, Inc., Suburban Illinois Bancorp, Inc. and Community Financial Shares, Inc., respectively. The Trusts were formed for purposes of issuing trust preferred securities to third-party investors and investing the proceeds from the issuance of the trust preferred securities and common securities solely in junior subordinated debentures issued by the Company (or assumed by the Company in connection with an acquisition), with the same maturities and interest rates as the trust preferred securities. The junior subordinated debentures are the sole assets of the Trusts. In each Trust, the common securities represent approximately 3% of the junior subordinated debentures and the trust preferred securities represent approximately 97% of the junior subordinated debentures. The Trusts are reported in the Company’s consolidated financial statements as unconsolidated subsidiaries. Accordingly, in the Consolidated Statements of Condition, the junior subordinated debentures issued by the Company to the Trusts are reported as liabilities and the common securities of the Trusts, all of which are owned by the Company, are included in investment securities. The following table provides a summary of the Company’s junior subordinated debentures as of March 31, 2021. The junior subordinated debentures represent the par value of the obligations owed to the Trusts. (Dollars in thousands) Common Trust Junior Rate Contractual rate Issue Maturity Earliest Wintrust Capital Trust III $ 774 $ 25,000 $ 25,774 L+3.25 3.49 % 04/2003 04/2033 04/2008 Wintrust Statutory Trust IV 619 20,000 20,619 L+2.80 3.00 % 12/2003 12/2033 12/2008 Wintrust Statutory Trust V 1,238 40,000 41,238 L+2.60 2.80 % 05/2004 05/2034 06/2009 Wintrust Capital Trust VII 1,550 50,000 51,550 L+1.95 2.13 % 12/2004 03/2035 03/2010 Wintrust Capital Trust VIII 1,238 25,000 26,238 L+1.45 1.65 % 08/2005 09/2035 09/2010 Wintrust Capital Trust IX 1,547 50,000 51,547 L+1.63 1.81 % 09/2006 09/2036 09/2011 Northview Capital Trust I 186 6,000 6,186 L+3.00 3.21 % 08/2003 11/2033 08/2008 Town Bankshares Capital Trust I 186 6,000 6,186 L+3.00 3.21 % 08/2003 11/2033 08/2008 First Northwest Capital Trust I 155 5,000 5,155 L+3.00 3.20 % 05/2004 05/2034 05/2009 Suburban Illinois Capital Trust II 464 15,000 15,464 L+1.75 1.93 % 12/2006 12/2036 12/2011 Community Financial Shares Statutory Trust II 109 3,500 3,609 L+1.62 1.80 % 06/2007 09/2037 06/2012 Total $ 253,566 2.39 % The junior subordinated debentures totaled $253.6 million at March 31, 2021, December 31, 2020 and March 31, 2020. The interest rates on the variable rate junior subordinated debentures are based on the three-month LIBOR rate and reset on a quarterly basis. At March 31, 2021, the weighted average contractual interest rate on the junior subordinated debentures was 2.39%. The Company entered into interest rate swaps with an aggregate notional value of $210.0 million to hedge the variable cash flows on certain junior subordinated debentures. The hedge-adjusted contractual interest rate on the junior subordinated debentures as of March 31, 2021, was 3.98%. Distributions on the common and preferred securities issued by the Trusts are payable quarterly at a rate per annum equal to the interest rates being earned by the Trusts on the junior subordinated debentures. Interest expense on the junior subordinated debentures is deductible for income tax purposes. The Company has guaranteed the payment of distributions and payments upon liquidation or redemption of the trust preferred securities, in each case to the extent of funds held by the Trusts. The Company and the Trusts believe that, taken together, the obligations of the Company under the guarantees, the junior subordinated debentures, and other related agreements provide, in the aggregate, a full, irrevocable and unconditional guarantee, on a subordinated basis, of all of the obligations of the Trusts under the trust preferred securities. Subject to certain limitations, the Company has the right to defer the payment of interest on the junior subordinated debentures at any time, or from time to time, for a period not to exceed 20 consecutive quarters. The trust preferred securities are subject to mandatory redemption, in whole or in part, upon repayment of the junior subordinated debentures at maturity or their earlier redemption. The junior subordinated debentures are redeemable in whole or in part prior to maturity at any time after the earliest redemption dates shown in the table, and earlier at the discretion of the Company if certain conditions are met, and, in any event, only after the Company has obtained Federal Reserve Bank ("FRB") approval, if then required under applicable guidelines or regulations. At March 31, 2021, the Company included $245.5 million of the junior subordinated debentures, net of common securities, in Tier 2 regulatory capital.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	Revenue from Contracts with Customers Disaggregation of Revenue The following table presents revenue from contracts with customers, disaggregated by the revenue source: (Dollars in thousands) Three Months Ended Revenue from contracts with customers Location in income statement March 31, March 31, Brokerage and insurance product commissions Wealth management $ 5,040 $ 5,281 Trust Wealth management 5,017 5,291 Asset management Wealth management 19,252 15,369 Total wealth management 29,309 25,941 Mortgage broker fees Mortgage banking 76 53 Service charges on deposit accounts Service charges on deposit accounts 12,036 11,265 Administrative services Other non-interest income 1,256 1,112 Card related fees Other non-interest income 1,774 2,106 Other deposit related fees Other non-interest income 3,317 3,178 Total revenue from contracts with customers $ 47,768 $ 43,655 Wealth Management Revenue Wealth management revenue is comprised of brokerage and insurance product commissions, managed money fees and trust and asset management revenue of the Company's four wealth management subsidiaries: Wintrust Investments, Great Lakes Advisors, LLC ("GLA"), The Chicago Trust Company, N.A. ("CTC") and CDEC. All wealth management revenue is recognized in the wealth management segment. Brokerage and insurance product commissions consists primarily of commissions earned from trade execution services on behalf of customers and from selling mutual funds, insurance and other investment products to customers. For trade execution services, the Company recognizes commissions and receives payment from the brokerage customers at the point of transaction execution. Commissions received from the investment or insurance product providers are recognized at the point of sale of the product. The Company also receives trail and other commissions from providers for certain plans. These are generally based on qualifying account values and are recognized once the performance obligation, specific to each provider, is satisfied on a monthly, quarterly or annual basis. Trust revenue is earned primarily from trust and custody services that are generally performed over time as well as fees earned on funds held during the facilitation of tax-deferred like-kind exchange transactions. Revenue is determined periodically based on a schedule of fees applied to the value of each customer account using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Fees are typically billed on a calendar month or quarter basis in advance or in arrears depending upon the contract. Upfront fees received related to the facilitation of tax-deferred like-kind exchange transactions are deferred until the transaction is completed. Additional fees earned for certain extraordinary services performed on behalf of the customers are recognized when the service has been performed. Asset management revenue is earned from money management and advisory services that are performed over time. Revenue is based primarily on the market value of assets under management or administration using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Fees are typically billed on a calendar month or quarter basis in advance or in arrears depending upon the contract. Certain programs provide the customer with an option of paying fees as a percentage of the account value or incurring commission charges for each trade similar to brokerage and insurance product commissions. Trade commissions and any other fees received for additional services are recognized at a point in time once the performance obligation is satisfied. Mortgage Broker Fees For customers desiring a mortgage product not currently offered by the Company, the Company may refer such customers and, with permission, direct such customers' applications to certain third party mortgage brokers. Mortgage broker fees are received from these brokers for such customer referrals upon settlement of the underlying mortgage. The Company's entitlement to the consideration is contingent on the settlement of the mortgage which is highly susceptible to factors outside of the Company's influence, such as third party broker's underwriting requirements. Also, the uncertainty surrounding the consideration could be resolved in varying lengths of time, dependent upon the third party brokers. Therefore, mortgage broker fees are recognized at the settlement of the underlying mortgage when the consideration is received. Broker fees are recognized in the community banking segment. Service Charges on Deposit Accounts Service charges on deposit accounts include fees charged to deposit customers for various services, including account analysis services, and are based on factors such as the size and type of customer, type of product and number of transactions. The fees are based on a standard schedule of fees and, depending on the nature of the service performed, the service is performed at a point in time or over a period of a month. When the service is performed at a point in time, the Company recognizes and receives revenue when the service has been performed. When the service is performed over a period of a month, the Company recognizes and receives revenue in the month the service has been performed. Service charges on deposit accounts are recognized in the community banking segment. Administrative Services Administrative services revenue is earned from providing outsourced administrative services, such as data processing of payrolls, billing and cash management services, to temporary staffing service clients located throughout the United States. Fees are charged periodically (typically a payroll cycle) and computed in accordance with the contractually determined rate applied to the total gross billings administered for the period. The revenue is recognized over the period using a time-elapsed method to measure progress toward complete satisfaction of the performance obligation. Other fees are charged on a per occurrence basis as the service is provided in the billing cycle. The Company has certain contracts with customers to perform outsourced administrative services and short-term accounts receivable financing. For these contracts, the total fee is allocated between the administrative services revenue and interest income during the client onboarding process based on the specific client and services provided. Administrative services revenue is recognized in the specialty finance segment. Card and Other Deposit Related Fees Card related fees include interchange and merchant revenue, and fees related to debit and credit cards. Interchange revenue is related to the Company issued debit cards. Other deposit related fees primarily include pay by phone processing fees, ATM and safe deposit box fees, check order charges and foreign currency related fees. Card and deposit related fees are generally based on volume of transactions and are recognized at the point in time when the service has been performed. For any consideration that is constrained, the revenue is recognized once the uncertainty is known. Upfront fees received from certain contracts are recognized on a straight line basis over the term of the contract. Card and deposit related fees are recognized in the community banking segment. Contract Balances The following table provides information about contract assets, contract liabilities and receivables from contracts with customers: (Dollars in thousands) March 31, December 31, March 31, Contract assets $ — $ — $ — Contract liabilities $ 1,818 $ 1,548 $ 728 Mortgage broker fees receivable $ 31 $ 20 $ 11 Administrative services receivable 215 64 214 Wealth management receivable 11,315 10,144 8,218 Card related fees receivable 1,075 783 422 Total receivables from contracts with customer $ 12,636 $ 11,011 $ 8,865 Contract liabilities represent upfront fees that the Company received at inception of certain contracts. The revenue recognized that was included in the contract liability balance at beginning of the period totaled $414,000 and $628,000 for the three months ended March 31, 2021 and 2020, respectively. Receivables are recognized in the period the Company provides services and when the Company's right to consideration is unconditional. Card related fee receivable is the result of volume based fee that the Company receives from a customer on an annual basis in the second quarter of each year. Payment terms on other invoiced amounts are typically 30 days or less. Contract liabilities and receivables from contracts with customers are included within the accrued interest payable and other liabilities and accrued interest receivable and other assets line items, respectively, in the Consolidated Statements of Condition. Transaction price allocated to the remaining performance obligations For contracts with an original expected length of more than one year, the following table presents the estimated future timing of recognition of upfront fees related to card and deposit related fees. These upfront fees represent performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period. (Dollars in thousands) Estimated remaining in 2021 $ 668 Estimated—2022 400 Estimated—2023 400 Estimated—2024 250 Estimated—2025 100 Total $ 1,818 Practical Expedients and Exemptions The Company does not adjust the promised amount of consideration for the effects of a significant financing component if the Company expects, at contract inception, that the period between when the Company transfers a promised service to a customer and when the customer pays for that service is one year or less. The Company recognizes the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that the entity otherwise would have recognized is one year or less.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information	Segment Information The Company’s operations consist of three primary segments: community banking, specialty finance and wealth management. The three reportable segments are strategic business units that are separately managed as they offer different products and services and have different marketing strategies. In addition, each segment’s customer base has varying characteristics and each segment has a different regulatory environment. While the Company’s management monitors each of the fifteen bank subsidiaries’ operations and profitability separately, these subsidiaries have been aggregated into one reportable operating segment due to the similarities in products and services, customer base, operations, profitability measures, and economic characteristics. For purposes of internal segment profitability, management allocates certain intersegment and parent company balances. Management allocates a portion of revenues to the specialty finance segment related to loans and leases originated by the specialty finance segment and sold or assigned to the community banking segment. Similarly, for purposes of analyzing the contribution from the wealth management segment, management allocates a portion of the net interest income earned by the community banking segment on deposit balances of customers of the wealth management segment to the wealth management segment. See Note 9 — Deposits, for more information on these deposits. Finally, expenses incurred at the Wintrust parent company are allocated to each segment based on each segment's risk-weighted assets. The segment financial information provided in the following table has been derived from the internal profitability reporting system used by management to monitor and manage the financial performance of the Company. The accounting policies of the segments are substantially similar to those described in “Summary of Significant Accounting Policies” in Note 1 of the Company’s 2020 Form 10-K. The Company evaluates segment performance based on after-tax profit or loss and other appropriate profitability measures common to each segment. The following is a summary of certain operating information for reportable segments: Three months ended $ Change in % Change in (Dollars in thousands) March 31, March 31, Net interest income: Community Banking $ 203,489 $ 206,835 $ (3,346) (2) % Specialty Finance 44,899 40,712 4,187 10 Wealth Management 7,449 7,792 (343) (4) Total Operating Segments 255,837 255,339 498 — Intersegment Eliminations 6,058 6,104 (46) (1) Consolidated net interest income $ 261,895 $ 261,443 $ 452 — % Provision for credit losses: Community Banking $ (46,572) $ 51,677 $ (98,249) (190) % Specialty Finance 1,225 1,284 (59) (5) Wealth Management — — — — Total Operating Segments (45,347) 52,961 (98,308) (186) Intersegment Eliminations — — — — Consolidated provision for credit losses $ (45,347) $ 52,961 $ (98,308) (186) % Non-interest income: Community Banking $ 147,268 $ 81,003 $ 66,265 82 % Specialty Finance 23,109 21,308 1,801 8 Wealth Management 30,251 24,130 6,121 25 Total Operating Segments 200,628 126,441 74,187 59 Intersegment Eliminations (14,122) (13,199) (923) 7 Consolidated non-interest income $ 186,506 $ 113,242 $ 73,264 65 % Net revenue: Community Banking $ 350,757 $ 287,838 $ 62,919 22 % Specialty Finance 68,008 62,020 5,988 10 Wealth Management 37,700 31,922 5,778 18 Total Operating Segments 456,465 381,780 74,685 20 Intersegment Eliminations (8,064) (7,095) (969) 14 Consolidated net revenue $ 448,401 $ 374,685 $ 73,716 20 % Segment profit: Community Banking $ 121,801 $ 34,589 $ 87,212 252 % Specialty Finance 23,903 22,133 1,770 8 Wealth Management 7,444 6,090 1,354 22 Consolidated net income $ 153,148 $ 62,812 $ 90,336 144 % Segment assets: Community Banking $ 37,102,603 $ 31,499,899 $ 5,602,704 18 % Specialty Finance 7,174,269 6,133,548 1,040,721 17 Wealth Management 1,405,330 1,166,400 238,930 20 Consolidated total assets $ 45,682,202 $ 38,799,847 $ 6,882,355 18 %

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments The Company primarily enters into derivative financial instruments as part of its strategy to manage its exposure to changes in interest rates. Derivative instruments represent contracts between parties that result in one party delivering cash to the other party based on a notional amount and an underlying term (such as a rate, security price or price index) as specified in the contract. The amount of cash delivered from one party to the other is determined based on the interaction of the notional amount of the contract with the underlying term. Derivatives are also implicit in certain contracts and commitments. The derivative financial instruments currently used by the Company to manage its exposure to interest rate risk include: (1) interest rate swaps and collars to manage the interest rate risk of certain fixed and variable rate assets and variable rate liabilities; (2) interest rate lock commitments provided to customers to fund certain mortgage loans to be sold into the secondary market; (3) forward commitments for the future delivery of such mortgage loans to protect the Company from adverse changes in interest rates and corresponding changes in the value of mortgage loans held-for-sale; (4) covered call options to economically hedge specific investment securities and receive fee income effectively enhancing the overall yield on such securities to compensate for net interest margin compression; and (5) options and swaps to economically hedge a portion of the fair value adjustments related to the Company's mortgage servicing rights portfolio. The Company also enters into derivatives (typically interest rate swaps) with certain qualified borrowers to facilitate the borrowers’ risk management strategies and concurrently enters into mirror-image derivatives with a third party counterparty, effectively making a market in the derivatives for such borrowers. Additionally, the Company enters into foreign currency contracts to manage foreign exchange risk associated with certain foreign currency denominated assets. The Company recognizes derivative financial instruments in the consolidated financial statements at fair value regardless of the purpose or intent for holding the instrument. The Company records derivative assets and derivative liabilities on the Consolidated Statements of Condition within accrued interest receivable and other assets and accrued interest payable and other liabilities, respectively. Changes in the fair value of derivative financial instruments are either recognized in income or in shareholders’ equity as a component of accumulated other comprehensive income or loss depending on whether the derivative financial instrument qualifies for hedge accounting and, if so, whether it qualifies as a fair value hedge or cash flow hedge. Changes in fair values of derivatives accounted for as fair value hedges are recorded in income in the same period and in the same income statement line as changes in the fair values of the hedged items that relate to the hedged risk(s). Changes in fair values of derivative financial instruments accounted for as cash flow hedges are recorded as a component of accumulated other comprehensive income or loss, net of deferred taxes, and reclassified to earnings when the hedged transaction affects earnings. Changes in fair values of derivative financial instruments not designated in a hedging relationship pursuant to ASC 815 are reported in non-interest income during the period of the change. Derivative financial instruments are valued by a third party and are corroborated by comparison with valuations provided by the respective counterparties. Fair values of certain mortgage banking derivatives (interest rate lock commitments and forward commitments to sell mortgage loans) are estimated based on changes in mortgage interest rates from the date of the loan commitment. The fair value of foreign currency derivatives is computed based on changes in foreign currency rates stated in the contract compared to those prevailing at the measurement date. The table below presents the fair value of the Company’s derivative financial instruments as of March 31, 2021, December 31, 2020 and March 31, 2020: Derivative Assets Derivative Liabilities (In thousands) March 31, December 31, March 31, March 31, December 31, March 31, Derivatives designated as hedging instruments under ASC 815: Interest rate derivatives designated as Cash Flow Hedges $ 50,420 $ 8,182 $ — $ 31,161 $ 39,715 $ 57,274 Interest rate derivatives designated as Fair Value Hedges 121 — — 9,569 14,520 16,123 Total derivatives designated as hedging instruments under ASC 815 $ 50,541 $ 8,182 $ — $ 40,730 $ 54,235 $ 73,397 Derivatives not designated as hedging instruments under ASC 815: Interest rate derivatives $ 155,695 $ 221,205 $ 259,986 $ 155,361 $ 221,608 $ 256,193 Interest rate lock commitments 44,313 48,925 39,816 1,342 — 1,105 Forward commitments to sell mortgage loans 2,920 — 1,514 3,283 12,510 36,872 Foreign exchange contracts 40 111 52 42 112 53 Total derivatives not designated as hedging instruments under ASC 815 $ 202,968 $ 270,241 $ 301,368 $ 160,028 $ 234,230 $ 294,223 Total Derivatives $ 253,509 $ 278,423 $ 301,368 $ 200,758 $ 288,465 $ 367,620 Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to net interest income and to manage its exposure to interest rate movements. To accomplish these objectives, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable-rate amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without the exchange of the underlying notional amount. Interest rate collars designated as cash flow hedges involve the receipt of amounts in which the interest rate specified in the contract exceeds the agreed upon cap strike price or the payment of amounts in which the interest rate specified in the contract is below the agreed upon floor strike price at the end of each period. As of March 31, 2021, the Company had 27 interest rate swap derivatives designated as cash flow hedges of variable rate deposits and certain junior subordinated debentures, and one interest rate collar derivative designated as a cash flow hedge of the Company's variable rate Term Facility. When the relationship between the hedged item and hedging instrument is highly effective at achieving offsetting changes in cash flows attributable to the hedged risk, changes in the fair value of these cash flow hedges are recorded in accumulated other comprehensive income or loss and are subsequently reclassified to interest expense as interest payments are made on such variable rate deposits. The changes in fair value (net of tax) are separately disclosed in the Consolidated Statements of Comprehensive Income. The table below provides details on these cash flow hedges, summarized by derivative type and maturity, as of March 31, 2021: March 31, 2021 (In thousands) Notional Fair Value Maturity Date Amount Asset (Liability) Interest Rate Swaps: October 2021 $ 25,000 $ (286) November 2021 20,000 (287) December 2021 165,000 (2,614) March 2022 500,000 (220) May 2022 370,000 (7,884) June 2022 160,000 (3,652) July 2022 230,000 (5,359) August 2022 235,000 (5,944) March 2023 250,000 (300) April 2024 250,000 598 July 2027 (1) 1,000,000 49,823 Interest Rate Collars: September 2023 96,429 (4,616) Total Cash Flow Hedges $ 3,301,429 $ 19,259 (1) Interest rate swaps effective starting in July 2022. A rollforward of the amounts in accumulated other comprehensive income or loss related to interest rate derivatives designated as cash flow hedges follows: Three Months Ended (In thousands) March 31, March 31, Unrealized loss at beginning of period $ (31,533) $ (17,943) Amount reclassified from accumulated other comprehensive income to interest expense on deposits, other borrowings and junior subordinated debentures 6,696 1,090 Amount of income (loss) recognized in other comprehensive income 44,096 (39,783) Unrealized gain (loss) at end of period $ 19,259 $ (56,636) As of March 31, 2021, the Company estimates that during the next twelve months $19.9 million will be reclassified from accumulated other comprehensive income or loss as an increase to interest expense. Fair Value Hedges of Interest Rate Risk Interest rate swaps designated as fair value hedges involve the payment of fixed amounts to a counterparty in exchange for the Company receiving variable payments over the life of the agreements without the exchange of the underlying notional amount. As of March 31, 2021, the Company has 17 interest rate swaps with an aggregate notional amount of $167.5 million that were designated as fair value hedges primarily associated with fixed rate commercial and industrial and commercial real estate loans as well as life insurance premium finance receivables. For derivatives designated and that qualify as fair value hedges, the net gain or loss from the entire change in the fair value of the derivative instrument is recognized in the same income statement line item as the earnings effect, including the net gain or loss, of the hedged item (interest income earned on fixed rate loans) when the hedged item affects earnings. The following table presents the carrying amount of the hedged assets/(liabilities) and the cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets/(liabilities) that are designated as a fair value hedge accounting relationship as of March 31, 2021: March 31, 2021 (In thousands) Derivatives in Fair Value Hedging Relationships Location in the Statement of Condition Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued Interest rate swaps Loans, net of unearned income $ 175,605 $ 9,262 $ (157) Available-for-sale debt securities 1,303 94 — The following table presents the loss or gain recognized related to derivative instruments that are designated as fair value hedges for the respective period: (In thousands) Derivatives in Fair Value Hedging Relationships Location of (Loss)/Gain Recognized Three Months Ended March 31, 2021 Interest rate swaps Interest and fees on loans $ (13) Interest income - investment securities — Non-Designated Hedges The Company does not use derivatives for speculative purposes. Derivatives not designated as accounting hedges are used to manage the Company’s economic exposure to interest rate movements and other identified risks but do not meet the strict hedge accounting requirements of ASC 815. Changes in the fair value of derivatives not designated in hedging relationships are recorded directly in earnings. Interest Rate Derivatives —Periodically, the Company may purchase interest rate cap derivatives designed to act as an economic hedge of the risk of the negative impact on its fixed-rate loan portfolios from rising interest rates, most notably the LIBOR index. As of March 31, 2021, the Company held interest rate caps with an aggregate notional value of $1.0 billion. Additionally, the Company has interest rate derivatives, including swaps and option products, resulting from a service the Company provides to certain qualified borrowers. The Company’s banking subsidiaries execute certain derivative products (typically interest rate swaps) directly with qualified commercial borrowers to facilitate their respective risk management strategies. For example, these arrangements allow the Company’s commercial borrowers to effectively convert a variable rate loan to a fixed rate. In order to minimize the Company’s exposure on these transactions, the Company simultaneously executes offsetting derivatives with third parties. In most cases, the offsetting derivatives have mirror-image terms, which result in the positions’ changes in fair value substantially offsetting through earnings each period. However, to the extent that the derivatives are not a mirror-image and because of differences in counterparty credit risk, changes in fair value will not completely offset resulting in some earnings impact each period. Changes in the fair value of these derivatives are included in other non-interest income. At March 31, 2021, the Company had interest rate derivative transactions with an aggregate notional amount of approximately $9.0 billion (all interest rate swaps and caps with customers and third parties) related to this program. These interest rate derivatives had maturity dates ranging from April 2021 to February 2045. Mortgage Banking Derivatives— These derivatives include interest rate lock commitments provided to customers to fund certain mortgage loans to be sold into the secondary market and forward commitments for the future delivery of such loans. It is the Company’s practice to enter into forward commitments for the future delivery of a portion of our residential mortgage loan production when interest rate lock commitments are entered into in order to economically hedge the effect of future changes in interest rates on its commitments to fund the loans as well as on its portfolio of mortgage loans held-for-sale. The Company’s mortgage banking derivatives have not been designated as being in hedge relationships. At March 31, 2021, the Company had forward commitments to sell mortgage loans with an aggregate notional amount of approximately $2.3 billion and interest rate lock commitments with an aggregate notional amount of approximately $1.1 billion. The fair values of these derivatives were estimated based on changes in mortgage rates from the dates of the commitments. Changes in the fair value of these mortgage banking derivatives are included in mortgage banking revenue. Foreign Currency Derivatives— These derivatives include foreign currency contracts used to manage the foreign exchange risk associated with foreign currency denominated assets and transactions. Foreign currency contracts, which include spot and forward contracts, represent agreements to exchange the currency of one country for the currency of another country at an agreed-upon price on an agreed-upon settlement date. As a result of fluctuations in foreign currencies, the U.S. dollar-equivalent value of the foreign currency denominated assets or forecasted transactions increase or decrease. Gains or losses on the derivative instruments related to these foreign currency denominated assets or forecasted transactions are expected to substantially offset this variability. As of March 31, 2021, the Company held foreign currency derivatives with an aggregate notional amount of approximately $3.8 million. Other Derivatives— Periodically, the Company will sell options to a bank or dealer for the right to purchase certain securities held within the banks’ investment portfolios (covered call options). These option transactions are designed primarily to mitigate overall interest rate risk and to increase the total return associated with the investment securities portfolio. These options do not qualify as accounting hedges pursuant to ASC 815, and, accordingly, changes in fair value of these contracts are recognized as other non-interest income. There were no covered call options outstanding as of March 31, 2021, December 31, 2020 or March 31, 2020. Periodically, the Company will purchase options for the right to purchase securities not currently held within the banks' investment portfolios or enter into interest rate swaps in which the Company elects to not designate such derivatives as hedging instruments. These option and swap transactions are designed primarily to economically hedge a portion of the fair value adjustments related to the Company's mortgage servicing rights portfolio. The gain or loss associated with these derivative contracts are included in mortgage banking revenue. There were no such options or swaps outstanding as of March 31, 2021. Amounts included in the Consolidated Statements of Income related to derivative instruments not designated in hedge relationships were as follows: (In thousands) Three Months Ended Derivative Location in income statement March 31, March 31, Interest rate swaps and caps Trading gains (losses), net $ 428 $ (428) Mortgage banking derivatives Mortgage banking revenue (17,479) 17,267 Foreign exchange contracts Trading gains (losses), net (5) (4) Covered call options Fees from covered call options — 2,292 Derivative contract held as economic hedge on MSRs Mortgage banking revenue — 4,160 Credit Risk Derivative instruments have inherent risks, primarily market risk and credit risk. Market risk is associated with changes in interest rates and credit risk relates to the risk that the counterparty will fail to perform according to the terms of the agreement. The amounts potentially subject to market and credit risks are the streams of interest payments under the contracts and the market value of the derivative instrument and not the notional principal amounts used to express the volume of the transactions. Market and credit risks are managed and monitored as part of the Company's overall asset-liability management process, except that the credit risk related to derivatives entered into with certain qualified borrowers is managed through the Company's standard loan underwriting process since these derivatives are secured through collateral provided by the loan agreements. Actual exposures are monitored against various types of credit limits established to contain risk within parameters. When deemed necessary, appropriate types and amounts of collateral are obtained to minimize credit exposure. The Company has agreements with certain of its interest rate derivative counterparties that contain cross-default provisions, which provide that if the Company defaults on any of its indebtedness, including default where repayment of the indebtedness has not been accelerated by the lender, then the Company could also be declared in default on its derivative obligations. The Company also has agreements with certain of its derivative counterparties that contain a provision allowing the counterparty to terminate the derivative positions if the Company fails to maintain its status as a well or adequately capitalized institution, which would require the Company to settle its obligations under the agreements. As of March 31, 2021, the fair value of interest rate derivatives in a net liability position that were subject to such agreements, which includes accrued interest related to these agreements, was $131.4 million. If the Company had breached any of these provisions and the derivatives were terminated as a result, the Company would have been required to settle its obligations under the agreements at the termination value and would have been required to pay any additional amounts due in excess of amounts previously posted as collateral with the respective counterparty. The Company is also exposed to the credit risk of its commercial borrowers who are counterparties to interest rate derivatives with the banks. This counterparty risk related to the commercial borrowers is managed and monitored through the banks' standard underwriting process applicable to loans since these derivatives are secured through collateral provided by the loan agreement. The counterparty risk associated with the mirror-image swaps executed with third parties is monitored and managed in connection with the Company's overall asset liability management process. The Company records interest rate derivatives subject to master netting agreements at their gross value and does not offset derivative assets and liabilities on the Consolidated Statements of Condition. The tables below summarize the Company's interest rate derivatives and offsetting positions as of the dates shown. Derivative Assets Derivative Liabilities Fair Value Fair Value (In thousands) March 31, December 31, March 31, March 31, December 31, March 31, Gross Amounts Recognized $ 206,236 $ 229,387 $ 259,986 $ 196,091 $ 275,843 $ 329,590 Less: Amounts offset in the Statements of Financial Condition — — — — — — Net amount presented in the Statements of Financial Condition $ 206,236 $ 229,387 $ 259,986 $ 196,091 $ 275,843 $ 329,590 Gross amounts not offset in the Statements of Financial Condition Offsetting Derivative Positions (60,593) (8,647) (1,048) (60,593) (8,647) (1,048) Collateral Posted — — — (125,818) (266,832) (328,542) Net Credit Exposure $ 145,643 $ 220,740 $ 258,938 $ 9,680 $ 364 $ —

Fair Values of Assets and Liabi

Fair Values of Assets and Liabilities	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Values of Assets and Liabilities	Fair Values of Assets and Liabilities The Company measures, monitors and discloses certain of its assets and liabilities on a fair value basis. These financial assets and financial liabilities are measured at fair value in three levels, based on the markets in which the assets and liabilities are traded and the observability of the inputs used to determine fair value. These levels are: • Level 1—unadjusted quoted prices in active markets for identical assets or liabilities. • Level 2 — inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability or inputs that are derived principally from or corroborated by observable market data by correlation or other means. • Level 3—significant unobservable inputs that reflect the Company’s own assumptions that market participants would use in pricing the assets or liabilities. Level 3 assets and liabilities include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. A financial instrument’s categorization within the above valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the assets or liabilities. The following is a description of the valuation methodologies used for the Company’s assets and liabilities measured at fair value on a recurring basis. Available-for-sale debt securities, trading account securities and equity securities with readily determinable fair value —Fair values for available-for-sale debt securities, trading account securities and equity securities with readily determinable fair value are typically based on prices obtained from independent pricing vendors. Securities measured with these valuation techniques are generally classified as Level 2 of the fair value hierarchy. Typically, standard inputs such as benchmark yields, reported trades for similar securities, issuer spreads, benchmark securities, bids, offers and reference data including market research publications are used to fair value these securities. When these inputs are not available, broker/dealer quotes may be obtained by the vendor to determine the fair value of the security. We review the vendor’s pricing methodologies to determine if observable market information is being used, versus unobservable inputs. Fair value measurements using significant inputs that are unobservable in the market due to limited activity or a less liquid market are classified as Level 3 in the fair value hierarchy. The fair value of U.S. Treasury securities and certain equity securities with readily determinable fair value are based on unadjusted quoted prices in active markets for identical securities. As such, these securities are classified as Level 1 in the fair value hierarchy. The Company’s Investment Operations Department is responsible for the valuation of Level 3 available-for-sale debt securities. The methodology and variables used as inputs in pricing Level 3 securities are derived from a combination of observable and unobservable inputs. The unobservable inputs are determined through internal assumptions that may vary from period to period due to external factors, such as market movement and credit rating adjustments. At March 31, 2021, the Company classified $101.7 million of municipal securities as Level 3. These municipal securities are bond issues for various municipal government entities primarily located in the Chicago metropolitan area and southern Wisconsin and are privately placed, non-rated bonds without CUSIP numbers. The Company also classified $1.8 million of U.S. Government agency securities as Level 3 at March 31, 2021. The Company’s methodology for pricing these securities focuses on three distinct inputs: equivalent rating, yield and other pricing terms. To determine the rating for a given non-rated investment debt security, the Investment Operations Department references a rated, publicly issued bond by the same issuer if available. A reduction is then applied to the rating obtained from the comparable bond, as the Company believes if liquidated, a non-rated bond would be valued less than a similar bond with a verifiable rating. The reduction applied by the Company is one complete rating grade (i.e. a “AA” rating for a comparable bond would be reduced to “A” for the Company’s valuation). For bond issues without comparable bond proxies, a rating of "BBB" was assigned. In the first quarter of 2021, all of the ratings derived by the Investment Operations Department using the above process were “BBB” or better. The fair value measurement noted above is sensitive to the rating input, as a higher rating typically results in an increased valuation. The remaining pricing inputs used in the bond valuation are observable. Based on the rating determined in the above process, Investment Operations obtains a corresponding current market yield curve available to market participants. Other terms including coupon, maturity date, redemption price, number of coupon payments per year, and accrual method are obtained from the individual bond term sheets. Certain municipal bonds held by the Company at March 31, 2021 are continuously callable. When valuing these bonds, the fair value is capped at par value as the Company assumes a market participant would not pay more than par for a continuously callable bond. To determine the rating for the U.S. Government agency securities, the Investment Operations Department assigned a “AAA” rating as it is guaranteed by the U.S. government. Mortgage loans held-for-sale —The fair value of mortgage loans held-for-sale is determined by reference to investor price sheets for loan products with similar characteristics. As such, these loans are classified as Level 2 in the fair value hierarchy. Loans held-for-investment —The fair value for loans in which the Company elected the fair value option is estimated by discounting future scheduled cash flows for the specific loan through maturity, adjusted for estimated credit losses and prepayments. The Company uses a discount rate based on the actual coupon rate of the underlying loan. At March 31, 2021, the Company classified $6.4 million of loans held-for-investment as Level 3. The weighted average discount rate used as an input to value these loans at March 31, 2021 was 2.38% with discount rates applied ranging from 2%-3%. The higher the rate utilized to discount estimated future cash flows, the lower the fair value measurement. As noted above, the fair value estimate also includes assumptions of prepayment speeds and credit losses. The Company included a prepayments speed assumption of 12.99% at March 31, 2021. Prepayment speeds are inversely related to the fair value of these loans as an increase in prepayment speeds results in a decreased valuation. Additionally, the weighted average credit discount used as an input to value the specific loans was 0.26% with credit loss discount ranging from 0%-3% at March 31, 2021. MSRs —Fair value for MSRs is determined utilizing a valuation model which calculates the fair value of each servicing rights based on the present value of estimated future cash flows. The Company uses a discount rate commensurate with the risk associated with each servicing rights, given current market conditions. At March 31, 2021, the Company classified $124.3 million of MSRs as Level 3. The weighted average discount rate used as an input to value the pool of MSRs at March 31, 2021 was 9.88% with discount rates applied ranging from 3%-19%. The higher the rate utilized to discount estimated future cash flows, the lower the fair value measurement. The fair value of MSRs was also estimated based on other assumptions including prepayment speeds and the cost to service. Prepayment speeds ranged from 6%-92% or a weighted average prepayment speed of 12.99%. Further, for current and delinquent loans, the Company assumed a weighted average cost of servicing of $76 and $354, respectively, per loan. Prepayment speeds and the cost to service are both inversely related to the fair value of MSRs as an increase in prepayment speeds or the cost to service results in a decreased valuation. See Note 8 - Mortgage Servicing Rights (“MSRs”) for further discussion of MSRs. Derivative instruments —The Company’s derivative instruments include interest rate swaps, caps and collars, commitments to fund mortgages for sale into the secondary market (interest rate locks), forward commitments to end investors for the sale of mortgage loans and foreign currency contracts. Interest rate swaps, caps and collars are valued by a third party, using models that primarily use market observable inputs, such as yield curves, and are classified as Level 2 in the fair value hierarchy. The credit risk associated with derivative financial instruments that are subject to master netting agreements is measured on a net basis by counterparty portfolio. The fair value for mortgage-related derivatives is based on changes in mortgage rates from the date of the commitments. The fair value of foreign currency derivatives is computed based on change in foreign currency rates stated in the contract compared to those prevailing at the measurement date. At March 31, 2021, the Company classified $25.6 million of derivative assets related to interest rate locks as Level 3. The fair value of interest rate locks is based on prices obtained for loans with similar characteristics from third parties, adjusted for the pull-through rate, which represents the Company’s best estimate of the likelihood that a committed loan will ultimately fund. The weighted-average pull-through rate at March 31, 2021 was 86% with pull-through rates applied ranging from 14% to 100%. Pull-through rates are directly related to the fair value of interest rate locks as an increase in the pull-through rate results in an increased valuation. Nonqualified deferred compensation assets —The underlying assets relating to the nonqualified deferred compensation plan are included in a trust and primarily consist of non-exchange traded institutional funds which are priced based by an independent third party service. These assets are classified as Level 2 in the fair value hierarchy. The following tables present the balances of assets and liabilities measured at fair value on a recurring basis for the periods presented: March 31, 2021 (In thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 65,001 $ 65,001 $ — $ — U.S. Government agencies 81,526 — 79,742 1,784 Municipal 148,300 — 46,552 101,748 Corporate notes 92,349 — 92,349 — Mortgage-backed 2,043,573 — 2,043,573 — Trading account securities 951 — 951 — Equity securities with readily determinable fair value 90,338 82,272 8,066 — Mortgage loans held-for-sale 1,260,193 — 1,260,193 — Loans held-for-investment 51,916 — 45,508 6,408 MSRs 124,316 — — 124,316 Nonqualified deferred compensation assets 15,891 — 15,891 — Derivative assets 253,509 — 227,875 25,634 Total $ 4,227,863 $ 147,273 $ 3,820,700 $ 259,890 Derivative liabilities $ 200,758 $ — $ 200,758 $ — December 31, 2020 (In thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 304,971 $ 304,971 $ — $ — U.S. Government agencies 84,513 — 82,547 1,966 Municipal 146,910 — 37,034 109,876 Corporate notes 91,405 — 91,405 — Mortgage-backed 2,428,040 — 2,428,040 — Trading account securities 671 — 671 — Equity securities with readily determinable fair value 90,862 82,796 8,066 — Mortgage loans held-for-sale 1,272,090 — 1,272,090 — Loans held-for-investment 55,134 — 44,854 10,280 MSRs 92,081 — — 92,081 Nonqualified deferred compensation assets 15,398 — 15,398 — Derivative assets 278,423 — 230,332 48,091 Total $ 4,860,498 $ 387,767 $ 4,210,437 $ 262,294 Derivative liabilities $ 288,465 $ — $ 288,465 $ — March 31, 2020 (In thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 121,670 $ 121,670 $ — $ — U.S. Government agencies 368,643 — 366,186 2,457 Municipal 146,609 — 33,342 113,267 Corporate notes 101,018 — 101,018 — Mortgage-backed 2,833,019 — 2,833,019 — Trading account securities 2,257 — 2,257 — Equity securities with readily determinable fair value 47,310 39,244 8,066 — Mortgage loans held-for-sale 656,934 — 656,934 — Loans held-for-investment 142,267 — 132,699 9,568 MSRs 73,504 — — 73,504 Nonqualified deferred compensation assets 12,253 — 12,253 — Derivative assets 301,368 — 261,552 39,816 Total $ 4,806,852 $ 160,914 $ 4,407,326 $ 238,612 Derivative liabilities $ 367,620 $ — $ 367,620 $ — The aggregate remaining contractual principal balance outstanding as of March 31, 2021, December 31, 2020 and March 31, 2020 for mortgage loans held-for-sale measured at fair value under ASC 825 was $1.2 billion, $1.2 billion and $618.7 million, respectively, while the aggregate fair value of mortgage loans held-for-sale was $1.3 billion, $1.3 billion and $656.9 million, for the same respective periods, as shown in the above tables. There were $115.2 million of loans past due greater than 90 days and still accruing in the mortgage loans held-for-sale portfolio as of March 31, 2021 compared to $134.1 million as of December 31, 2020 and $358,000 as of March 31, 2020. All of the loans past due greater than 90 days and still accruing as of March 31, 2021 were individual delinquent mortgage loans bought back from GNMA at the unconditional option of the Company as servicer for those loans. The changes in Level 3 assets measured at fair value on a recurring basis during the three months ended March 31, 2021 and 2020 are summarized as follows: U.S. Government agencies Loans held-for- investment Mortgage Derivative assets (In thousands) Municipal Balance at January 1, 2021 $ 109,876 $ 1,966 $ 10,280 $ 92,081 $ 48,091 Total net gains (losses) included in: Net income (1) — — (530) 32,235 (22,457) Other comprehensive income (loss) (2,068) (24) — — — Purchases — — — — — Issuances — — — — — Sales — — — — — Settlements (6,060) (158) (3,918) — — Net transfers into/(out of) Level 3 — — 576 — — Balance at March 31, 2021 $ 101,748 $ 1,784 $ 6,408 $ 124,316 $ 25,634 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income. U.S. Government agencies Loans held-for- investment Mortgage Derivative assets (In thousands) Municipal Balance at January 1, 2020 $ 111,950 $ 2,646 $ 9,620 $ 85,638 $ 2,631 Total net gains (losses) included in: Net income (1) — — (78) (12,134) 37,185 Other comprehensive income (loss) (1,249) (32) — — — Purchases 5,875 — — — — Issuances — — — — — Sales — — — — — Settlements (3,309) (157) (96) — — Net transfers into/(out of) Level 3 — — 122 — — Balance at March 31, 2020 $ 113,267 $ 2,457 $ 9,568 $ 73,504 $ 39,816 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income. Also, the Company may be required, from time to time, to measure certain other assets at fair value on a nonrecurring basis in accordance with GAAP. These adjustments to fair value usually result from impairment charges on individual assets. For assets measured at fair value on a nonrecurring basis that were still held in the balance sheet at the end of the period, the following table provides the carrying value of the related individual assets or portfolios at March 31, 2021: March 31, 2021 Three Months Ended March 31, 2021 (In thousands) Total Level 1 Level 2 Level 3 Individually assessed loans - foreclosure probable and collateral-dependent $ 87,757 $ — $ — $ 87,757 $ 12,548 Other real estate owned (1) 15,813 — — 15,813 170 Total $ 103,570 $ — $ — $ 103,570 $ 12,718 (1) Fair value losses recognized, net on other real estate owned include valuation adjustments and charge-offs during the respective period. Individually assessed loans —In accordance with ASC 326, the allowance for credit losses for loans and other financial assets held at amortized cost should be measured on a collective or pooled basis when such assets exhibit similar risk characteristics. In instances in which a financial asset does not exhibit similar risk characteristics to a pool, the Company is required to measure such allowance for credit losses on an individual asset basis. For the Company's loan portfolio, nonaccrual loans and TDRs are considered to not exhibit similar risk characteristics as pools and thus are individually assessed. Credit losses are measured by estimating the fair value of the loan based on the present value of expected cash flows, the market price of the loan, or the fair value of the underlying collateral. Individually assessed loans are considered a fair value measurement where an allowance for credit loss is established based on the fair value of collateral. Appraised values on relevant real estate properties, which may require adjustments to market-based valuation inputs, are generally used on foreclosure probable and collateral-dependent loans within the real estate portfolios. The Company’s Managed Assets Division is primarily responsible for the valuation of Level 3 inputs of individually assessed loans. For more information on individually assessed loans refer to Note 6 – Allowance for Credit Losses. At March 31, 2021, the Company had $124.4 million of individually assessed loans classified as Level 3. Of the $124.4 million of individually assessed loans, $87.8 million were measured at fair value based on the underlying collateral of the loan as shown in the table above. The remaining $36.6 million were valued based on discounted cash flows in accordance with ASC 310. Other real estate owned —Other real estate owned is comprised of real estate acquired in partial or full satisfaction of loans and is included in other assets. Other real estate owned is recorded at its estimated fair value less estimated selling costs at the date of transfer, with any excess of the related loan balance over the fair value less expected selling costs charged to the allowance for loan losses. Subsequent changes in value are reported as adjustments to the carrying amount and are recorded in other non-interest expense. Gains and losses upon sale, if any, are also charged to other non-interest expense. Fair value is generally based on third party appraisals and internal estimates that are adjusted by a discount representing the estimated cost of sale and is therefore considered a Level 3 valuation. The Company’s Managed Assets Division is primarily responsible for the valuation of Level 3 inputs for other real estate owned. At March 31, 2021, the Company had $15.8 million of other real estate owned classified as Level 3. The unobservable input applied to other real estate owned relates to the 10% reduction to the appraisal value representing the estimated cost of sale of the foreclosed property. A higher discount for the estimated cost of sale results in a decreased carrying value. The valuation techniques and significant unobservable inputs used to measure both recurring and non-recurring Level 3 fair value measurements at March 31, 2021 were as follows: (Dollars in thousands) Fair Value Valuation Methodology Significant Unobservable Input Range Weighted Impact to valuation Measured at fair value on a recurring basis: Municipal Securities $ 101,748 Bond pricing Equivalent rating BBB-AA+ N/A Increase U.S. Government agencies 1,784 Bond pricing Equivalent rating AAA AAA Increase Loans held-for-investment 6,408 Discounted cash flows Discount rate 2%-3% 2.38% Decrease Credit discount 0%-3% 0.26% Decrease Constant prepayment rate (CPR) 12.99% 12.99% Decrease MSRs 124,316 Discounted cash flows Discount rate 3%-19% 9.88% Decrease Constant prepayment rate (CPR) 6%-92% 12.99% Decrease Cost of servicing $70-$200 $76 Decrease Cost of servicing - delinquent $200-$1,000 $354 Decrease Derivatives 25,634 Discounted cash flows Pull-through rate 14%-100% 86.39% Increase Measured at fair value on a non-recurring basis: Individually assessed loans - foreclosure probable and collateral-dependent $ 87,757 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease Other real estate owned 15,813 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease The Company is required under applicable accounting guidance to report the fair value of all financial instruments on the Consolidated Statements of Condition, including those financial instruments carried at cost. The table below presents the carrying amounts and estimated fair values of the Company’s financial instruments as of the dates shown: At March 31, 2021 At December 31, 2020 At March 31, 2020 Carrying Fair Carrying Fair Carrying Fair (In thousands) Value Value Value Value Value Value Financial Assets: Cash and cash equivalents $ 426,377 $ 426,377 $ 322,474 $ 322,474 $ 349,427 $ 349,427 Interest-bearing deposits with banks 3,348,794 3,348,794 4,802,527 4,802,527 1,943,743 1,943,743 Available-for-sale securities 2,430,749 2,430,749 3,055,839 3,055,839 3,570,959 3,570,959 Held-to-maturity securities 2,166,419 2,121,065 579,138 593,767 865,376 879,192 Trading account securities 951 951 671 671 2,257 2,257 Equity securities with readily determinable fair value 90,338 90,338 90,862 90,862 47,310 47,310 FHLB and FRB stock, at cost 135,881 135,881 135,588 135,588 134,546 134,546 Brokerage customer receivables 19,056 19,056 17,436 17,436 16,293 16,293 Mortgage loans held-for-sale, at fair value 1,260,193 1,260,193 1,272,090 1,272,090 656,934 656,934 Loans held-for-investment, at fair value 51,916 51,916 55,134 55,134 142,267 142,267 Loans held-for-investment, at amortized cost 33,119,317 33,066,760 32,023,939 31,871,683 27,665,054 27,469,489 Nonqualified deferred compensation assets 15,891 15,891 15,398 15,398 12,253 12,253 Derivative assets 253,509 253,509 278,423 278,423 301,368 301,368 Accrued interest receivable and other 281,020 281,020 272,339 272,339 275,499 275,499 Total financial assets $ 43,600,411 $ 43,502,500 $ 42,921,858 $ 42,784,231 $ 35,983,286 $ 35,801,537 Financial Liabilities Non-maturity deposits $ 33,061,502 $ 33,061,502 $ 32,116,023 $ 32,116,023 $ 26,071,881 $ 26,071,881 Deposits with stated maturities 4,811,150 4,801,257 4,976,628 4,969,849 5,389,779 5,394,523 FHLB advances 1,228,436 1,121,269 1,228,429 1,172,315 1,174,894 1,130,327 Other borrowings 516,877 516,877 518,928 518,928 487,503 487,503 Subordinated notes 436,595 458,832 436,506 473,093 436,179 487,745 Junior subordinated debentures 253,566 208,132 253,566 204,713 253,566 224,523 Derivative liabilities 200,758 200,758 288,465 288,465 367,620 367,620 Accrued interest payable 19,940 19,940 15,645 15,645 27,696 27,696 Total financial liabilities $ 40,528,824 $ 40,388,567 $ 39,834,190 $ 39,759,031 $ 34,209,118 $ 34,191,818 Not all the financial instruments listed in the table above are subject to the disclosure provisions of ASC Topic 820, as certain assets and liabilities result in their carrying value approximating fair value. These include cash and cash equivalents, interest bearing deposits with banks, brokerage customer receivables, FHLB and FRB stock, accrued interest receivable and accrued interest payable and non-maturity deposits. The following methods and assumptions were used by the Company in estimating fair values of financial instruments that were not previously disclosed. Held-to-maturity securities. Held-to-maturity securities include U.S. Government-sponsored agency securities and municipal bonds issued by various municipal government entities primarily located in the Chicago metropolitan area and southern Wisconsin. Fair values for held-to-maturity securities are typically based on prices obtained from independent pricing vendors. In accordance with ASC 820, the Company has generally categorized these held-to-maturity securities as a Level 2 fair value measurement. Fair values for certain other held-to-maturity securities are based on the bond pricing methodology discussed previously related to certain available-for-sale securities. In accordance with ASC 820, the Company has categorized these held-to-maturity securities as a Level 3 fair value measurement. Loans held-for-investment, at amortized cost. Fair values are estimated for portfolios of loans with similar financial characteristics. Loans are analyzed by type such as commercial, residential real estate, etc. Each category is further segmented by interest rate type (fixed and variable) and term. For variable-rate loans that reprice frequently, estimated fair values are based on carrying values. The fair value of residential loans is based on secondary market sources for securities backed by similar loans, adjusted for differences in loan characteristics. The fair value for other fixed rate loans is estimated by discounting scheduled cash flows through the estimated maturity using estimated market discount rates that reflect credit and interest rate risks inherent in the loan. In accordance with ASC 820, the Company has categorized loans as a Level 3 fair value measurement. Deposits with stated maturities. The fair value of certificates of deposit is based on the discounted value of contractual cash flows. The discount rate is estimated using the rates currently in effect for deposits of similar remaining maturities. In accordance with ASC 820, the Company has categorized deposits with stated maturities as a Level 3 fair value measurement. FHLB advances. The fair value of FHLB advances is obtained from the FHLB which uses a discounted cash flow analysis based on current market rates of similar maturity debt securities to discount cash flows. In accordance with ASC 820, the Company has categorized FHLB advances as a Level 3 fair value measurement. Subordinated notes. The fair value of the subordinated notes is based on a market price obtained from an independent pricing vendor. In accordance with ASC 820, the Company has categorized subordinated notes as a Level 2 fair value measurement. Junior subordinated debentures. The fair value of the junior subordinated debentures is based on the discounted value of contractual cash flows. In accordance with ASC 820, the Company has categorized junior subordinated debentures as a Level 3 fair value measurement.

Stock-Based Compensation Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement, Noncash Expense [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans In May 2015, the Company’s shareholders approved the 2015 Stock Incentive Plan (“the 2015 Plan”) which provides for the issuance of up to 5,485,000 shares of common stock. The 2015 Plan replaced the 2007 Stock Incentive Plan (“the 2007 Plan”) which replaced the 1997 Stock Incentive Plan (“the 1997 Plan”). The 2015 Plan, the 2007 Plan and the 1997 Plan are collectively referred to as “the Plans.” The 2015 Plan has substantially similar terms to the 2007 Plan and the 1997 Plan. Awards granted under the Plans for which common shares are not issued by reason of cancellation, forfeiture, lapse of such award or settlement of such award in cash, are again available under the 2015 Plan. All grants made after the approval of the 2015 Plan are made pursuant to the 2015 Plan. As of March 31, 2021, approximately 951,000 shares were available for future grants assuming the maximum number of shares are issued for the performance awards outstanding. The Plans cover substantially all employees of Wintrust. The Compensation Committee of the Board of Directors administers all stock-based compensation programs and authorizes all awards granted pursuant to the Plans. The Plans permit the grant of incentive stock options, non-qualified stock options, stock appreciation rights, stock awards, restricted share or unit awards, performance awards and other incentive awards valued in whole or in part by reference to the Company’s common stock, all on a stand alone, combination or tandem basis. The Company historically awarded stock-based compensation in the form of time-vested non-qualified stock options and time-vested restricted share unit awards (“restricted shares”). The grants of options provide for the purchase of shares of the Company’s common stock at the fair market value of the stock on the date the options are granted. Stock options generally vest ratably over periods of three one Beginning in 2011, the Company has awarded annual grants under the Long-Term Incentive Program (“LTIP”), which is administered under the Plans. The LTIP is designed in part to align the interests of management with the interests of shareholders, foster retention, create a long-term focus based on sustainable results and provide participants with a target long-term incentive opportunity. LTIP grants in 2021 consisted of a combination of performance-based stock awards with a performance condition metric, performance-based stock awards with a market condition metric and time vested restricted shares, and in 2020 consisted of a combination of performance-based stock awards and performance-based cash awards (both with a performance condition metric) and time vested restricted shares. LTIP grants from 2017 through 2019 consisted of a combination of performance-based stock awards and performance-based cash awards, and prior to 2017, nonqualified stock options were in the mix of award types. Stock options granted under the LTIP have a term of seven years and generally vested equally over three years based on continued service. Performance-based stock and cash awards granted under the LTIP are contingent upon the achievement of pre-established long-term performance goals set in advance by the Compensation Committee over a three-year period starting at the beginning of each calendar year. Performance-based stock awards with a market condition metric are contingent on the total shareholder return performance over a three-year period starting at the beginning of each calendar year relative to the KBW Regional Bank Index. These performance awards are granted at a target level, and based on the Company’s achievement of the pre-established long-term goals, the actual payouts can range from 0% to a maximum of 150% of the target award. The awards typically vest in the quarter after the end of the performance period upon certification of the payout by the Compensation Committee of the Board of Directors. Holders of performance-based stock awards are entitled to receive, at no cost, the shares earned based on the achievement of the pre-established long-term goals. Holders of restricted share awards and performance-based stock awards received under the Plans are not entitled to vote or receive cash dividends (or cash payments equal to the cash dividends) on the underlying common shares until the awards are vested and shares are issued. Shares that are vested but not issuable pursuant to deferred compensation arrangements accrue additional shares based on the value of dividends otherwise paid. Except in limited circumstances, these awards are canceled upon termination of employment without any payment of consideration by the Company. Stock-based compensation is measured as the fair value of an award on the date of grant, and the measured cost is recognized over the period which the recipient is required to provide service in exchange for the award. The fair value of restricted share and performance-based stock awards with a performance condition metric is determined based on the average of the high and low trading prices on the grant date. The fair value of performance stock awards with a market condition metric is estimated using a Monte Carlo simulation model and the fair value of stock options is estimated using a Black-Scholes option-pricing model. The Monte Carlo simulation model and the Black-Scholes option-pricing model require the input of highly subjective assumptions and are sensitive to changes in the award's expected life and the price volatility of the underlying stock, which can materially affect the fair value estimates. Management periodically reviews and adjusts the assumptions used to calculate the fair value of such awards when granted. No options have been granted since 2016. Stock based compensation is recognized based upon the number of awards that are ultimately expected to vest, taking into account expected forfeitures. In addition, for performance-based awards with a performance metric, an estimate is made of the number of shares expected to vest as a result of actual performance against the performance criteria in the award to determine the amount of compensation expense to recognize. The estimate is re-evaluated quarterly and total compensation expense is adjusted for any change in estimate in the current period. Stock-based compensation expense recognized in the Consolidated Statements of Income was $2.9 million in the first quarter of 2021 and $(2.8) million in the first quarter of 2020. A summary of the Company's stock option activity for the three months ended March 31, 2021 and March 31, 2020 is presented below: Stock Options Common Weighted Remaining Contractual Term (1) Intrinsic Value (2) (in thousands) Outstanding at January 1, 2021 520,663 $ 42.47 Granted — — Exercised (208,579) 42.96 Forfeited or canceled (590) 46.86 Outstanding at March 31, 2021 311,494 $ 42.14 1.8 $ 10,485 Exercisable at March 31, 2021 309,945 $ 42.11 1.8 $ 10,441 Stock Options Common Weighted Remaining Contractual Term (1) Intrinsic Value (2) (in thousands) Outstanding at January 1, 2020 755,332 $ 42.43 Granted — — Exercised (94,653) 38.69 Forfeited or canceled — — Outstanding at March 31, 2020 660,679 $ 42.97 2.5 $ — Exercisable at March 31, 2020 650,456 $ 42.95 2.4 $ 1 (1) Represents the remaining weighted average contractual life in years. (2) Aggregate intrinsic value represents the total pre-tax intrinsic value (i.e., the difference between the Company's stock price on the last trading day of the quarter and the option exercise price, multiplied by the number of shares) that would have been received by the option holders if they had exercised their options on the last day of the quarter. Options with exercise prices above the stock price on the last trading day of the quarter are excluded from the calculation of intrinsic value. The intrinsic value will change based on the fair market value of the Company's stock. The aggregate intrinsic value of options exercised during the three months ended March 31, 2021 and March 31, 2020, was $6.6 million and $2.7 million, respectively. Cash received from option exercises under the Plans for the three months ended March 31, 2021 and March 31, 2020 was $9.0 million and $3.7 million, respectively. A summary of the Plans' restricted share activity for the three months ended March 31, 2021 and March 31, 2020 is presented below: Three months ended March 31, 2021 Three months ended March 31, 2020 Restricted Shares Common Weighted Common Weighted Outstanding at January 1 234,794 $ 59.02 144,328 $ 60.37 Granted 257,189 62.79 99,963 64.10 Vested and issued (7,104) 78.13 (9,633) 75.69 Forfeited or canceled (849) 63.44 (3,538) 81.89 Outstanding at March 31 484,030 $ 60.73 231,120 $ 61.02 Vested, but not issuable at March 31 94,348 $ 52.21 92,244 $ 52.23 A summary of the Plans' performance-based stock award activity, based on the target level of the awards, for the three months ended March 31, 2021 and March 31, 2020 is presented below: Three months ended March 31, 2021 Three months ended March 31, 2020 Performance-based Stock Common Weighted Common Weighted Outstanding at January 1 482,608 $ 71.15 465,515 $ 74.37 Granted 206,465 58.85 166,547 64.10 Added by performance factor at vesting — — 48,831 72.59 Vested and issued — — (180,596) 72.59 Expired, canceled or forfeited (125,622) 87.88 (6,071) 73.66 Outstanding at March 31 563,451 $ 62.91 494,226 $ 71.39 Vested, but deferred at March 31 34,748 $ 43.28 34,166 $ 43.27

Shareholders' Equity and Earnin

Shareholders' Equity and Earnings Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Shareholders' Equity and Earnings Per Share	Shareholders’ Equity and Earnings Per Share Series D Preferred Stock In June 2015, the Company issued and sold 5,000,000 shares of fixed-to-floating non-cumulative perpetual preferred stock, Series D, liquidation preference $25 per share (the “Series D Preferred Stock”) for $125.0 million in a public offering. When, as and if declared, dividends on the Series D Preferred Stock are payable quarterly in arrears at a fixed rate of 6.50% per annum from the original issuance date to, but excluding, July 15, 2025, and from (and including) that date at a floating rate equal to three-month LIBOR plus a spread of 4.06% per annum. Series E Preferred Stock In May 2020, the Company issued 11,500 shares of fixed-rate reset non-cumulative perpetual preferred stock, Series E, liquidation preference $25,000 per share (the “Series E Preferred Stock”) as part of a $287.5 million public offering of 11,500,000 depositary shares, each representing a 1/1,000th interest in a share of Series E Preferred Stock. When, as and if declared, dividends on the Series E Preferred Stock are payable quarterly in arrears at a fixed rate of 6.875% per annum starting on October 15, 2020. Other At the January 2021 Board of Directors meeting, a quarterly cash dividend of $0.31 per share ($1.24 on an annualized basis) was declared. It was paid on February 25, 2021 to shareholders of record as of February 11, 2021. Accumulated Other Comprehensive Income (Loss) The following tables summarize the components of other comprehensive income (loss), including the related income tax effects, and the related amount reclassified to net income for the periods presented (in thousands). Accumulated Accumulated Accumulated Total Balance at January 1, 2021 $ 70,737 $ (23,090) $ (32,265) $ 15,382 Other comprehensive (loss) income during the period, net of tax, before reclassifications (44,519) 32,345 2,180 (9,994) Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax (154) 4,912 — 4,758 Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax (42) — — (42) Net other comprehensive (loss) income during the period, net of tax $ (44,715) $ 37,257 $ 2,180 $ (5,278) Balance at March 31, 2021 $ 26,022 $ 14,167 $ (30,085) $ 10,104 Balance at January 1, 2020 $ 14,982 $ (13,141) $ (36,519) $ (34,678) Other comprehensive income (loss) during the period, net of tax, before reclassifications 67,007 (29,170) (11,145) 26,692 Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax (359) 799 — 440 Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax (57) — — (57) Net other comprehensive income (loss) during the period, net of tax $ 66,591 $ (28,371) $ (11,145) $ 27,075 Balance at March 31, 2020 $ 81,573 $ (41,512) $ (47,664) $ (7,603) Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Details Regarding the Component of Accumulated Other Comprehensive Income (Loss) Three Months Ended Impacted Line on the March 31, 2021 2020 Accumulated unrealized gains on securities Gains included in net income $ 210 $ 491 Gains (losses) on investment securities, net 210 491 Income before taxes Tax effect (56) (132) Income tax expense Net of tax $ 154 $ 359 Net income Accumulated unrealized gains on derivative instruments Amount reclassified to interest expense on deposits $ 4,897 $ 559 Interest on deposits Amount reclassified to interest expense on other borrowings 669 292 Interest on other borrowings Amount reclassified to interest expense on junior subordinated debentures 1,130 239 Interest on junior subordinated debentures (6,696) (1,090) Income before taxes Tax effect 1,784 291 Income tax expense Net of tax $ (4,912) $ (799) Net income Earnings per Share The following table shows the computation of basic and diluted earnings per share for the periods indicated: Three Months Ended (In thousands, except per share data) March 31, March 31, Net income $ 153,148 $ 62,812 Less: Preferred stock dividends 6,991 2,050 Net income applicable to common shares (A) $ 146,157 $ 60,762 Weighted average common shares outstanding (B) 56,904 57,620 Effect of dilutive potential common shares Common stock equivalents 681 575 Weighted average common shares and effect of dilutive potential common shares (C) 57,585 58,195 Net income per common share: Basic (A/B) $ 2.57 $ 1.05 Diluted (A/C) $ 2.54 $ 1.04 Potentially dilutive common shares can result from stock options, restricted stock unit awards, stock warrants and shares to be issued under the Employee Stock Purchase Plan and the Directors Deferred Fee and Stock Plan, being treated as if they had been either exercised or issued, computed by application of the treasury stock method. While potentially dilutive common shares are typically included in the computation of diluted earnings per share, potentially dilutive common shares are excluded from this computation in periods in which the effect would reduce the loss per share or increase the income per share.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	ubsequent EventsOn April 23, 2021, the Company and Greenwoods Financial Group, Inc., the parent company of The Greenwood’s State Bank (“Greenwoods”), announced the closing of the previously announced branch purchase and assumption transaction for three southwestern Wisconsin branch locations of Town Bank, N.A., the Company’s wholly-owned subsidiary. The three branches subject to the transaction are located in Albany, Darlington and Monroe, Wisconsin. Through this transaction, Greenwoods assumed approximately $77.4 million of deposits and acquired the branch facilities and various other assets.

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Accounting	The interim consolidated financial statements of Wintrust Financial Corporation and its subsidiaries (collectively, “Wintrust” or the “Company”) presented herein are unaudited, but in the opinion of management, reflect all necessary adjustments of a normal or recurring nature for a fair presentation of results as of the dates and for the periods covered by the interim consolidated financial statements. The accompanying interim consolidated financial statements are unaudited and do not include information or footnotes necessary for a complete presentation of financial condition, results of operations or cash flows in accordance with U.S. generally accepted accounting principles (“GAAP”). The interim unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020 (“2020 Form 10-K”). Operating results reported for the period are not necessarily indicative of the results which may be expected for the entire year. Reclassifications of certain prior period amounts have been made to conform to the current period presentation. The preparation of the financial statements requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities. Management believes that the estimates made are reasonable; however, changes in estimates may be required if economic or other conditions develop differently from management’s expectations. Certain policies and accounting principles inherently have a greater reliance on the use of estimates, assumptions and judgments and as such have a greater possibility of producing results that could be materially different than originally reported. Management views critical accounting policies to be those which are highly dependent on subjective or complex judgments, estimates and assumptions, and where changes in those estimates and assumptions could have a significant impact on the financial statements. Management currently views the determination of the allowance for credit losses, including the allowance for loan losses, the allowance for unfunded commitment losses and the allowance for held-to-maturity securities losses, estimations of fair value, the valuations required for impairment testing of goodwill, the valuation and accounting for derivative instruments and income taxes as the accounting areas that require the most subjective and complex judgments, and as such could be the most subject to revision as new information becomes available. Descriptions of the Company's significant accounting policies are included in Note 1 - “Summary of Significant Accounting Policies” of the 2020 Form 10-K.
Recent Accounting Developments	Legislation and Regulations Issued as a Result of the COVID-19 Pandemic On March 27, 2020, the President of the United States signed the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act" or the "Act"), which provides entities with optional temporary relief from certain accounting and financial reporting requirements under U.S. GAAP. Section 4013 of the CARES Act allows financial institutions to suspend application of certain current troubled debt restructuring ("TDR") accounting guidance under Accounting Standards Codification (“ASC”) 310-40 for loan modifications related to the COVID-19 pandemic made between March 1, 2020 and the earlier of December 31, 2020 or 60 days after the end of the COVID-19 national emergency, provided certain criteria are met. This relief can be applied to loan modifications for borrowers that were not more than 30 days past due as of December 31, 2019 and to loan modifications that defer or delay the payment of principal or interest, or change the interest rate on the loan. On December 27, 2020, the Consolidated Appropriations Act, 2021 (the "CAA"), which combined stimulus relief for the COVID-19 pandemic with an omnibus spending bill for the 2021 fiscal year, was signed by the President of the United States. The CAA included extension of TDR accounting relief provided under the CARES Act to January 1, 2022. The Company chose to apply this relief to eligible loan modifications. The business tax provisions of the Act include temporary changes to income and non-income based tax laws, including immediate recovery of qualified improvement property costs and acceleration of Alternative Minimum Tax (AMT) credits. These provisions did not have a material impact on the Company's deferred taxes. In April 2020, federal and state banking regulators issued the Interagency Statement on Loan Modifications and Reporting for Financial Institutions Working with Customers Affected by the Coronavirus to provide separate relief, specifically indicating that if a modification is either short-term (e.g., six months) or mandated by a federal or state government in response to the COVID-19 pandemic, the borrower is not considered to be experiencing financial difficulty and thus does not represent a TDR under ASC 310-40. Additionally, in August 2020, regulators issued the Joint Statement on Additional Loan Accommodations Related to the COVID-19 pandemic to provide prudent risk management and consumer protection principles for financial institutions to consider while working with borrowers as loans near the end of initial loan accommodation periods applicable during the COVID-19 pandemic. The Company continues to prudently work with borrowers negatively impacted by the COVID-19 pandemic while managing credit risks and recognizing appropriate allowance for credit losses on its loan portfolio. Reference Rate Reform In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848),” which provides temporary optional relief for contracts modified as a result of reference rate reform meeting certain modification criteria, generally allowing an entity to account for contract modifications occurring due to reference rate reform as an event that does not require contract remeasurement or reassessment of a previous accounting determination at the modification date. The guidance also includes temporary optional expedients intended to provide relief from various hedge effectiveness requirements for hedging relationships affected by reference rate reform, provided certain criteria are met, and allows a one-time election to sell or transfer to either available-for-sale or trading any held-to-maturity ("HTM") debt securities that refer to an interest rate affected by reference rate reform and were classified as HTM prior to January 1, 2020. Additionally, in January 2021, the FASB issued ASU No. 2021-01, “Reference Rate Reform (Topic 848): Scope,” which provided additional clarification that certain optional expedients and exceptions noted above apply to derivative instruments that use an interest rate for margining, discounting or contract price alignment that is modified as a result of reference rate reform. This guidance was effective upon issuance and can be applied prospectively, with certain exceptions, through December 31, 2022. In November 2020, federal and state banking regulators issued the “Interagency Policy Statement on Reference Rates for Loans" to reiterate that a specific replacement rate for loans impacted by reference rate reform has not been endorsed and entities may utilize any replacement reference rate determined to be appropriate based on its funding model and customer needs. As discussed in the “Interagency Policy Statement on Reference Rates for Loans," fallback language should be included in lending contracts to provide for use of a robust fallback rate if the initial reference rate is discontinued. Additionally, federal banking regulators issued the "Interagency Statement on LIBOR Transition" acknowledging that the administrator of USD LIBOR benchmarks has announced it will consult on its intention to cease the publication of the one week and two month USD LIBOR settings immediately following the LIBOR publication on December 31, 2021, and the remaining USD LIBOR settings immediately following the LIBOR publication on June 30, 2023. On March 5, 2021, the administrator of USD LIBOR benchmarks confirmed these dates and will cease publication of USD LIBOR tenors accordingly. As discussed in the "Interagency Statement on LIBOR Transition," regulators encouraged banks to cease entering into new contracts that use USD LIBOR as a reference rate as soon as practicable and in any event by December 31, 2021, in order to facilitate an orderly, safe and sound LIBOR transition. The Company continues to monitor efforts and evaluate the impact of reference rate reform on its consolidated financial statements. Income Taxes In December 2019, the FASB issued ASU No. 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes," to simplify the accounting for income taxes by removing certain exceptions to the general principles of ASC 740, "Income Taxes". The guidance also improved consistent application by clarifying and amending existing guidance from ASC 740. The Company adopted ASU No. 2019-12 as of January 1, 2021. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Investment Securities In January 2020, the FASB issued ASU No. 2020-01, “Clarifying the Interactions Between Investments-Equity Securities (ASC Topic 321), Investments-Equity Method and Joint Ventures (ASC Topic 323), and Derivatives and Hedging (ASC Topic 815),” which amended ASC 323, Investments-Equity Method & Joint Ventures to clarify that an entity should consider observable transactions that require it to either apply or discontinue using the equity method of accounting for purposes of applying the measurement alternative in accordance with ASC 321, Investments-Equity Securities, immediately before applying or discontinuing the equity method under ASC 323. The guidance also amended ASC 815, Derivatives & Hedging, to clarify that, when determining the accounting for certain nonderivative forward contracts and purchased options, an entity should not consider how to account for the resulting investments upon eventual settlement or exercise, and that an entity should evaluate the remaining characteristics in accordance with ASC 815 to determine the accounting for those forward contracts and purchased options. The Company adopted ASU No. 2020-01 as of January 1, 2021 under a prospective approach. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Codification Improvements In October 2020, the FASB issued ASU No. 2020-08, “Codification Improvements to Subtopic 310-20, Receivables — Nonrefundable Fees and Other Costs,” clarifying that, for each reporting period, an entity should reevaluate whether a callable debt security with multiple call dates is within the scope of ASC 310-20, which was amended to require amortization of any premium to the next call date. The next call date was defined as the first date when a call option at a specified price becomes exercisable. The Company adopted ASU No. 2020-08 as of January 1, 2021 under a prospective approach. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. Additionally, the FASB issued ASU No. 2020-10, “Codification Improvements,” in October 2020 to improve the consistency of the Codification by adding or moving disclosure-specific guidance contained in the Other Presentation Matters section to the appropriate Disclosure Section for various Topics. The Company adopted ASU No. 2020-10 as of January 1, 2021 under a retrospective approach. Adoption of this standard did not have a material impact on the Company’s consolidated financial statements. SEC Amendments to Financial Disclosures about Acquired and Disposed Businesses In May 2020, the SEC issued a final rule on “Amendments to Financial Disclosures about Acquired and Disposed Businesses,” which provides for specific disclosure changes, including revising the investment and income significance tests, conforming the significance threshold and tests for a disposed business to those used for an acquired business, permitting abbreviated financial statements for certain acquisitions of a component of an entity, and reducing the maximum number of years for which financial statements are required for acquired businesses from three years to two years, among other amendments. This guidance was effective on January 1, 2021. Debt In August 2020, the FASB issued ASU No. 2020-06, “Debt-Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity,” which includes provisions for reducing the number of accounting models used in accounting for convertible debt instruments and convertible preferred stock, amending derivatives and earnings-per-share (EPS) guidance and expanding disclosures for convertible debt instruments and EPS. This guidance is effective for fiscal years beginning after December 15, 2021, including interim periods therein, and is to be applied under either a full or modified retrospective approach. Early adoption is permitted. The Company does not expect this guidance to have a material impact on the Company’s consolidated financial statements. SEC Update of Statistical Disclosures for Bank and Savings and Loan Registrants In September 2020, the SEC issued a final rule on the “Update of Statistical Disclosures for Bank and Savings and Loan Registrants,” which adopts rules to update statistical disclosure requirements for banking registrants. The amendments update and expand the disclosures that registrants are required to provide, codify certain Industry Guide 3 disclosure items and eliminate other Guide 3 disclosures that overlap with SEC rules, GAAP or IFRS standards. In addition, Guide 3 is being rescinded and replaced with a new subpart of Regulation S-K. The SEC ruling is applicable to fiscal years beginning after December 15, 2021 and early compliance is permitted. The Company does not expect this guidance to have a material impact on the Company’s consolidated financial statements.

Investment Securities (Tables)

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	The following tables are a summary of the investment securities portfolios as of the dates shown: March 31, 2021 (Dollars in thousands) Amortized Gross Gross Fair Available-for-sale securities U.S. Treasury $ 64,999 $ 2 $ — $ 65,001 U.S. Government agencies 77,908 3,618 — 81,526 Municipal 143,711 4,761 (172) 148,300 Corporate notes: Financial issuers 91,806 461 (935) 91,332 Other 1,000 17 — 1,017 Mortgage-backed: (1) Mortgage-backed securities 2,007,092 52,855 (26,038) 2,033,909 Collateralized mortgage obligations 9,411 253 — 9,664 Total available-for-sale securities $ 2,395,927 $ 61,967 $ (27,145) $ 2,430,749 Held-to-maturity securities U.S. Government agencies $ 176,160 $ 1,644 $ (7,230) $ 170,574 Municipal 197,865 10,713 (535) 208,043 Mortgage-backed securities 1,737,115 265 (49,114) 1,688,266 Corporate notes 55,378 — (1,196) 54,182 Total held-to-maturity securities $ 2,166,518 $ 12,622 $ (58,075) $ 2,121,065 Less: Allowance for credit losses (99) Held-to-maturity securities, net of allowance for credit losses $ 2,166,419 Equity securities with readily determinable fair value $ 86,121 $ 5,362 $ (1,145) $ 90,338 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. December 31, 2020 Amortized Gross Gross Fair (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 304,956 $ 15 $ — $ 304,971 U.S. Government agencies 80,074 4,439 — 84,513 Municipal 141,244 5,707 (41) 146,910 Corporate notes: Financial issuers 91,786 1,363 (2,764) 90,385 Other 1,000 20 — 1,020 Mortgage-backed: (1) Mortgage-backed securities 2,330,332 86,721 (15) 2,417,038 Collateralized mortgage obligations 10,689 313 — 11,002 Total available-for-sale securities $ 2,960,081 $ 98,578 $ (2,820) $ 3,055,839 Held-to-maturity securities U.S. Government agencies $ 177,959 $ 2,552 $ — $ 180,511 Municipal 200,707 12,232 (214) 212,725 Mortgage-backed securities 200,531 — — 200,531 Total held-to-maturity securities $ 579,197 $ 14,784 $ (214) $ 593,767 Less: Allowance for credit losses (59) Held-to-maturity securities, net of allowance for credit losses $ 579,138 Equity securities with readily determinable fair value $ 87,618 $ 3,674 $ (430) $ 90,862 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime. March 31, 2020 Amortized Gross Gross Fair (Dollars in thousands) Available-for-sale securities U.S. Treasury $ 120,404 $ 1,266 $ — $ 121,670 U.S. Government agencies 362,969 5,674 — 368,643 Municipal 143,273 3,571 (235) 146,609 Corporate notes: Financial issuers 111,718 90 (11,821) 99,987 Other 1,000 31 — 1,031 Mortgage-backed: (1) Mortgage-backed securities 2,697,264 111,275 (4) 2,808,535 Collateralized mortgage obligations 24,077 416 (9) 24,484 Total available-for-sale securities $ 3,460,705 $ 122,323 $ (12,069) $ 3,570,959 Held-to-maturity securities U.S. Government agencies $ 646,976 $ 5,996 $ (4) $ 652,968 Municipal $ 218,470 7,909 (155) 226,224 Total held-to-maturity securities $ 865,446 $ 13,905 $ (159) $ 879,192 Less: Allowance for credit losses (70) Held-to-maturity securities, net of allowance for credit losses $ 865,376 Equity securities with readily determinable fair value $ 48,060 $ 781 $ (1,531) $ 47,310 (1) Consisting entirely of residential mortgage-backed securities, none of which are subprime.
Investment Securities, Continuous Unrealized Loss Position, Fair Value	The following table presents the portion of the Company’s available-for-sale investment securities portfolios that have gross unrealized losses, reflecting the length of time that individual securities have been in a continuous unrealized loss position at March 31, 2021: Continuous unrealized Continuous unrealized Total (Dollars in thousands) Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Available-for-sale securities U.S. Treasury $ — $ — $ — $ — $ — $ — U.S. Government agencies — — — — — — Municipal 24,326 (168) 110 (4) 24,436 (172) Corporate notes: Financial issuers 14,850 (150) 48,196 (785) 63,046 (935) Other — — — — — — Mortgage-backed: Mortgage-backed securities 571,821 (26,037) 61 (1) 571,882 (26,038) Collateralized mortgage obligations — — — — — — Total available-for-sale securities $ 610,997 $ (26,355) $ 48,367 $ (790) $ 659,364 $ (27,145)
Schedule of Gross Gains and Losses on Investment Securities	The following table provides information as to the amount of gross gains and losses, adjustments and impairment on investment securities recognized in earnings and proceeds received through the sale or call of investment securities: Three months ended March 31, (Dollars in thousands) 2021 2020 Realized gains on investment securities $ 216 $ 496 Realized losses on investment securities (6) (5) Net realized gains on investment securities 210 491 Unrealized gains on equity securities with readily determinable fair value 1,875 — Unrealized losses on equity securities with readily determinable fair value (901) (3,546) Net unrealized gains (losses) on equity securities with readily determinable fair value 974 (3,546) Upward adjustments of equity securities without readily determinable fair values — 393 Downward adjustments of equity securities without readily determinable fair values — — Impairment of equity securities without readily determinable fair values (30) (1,697) Adjustment and impairment, net, of equity securities without readily determinable fair values (30) (1,304) Gains (losses) on investment securities, net $ 1,154 $ (4,359) Proceeds from sales of available-for-sale securities (1) $ — $ — Proceeds from sales of equity securities with readily determinable fair value 1,509 30 Proceeds from sales and capital distributions of equity securities without readily determinable fair value 386 288 (1) Includes proceeds from available-for-sale securities sold in accordance with written covered call options sold to a third party.
Investments Classified by Contractual Maturity Date	The amortized cost and fair value of available-for-sale and held-to-maturity investment securities as of March 31, 2021, December 31, 2020 and March 31, 2020, by contractual maturity, are shown in the following table. Contractual maturities may differ from actual maturities as borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Mortgage-backed securities are not included in the maturity categories in the following maturity summary as actual maturities may differ from contractual maturities because the underlying mortgages may be called or prepaid without penalties: March 31, 2021 December 31, 2020 March 31, 2020 (Dollars in thousands) Amortized Cost Fair Value Amortized Cost Fair Value Amortized Cost Fair Value Available-for-sale securities Due in one year or less $ 100,140 $ 100,361 $ 343,601 $ 343,846 $ 186,538 $ 187,789 Due in one to five years 76,104 78,291 67,901 70,334 70,812 71,825 Due in five to ten years 110,125 110,928 111,886 112,178 174,262 164,479 Due after ten years 93,055 97,596 95,672 101,441 307,752 313,847 Mortgage-backed 2,016,503 2,043,573 2,341,021 2,428,040 2,721,341 2,833,019 Total available-for-sale securities $ 2,395,927 $ 2,430,749 $ 2,960,081 $ 3,055,839 $ 3,460,705 $ 3,570,959 Held-to-maturity securities Due in one year or less $ 6,812 $ 6,863 $ 7,138 $ 7,186 $ 5,310 $ 5,333 Due in one to five years 50,318 50,734 22,217 23,068 23,801 24,158 Due in five to ten years 184,677 191,539 150,621 159,293 143,783 148,746 Due after ten years 187,596 183,663 198,690 203,689 692,552 700,955 Mortgage-backed 1,737,115 1,688,266 200,531 200,531 — — Total held-to-maturity securities $ 2,166,518 $ 2,121,065 $ 579,197 $ 593,767 $ 865,446 $ 879,192 Less: Allowance for credit losses (99) (59) (70) Held-to-maturity securities, net of allowance for credit losses $ 2,166,419 $ 579,138 $ 865,376

Loans (Tables)

Loans (Tables)	3 Months Ended
	Mar. 31, 2021
Loans and Leases Receivable Disclosure [Abstract]
Summary of Loan Portfolio	The following table shows the Company’s loan portfolio by category as of the dates shown: March 31, December 31, March 31, (Dollars in thousands) 2021 2020 2020 Balance: Commercial $ 12,708,207 $ 11,955,967 $ 9,025,886 Commercial real estate 8,544,779 8,494,132 8,185,531 Home equity 390,253 425,263 494,655 Residential real estate 1,421,973 1,259,598 1,377,389 Premium finance receivables Commercial insurance 3,958,543 4,054,489 3,465,055 Life insurance 6,111,495 5,857,436 5,221,639 Consumer and other 35,983 32,188 37,166 Total loans, net of unearned income $ 33,171,233 $ 32,079,073 $ 27,807,321 Mix: Commercial 38 % 37 % 32 % Commercial real estate 26 26 29 Home equity 1 1 2 Residential real estate 4 5 5 Premium finance receivables Commercial insurance 12 13 13 Life insurance 19 18 19 Consumer and other 0 0 0 Total loans, net of unearned income 100 % 100 % 100 %

Allowance for Credit Losses (Ta

Allowance for Credit Losses (Tables)	3 Months Ended
	Mar. 31, 2021
Credit Loss [Abstract]
Aging of the Loan Portfolio	As of March 31, 2021 90+ days and still accruing 60-89 days past due 30-59 days past due (In thousands) Nonaccrual Current Total Loans Loan Balances (includes PCD): Commercial Commercial, industrial and other, excluding PPP loans $ 22,459 $ — $ 13,292 $ 35,535 $ 9,343,939 $ 9,415,225 Commercial PPP loans — — — 6 3,292,976 3,292,982 Commercial real estate Construction and development 2,673 — 499 23,967 1,326,185 1,353,324 Non-construction 31,707 — 7,657 46,201 7,105,890 7,191,455 Home equity 5,536 — 492 780 383,445 390,253 Residential real estate 21,553 — 944 13,768 1,385,708 1,421,973 Premium finance receivables Commercial insurance loans 9,690 4,592 5,113 16,552 3,922,596 3,958,543 Life insurance loans — 191 — 14,821 6,096,483 6,111,495 Consumer and other 497 161 8 74 35,243 35,983 Total loans, net of unearned income $ 94,115 $ 4,944 $ 28,005 $ 151,704 $ 32,892,465 $ 33,171,233 As of December 31, 2020 90+ days and still accruing 60-89 days past due 30-59 days past due (In thousands) Nonaccrual Current Total Loans Loan Balances (includes PCD): Commercial Commercial, industrial and other, excluding PPP loans $ 21,743 $ 307 $ 6,900 $ 44,345 $ 9,166,751 $ 9,240,046 Commercial PPP loans — — — 36 2,715,885 2,715,921 Commercial real estate Construction and development 5,633 — — 5,344 1,360,825 1,371,802 Non-construction 40,474 — 5,178 26,772 7,049,906 7,122,330 Home equity 6,529 — 47 637 418,050 425,263 Residential real estate 26,071 — 1,635 12,584 1,219,308 1,259,598 Premium finance receivables Commercial insurance loans 13,264 12,792 6,798 18,809 4,002,826 4,054,489 Life insurance loans — — 21,003 30,465 5,805,968 5,857,436 Consumer and other 436 264 24 136 31,328 32,188 Total loans, net of unearned income $ 114,150 $ 13,363 $ 41,585 $ 139,128 $ 31,770,847 $ 32,079,073 As of March 31, 2020 90+ days and still accruing 60-89 days past due 30-59 days past due (In thousands) Nonaccrual Current Total Loans Loan Balances (includes PCD): Commercial Commercial, industrial and other, excluding PPP loans $ 49,916 $ 1,241 $ 8,873 $ 86,129 $ 8,879,727 $ 9,025,886 Commercial PPP loans — — — — — — Commercial real estate Construction and development 7,422 147 1,859 16,938 1,274,987 1,301,353 Non-construction 55,408 369 8,353 58,130 6,761,918 6,884,178 Home equity 7,243 — 214 2,096 485,102 494,655 Residential real estate 18,965 605 345 28,983 1,328,491 1,377,389 Premium finance receivables Commercial insurance loans 21,058 16,505 10,327 32,811 3,384,354 3,465,055 Life insurance loans — — 2,403 37,374 5,181,862 5,221,639 Consumer and other 403 78 625 207 35,853 37,166 Total loans, net of unearned income $ 160,415 $ 18,945 $ 32,999 $ 262,668 $ 27,332,294 $ 27,807,321
Loan Portfolio by Credit Quality Indicator	The table below shows the Company’s loan portfolio by credit quality indicator and year of origination at March 31, 2021: As of March 31, 2021 Year of Origination Revolving Total (In thousands) 2021 2020 2019 2018 2017 Prior Revolving to Term Loans Loan Balances: Commercial, industrial and other Pass $ 574,195 $ 1,951,426 $ 1,158,699 $ 840,181 $ 611,479 $ 742,116 $ 2,908,239 $ 4,925 $ 8,791,260 Special mention 965 27,786 83,315 38,930 33,116 24,760 86,729 36 295,637 Substandard accrual 22,738 19,675 65,902 71,312 25,052 61,313 39,766 111 305,869 Substandard nonaccrual/doubtful — 1,887 1,770 2,117 2,078 14,074 533 — 22,459 Total commercial, industrial and other $ 597,898 $ 2,000,774 $ 1,309,686 $ 952,540 $ 671,725 $ 842,263 $ 3,035,267 $ 5,072 $ 9,415,225 Commercial PPP Pass $ 1,242,766 $ 2,049,342 $ — $ — $ — $ — $ — $ — $ 3,292,108 Special mention 874 — — — — — — — 874 Substandard accrual — — — — — — — — — Substandard nonaccrual/doubtful — — — — — — — — — Total commercial PPP $ 1,243,640 $ 2,049,342 $ — $ — $ — $ — $ — $ — $ 3,292,982 Construction and development Pass $ 40,266 $ 346,452 $ 433,184 $ 196,502 $ 89,377 $ 109,596 $ 29,747 $ — $ 1,245,124 Special mention 282 11,935 16,864 21,075 24,465 4,068 — — 78,689 Substandard accrual — — 1,207 21,872 2,929 678 152 — 26,838 Substandard nonaccrual/doubtful — — — 1,571 — 1,102 — — 2,673 Total construction and development $ 40,548 $ 358,387 $ 451,255 $ 241,020 $ 116,771 $ 115,444 $ 29,899 $ — $ 1,353,324 Non-construction Pass $ 249,241 $ 1,295,535 $ 1,030,111 $ 816,725 $ 772,702 $ 2,189,960 $ 184,304 $ 244 $ 6,538,822 Special mention 3,875 9,905 65,413 66,860 69,759 220,549 — — 436,361 Substandard accrual — 2,023 42,238 9,358 21,352 109,584 10 — 184,565 Substandard nonaccrual/doubtful — — 266 1,221 2,131 28,089 — — 31,707 Total non-construction $ 253,116 $ 1,307,463 $ 1,138,028 $ 894,164 $ 865,944 $ 2,548,182 $ 184,314 $ 244 $ 7,191,455 Home equity Pass $ — $ 44 $ — $ 47 $ 28 $ 7,082 $ 356,197 $ — $ 363,398 Special mention — — — — — 2,103 4,905 245 7,253 Substandard accrual — — — 317 — 11,953 1,053 743 14,066 Substandard nonaccrual/doubtful — — — — 157 3,799 1,580 — 5,536 Total home equity $ — $ 44 $ — $ 364 $ 185 $ 24,937 $ 363,735 $ 988 $ 390,253 Residential real estate Pass $ 301,904 $ 346,823 $ 265,543 $ 100,023 $ 115,609 $ 240,205 $ — $ — $ 1,370,107 Special mention 80 302 237 2,017 2,163 8,467 — — 13,266 Substandard accrual 291 2,304 1,025 897 2,300 10,230 — — 17,047 Substandard nonaccrual/doubtful — 186 1,121 745 5,034 14,467 — — 21,553 Total residential real estate $ 302,275 $ 349,615 $ 267,926 $ 103,682 $ 125,106 $ 273,369 $ — $ — $ 1,421,973 Premium finance receivables - commercial Pass $ 2,001,412 $ 1,896,547 $ 27,366 $ 2,961 $ 54 $ — $ — $ — $ 3,928,340 Special mention 8,051 11,093 8 — — — — — 19,152 Substandard accrual 1 1,267 13 80 — — — — 1,361 Substandard nonaccrual/doubtful 512 7,898 1,252 28 — — — — 9,690 Total premium finance receivables - commercial $ 2,009,976 $ 1,916,805 $ 28,639 $ 3,069 $ 54 $ — $ — $ — $ 3,958,543 Premium finance receivables - life Pass $ 112,896 $ 636,815 $ 658,163 $ 620,034 $ 678,197 $ 3,404,823 $ — $ — $ 6,110,928 Special mention — — — — 567 — — — 567 Substandard accrual — — — — — — — — — Substandard nonaccrual/doubtful — — — — — — — — — Total premium finance receivables - life $ 112,896 $ 636,815 $ 658,163 $ 620,034 $ 678,764 $ 3,404,823 $ — $ — $ 6,111,495 Consumer and other Pass $ 1,204 $ 1,955 $ 1,749 $ 1,389 $ 179 $ 14,366 $ 14,206 $ — $ 35,048 Special mention 3 10 19 — 86 91 6 — 215 Substandard accrual — 4 1 — — 215 3 — 223 Substandard nonaccrual/doubtful — 1 — 104 — 392 — — 497 Total consumer and other $ 1,207 $ 1,970 $ 1,769 $ 1,493 $ 265 $ 15,064 $ 14,215 $ — $ 35,983 Total loans (1) Pass $ 4,523,884 $ 8,524,939 $ 3,574,815 $ 2,577,862 $ 2,267,625 $ 6,708,148 $ 3,492,693 $ 5,169 $ 31,675,135 Special mention 14,130 61,031 165,856 128,882 130,156 260,038 91,640 281 852,014 Substandard accrual 23,030 25,273 110,386 103,836 51,633 193,973 40,984 854 549,969 Substandard nonaccrual/doubtful 512 9,972 4,409 5,786 9,400 61,923 2,113 — 94,115 Total loans $ 4,561,556 $ 8,621,215 $ 3,855,466 $ 2,816,366 $ 2,458,814 $ 7,224,082 $ 3,627,430 $ 6,304 $ 33,171,233 (1) Includes $164.7 million of loans with COVID-19 related modifications that migrated from pass as of March 1, 2020 to special mention or substandard accrual as of March 31, 2021. These loans were further qualitatively evaluated as a part of the measurement of the allowance for credit losses as of March 31, 2021.
Held-to-Maturity Debt Securities by Credit Quality Indicator	As of March 31, 2021 Year of Origination Total (In thousands) 2021 2020 2019 2018 2017 Prior Balance Amortized Cost Balances: U.S. government agencies 1-4 internal grade $ 97,786 $ 25,000 $ — $ 50,000 $ — $ 3,374 $ 176,160 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total U.S. government agencies $ 97,786 $ 25,000 $ — $ 50,000 $ — $ 3,374 $ 176,160 Municipal 1-4 internal grade $ 1,377 $ — $ 161 $ 7,549 $ 43,603 $ 145,175 $ 197,865 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total municipal $ 1,377 $ — $ 161 $ 7,549 $ 43,603 $ 145,175 $ 197,865 Mortgage-backed securities 1-4 internal grade $ 1,737,115 $ — $ — $ — $ — $ — $ 1,737,115 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total mortgage-backed securities $ 1,737,115 $ — $ — $ — $ — $ — $ 1,737,115 Corporate notes 1-4 internal grade $ — $ 13,661 $ 7,462 $ 3,325 $ 3,282 $ 27,648 $ 55,378 5-7 internal grade — — — — — — — 8-10 internal grade — — — — — — — Total corporate notes $ — $ 13,661 $ 7,462 $ 3,325 $ 3,282 $ 27,648 $ 55,378 Total held-to-maturity securities $ 2,166,518 Less: Allowance for credit losses (99) Held-to-maturity securities, net of allowance for credit losses $ 2,166,419
Components of Allowance for Credit Losses	March 31, December 31, March 31, (In thousands) 2021 2020 2020 Allowance for loan losses $ 277,709 $ 319,374 $ 216,050 Allowance for unfunded lending-related commitments losses 43,500 60,536 37,362 Allowance for loan losses and unfunded lending-related commitments losses 321,209 379,910 253,412 Allowance for held-to-maturity securities losses 99 59 70 Allowance for credit losses $ 321,308 $ 379,969 $ 253,482
Summary of Activity in the Allowance for Credit Losses	A summary of activity in the allowance for credit losses, specifically for the loan portfolio (i.e. allowance for loan losses and allowance for unfunded commitment losses), for the three months ended March 31, 2021 and 2020 is as follows. Three months ended March 31, 2021 Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total Loans (In thousands) Commercial Allowance for credit losses at beginning of period $ 94,212 $ 243,603 $ 11,437 $ 12,459 $ 17,777 $ 422 $ 379,910 Other adjustments — — — — 30 — 30 Charge-offs (11,781) (980) — (2) (3,239) (114) (16,116) Recoveries 452 200 101 204 1,782 32 2,771 Provision for credit losses 12,757 (61,031) (156) 1,581 1,127 336 (45,386) Allowance for credit losses at period end $ 95,640 $ 181,792 $ 11,382 $ 14,242 $ 17,477 $ 676 $ 321,209 Individually measured $ 5,046 $ 2,042 $ 338 $ 822 $ — $ 81 $ 8,329 Collectively measured 90,594 179,750 11,044 13,420 17,477 595 312,880 Loans at period end Individually measured $ 30,144 $ 43,858 $ 21,167 $ 28,675 $ — $ 560 $ 124,404 Collectively measured 12,678,063 8,500,921 369,086 1,341,382 10,070,038 35,423 32,994,913 Loans held at fair value — — — 51,916 — — 51,916 Three months ended March 31, 2020 Commercial Commercial Real Estate Home Equity Residential Real Estate Premium Finance Receivables Consumer and Other Total Loans (In thousands) Allowance for credit losses at beginning of period $ 64,920 $ 68,511 $ 3,878 $ 9,800 $ 9,647 $ 1,705 $ 158,461 Cumulative effect adjustment from the adoption of ASU 2016-13 9,039 32,064 9,061 3,002 (4,959) (863) 47,344 Other adjustments — — — — (73) — (73) Charge-offs (2,153) (570) (1,001) (401) (3,184) (128) (7,437) Recoveries 384 263 294 60 1,110 41 2,152 Provision for credit losses 35,156 12,528 162 89 5,339 (309) 52,965 Allowance for credit losses at period end $ 107,346 $ 112,796 $ 12,394 $ 12,550 $ 7,880 $ 446 $ 253,412 Individually measured $ 12,524 $ 9,108 $ 290 $ 466 $ — $ 104 $ 22,492 Collectively measured 94,822 103,688 12,104 12,084 7,880 342 230,920 Loans at period end Individually measured $ 56,416 $ 80,873 $ 23,060 $ 27,854 $ — $ 537 $ 188,740 Collectively measured 8,969,470 8,104,658 471,595 1,207,268 8,686,694 36,629 27,476,314 Loans held at fair value — — — 142,267 — — 142,267
Summary of the Post-Modification Balance of TDRs and Loans Restructured in TDRs	The tables below present a summary of the post-modification balance of loans restructured during the three months ended March 31, 2021 and 2020, respectively, which represent TDRs: Three months ended March 31, 2021 Total (1)(2) Extension at Below Market (2) Reduction of Interest Rate (2) Modification to Interest-only Payments (2) Forgiveness of Debt (2) Count Balance Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 2 $ 151 2 $ 151 — $ — — $ — — $ — Commercial real estate Non-construction 2 237 2 237 1 113 1 113 — — Residential real estate and other 16 1,738 16 1,738 9 1,290 — — — — Total loans 20 $ 2,126 20 $ 2,126 10 $ 1,403 1 $ 113 — $ — Three months ended March 31, 2020 Total (1)(2) Extension at Below Market Terms (2) Reduction of Interest Rate (2) Modification to Interest-only Payments (2) Forgiveness of Debt (2) Count Balance Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 5 $ 5,602 3 $ 4,316 — $ — — $ — 1 $ 432 Commercial real estate Non-construction 13 16,053 11 13,511 3 921 5 3,463 — — Residential real estate and other 20 2,142 12 1,890 5 786 — — — — Total loans 38 $ 23,797 26 $ 19,717 8 $ 1,707 5 $ 3,463 1 $ 432 (1) TDRs may have more than one modification representing a concession. As such, TDRs during the period may be represented in more than one of the categories noted above. (2) Balances represent the recorded investment in the loan at the time of the restructuring. The following table presents a summary of all loans restructured in TDRs during the twelve months ended March 31, 2021 and 2020, and such loans that were in payment default under the restructured terms during the respective periods below: (Dollars in thousands) As of March 31, 2021 Three Months Ended As of March 31, 2020 Three Months Ended Total (1)(3) Payments in Default (2)(3) Payments in Default (2)(3) Payments in Default (2)(3) Count Balance Count Balance Count Balance Count Balance Commercial Commercial, industrial and other 18 $ 6,910 5 $ 1,496 20 $ 13,013 8 $ 4,836 Commercial real estate Non-construction 7 3,466 3 3,121 19 22,770 3 758 Residential real estate and other 81 13,825 5 596 145 17,863 11 2,510 Total loans 106 $ 24,201 13 $ 5,213 184 $ 53,646 22 $ 8,104 (1) Total TDRs represent all loans restructured in TDRs during the previous twelve months from the date indicated. (2) TDRs considered to be in payment default are over 30 days past-due subsequent to the restructuring. (3) Balances represent the recorded investment in the loan at the time of the restructuring.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill Assets by Business Segment	A summary of the Company’s goodwill assets by reporting unit is presented in the following table: (In thousands) December 31, Goodwill Impairment Goodwill Adjustments March 31, Community banking $ 536,396 $ — $ — $ — $ 536,396 Specialty finance 39,938 — — 310 40,248 Wealth management 69,373 — — — 69,373 Total $ 645,707 $ — $ — $ 310 $ 646,017
Summary of Intangible Assets	A summary of intangible assets as of the dates shown and the expected amortization of finite-lived intangible assets as of March 31, 2021 is as follows: (In thousands) March 31, December 31, March 31, Community banking segment: Core deposit intangibles with finite lives: Gross carrying amount $ 55,206 $ 55,206 $ 55,206 Accumulated amortization (34,099) (32,680) (28,024) Net carrying amount $ 21,107 $ 22,526 $ 27,182 Trademark with indefinite lives: Carrying amount 5,800 5,800 5,800 Total net carrying amount $ 26,907 $ 28,326 $ 32,982 Specialty finance segment: Customer list intangibles with finite lives: Gross carrying amount $ 1,968 $ 1,966 $ 1,956 Accumulated amortization (1,665) (1,644) (1,574) Net carrying amount $ 303 $ 322 $ 382 Wealth management segment: Customer list and other intangibles with finite lives: Gross carrying amount $ 20,430 $ 20,430 $ 20,430 Accumulated amortization (13,605) (13,038) (9,609) Net carrying amount $ 6,825 $ 7,392 $ 10,821 Total intangible assets: Gross carrying amount $ 83,404 $ 83,402 $ 83,392 Accumulated amortization (49,369) (47,362) (39,207) Total intangible assets, net $ 34,035 $ 36,040 $ 44,185
Summary of Intangible Assets	A summary of intangible assets as of the dates shown and the expected amortization of finite-lived intangible assets as of March 31, 2021 is as follows: (In thousands) March 31, December 31, March 31, Community banking segment: Core deposit intangibles with finite lives: Gross carrying amount $ 55,206 $ 55,206 $ 55,206 Accumulated amortization (34,099) (32,680) (28,024) Net carrying amount $ 21,107 $ 22,526 $ 27,182 Trademark with indefinite lives: Carrying amount 5,800 5,800 5,800 Total net carrying amount $ 26,907 $ 28,326 $ 32,982 Specialty finance segment: Customer list intangibles with finite lives: Gross carrying amount $ 1,968 $ 1,966 $ 1,956 Accumulated amortization (1,665) (1,644) (1,574) Net carrying amount $ 303 $ 322 $ 382 Wealth management segment: Customer list and other intangibles with finite lives: Gross carrying amount $ 20,430 $ 20,430 $ 20,430 Accumulated amortization (13,605) (13,038) (9,609) Net carrying amount $ 6,825 $ 7,392 $ 10,821 Total intangible assets: Gross carrying amount $ 83,404 $ 83,402 $ 83,392 Accumulated amortization (49,369) (47,362) (39,207) Total intangible assets, net $ 34,035 $ 36,040 $ 44,185
Estimated Amortization	Estimated amortization Actual in three months ended March 31, 2021 $ 2,007 Estimated remaining in 2021 5,685 Estimated—2022 6,135 Estimated—2023 4,670 Estimated—2024 3,263 Estimated—2025 2,552

Mortgage Servicing Rights ("M_2

Mortgage Servicing Rights ("MSRs") (Tables)	3 Months Ended
	Mar. 31, 2021
Disclosures Pertaining to Servicing Assets and Servicing Liabilities [Abstract]
Schedule of Servicing Assets at Fair Value	The following is a summary of the changes in the carrying value of MSRs, accounted for at fair value, for the periods indicated: Three Months Ended March 31, March 31, (In thousands) 2021 2020 Balance at beginning of the period $ 92,081 $ 85,638 Additions from loans sold with servicing retained 24,616 9,447 Estimate of changes in fair value due to: Early buyout options (“EBO”) exercised (258) — Payoffs and paydowns (10,168) (7,024) Changes in valuation inputs or assumptions 18,045 (14,557) Fair value at end of the period $ 124,316 $ 73,504 Unpaid principal balance of mortgage loans serviced for others $ 11,530,676 $ 8,314,634

Deposits (Tables)

Deposits (Tables)	3 Months Ended
	Mar. 31, 2021
Deposits [Abstract]
Summary of Deposits	The following table is a summary of deposits as of the dates shown: (Dollars in thousands) March 31, December 31, March 31, Balance: Non-interest-bearing $ 12,297,337 $ 11,748,455 $ 7,556,755 NOW and interest-bearing demand deposits 3,562,312 3,349,021 3,181,159 Wealth management deposits 4,274,527 4,138,712 3,936,968 Money market 9,236,434 9,348,806 8,114,659 Savings 3,690,892 3,531,029 3,282,340 Time certificates of deposit 4,811,150 4,976,628 5,389,779 Total deposits $ 37,872,652 $ 37,092,651 $ 31,461,660 Mix: Non-interest-bearing 32 % 32 % 24 % NOW and interest-bearing demand deposits 9 9 10 Wealth management deposits 11 11 13 Money market 25 25 26 Savings 10 10 10 Time certificates of deposit 13 13 17 Total deposits 100 % 100 % 100 %

FHLB Advances, Other Borrowin_2

FHLB Advances, Other Borrowings and Subordinated Notes (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Summary of Debt	The following table is a summary of FHLB advances, other borrowings and subordinated notes as of the dates shown: (In thousands) March 31, December 31, March 31, FHLB advances $ 1,228,436 $ 1,228,429 $ 1,174,894 Other borrowings: Notes payable 96,363 101,710 167,746 Short-term borrowings 12,416 11,366 12,127 Other 64,659 65,108 66,266 Secured borrowings 343,439 340,744 241,364 Total other borrowings 516,877 518,928 487,503 Subordinated notes 436,595 436,506 436,179 Total FHLB advances, other borrowings and subordinated notes $ 2,181,908 $ 2,183,863 $ 2,098,576
Summary of Pledged Securities Related to Securities Sold Under Repurchase Agreements	The following is a summary of these securities pledged as of March 31, 2021 disaggregated by investment category and maturity of the related customer sweep account, and reconciled to the outstanding balance of securities sold under repurchase agreements: (In thousands) Overnight Sweep Collateral Available-for-sale securities pledged Mortgage-backed securities $ 20,580 Total collateral pledged 20,580 Excess collateral 8,164 Securities sold under repurchase agreements $ 12,416

Junior Subordinated Debentures

Junior Subordinated Debentures (Tables)	3 Months Ended
	Mar. 31, 2021
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust [Abstract]
Summary of Junior Subordinated Debentures	The following table provides a summary of the Company’s junior subordinated debentures as of March 31, 2021. The junior subordinated debentures represent the par value of the obligations owed to the Trusts. (Dollars in thousands) Common Trust Junior Rate Contractual rate Issue Maturity Earliest Wintrust Capital Trust III $ 774 $ 25,000 $ 25,774 L+3.25 3.49 % 04/2003 04/2033 04/2008 Wintrust Statutory Trust IV 619 20,000 20,619 L+2.80 3.00 % 12/2003 12/2033 12/2008 Wintrust Statutory Trust V 1,238 40,000 41,238 L+2.60 2.80 % 05/2004 05/2034 06/2009 Wintrust Capital Trust VII 1,550 50,000 51,550 L+1.95 2.13 % 12/2004 03/2035 03/2010 Wintrust Capital Trust VIII 1,238 25,000 26,238 L+1.45 1.65 % 08/2005 09/2035 09/2010 Wintrust Capital Trust IX 1,547 50,000 51,547 L+1.63 1.81 % 09/2006 09/2036 09/2011 Northview Capital Trust I 186 6,000 6,186 L+3.00 3.21 % 08/2003 11/2033 08/2008 Town Bankshares Capital Trust I 186 6,000 6,186 L+3.00 3.21 % 08/2003 11/2033 08/2008 First Northwest Capital Trust I 155 5,000 5,155 L+3.00 3.20 % 05/2004 05/2034 05/2009 Suburban Illinois Capital Trust II 464 15,000 15,464 L+1.75 1.93 % 12/2006 12/2036 12/2011 Community Financial Shares Statutory Trust II 109 3,500 3,609 L+1.62 1.80 % 06/2007 09/2037 06/2012 Total $ 253,566 2.39 %

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue by Source	The following table presents revenue from contracts with customers, disaggregated by the revenue source: (Dollars in thousands) Three Months Ended Revenue from contracts with customers Location in income statement March 31, March 31, Brokerage and insurance product commissions Wealth management $ 5,040 $ 5,281 Trust Wealth management 5,017 5,291 Asset management Wealth management 19,252 15,369 Total wealth management 29,309 25,941 Mortgage broker fees Mortgage banking 76 53 Service charges on deposit accounts Service charges on deposit accounts 12,036 11,265 Administrative services Other non-interest income 1,256 1,112 Card related fees Other non-interest income 1,774 2,106 Other deposit related fees Other non-interest income 3,317 3,178 Total revenue from contracts with customers $ 47,768 $ 43,655
Contract Assets, Contract Liabilities and Receivables from Contracts with Customers	The following table provides information about contract assets, contract liabilities and receivables from contracts with customers: (Dollars in thousands) March 31, December 31, March 31, Contract assets $ — $ — $ — Contract liabilities $ 1,818 $ 1,548 $ 728 Mortgage broker fees receivable $ 31 $ 20 $ 11 Administrative services receivable 215 64 214 Wealth management receivable 11,315 10,144 8,218 Card related fees receivable 1,075 783 422 Total receivables from contracts with customer $ 12,636 $ 11,011 $ 8,865
Performance Obligations Unsatisfied at End of Period	These upfront fees represent performance obligations that are unsatisfied or partially unsatisfied at the end of the reporting period. (Dollars in thousands) Estimated remaining in 2021 $ 668 Estimated—2022 400 Estimated—2023 400 Estimated—2024 250 Estimated—2025 100 Total $ 1,818

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Summary of Segment Information	The following is a summary of certain operating information for reportable segments: Three months ended $ Change in % Change in (Dollars in thousands) March 31, March 31, Net interest income: Community Banking $ 203,489 $ 206,835 $ (3,346) (2) % Specialty Finance 44,899 40,712 4,187 10 Wealth Management 7,449 7,792 (343) (4) Total Operating Segments 255,837 255,339 498 — Intersegment Eliminations 6,058 6,104 (46) (1) Consolidated net interest income $ 261,895 $ 261,443 $ 452 — % Provision for credit losses: Community Banking $ (46,572) $ 51,677 $ (98,249) (190) % Specialty Finance 1,225 1,284 (59) (5) Wealth Management — — — — Total Operating Segments (45,347) 52,961 (98,308) (186) Intersegment Eliminations — — — — Consolidated provision for credit losses $ (45,347) $ 52,961 $ (98,308) (186) % Non-interest income: Community Banking $ 147,268 $ 81,003 $ 66,265 82 % Specialty Finance 23,109 21,308 1,801 8 Wealth Management 30,251 24,130 6,121 25 Total Operating Segments 200,628 126,441 74,187 59 Intersegment Eliminations (14,122) (13,199) (923) 7 Consolidated non-interest income $ 186,506 $ 113,242 $ 73,264 65 % Net revenue: Community Banking $ 350,757 $ 287,838 $ 62,919 22 % Specialty Finance 68,008 62,020 5,988 10 Wealth Management 37,700 31,922 5,778 18 Total Operating Segments 456,465 381,780 74,685 20 Intersegment Eliminations (8,064) (7,095) (969) 14 Consolidated net revenue $ 448,401 $ 374,685 $ 73,716 20 % Segment profit: Community Banking $ 121,801 $ 34,589 $ 87,212 252 % Specialty Finance 23,903 22,133 1,770 8 Wealth Management 7,444 6,090 1,354 22 Consolidated net income $ 153,148 $ 62,812 $ 90,336 144 % Segment assets: Community Banking $ 37,102,603 $ 31,499,899 $ 5,602,704 18 % Specialty Finance 7,174,269 6,133,548 1,040,721 17 Wealth Management 1,405,330 1,166,400 238,930 20 Consolidated total assets $ 45,682,202 $ 38,799,847 $ 6,882,355 18 %

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Fair Value Of Derivative Financial Instruments	The table below presents the fair value of the Company’s derivative financial instruments as of March 31, 2021, December 31, 2020 and March 31, 2020: Derivative Assets Derivative Liabilities (In thousands) March 31, December 31, March 31, March 31, December 31, March 31, Derivatives designated as hedging instruments under ASC 815: Interest rate derivatives designated as Cash Flow Hedges $ 50,420 $ 8,182 $ — $ 31,161 $ 39,715 $ 57,274 Interest rate derivatives designated as Fair Value Hedges 121 — — 9,569 14,520 16,123 Total derivatives designated as hedging instruments under ASC 815 $ 50,541 $ 8,182 $ — $ 40,730 $ 54,235 $ 73,397 Derivatives not designated as hedging instruments under ASC 815: Interest rate derivatives $ 155,695 $ 221,205 $ 259,986 $ 155,361 $ 221,608 $ 256,193 Interest rate lock commitments 44,313 48,925 39,816 1,342 — 1,105 Forward commitments to sell mortgage loans 2,920 — 1,514 3,283 12,510 36,872 Foreign exchange contracts 40 111 52 42 112 53 Total derivatives not designated as hedging instruments under ASC 815 $ 202,968 $ 270,241 $ 301,368 $ 160,028 $ 234,230 $ 294,223 Total Derivatives $ 253,509 $ 278,423 $ 301,368 $ 200,758 $ 288,465 $ 367,620
Schedule Of Cash Flow Hedging Instruments	The table below provides details on these cash flow hedges, summarized by derivative type and maturity, as of March 31, 2021: March 31, 2021 (In thousands) Notional Fair Value Maturity Date Amount Asset (Liability) Interest Rate Swaps: October 2021 $ 25,000 $ (286) November 2021 20,000 (287) December 2021 165,000 (2,614) March 2022 500,000 (220) May 2022 370,000 (7,884) June 2022 160,000 (3,652) July 2022 230,000 (5,359) August 2022 235,000 (5,944) March 2023 250,000 (300) April 2024 250,000 598 July 2027 (1) 1,000,000 49,823 Interest Rate Collars: September 2023 96,429 (4,616) Total Cash Flow Hedges $ 3,301,429 $ 19,259 (1) Interest rate swaps effective starting in July 2022.
Rollforward Of Amounts In Accumulated Other Comprehensive Income Related To Interest Rate Swaps Designated As Cash Flow Hedges	A rollforward of the amounts in accumulated other comprehensive income or loss related to interest rate derivatives designated as cash flow hedges follows: Three Months Ended (In thousands) March 31, March 31, Unrealized loss at beginning of period $ (31,533) $ (17,943) Amount reclassified from accumulated other comprehensive income to interest expense on deposits, other borrowings and junior subordinated debentures 6,696 1,090 Amount of income (loss) recognized in other comprehensive income 44,096 (39,783) Unrealized gain (loss) at end of period $ 19,259 $ (56,636)
Schedule of Carrying Amount of Hedged Assets/(Liabilities)	The following table presents the carrying amount of the hedged assets/(liabilities) and the cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets/(liabilities) that are designated as a fair value hedge accounting relationship as of March 31, 2021: March 31, 2021 (In thousands) Derivatives in Fair Value Hedging Relationships Location in the Statement of Condition Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities) Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued Interest rate swaps Loans, net of unearned income $ 175,605 $ 9,262 $ (157) Available-for-sale debt securities 1,303 94 — The following table presents the loss or gain recognized related to derivative instruments that are designated as fair value hedges for the respective period: (In thousands) Derivatives in Fair Value Hedging Relationships Location of (Loss)/Gain Recognized Three Months Ended March 31, 2021 Interest rate swaps Interest and fees on loans $ (13) Interest income - investment securities —
Summary Amounts Included In Consolidated Statement Of Income Related To Derivatives	Amounts included in the Consolidated Statements of Income related to derivative instruments not designated in hedge relationships were as follows: (In thousands) Three Months Ended Derivative Location in income statement March 31, March 31, Interest rate swaps and caps Trading gains (losses), net $ 428 $ (428) Mortgage banking derivatives Mortgage banking revenue (17,479) 17,267 Foreign exchange contracts Trading gains (losses), net (5) (4) Covered call options Fees from covered call options — 2,292 Derivative contract held as economic hedge on MSRs Mortgage banking revenue — 4,160
Offsetting Assets	The tables below summarize the Company's interest rate derivatives and offsetting positions as of the dates shown. Derivative Assets Derivative Liabilities Fair Value Fair Value (In thousands) March 31, December 31, March 31, March 31, December 31, March 31, Gross Amounts Recognized $ 206,236 $ 229,387 $ 259,986 $ 196,091 $ 275,843 $ 329,590 Less: Amounts offset in the Statements of Financial Condition — — — — — — Net amount presented in the Statements of Financial Condition $ 206,236 $ 229,387 $ 259,986 $ 196,091 $ 275,843 $ 329,590 Gross amounts not offset in the Statements of Financial Condition Offsetting Derivative Positions (60,593) (8,647) (1,048) (60,593) (8,647) (1,048) Collateral Posted — — — (125,818) (266,832) (328,542) Net Credit Exposure $ 145,643 $ 220,740 $ 258,938 $ 9,680 $ 364 $ —
Offsetting Liabilities	The tables below summarize the Company's interest rate derivatives and offsetting positions as of the dates shown. Derivative Assets Derivative Liabilities Fair Value Fair Value (In thousands) March 31, December 31, March 31, March 31, December 31, March 31, Gross Amounts Recognized $ 206,236 $ 229,387 $ 259,986 $ 196,091 $ 275,843 $ 329,590 Less: Amounts offset in the Statements of Financial Condition — — — — — — Net amount presented in the Statements of Financial Condition $ 206,236 $ 229,387 $ 259,986 $ 196,091 $ 275,843 $ 329,590 Gross amounts not offset in the Statements of Financial Condition Offsetting Derivative Positions (60,593) (8,647) (1,048) (60,593) (8,647) (1,048) Collateral Posted — — — (125,818) (266,832) (328,542) Net Credit Exposure $ 145,643 $ 220,740 $ 258,938 $ 9,680 $ 364 $ —

Fair Values of Assets and Lia_2

Fair Values of Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Summary Of Balances Of Assets And Liabilities Measured At Fair Value On A Recurring Basis	The following tables present the balances of assets and liabilities measured at fair value on a recurring basis for the periods presented: March 31, 2021 (In thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 65,001 $ 65,001 $ — $ — U.S. Government agencies 81,526 — 79,742 1,784 Municipal 148,300 — 46,552 101,748 Corporate notes 92,349 — 92,349 — Mortgage-backed 2,043,573 — 2,043,573 — Trading account securities 951 — 951 — Equity securities with readily determinable fair value 90,338 82,272 8,066 — Mortgage loans held-for-sale 1,260,193 — 1,260,193 — Loans held-for-investment 51,916 — 45,508 6,408 MSRs 124,316 — — 124,316 Nonqualified deferred compensation assets 15,891 — 15,891 — Derivative assets 253,509 — 227,875 25,634 Total $ 4,227,863 $ 147,273 $ 3,820,700 $ 259,890 Derivative liabilities $ 200,758 $ — $ 200,758 $ — December 31, 2020 (In thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 304,971 $ 304,971 $ — $ — U.S. Government agencies 84,513 — 82,547 1,966 Municipal 146,910 — 37,034 109,876 Corporate notes 91,405 — 91,405 — Mortgage-backed 2,428,040 — 2,428,040 — Trading account securities 671 — 671 — Equity securities with readily determinable fair value 90,862 82,796 8,066 — Mortgage loans held-for-sale 1,272,090 — 1,272,090 — Loans held-for-investment 55,134 — 44,854 10,280 MSRs 92,081 — — 92,081 Nonqualified deferred compensation assets 15,398 — 15,398 — Derivative assets 278,423 — 230,332 48,091 Total $ 4,860,498 $ 387,767 $ 4,210,437 $ 262,294 Derivative liabilities $ 288,465 $ — $ 288,465 $ — March 31, 2020 (In thousands) Total Level 1 Level 2 Level 3 Available-for-sale securities U.S. Treasury $ 121,670 $ 121,670 $ — $ — U.S. Government agencies 368,643 — 366,186 2,457 Municipal 146,609 — 33,342 113,267 Corporate notes 101,018 — 101,018 — Mortgage-backed 2,833,019 — 2,833,019 — Trading account securities 2,257 — 2,257 — Equity securities with readily determinable fair value 47,310 39,244 8,066 — Mortgage loans held-for-sale 656,934 — 656,934 — Loans held-for-investment 142,267 — 132,699 9,568 MSRs 73,504 — — 73,504 Nonqualified deferred compensation assets 12,253 — 12,253 — Derivative assets 301,368 — 261,552 39,816 Total $ 4,806,852 $ 160,914 $ 4,407,326 $ 238,612 Derivative liabilities $ 367,620 $ — $ 367,620 $ —
Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis	The changes in Level 3 assets measured at fair value on a recurring basis during the three months ended March 31, 2021 and 2020 are summarized as follows: U.S. Government agencies Loans held-for- investment Mortgage Derivative assets (In thousands) Municipal Balance at January 1, 2021 $ 109,876 $ 1,966 $ 10,280 $ 92,081 $ 48,091 Total net gains (losses) included in: Net income (1) — — (530) 32,235 (22,457) Other comprehensive income (loss) (2,068) (24) — — — Purchases — — — — — Issuances — — — — — Sales — — — — — Settlements (6,060) (158) (3,918) — — Net transfers into/(out of) Level 3 — — 576 — — Balance at March 31, 2021 $ 101,748 $ 1,784 $ 6,408 $ 124,316 $ 25,634 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income. U.S. Government agencies Loans held-for- investment Mortgage Derivative assets (In thousands) Municipal Balance at January 1, 2020 $ 111,950 $ 2,646 $ 9,620 $ 85,638 $ 2,631 Total net gains (losses) included in: Net income (1) — — (78) (12,134) 37,185 Other comprehensive income (loss) (1,249) (32) — — — Purchases 5,875 — — — — Issuances — — — — — Sales — — — — — Settlements (3,309) (157) (96) — — Net transfers into/(out of) Level 3 — — 122 — — Balance at March 31, 2020 $ 113,267 $ 2,457 $ 9,568 $ 73,504 $ 39,816 (1) Changes in the balance of MSRs and derivative assets related to fair value adjustments are recorded as components of mortgage banking revenue. Changes in the balance of loans held-for-investment related to fair value adjustments are recorded as other non-interest income.
Summary Of Assets Measured At Fair Value On A Nonrecurring Basis	For assets measured at fair value on a nonrecurring basis that were still held in the balance sheet at the end of the period, the following table provides the carrying value of the related individual assets or portfolios at March 31, 2021: March 31, 2021 Three Months Ended March 31, 2021 (In thousands) Total Level 1 Level 2 Level 3 Individually assessed loans - foreclosure probable and collateral-dependent $ 87,757 $ — $ — $ 87,757 $ 12,548 Other real estate owned (1) 15,813 — — 15,813 170 Total $ 103,570 $ — $ — $ 103,570 $ 12,718 (1) Fair value losses recognized, net on other real estate owned include valuation adjustments and charge-offs during the respective period.
Schedule Of Valuation Techniques And Significant Unobservable Inputs Used To Measure Both Recurring And Non-Recurring	The valuation techniques and significant unobservable inputs used to measure both recurring and non-recurring Level 3 fair value measurements at March 31, 2021 were as follows: (Dollars in thousands) Fair Value Valuation Methodology Significant Unobservable Input Range Weighted Impact to valuation Measured at fair value on a recurring basis: Municipal Securities $ 101,748 Bond pricing Equivalent rating BBB-AA+ N/A Increase U.S. Government agencies 1,784 Bond pricing Equivalent rating AAA AAA Increase Loans held-for-investment 6,408 Discounted cash flows Discount rate 2%-3% 2.38% Decrease Credit discount 0%-3% 0.26% Decrease Constant prepayment rate (CPR) 12.99% 12.99% Decrease MSRs 124,316 Discounted cash flows Discount rate 3%-19% 9.88% Decrease Constant prepayment rate (CPR) 6%-92% 12.99% Decrease Cost of servicing $70-$200 $76 Decrease Cost of servicing - delinquent $200-$1,000 $354 Decrease Derivatives 25,634 Discounted cash flows Pull-through rate 14%-100% 86.39% Increase Measured at fair value on a non-recurring basis: Individually assessed loans - foreclosure probable and collateral-dependent $ 87,757 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease Other real estate owned 15,813 Appraisal value Appraisal adjustment - cost of sale 10% 10.00% Decrease
Summary Of Carrying Amounts And Estimated Fair Values Of Financial Instruments	The table below presents the carrying amounts and estimated fair values of the Company’s financial instruments as of the dates shown: At March 31, 2021 At December 31, 2020 At March 31, 2020 Carrying Fair Carrying Fair Carrying Fair (In thousands) Value Value Value Value Value Value Financial Assets: Cash and cash equivalents $ 426,377 $ 426,377 $ 322,474 $ 322,474 $ 349,427 $ 349,427 Interest-bearing deposits with banks 3,348,794 3,348,794 4,802,527 4,802,527 1,943,743 1,943,743 Available-for-sale securities 2,430,749 2,430,749 3,055,839 3,055,839 3,570,959 3,570,959 Held-to-maturity securities 2,166,419 2,121,065 579,138 593,767 865,376 879,192 Trading account securities 951 951 671 671 2,257 2,257 Equity securities with readily determinable fair value 90,338 90,338 90,862 90,862 47,310 47,310 FHLB and FRB stock, at cost 135,881 135,881 135,588 135,588 134,546 134,546 Brokerage customer receivables 19,056 19,056 17,436 17,436 16,293 16,293 Mortgage loans held-for-sale, at fair value 1,260,193 1,260,193 1,272,090 1,272,090 656,934 656,934 Loans held-for-investment, at fair value 51,916 51,916 55,134 55,134 142,267 142,267 Loans held-for-investment, at amortized cost 33,119,317 33,066,760 32,023,939 31,871,683 27,665,054 27,469,489 Nonqualified deferred compensation assets 15,891 15,891 15,398 15,398 12,253 12,253 Derivative assets 253,509 253,509 278,423 278,423 301,368 301,368 Accrued interest receivable and other 281,020 281,020 272,339 272,339 275,499 275,499 Total financial assets $ 43,600,411 $ 43,502,500 $ 42,921,858 $ 42,784,231 $ 35,983,286 $ 35,801,537 Financial Liabilities Non-maturity deposits $ 33,061,502 $ 33,061,502 $ 32,116,023 $ 32,116,023 $ 26,071,881 $ 26,071,881 Deposits with stated maturities 4,811,150 4,801,257 4,976,628 4,969,849 5,389,779 5,394,523 FHLB advances 1,228,436 1,121,269 1,228,429 1,172,315 1,174,894 1,130,327 Other borrowings 516,877 516,877 518,928 518,928 487,503 487,503 Subordinated notes 436,595 458,832 436,506 473,093 436,179 487,745 Junior subordinated debentures 253,566 208,132 253,566 204,713 253,566 224,523 Derivative liabilities 200,758 200,758 288,465 288,465 367,620 367,620 Accrued interest payable 19,940 19,940 15,645 15,645 27,696 27,696 Total financial liabilities $ 40,528,824 $ 40,388,567 $ 39,834,190 $ 39,759,031 $ 34,209,118 $ 34,191,818

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement, Noncash Expense [Abstract]
Summary Of Stock Option Activity	A summary of the Company's stock option activity for the three months ended March 31, 2021 and March 31, 2020 is presented below: Stock Options Common Weighted Remaining Contractual Term (1) Intrinsic Value (2) (in thousands) Outstanding at January 1, 2021 520,663 $ 42.47 Granted — — Exercised (208,579) 42.96 Forfeited or canceled (590) 46.86 Outstanding at March 31, 2021 311,494 $ 42.14 1.8 $ 10,485 Exercisable at March 31, 2021 309,945 $ 42.11 1.8 $ 10,441 Stock Options Common Weighted Remaining Contractual Term (1) Intrinsic Value (2) (in thousands) Outstanding at January 1, 2020 755,332 $ 42.43 Granted — — Exercised (94,653) 38.69 Forfeited or canceled — — Outstanding at March 31, 2020 660,679 $ 42.97 2.5 $ — Exercisable at March 31, 2020 650,456 $ 42.95 2.4 $ 1 (1) Represents the remaining weighted average contractual life in years. (2) Aggregate intrinsic value represents the total pre-tax intrinsic value (i.e., the difference between the Company's stock price on the last trading day of the quarter and the option exercise price, multiplied by the number of shares) that would have been received by the option holders if they had exercised their options on the last day of the quarter. Options with exercise prices above the stock price on the last trading day of the quarter are excluded from the calculation of intrinsic value. The intrinsic value will change based on the fair market value of the Company's stock.
Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity	A summary of the Plans' restricted share activity for the three months ended March 31, 2021 and March 31, 2020 is presented below: Three months ended March 31, 2021 Three months ended March 31, 2020 Restricted Shares Common Weighted Common Weighted Outstanding at January 1 234,794 $ 59.02 144,328 $ 60.37 Granted 257,189 62.79 99,963 64.10 Vested and issued (7,104) 78.13 (9,633) 75.69 Forfeited or canceled (849) 63.44 (3,538) 81.89 Outstanding at March 31 484,030 $ 60.73 231,120 $ 61.02 Vested, but not issuable at March 31 94,348 $ 52.21 92,244 $ 52.23 A summary of the Plans' performance-based stock award activity, based on the target level of the awards, for the three months ended March 31, 2021 and March 31, 2020 is presented below: Three months ended March 31, 2021 Three months ended March 31, 2020 Performance-based Stock Common Weighted Common Weighted Outstanding at January 1 482,608 $ 71.15 465,515 $ 74.37 Granted 206,465 58.85 166,547 64.10 Added by performance factor at vesting — — 48,831 72.59 Vested and issued — — (180,596) 72.59 Expired, canceled or forfeited (125,622) 87.88 (6,071) 73.66 Outstanding at March 31 563,451 $ 62.91 494,226 $ 71.39 Vested, but deferred at March 31 34,748 $ 43.28 34,166 $ 43.27

Shareholders' Equity and Earn_2

Shareholders' Equity and Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Components Of Other Comprehensive Income (Loss)	The following tables summarize the components of other comprehensive income (loss), including the related income tax effects, and the related amount reclassified to net income for the periods presented (in thousands). Accumulated Accumulated Accumulated Total Balance at January 1, 2021 $ 70,737 $ (23,090) $ (32,265) $ 15,382 Other comprehensive (loss) income during the period, net of tax, before reclassifications (44,519) 32,345 2,180 (9,994) Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax (154) 4,912 — 4,758 Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax (42) — — (42) Net other comprehensive (loss) income during the period, net of tax $ (44,715) $ 37,257 $ 2,180 $ (5,278) Balance at March 31, 2021 $ 26,022 $ 14,167 $ (30,085) $ 10,104 Balance at January 1, 2020 $ 14,982 $ (13,141) $ (36,519) $ (34,678) Other comprehensive income (loss) during the period, net of tax, before reclassifications 67,007 (29,170) (11,145) 26,692 Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax (359) 799 — 440 Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax (57) — — (57) Net other comprehensive income (loss) during the period, net of tax $ 66,591 $ (28,371) $ (11,145) $ 27,075 Balance at March 31, 2020 $ 81,573 $ (41,512) $ (47,664) $ (7,603)
Other Comprehensive Income Reclassified from AOCI	Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Details Regarding the Component of Accumulated Other Comprehensive Income (Loss) Three Months Ended Impacted Line on the March 31, 2021 2020 Accumulated unrealized gains on securities Gains included in net income $ 210 $ 491 Gains (losses) on investment securities, net 210 491 Income before taxes Tax effect (56) (132) Income tax expense Net of tax $ 154 $ 359 Net income Accumulated unrealized gains on derivative instruments Amount reclassified to interest expense on deposits $ 4,897 $ 559 Interest on deposits Amount reclassified to interest expense on other borrowings 669 292 Interest on other borrowings Amount reclassified to interest expense on junior subordinated debentures 1,130 239 Interest on junior subordinated debentures (6,696) (1,090) Income before taxes Tax effect 1,784 291 Income tax expense Net of tax $ (4,912) $ (799) Net income
Computation Of Basic And Diluted Earnings Per Common Share	The following table shows the computation of basic and diluted earnings per share for the periods indicated: Three Months Ended (In thousands, except per share data) March 31, March 31, Net income $ 153,148 $ 62,812 Less: Preferred stock dividends 6,991 2,050 Net income applicable to common shares (A) $ 146,157 $ 60,762 Weighted average common shares outstanding (B) 56,904 57,620 Effect of dilutive potential common shares Common stock equivalents 681 575 Weighted average common shares and effect of dilutive potential common shares (C) 57,585 58,195 Net income per common share: Basic (A/B) $ 2.57 $ 1.05 Diluted (A/C) $ 2.54 $ 1.04

Investment Securities (Marketab

Investment Securities (Marketable Securities) (Detail) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Available-for-sale securities
Amortized Cost	$ 2,395,927,000	$ 2,960,081,000	$ 3,460,705,000
Gross Unrealized Gains	61,967,000	98,578,000	122,323,000
Gross Unrealized Losses	(27,145,000)	(2,820,000)	(12,069,000)
Fair Value	2,430,749,000	3,055,839,000	3,570,959,000
Held-to-maturity securities
Amortized Cost	2,166,518,000	579,197,000	865,446,000
Gross Unrealized Gains	12,622,000	14,784,000	13,905,000
Gross Unrealized Losses	(58,075,000)	(214,000)	(159,000)
Fair Value	2,121,065,000	593,767,000	879,192,000
Less: Allowance for credit losses	(99,000)	(59,000)	(70,000)
Held-to-maturity securities, net of allowance for credit losses		579,138,000	865,376,000
Equity securities with readily determinable fair value
Amortized Cost	86,121,000	87,618,000	48,060,000
Gross Unrealized Gains	5,362,000	3,674,000	781,000
Gross Unrealized Losses	(1,145,000)	(430,000)	(1,531,000)
Fair Value	90,338,000	90,862,000	47,310,000
U.S. Treasury
Available-for-sale securities
Amortized Cost	64,999,000	304,956,000	120,404,000
Gross Unrealized Gains	2,000	15,000	1,266,000
Gross Unrealized Losses	0	0	0
Fair Value	65,001,000	304,971,000	121,670,000
U.S. Government agencies
Available-for-sale securities
Amortized Cost	77,908,000	80,074,000	362,969,000
Gross Unrealized Gains	3,618,000	4,439,000	5,674,000
Gross Unrealized Losses	0	0	0
Fair Value	81,526,000	84,513,000	368,643,000
Held-to-maturity securities
Amortized Cost	176,160,000	177,959,000	646,976,000
Gross Unrealized Gains	1,644,000	2,552,000	5,996,000
Gross Unrealized Losses	(7,230,000)	0	(4,000)
Fair Value	170,574,000	180,511,000	652,968,000
Municipal
Available-for-sale securities
Amortized Cost	143,711,000	141,244,000	143,273,000
Gross Unrealized Gains	4,761,000	5,707,000	3,571,000
Gross Unrealized Losses	(172,000)	(41,000)	(235,000)
Fair Value	148,300,000	146,910,000	146,609,000
Held-to-maturity securities
Amortized Cost	197,865,000	200,707,000	218,470,000
Gross Unrealized Gains	10,713,000	12,232,000	7,909,000
Gross Unrealized Losses	(535,000)	(214,000)	(155,000)
Fair Value	208,043,000	212,725,000	226,224,000
Corporate notes
Held-to-maturity securities
Amortized Cost	55,378,000
Gross Unrealized Gains	0
Gross Unrealized Losses	(1,196,000)
Fair Value	54,182,000
Corporate notes, financial issuers
Available-for-sale securities
Amortized Cost	91,806,000	91,786,000	111,718,000
Gross Unrealized Gains	461,000	1,363,000	90,000
Gross Unrealized Losses	(935,000)	(2,764,000)	(11,821,000)
Fair Value	91,332,000	90,385,000	99,987,000
Corporate notes, other
Available-for-sale securities
Amortized Cost	1,000,000	1,000,000	1,000,000
Gross Unrealized Gains	17,000	20,000	31,000
Gross Unrealized Losses	0	0	0
Fair Value	1,017,000	1,020,000	1,031,000
Mortgage-backed securities
Available-for-sale securities
Amortized Cost	2,007,092,000	2,330,332,000	2,697,264,000
Gross Unrealized Gains	52,855,000	86,721,000	111,275,000
Gross Unrealized Losses	(26,038,000)	(15,000)	(4,000)
Fair Value	2,033,909,000	2,417,038,000	2,808,535,000
Held-to-maturity securities
Amortized Cost	1,737,115,000	200,531,000
Gross Unrealized Gains	265,000	0
Gross Unrealized Losses	(49,114,000)	0
Fair Value	1,688,266,000	200,531,000
Collateralized mortgage obligations
Available-for-sale securities
Amortized Cost	9,411,000	10,689,000	24,077,000
Gross Unrealized Gains	253,000	313,000	416,000
Gross Unrealized Losses	0	0	(9,000)
Fair Value	9,664,000	11,002,000	24,484,000
Mortgage-backed securities, subprime
Available-for-sale securities
Fair Value	$ 0	$ 0	$ 0

Investment Securities (Continuo

Investment Securities (Continuous Unrealized Loss Position, Fair Value) (Detail) $ in Thousands	Mar. 31, 2021USD ($)
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	$ 610,997
Continuous unrealized losses existing for less than 12 months, unrealized losses	(26,355)
Continuous unrealized losses existing for greater than 12 months, fair value	48,367
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(790)
Total, fair value	659,364
Total, unrealized losses	(27,145)
U.S. Treasury
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
U.S. Government agencies
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
Municipal
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	24,326
Continuous unrealized losses existing for less than 12 months, unrealized losses	(168)
Continuous unrealized losses existing for greater than 12 months, fair value	110
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(4)
Total, fair value	24,436
Total, unrealized losses	(172)
Corporate notes, financial issuers
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	14,850
Continuous unrealized losses existing for less than 12 months, unrealized losses	(150)
Continuous unrealized losses existing for greater than 12 months, fair value	48,196
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(785)
Total, fair value	63,046
Total, unrealized losses	(935)
Corporate notes, other
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
Mortgage-backed securities
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	571,821
Continuous unrealized losses existing for less than 12 months, unrealized losses	(26,037)
Continuous unrealized losses existing for greater than 12 months, fair value	61
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(1)
Total, fair value	571,882
Total, unrealized losses	(26,038)
Collateralized mortgage obligations
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	$ 0

Investment Securities (Schedule

Investment Securities (Schedule of Realized Gain (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Realized gains on investment securities	$ 216	$ 496
Realized losses on investment securities	(6)	(5)
Net realized gains on investment securities	210	491
Unrealized gains on equity securities with readily determinable fair value	1,875	0
Unrealized losses on equity securities with readily determinable fair value	(901)	(3,546)
Net unrealized gains (losses) on equity securities with readily determinable fair value	974	(3,546)
Upward adjustments of equity securities without readily determinable fair values	0	393
Downward adjustments of equity securities without readily determinable fair values	0	0
Impairment of equity securities without readily determinable fair values	(30)	(1,697)
Adjustment and impairment, net, of equity securities without readily determinable fair values	(30)	(1,304)
Gains (losses) on investment securities, net	1,154	(4,359)
Proceeds from sales of available-for-sale securities	0	0
Proceeds from sales of equity securities with readily determinable fair value	1,509	30
Proceeds from sales and capital distributions of equity securities without readily determinable fair value	$ 386	$ 288

Investment Securities (Investme

Investment Securities (Investments Classified by Contractual Maturity Date) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Available-for-sale securities
Due in one year or less, amortized cost	$ 100,140	$ 343,601	$ 186,538
Due in one to five years, amortized cost	76,104	67,901	70,812
Due in five to ten years, amortized cost	110,125	111,886	174,262
Due after ten years, amortized cost	93,055	95,672	307,752
Amortized Cost	2,395,927	2,960,081	3,460,705
Due in one year or less, fair value	100,361	343,846	187,789
Due in one to five years, fair value	78,291	70,334	71,825
Due in five to ten years, fair value	110,928	112,178	164,479
Due after ten years, fair value	97,596	101,441	313,847
Fair Value	2,430,749	3,055,839	3,570,959
Held-to-maturity securities
Held-to-maturity securities, Due in one year or less, amortized cost	6,812	7,138	5,310
Held-to-maturity securities, Due in one to five years, amortized cost	50,318	22,217	23,801
Held-to-maturity securities, Due in five to ten years, amortized cost	184,677	150,621	143,783
Held-to-maturity securities, Due after ten years, amortized cost	187,596	198,690	692,552
Amortized Cost	2,166,518	579,197	865,446
Less: Allowance for credit losses	(99)	(59)	(70)
Held-to-maturity securities, net of allowance for credit losses	2,166,419	579,138	865,376
Held-to-maturity securities, Due in one year or less, fair value	6,863	7,186	5,333
Held-to-maturity securities, Due in one to five years, fair value	50,734	23,068	24,158
Held-to-maturity securities, Due in five to ten years, fair value	191,539	159,293	148,746
Held-to-maturity securities, Due after ten years, fair value	183,663	203,689	700,955
Fair Value	2,121,065	593,767	879,192
Mortgage-backed
Available-for-sale securities
Mortgage-backed, without single maturity date, amortized cost	2,016,503	2,341,021	2,721,341
Mortgage-backed, without single maturity date, fair value	2,043,573	2,428,040	2,833,019
Held-to-maturity securities
Mortgage-backed, amortized cost	1,737,115	200,531	0
Mortgage-backed, fair value	$ 1,688,266	$ 200,531	$ 0

Investment Securities (Narrativ

Investment Securities (Narrative) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)security	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Investments, Debt and Equity Securities [Abstract]
Equity securities without readily determinable fair value	$ 33,300
Upward adjustments of equity securities without readily determinable fair values	0	$ 393
Downward adjustments of equity securities without readily determinable fair values	0	0
Impairment of equity securities without readily determinable fair values	30	1,697
Pledged securities	$ 2,100,000	$ 1,500,000	$ 2,400,000
Number of securities by a single non-government sponsored issuer exceeding 10% of shareholders' equity | security	0

Loans (Summary of Loan Portfoli

Loans (Summary of Loan Portfolio) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Loans [Line Items]
Total loans, net of unearned income	$ 33,171,233	$ 32,079,073	$ 27,807,321
Total loans, net of unearned income, percentage	100.00%	100.00%	100.00%
Commercial
Loans [Line Items]
Total loans, net of unearned income	$ 12,708,207	$ 11,955,967	$ 9,025,886
Total loans, net of unearned income, percentage	38.00%	37.00%	32.00%
Commercial real estate
Loans [Line Items]
Total loans, net of unearned income	$ 8,544,779	$ 8,494,132	$ 8,185,531
Total loans, net of unearned income, percentage	26.00%	26.00%	29.00%
Home equity
Loans [Line Items]
Total loans, net of unearned income	$ 390,253	$ 425,263	$ 494,655
Total loans, net of unearned income, percentage	1.00%	1.00%	2.00%
Residential real estate
Loans [Line Items]
Total loans, net of unearned income	$ 1,421,973	$ 1,259,598	$ 1,377,389
Total loans, net of unearned income, percentage	4.00%	5.00%	5.00%
Premium finance receivables | Commercial insurance loans
Loans [Line Items]
Total loans, net of unearned income	$ 3,958,543	$ 4,054,489	$ 3,465,055
Total loans, net of unearned income, percentage	12.00%	13.00%	13.00%
Premium finance receivables | Life insurance
Loans [Line Items]
Total loans, net of unearned income	$ 6,111,495	$ 5,857,436	$ 5,221,639
Total loans, net of unearned income, percentage	19.00%	18.00%	19.00%
Consumer and other
Loans [Line Items]
Total loans, net of unearned income	$ 35,983	$ 32,188	$ 37,166
Total loans, net of unearned income, percentage	0.00%	0.00%	0.00%

Loans (Narrative) (Detail)

Loans (Narrative) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Schedule Of Accretable Yield Activity Related to Loans Acquired With Evidence Of Credit Quality Deterioration Since Origination Table [Line Items]
Loans, net of unearned income	$ 33,171,233	$ 32,079,073	$ 27,807,321
Net deferred loan fees and costs and fair value accounting adjustments	(32,200)	(3,200)	11,100
Net deferred loan fees and costs and fair value accounting adjustments, paid by SBA under PPP	64,600
Commercial
Schedule Of Accretable Yield Activity Related to Loans Acquired With Evidence Of Credit Quality Deterioration Since Origination Table [Line Items]
Loans, net of unearned income	12,708,207	11,955,967	9,025,886
Premium finance receivables
Schedule Of Accretable Yield Activity Related to Loans Acquired With Evidence Of Credit Quality Deterioration Since Origination Table [Line Items]
Unearned income portion of premium finance receivables	114,400	113,100	115,200
Commercial PPP loans | Commercial
Schedule Of Accretable Yield Activity Related to Loans Acquired With Evidence Of Credit Quality Deterioration Since Origination Table [Line Items]
Loans, net of unearned income	$ 3,292,982	$ 2,715,921	$ 0

Allowance for Credit Losses (Sc

Allowance for Credit Losses (Schedule of Aging of the Company's Loan Portfolio) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Credit Loss [Abstract]
Financial assets held at amortized cost, accrued interest	$ 128,800	$ 121,900	$ 116,400
Financing Receivable, Past Due [Line Items]
Nonaccrual	94,115	114,150	160,415
90+ days and still accruing	4,944	13,363	18,945
Current	32,892,465	31,770,847	27,332,294
Total Loans	33,171,233	32,079,073	27,807,321
60-89 days past due
Financing Receivable, Past Due [Line Items]
Past Due	28,005	41,585	32,999
30-59 days past due
Financing Receivable, Past Due [Line Items]
Past Due	151,704	139,128	262,668
Commercial
Financing Receivable, Past Due [Line Items]
Total Loans	12,708,207	11,955,967	9,025,886
Commercial | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	22,459	21,743	49,916
90+ days and still accruing	0	307	1,241
Current	9,343,939	9,166,751	8,879,727
Total Loans	9,415,225	9,240,046	9,025,886
Commercial | Commercial PPP loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	0	0	0
Current	3,292,976	2,715,885	0
Total Loans	3,292,982	2,715,921	0
Commercial | 60-89 days past due | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Past Due [Line Items]
Past Due	13,292	6,900	8,873
Commercial | 60-89 days past due | Commercial PPP loans
Financing Receivable, Past Due [Line Items]
Past Due	0	0	0
Commercial | 30-59 days past due | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Past Due [Line Items]
Past Due	35,535	44,345	86,129
Commercial | 30-59 days past due | Commercial PPP loans
Financing Receivable, Past Due [Line Items]
Past Due	6	36	0
Commercial real estate
Financing Receivable, Past Due [Line Items]
Total Loans	8,544,779	8,494,132	8,185,531
Commercial real estate | Construction and development
Financing Receivable, Past Due [Line Items]
Nonaccrual	2,673	5,633	7,422
90+ days and still accruing	0	0	147
Current	1,326,185	1,360,825	1,274,987
Total Loans	1,353,324	1,371,802	1,301,353
Commercial real estate | Non-construction
Financing Receivable, Past Due [Line Items]
Nonaccrual	31,707	40,474	55,408
90+ days and still accruing	0	0	369
Current	7,105,890	7,049,906	6,761,918
Total Loans	7,191,455	7,122,330	6,884,178
Commercial real estate | 60-89 days past due | Construction and development
Financing Receivable, Past Due [Line Items]
Past Due	499	0	1,859
Commercial real estate | 60-89 days past due | Non-construction
Financing Receivable, Past Due [Line Items]
Past Due	7,657	5,178	8,353
Commercial real estate | 30-59 days past due | Construction and development
Financing Receivable, Past Due [Line Items]
Past Due	23,967	5,344	16,938
Commercial real estate | 30-59 days past due | Non-construction
Financing Receivable, Past Due [Line Items]
Past Due	46,201	26,772	58,130
Home equity
Financing Receivable, Past Due [Line Items]
Nonaccrual	5,536	6,529	7,243
90+ days and still accruing	0	0	0
Current	383,445	418,050	485,102
Total Loans	390,253	425,263	494,655
Home equity | 60-89 days past due
Financing Receivable, Past Due [Line Items]
Past Due	492	47	214
Home equity | 30-59 days past due
Financing Receivable, Past Due [Line Items]
Past Due	780	637	2,096
Residential real estate
Financing Receivable, Past Due [Line Items]
Nonaccrual	21,553	26,071	18,965
90+ days and still accruing	0	0	605
Current	1,385,708	1,219,308	1,328,491
Total Loans	1,421,973	1,259,598	1,377,389
Residential real estate | 60-89 days past due
Financing Receivable, Past Due [Line Items]
Past Due	944	1,635	345
Residential real estate | 30-59 days past due
Financing Receivable, Past Due [Line Items]
Past Due	13,768	12,584	28,983
Premium finance receivables | Commercial insurance loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	9,690	13,264	21,058
90+ days and still accruing	4,592	12,792	16,505
Current	3,922,596	4,002,826	3,384,354
Total Loans	3,958,543	4,054,489	3,465,055
Premium finance receivables | Life insurance loans
Financing Receivable, Past Due [Line Items]
Nonaccrual	0	0	0
90+ days and still accruing	191	0	0
Current	6,096,483	5,805,968	5,181,862
Total Loans	6,111,495	5,857,436	5,221,639
Premium finance receivables | 60-89 days past due | Commercial insurance loans
Financing Receivable, Past Due [Line Items]
Past Due	5,113	6,798	10,327
Premium finance receivables | 60-89 days past due | Life insurance loans
Financing Receivable, Past Due [Line Items]
Past Due	0	21,003	2,403
Premium finance receivables | 30-59 days past due | Commercial insurance loans
Financing Receivable, Past Due [Line Items]
Past Due	16,552	18,809	32,811
Premium finance receivables | 30-59 days past due | Life insurance loans
Financing Receivable, Past Due [Line Items]
Past Due	14,821	30,465	37,374
Consumer and other
Financing Receivable, Past Due [Line Items]
Nonaccrual	497	436	403
90+ days and still accruing	161	264	78
Current	35,243	31,328	35,853
Total Loans	35,983	32,188	37,166
Consumer and other | 60-89 days past due
Financing Receivable, Past Due [Line Items]
Past Due	8	24	625
Consumer and other | 30-59 days past due
Financing Receivable, Past Due [Line Items]
Past Due	$ 74	$ 136	$ 207

Allowance for Credit Losses (Lo

Allowance for Credit Losses (Loan Portfolio by Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2020	$ 4,561,556
2019	8,621,215
2018	3,855,466
2017	2,816,366
2016	2,458,814
Prior	7,224,082
Revolving	3,627,430
Revolving to Term	6,304
Total Loans	33,171,233	$ 32,079,073	$ 27,807,321
Loans with COVID-19 related modifications	164,700
Commercial, industrial and other, excluding PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	597,898
2019	2,000,774
2018	1,309,686
2017	952,540
2016	671,725
Prior	842,263
Revolving	3,035,267
Revolving to Term	5,072
Total Loans	9,415,225
Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,243,640
2019	2,049,342
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	3,292,982
Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2020	40,548
2019	358,387
2018	451,255
2017	241,020
2016	116,771
Prior	115,444
Revolving	29,899
Revolving to Term	0
Total Loans	1,353,324
Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2020	253,116
2019	1,307,463
2018	1,138,028
2017	894,164
2016	865,944
Prior	2,548,182
Revolving	184,314
Revolving to Term	244
Total Loans	7,191,455
Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	44
2018	0
2017	364
2016	185
Prior	24,937
Revolving	363,735
Revolving to Term	988
Total Loans	390,253	425,263	494,655
Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	302,275
2019	349,615
2018	267,926
2017	103,682
2016	125,106
Prior	273,369
Revolving	0
Revolving to Term	0
Total Loans	1,421,973	1,259,598	1,377,389
Premium finance receivables - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,009,976
2019	1,916,805
2018	28,639
2017	3,069
2016	54
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	3,958,543
Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2020	112,896
2019	636,815
2018	658,163
2017	620,034
2016	678,764
Prior	3,404,823
Revolving	0
Revolving to Term	0
Total Loans	6,111,495
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,207
2019	1,970
2018	1,769
2017	1,493
2016	265
Prior	15,064
Revolving	14,215
Revolving to Term	0
Total Loans	35,983	$ 32,188	$ 37,166
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2020	4,523,884
2019	8,524,939
2018	3,574,815
2017	2,577,862
2016	2,267,625
Prior	6,708,148
Revolving	3,492,693
Revolving to Term	5,169
Total Loans	31,675,135
Pass | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	574,195
2019	1,951,426
2018	1,158,699
2017	840,181
2016	611,479
Prior	742,116
Revolving	2,908,239
Revolving to Term	4,925
Total Loans	8,791,260
Pass | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,242,766
2019	2,049,342
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	3,292,108
Pass | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2020	40,266
2019	346,452
2018	433,184
2017	196,502
2016	89,377
Prior	109,596
Revolving	29,747
Revolving to Term	0
Total Loans	1,245,124
Pass | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2020	249,241
2019	1,295,535
2018	1,030,111
2017	816,725
2016	772,702
Prior	2,189,960
Revolving	184,304
Revolving to Term	244
Total Loans	6,538,822
Pass | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	44
2018	0
2017	47
2016	28
Prior	7,082
Revolving	356,197
Revolving to Term	0
Total Loans	363,398
Pass | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	301,904
2019	346,823
2018	265,543
2017	100,023
2016	115,609
Prior	240,205
Revolving	0
Revolving to Term	0
Total Loans	1,370,107
Pass | Premium finance receivables - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	2,001,412
2019	1,896,547
2018	27,366
2017	2,961
2016	54
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	3,928,340
Pass | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2020	112,896
2019	636,815
2018	658,163
2017	620,034
2016	678,197
Prior	3,404,823
Revolving	0
Revolving to Term	0
Total Loans	6,110,928
Pass | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1,204
2019	1,955
2018	1,749
2017	1,389
2016	179
Prior	14,366
Revolving	14,206
Revolving to Term	0
Total Loans	35,048
Special mention
Financing Receivable, Credit Quality Indicator [Line Items]
2020	14,130
2019	61,031
2018	165,856
2017	128,882
2016	130,156
Prior	260,038
Revolving	91,640
Revolving to Term	281
Total Loans	852,014
Special mention | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	965
2019	27,786
2018	83,315
2017	38,930
2016	33,116
Prior	24,760
Revolving	86,729
Revolving to Term	36
Total Loans	295,637
Special mention | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	874
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	874
Special mention | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2020	282
2019	11,935
2018	16,864
2017	21,075
2016	24,465
Prior	4,068
Revolving	0
Revolving to Term	0
Total Loans	78,689
Special mention | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3,875
2019	9,905
2018	65,413
2017	66,860
2016	69,759
Prior	220,549
Revolving	0
Revolving to Term	0
Total Loans	436,361
Special mention | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	2,103
Revolving	4,905
Revolving to Term	245
Total Loans	7,253
Special mention | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	80
2019	302
2018	237
2017	2,017
2016	2,163
Prior	8,467
Revolving	0
Revolving to Term	0
Total Loans	13,266
Special mention | Premium finance receivables - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	8,051
2019	11,093
2018	8
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	19,152
Special mention | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	567
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	567
Special mention | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	3
2019	10
2018	19
2017	0
2016	86
Prior	91
Revolving	6
Revolving to Term	0
Total Loans	215
Substandard accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2020	23,030
2019	25,273
2018	110,386
2017	103,836
2016	51,633
Prior	193,973
Revolving	40,984
Revolving to Term	854
Total Loans	549,969
Substandard accrual | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	22,738
2019	19,675
2018	65,902
2017	71,312
2016	25,052
Prior	61,313
Revolving	39,766
Revolving to Term	111
Total Loans	305,869
Substandard accrual | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard accrual | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	1,207
2017	21,872
2016	2,929
Prior	678
Revolving	152
Revolving to Term	0
Total Loans	26,838
Substandard accrual | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	2,023
2018	42,238
2017	9,358
2016	21,352
Prior	109,584
Revolving	10
Revolving to Term	0
Total Loans	184,565
Substandard accrual | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	317
2016	0
Prior	11,953
Revolving	1,053
Revolving to Term	743
Total Loans	14,066
Substandard accrual | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	291
2019	2,304
2018	1,025
2017	897
2016	2,300
Prior	10,230
Revolving	0
Revolving to Term	0
Total Loans	17,047
Substandard accrual | Premium finance receivables - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	1
2019	1,267
2018	13
2017	80
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	1,361
Substandard accrual | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard accrual | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	4
2018	1
2017	0
2016	0
Prior	215
Revolving	3
Revolving to Term	0
Total Loans	223
Substandard nonaccrual/doubtful
Financing Receivable, Credit Quality Indicator [Line Items]
2020	512
2019	9,972
2018	4,409
2017	5,786
2016	9,400
Prior	61,923
Revolving	2,113
Revolving to Term	0
Total Loans	94,115
Substandard nonaccrual/doubtful | Commercial, industrial and other, excluding PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1,887
2018	1,770
2017	2,117
2016	2,078
Prior	14,074
Revolving	533
Revolving to Term	0
Total Loans	22,459
Substandard nonaccrual/doubtful | Commercial PPP loans
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard nonaccrual/doubtful | Construction and development
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	1,571
2016	0
Prior	1,102
Revolving	0
Revolving to Term	0
Total Loans	2,673
Substandard nonaccrual/doubtful | Non-construction
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	266
2017	1,221
2016	2,131
Prior	28,089
Revolving	0
Revolving to Term	0
Total Loans	31,707
Substandard nonaccrual/doubtful | Home equity
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	157
Prior	3,799
Revolving	1,580
Revolving to Term	0
Total Loans	5,536
Substandard nonaccrual/doubtful | Residential real estate
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	186
2018	1,121
2017	745
2016	5,034
Prior	14,467
Revolving	0
Revolving to Term	0
Total Loans	21,553
Substandard nonaccrual/doubtful | Premium finance receivables - commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2020	512
2019	7,898
2018	1,252
2017	28
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	9,690
Substandard nonaccrual/doubtful | Premium finance receivables - life
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving	0
Revolving to Term	0
Total Loans	0
Substandard nonaccrual/doubtful | Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2020	0
2019	1
2018	0
2017	104
2016	0
Prior	392
Revolving	0
Revolving to Term	0
Total Loans	$ 497

Allowance for Credit Losses (He

Allowance for Credit Losses (Held-to-Maturity Debt Securities by Credit Quality Indication) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Amortized Cost	$ 2,166,518	$ 579,197	$ 865,446
Less: Allowance for credit losses	(99)	(59)	(70)
Held-to-maturity securities, net of allowance for credit losses	2,166,419	579,138	865,376
U.S. Government agencies
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	97,786
2019	25,000
2018	0
2017	50,000
2016	0
Prior	3,374
Amortized Cost	176,160	177,959	646,976
U.S. Government agencies | 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	97,786
2019	25,000
2018	0
2017	50,000
2016	0
Prior	3,374
Amortized Cost	176,160
U.S. Government agencies | 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
U.S. Government agencies | 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
Municipal
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	1,377
2019	0
2018	161
2017	7,549
2016	43,603
Prior	145,175
Amortized Cost	197,865	$ 200,707	$ 218,470
Municipal | 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	1,377
2019	0
2018	161
2017	7,549
2016	43,603
Prior	145,175
Amortized Cost	197,865
Municipal | 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
Municipal | 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
Mortgage-backed securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	1,737,115
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	1,737,115
Mortgage-backed securities | 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	1,737,115
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	1,737,115
Mortgage-backed securities | 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
Mortgage-backed securities | 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
Corporate notes
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	13,661
2018	7,462
2017	3,325
2016	3,282
Prior	27,648
Amortized Cost	55,378
Corporate notes | 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	13,661
2018	7,462
2017	3,325
2016	3,282
Prior	27,648
Amortized Cost	55,378
Corporate notes | 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	0
Corporate notes | 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Amortized Cost	$ 0

Allowance for Credit Losses (Co

Allowance for Credit Losses (Components of Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	$ 321,209	$ 379,910	$ 253,412	$ 158,461
Allowance for held-to-maturity securities losses	99	59	70
Allowance for credit losses	321,308	379,969	253,482
Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	277,709	319,374	216,050
Unfunded lending-related commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	43,500	60,536	37,362
Loan losses and unfunded lending-related commitments losses
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	$ 321,209	$ 379,910	$ 253,412

Allowance for Credit Losses (Su

Allowance for Credit Losses (Summary of Activity in the Allowance for Credit Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	$ 379,910	$ 158,461
Other adjustments	30	(73)
Charge-offs	(16,116)	(7,437)
Recoveries	2,771	2,152
Provision for credit losses	(45,386)	52,965
Allowance for credit losses at period end	321,209	253,412
Individually measured	8,329	22,492
Collectively measured	312,880	230,920
Loans at period end, Individually evaluated for impairment	124,404	188,740
Loans at period end, Collectively evaluated for impairment	32,994,913	27,476,314
Loans held at fair value	51,916	142,267
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	94,212	64,920
Other adjustments	0	0
Charge-offs	(11,781)	(2,153)
Recoveries	452	384
Provision for credit losses	12,757	35,156
Allowance for credit losses at period end	95,640	107,346
Individually measured	5,046	12,524
Collectively measured	90,594	94,822
Loans at period end, Individually evaluated for impairment	30,144	56,416
Loans at period end, Collectively evaluated for impairment	12,678,063	8,969,470
Loans held at fair value	0	0
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	243,603	68,511
Other adjustments	0	0
Charge-offs	(980)	(570)
Recoveries	200	263
Provision for credit losses	(61,031)	12,528
Allowance for credit losses at period end	181,792	112,796
Individually measured	2,042	9,108
Collectively measured	179,750	103,688
Loans at period end, Individually evaluated for impairment	43,858	80,873
Loans at period end, Collectively evaluated for impairment	8,500,921	8,104,658
Loans held at fair value	0	0
Home equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	11,437	3,878
Other adjustments	0	0
Charge-offs	0	(1,001)
Recoveries	101	294
Provision for credit losses	(156)	162
Allowance for credit losses at period end	11,382	12,394
Individually measured	338	290
Collectively measured	11,044	12,104
Loans at period end, Individually evaluated for impairment	21,167	23,060
Loans at period end, Collectively evaluated for impairment	369,086	471,595
Loans held at fair value	0	0
Residential real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	12,459	9,800
Other adjustments	0	0
Charge-offs	(2)	(401)
Recoveries	204	60
Provision for credit losses	1,581	89
Allowance for credit losses at period end	14,242	12,550
Individually measured	822	466
Collectively measured	13,420	12,084
Loans at period end, Individually evaluated for impairment	28,675	27,854
Loans at period end, Collectively evaluated for impairment	1,341,382	1,207,268
Loans held at fair value	51,916	142,267
Premium finance receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	17,777	9,647
Other adjustments	30	(73)
Charge-offs	(3,239)	(3,184)
Recoveries	1,782	1,110
Provision for credit losses	1,127	5,339
Allowance for credit losses at period end	17,477	7,880
Individually measured	0	0
Collectively measured	17,477	7,880
Loans at period end, Individually evaluated for impairment	0	0
Loans at period end, Collectively evaluated for impairment	10,070,038	8,686,694
Loans held at fair value	0	0
Consumer and other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	422	1,705
Other adjustments	0	0
Charge-offs	(114)	(128)
Recoveries	32	41
Provision for credit losses	336	(309)
Allowance for credit losses at period end	676	446
Individually measured	81	104
Collectively measured	595	342
Loans at period end, Individually evaluated for impairment	560	537
Loans at period end, Collectively evaluated for impairment	35,423	36,629
Loans held at fair value	0	0
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	47,344
Cumulative Effect, Period of Adoption, Adjustment | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period		$ 9,039
Cumulative Effect, Period of Adoption, Adjustment | Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	32,064
Cumulative Effect, Period of Adoption, Adjustment | Home equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	9,061
Cumulative Effect, Period of Adoption, Adjustment | Residential real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	3,002
Cumulative Effect, Period of Adoption, Adjustment | Premium finance receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	(4,959)
Cumulative Effect, Period of Adoption, Adjustment | Consumer and other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	$ (863)

Allowance for Credit Losses (Al

Allowance for Credit Losses (Allowance for Credit Losses Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Nonaccrual loans with no related allowance for credit losses	$ 56,800
Loans reasonably expected to be modified into TDRs	198
Allowance for loan losses	321,209	$ 253,412	$ 379,910		$ 158,461
Provision for credit losses	(45,386)	52,965
Loan net charge-offs	13,300
Allowance for held-to-maturity securities losses	99	70	59
Provision for credit losses	39
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses			47,344
Allowance for held-to-maturity securities losses				$ 74
Loans acquired with deteriorated credit quality | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses				11,000
Loans acquired without deteriorated credit quality | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses				3,200
Unfunded lending-related commitments
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	43,500	37,362	60,536
Unfunded lending-related commitments | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses				33,200
Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses	$ 277,709	$ 216,050	$ 319,374
Loans | Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for loan losses				$ 14,200

Allowance for Credit Losses (_2

Allowance for Credit Losses (Summary of the Post-Modification Balance of TDRs) (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	20	38	106	184
TDRs, balance | $	$ 2,126	$ 23,797	$ 24,201	$ 53,646
Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	20	26
TDRs, balance | $	$ 2,126	$ 19,717
Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	10	8
TDRs, balance | $	$ 1,403	$ 1,707
Modification to Interest Only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	1	5
TDRs, balance | $	$ 113	$ 3,463
Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	1
TDRs, balance | $	$ 0	$ 432
Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	5	18	20
TDRs, balance | $	$ 151	$ 5,602	$ 6,910	$ 13,013
Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	3
TDRs, balance | $	$ 151	$ 4,316
Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other | Modification to Interest Only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	1
TDRs, balance | $	$ 0	$ 432
Commercial real estate | Non-construction
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	13	7	19
TDRs, balance | $	$ 237	$ 16,053	$ 3,466	$ 22,770
Commercial real estate | Non-construction | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	2	11
TDRs, balance | $	$ 237	$ 13,511
Commercial real estate | Non-construction | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	1	3
TDRs, balance | $	$ 113	$ 921
Commercial real estate | Non-construction | Modification to Interest Only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	1	5
TDRs, balance | $	$ 113	$ 3,463
Commercial real estate | Non-construction | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Residential real estate and other
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	16	20	81	145
TDRs, balance | $	$ 1,738	$ 2,142	$ 13,825	$ 17,863
Residential real estate and other | Extension at Below Market Terms
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	16	12
TDRs, balance | $	$ 1,738	$ 1,890
Residential real estate and other | Reduction of Interest Rate
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	9	5
TDRs, balance | $	$ 1,290	$ 786
Residential real estate and other | Modification to Interest Only Payments
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Residential real estate and other | Forgiveness of Debt
Financing Receivable, Troubled Debt Restructuring [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0

Allowance for Credit Losses (_3

Allowance for Credit Losses (Summary of TDRs Subsequent Default Under the Restructured Terms) (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	20	38	106	184
TDRs, balance | $	$ 2,126	$ 23,797	$ 24,201	$ 53,646
Payments in default, count | contract	13	22
Payments in default, balance | $	$ 5,213	$ 8,104
Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	2	5	18	20
TDRs, balance | $	$ 151	$ 5,602	$ 6,910	$ 13,013
Payments in default, count | contract	5	8
Payments in default, balance | $	$ 1,496	$ 4,836
Commercial real estate | Non-construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	2	13	7	19
TDRs, balance | $	$ 237	$ 16,053	$ 3,466	$ 22,770
Payments in default, count | contract	3	3
Payments in default, balance | $	$ 3,121	$ 758
Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	16	20	81	145
TDRs, balance | $	$ 1,738	$ 2,142	$ 13,825	$ 17,863
Payments in default, count | contract	5	11
Payments in default, balance | $	$ 596	$ 2,510
Extension at Below Market Terms
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	20	26
TDRs, balance | $	$ 2,126	$ 19,717
Extension at Below Market Terms | Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	2	3
TDRs, balance | $	$ 151	$ 4,316
Extension at Below Market Terms | Commercial real estate | Non-construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	2	11
TDRs, balance | $	$ 237	$ 13,511
Extension at Below Market Terms | Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	16	12
TDRs, balance | $	$ 1,738	$ 1,890
Reduction of Interest Rate
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	10	8
TDRs, balance | $	$ 1,403	$ 1,707
Reduction of Interest Rate | Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Reduction of Interest Rate | Commercial real estate | Non-construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	1	3
TDRs, balance | $	$ 113	$ 921
Reduction of Interest Rate | Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	9	5
TDRs, balance | $	$ 1,290	$ 786
Modification to Interest Only Payments
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	1	5
TDRs, balance | $	$ 113	$ 3,463
Modification to Interest Only Payments | Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Modification to Interest Only Payments | Commercial real estate | Non-construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	1	5
TDRs, balance | $	$ 113	$ 3,463
Modification to Interest Only Payments | Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Forgiveness of Debt
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	1
TDRs, balance | $	$ 0	$ 432
Forgiveness of Debt | Commercial, industrial and other, excluding PPP loans | Commercial, industrial and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	1
TDRs, balance | $	$ 0	$ 432
Forgiveness of Debt | Commercial real estate | Non-construction
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0
Forgiveness of Debt | Residential real estate and other
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
TDRs, count | contract	0	0
TDRs, balance | $	$ 0	$ 0

Allowance for Credit Losses (TD

Allowance for Credit Losses (TDRs Narrative) (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract	Mar. 31, 2021USD ($)contract	Mar. 31, 2020USD ($)contract
Financing Receivable, Allowance for Credit Loss [Line Items]
TDRs, count | contract	20	38	106	184
Foreclosed residential real estate properties	$ 4,000		$ 4,000
TDRs, balance	$ 2,126	$ 23,797	24,201	$ 53,646
Weighted average extension term	110 months	8 months
Weighted average decrease in stated interest rate	1.27%	1.73%
Interest-only payment terms	6 months	21 months
Loan forgiveness	$ 0	$ 453
Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans modified in TDRs	$ 56,600		56,600
TDRs, count | contract	273
Allowance for loan losses related to impaired loans	$ 2,500		2,500
Residential Real Estate | Financing Receivable
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded investment, foreclosure proceedings in process	$ 13,800	$ 10,600	$ 13,800	$ 10,600

Goodwill And Other Intangible_3

Goodwill And Other Intangible Assets (Goodwill Assets by Business Segment) (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 645,707
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	310
Ending balance	646,017
Community banking
Goodwill [Roll Forward]
Beginning balance	536,396
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	536,396
Specialty finance
Goodwill [Roll Forward]
Beginning balance	39,938
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	310
Ending balance	40,248
Wealth management
Goodwill [Roll Forward]
Beginning balance	69,373
Goodwill Acquired	0
Impairment Loss	0
Goodwill Adjustments	0
Ending balance	$ 69,373

Goodwill And Other Intangible_4

Goodwill And Other Intangible Assets (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Indefinite-lived Intangible Assets [Line Items]
Amortization of other intangible assets	$ 2,007	$ 2,863
Community banking | Core deposit intangibles
Indefinite-lived Intangible Assets [Line Items]
Amortization period in years, other intangible assets	10 years
Specialty finance
Indefinite-lived Intangible Assets [Line Items]
Goodwill increase (decrease) for foreign currency translation adjustments	$ 310
Specialty finance | Customer list intangibles
Indefinite-lived Intangible Assets [Line Items]
Amortization period in years, other intangible assets	18 years
Wealth management | Customer list intangibles
Indefinite-lived Intangible Assets [Line Items]
Amortization period in years, other intangible assets	10 years

Goodwill And Other Intangible_5

Goodwill And Other Intangible Assets (Summary of Intangible Assets) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Intangibles with finite lives
Accumulated amortization	$ (49,369)	$ (47,362)	$ (39,207)
Intangibles with indefinite lives
Gross carrying amount	83,404	83,402	83,392
Total net carrying amount	34,035	36,040	44,185
Community banking
Intangibles with indefinite lives
Total net carrying amount	26,907	28,326	32,982
Trademark | Community banking
Intangibles with indefinite lives
Carrying amount	5,800	5,800	5,800
Core deposit intangibles | Community banking
Intangibles with finite lives
Gross carrying amount	55,206	55,206	55,206
Accumulated amortization	(34,099)	(32,680)	(28,024)
Net carrying amount	21,107	22,526	27,182
Customer list intangibles | Specialty finance
Intangibles with finite lives
Gross carrying amount	1,968	1,966	1,956
Accumulated amortization	(1,665)	(1,644)	(1,574)
Net carrying amount	303	322	382
Customer list and other intangibles | Wealth management
Intangibles with finite lives
Gross carrying amount	20,430	20,430	20,430
Accumulated amortization	(13,605)	(13,038)	(9,609)
Net carrying amount	$ 6,825	$ 7,392	$ 10,821

Goodwill And Other Intangible_6

Goodwill And Other Intangible Assets (Estimated Amortization) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Actual in three months ended March 31, 2021	$ 2,007	$ 2,863
Estimated remaining in 2021	5,685
Estimated—2022	6,135
Estimated—2023	4,670
Estimated—2024	3,263
Estimated—2025	$ 2,552

Mortgage Servicing Rights ("M_3

Mortgage Servicing Rights ("MSRs") (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of the period	$ 92,081	$ 85,638
Additions from loans sold with servicing retained	24,616	9,447
Estimate of changes in fair value due to:
Early buyout options (“EBO”) exercised	(258)	0
Payoffs and paydowns	(10,168)	(7,024)
Changes in valuation inputs or assumptions	18,045	(14,557)
Fair value at end of the period	124,316	73,504
Unpaid principal balance of mortgage loans serviced for others	$ 11,530,676	$ 8,314,634

Deposits (Detail)

Deposits (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Balance:
Non-interest-bearing	$ 12,297,337	$ 11,748,455	$ 7,556,755
NOW and interest-bearing demand deposits	3,562,312	3,349,021	3,181,159
Wealth management deposits	4,274,527	4,138,712	3,936,968
Money market	9,236,434	9,348,806	8,114,659
Savings	3,690,892	3,531,029	3,282,340
Time certificates of deposit	4,811,150	4,976,628	5,389,779
Total deposits	$ 37,872,652	$ 37,092,651	$ 31,461,660
Mix:
Non-interest-bearing	32.00%	32.00%	24.00%
NOW and interest-bearing demand deposits	9.00%	9.00%	10.00%
Wealth management deposits	11.00%	11.00%	13.00%
Money market	25.00%	25.00%	26.00%
Savings	10.00%	10.00%	10.00%
Time certificates of deposit	13.00%	13.00%	17.00%
Total deposits	100.00%	100.00%	100.00%

FHLB Advances, Other Borrowin_3

FHLB Advances, Other Borrowings and Subordinated Notes (Summary of Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Sep. 18, 2018
Debt Disclosure [Abstract]
FHLB advances	$ 1,228,436	$ 1,228,429	$ 1,174,894
Other borrowings:
Notes payable	96,363	101,710	167,746	$ 150,000
Short-term borrowings	12,416	11,366	12,127
Other	64,659	65,108	66,266
Secured borrowings	343,439	340,744	241,364
Total other borrowings	516,877	518,928	487,503
Subordinated notes	436,595	436,506	436,179
Total FHLB advances, other borrowings and subordinated notes	$ 2,181,908	$ 2,183,863	$ 2,098,576

FHLB Advances, Other Borrowin_4

FHLB Advances, Other Borrowings and Subordinated Notes (Summary of Pledged Securities Related to Securities Sold Under Repurchase Agreements) (Details) - Securities sold under repurchase agreements - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities sold under agreements to repurchase		$ 11,400	$ 12,100
Overnight Sweep Collateral
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged financial instruments	$ 20,580
Excess collateral	8,164
Securities sold under agreements to repurchase	$ 12,416

FHLB Advances, Other Borrowin_5

FHLB Advances, Other Borrowings and Subordinated Notes (Narrative) (Details) $ in Millions

1 Months Ended

3 Months Ended

12 Months Ended

24 Months Ended

48 Months Ended

54 Months Ended

62 Months Ended

65 Months Ended

73 Months Ended

77 Months Ended

May 31, 2020CAD ($)

Jan. 31, 2020CAD ($)

May 31, 2019CAD ($)

Feb. 28, 2019CAD ($)

Jun. 30, 2018CAD ($)

Dec. 31, 2017CAD ($)

Dec. 31, 2015CAD ($)

Dec. 31, 2014CAD ($)

Mar. 31, 2021USD ($)buildingRate

Jun. 30, 2019USD ($)

Dec. 31, 2014USD ($)

Dec. 31, 2015CAD ($)

Dec. 31, 2017CAD ($)

Jun. 30, 2018CAD ($)

Feb. 28, 2019CAD ($)

May 31, 2019CAD ($)

Jan. 31, 2020CAD ($)

May 31, 2020CAD ($)

Dec. 31, 2020USD ($)

Apr. 01, 2020USD ($)

Mar. 31, 2020USD ($)

Sep. 18, 2018USD ($)

Debt Instrument [Line Items]

Notes payable

$ 96,363,000

$ 101,710,000

$ 167,746,000

$ 150,000,000

Short-term borrowings

12,416,000

11,366,000

12,127,000

Other borrowings

64,659,000

65,108,000

66,266,000

Secured borrowings

343,439,000

340,744,000

241,364,000

Subordinated notes

436,595,000

436,506,000

436,179,000

Collateral Pledged

Debt Instrument [Line Items]

Pledged financial instruments

20,600,000

Term Facility

Debt Instrument [Line Items]

Notes payable

96,400,000

150,000,000

Revolving Credit Facility

Debt Instrument [Line Items]

Notes payable

50,000,000

Amount outstanding

$ 0

Subordinated debt maturing June 2029

Debt Instrument [Line Items]

Proceeds from the issuance of subordinated notes, net

$ 296,700,000

Base Rate Loan | Base Rate | Term Facility

Debt Instrument [Line Items]

Basis spread on variable rate

0.75%

Base Rate Loan | Base Rate | Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

0.60%

Base Rate Loan | Federal Funds Rate | Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

0.50%

Base Rate Loan | Eurodollar rate | Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

1.00%

Eurodollar Rate Loan | London Interbank Offered Rate (LIBOR) | Term Facility

Debt Instrument [Line Items]

Basis spread on variable rate

1.25%

Eurodollar Rate Loan | London Interbank Offered Rate (LIBOR) | Revolving Credit Facility

Debt Instrument [Line Items]

Basis spread on variable rate

1.35%

Line of Credit

Debt Instrument [Line Items]

Loan agreement with unaffiliated banks

$ 200,000,000

Revolving Credit Facility

Debt Instrument [Line Items]

Commitment fee | Rate

0.30%

Securities sold under repurchase agreements

Debt Instrument [Line Items]

Securities sold under agreements to repurchase

11,400,000

12,100,000

Securities sold under repurchase agreements | Overnight Sweep Collateral

Debt Instrument [Line Items]

Securities sold under agreements to repurchase

$ 12,416,000

Pledged financial instruments

$ 20,580,000

Fixed Rate Promissory Note

Debt Instrument [Line Items]

Number of properties securing debt | building

3

Other borrowings

$ 64,700,000

65,100,000

$ 66,300,000

Fixed interest rate

3.00%

3.36%

Principal amount of notes

$ 66,400,000

Secured Debt

Debt Instrument [Line Items]

Secured borrowings

$ 9,400,000

Secured Debt | Receivables Purchase Agreement

Debt Instrument [Line Items]

Fixed interest rate

1.1015%

Proceeds from debt issuance

$ 100

$ 40

$ 70

$ 20

$ 20

$ 10

$ 10

$ 150

$ 160

$ 170

$ 190

$ 210

$ 280

$ 320

$ 420

Secured borrowings

$ 334,100,000

$ 329,900,000

$ 227,400,000

Subordinated Debt | Subordinated debt maturing June 2029

Debt Instrument [Line Items]

Fixed interest rate

4.85%

Principal amount of notes

$ 300,000,000

Subordinated Debt | Subordinated debt maturing June 2024

Debt Instrument [Line Items]

Fixed interest rate

5.00%

Principal amount of notes

$ 140,000,000

Proceeds from debt issuance

$ 139,100,000

Junior Subordinated Debenture_2

Junior Subordinated Debentures (Summary of Junior Subordinated Debentures) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures	$ 253,566,000	$ 253,566,000	$ 253,566,000
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Junior Subordinated Debentures	$ 253,566,000	$ 253,600,000	$ 253,600,000
Average contractual rate	2.39%
Junior Subordinated Debt | Wintrust Capital Trust III
Subordinated Borrowing [Line Items]
Common Securities	$ 774,000
Trust  Preferred Securities	25,000,000
Junior Subordinated Debentures	$ 25,774,000
Contractual rate	3.49%
Junior Subordinated Debt | Wintrust Capital Trust III | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	3.25%
Junior Subordinated Debt | Wintrust Statutory Trust IV
Subordinated Borrowing [Line Items]
Common Securities	$ 619,000
Trust  Preferred Securities	20,000,000
Junior Subordinated Debentures	$ 20,619,000
Contractual rate	3.00%
Junior Subordinated Debt | Wintrust Statutory Trust IV | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	2.80%
Junior Subordinated Debt | Wintrust Statutory Trust V
Subordinated Borrowing [Line Items]
Common Securities	$ 1,238,000
Trust  Preferred Securities	40,000,000
Junior Subordinated Debentures	$ 41,238,000
Contractual rate	2.80%
Junior Subordinated Debt | Wintrust Statutory Trust V | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	2.60%
Junior Subordinated Debt | Wintrust Capital Trust VII
Subordinated Borrowing [Line Items]
Common Securities	$ 1,550,000
Trust  Preferred Securities	50,000,000
Junior Subordinated Debentures	$ 51,550,000
Contractual rate	2.13%
Junior Subordinated Debt | Wintrust Capital Trust VII | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	1.95%
Junior Subordinated Debt | Wintrust Capital Trust VIII
Subordinated Borrowing [Line Items]
Common Securities	$ 1,238,000
Trust  Preferred Securities	25,000,000
Junior Subordinated Debentures	$ 26,238,000
Contractual rate	1.65%
Junior Subordinated Debt | Wintrust Capital Trust VIII | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	1.45%
Junior Subordinated Debt | Wintrust Capital Trust IX
Subordinated Borrowing [Line Items]
Common Securities	$ 1,547,000
Trust  Preferred Securities	50,000,000
Junior Subordinated Debentures	$ 51,547,000
Contractual rate	1.81%
Junior Subordinated Debt | Wintrust Capital Trust IX | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	1.63%
Junior Subordinated Debt | Northview Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186,000
Trust  Preferred Securities	6,000,000
Junior Subordinated Debentures	$ 6,186,000
Contractual rate	3.21%
Junior Subordinated Debt | Northview Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	3.00%
Junior Subordinated Debt | Town Bankshares Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 186,000
Trust  Preferred Securities	6,000,000
Junior Subordinated Debentures	$ 6,186,000
Contractual rate	3.21%
Junior Subordinated Debt | Town Bankshares Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	3.00%
Junior Subordinated Debt | First Northwest Capital Trust I
Subordinated Borrowing [Line Items]
Common Securities	$ 155,000
Trust  Preferred Securities	5,000,000
Junior Subordinated Debentures	$ 5,155,000
Contractual rate	3.20%
Junior Subordinated Debt | First Northwest Capital Trust I | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	3.00%
Junior Subordinated Debt | Suburban Illinois Capital Trust II
Subordinated Borrowing [Line Items]
Common Securities	$ 464,000
Trust  Preferred Securities	15,000,000
Junior Subordinated Debentures	$ 15,464,000
Contractual rate	1.93%
Junior Subordinated Debt | Suburban Illinois Capital Trust II | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	1.75%
Junior Subordinated Debt | Community Financial Shares Statutory Trust II
Subordinated Borrowing [Line Items]
Common Securities	$ 109,000
Trust  Preferred Securities	3,500,000
Junior Subordinated Debentures	$ 3,609,000
Contractual rate	1.80%
Junior Subordinated Debt | Community Financial Shares Statutory Trust II | London Interbank Offered Rate (LIBOR)
Subordinated Borrowing [Line Items]
Rate structure, spread on variable interest rate	1.62%

Junior Subordinated Debenture_3

Junior Subordinated Debentures (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2021USD ($)trustRate	Dec. 31, 2020USD ($)	Mar. 31, 2020USD ($)
Subordinated Borrowing [Line Items]
Percentage ownership interest in subsidiary trusts	100.00%
Number of unconsolidated subsidiary trusts | trust	11
Common securities, approximate percentage of junior subordinated debentures	3.00%
Trust preferred securities, approximate percentage of junior subordinated debentures	97.00%
Junior subordinated debentures	$ 253,566,000	$ 253,566,000	$ 253,566,000
Period of deferred payment, not to exceed	60 months
Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Junior subordinated debentures	$ 253,566,000	$ 253,600,000	$ 253,600,000
Average contractual rate | Rate	2.39%
Tier two risk based capital	$ 245,500,000
Interest rate swaps | Junior Subordinated Debt
Subordinated Borrowing [Line Items]
Derivative notional amount	$ 210,000,000
Hedge-adjusted contractual interest rate	3.98%

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Disaggregation of Revenue by Source) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 47,768	$ 43,655
Brokerage and insurance product commissions
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,040	5,281
Trust
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5,017	5,291
Asset management
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	19,252	15,369
Wealth management
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	29,309	25,941
Mortgage broker fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	76	53
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	12,036	11,265
Administrative services
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,256	1,112
Card related fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1,774	2,106
Other deposit related fees
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 3,317	$ 3,178

Revenue from Contracts with C_4

Revenue from Contracts with Customers (Contract Assets, Contract Liabilities and Receivables from Contracts with Customers) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract assets	$ 0	$ 0	$ 0
Contract liabilities	1,818	1,548	728
Mortgage broker fees receivable	31	20	11
Administrative services receivable	215	64	214
Wealth management receivable	11,315	10,144	8,218
Card related fees receivable	1,075	783	422
Total receivables from contracts with customer	$ 12,636	$ 11,011	$ 8,865

Revenue from Contracts with C_5

Revenue from Contracts with Customers (Performance Obligations Unsatisfied at End of Period) (Details) $ in Thousands	Mar. 31, 2021USD ($)
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially unsatisfied	$ 1,818
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially unsatisfied	$ 668
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated remaining performance period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially unsatisfied	$ 400
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated remaining performance period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially unsatisfied	$ 400
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated remaining performance period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially unsatisfied	$ 250
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated remaining performance period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially unsatisfied	$ 100
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated remaining performance period	1 year

Revenue from Contracts with C_6

Revenue from Contracts with Customers (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)subsidiary	Mar. 31, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Number of wealth management subsidiaries | subsidiary	4
Revenue recognized from contract liability balance | $	$ 414	$ 628

Segment Information (Narrative)

Segment Information (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2021segmentsubsidiary
Segment Reporting Information [Line Items]
Number of reportable segments	3
Number of subsidiaries | subsidiary	15
Community banking
Segment Reporting Information [Line Items]
Number of reportable segments	1

Segment Information (Summary of

Segment Information (Summary of Segment Information) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Net interest income:
Net interest income	$ 261,895	$ 261,443
Net interest income, Change in Contribution	$ 452
Net interest income, Change in Contribution (as a percent)	0.00%
Provision for credit losses:
Provision for credit losses	$ (45,347)	52,961
Provision for credit losses, Change in Contribution	$ (98,308)
Provision for credit losses, Change in Contribution (as a percent)	(186.00%)
Non-interest income:
Non-interest income	$ 186,506	113,242
Non-interest income, Change in Contribution	$ 73,264
Non-interest income, Change in Contribution (as a percent)	65.00%
Net revenue:
Net revenue	$ 448,401	374,685
Net revenue, Change in Contribution	$ 73,716
Net revenue, Change in Contribution (as a percent)	20.00%
Segment profit:
Segment profit	$ 153,148	62,812
Segment profit, Change in Contribution	$ 90,336
Segment profit, Change in Contribution (as a percent)	144.00%
Segment assets:
Segment assets	$ 45,682,202	38,799,847	$ 45,080,768
Segment assets, Change in Contribution	$ 6,882,355
Segment assets, Change in Contribution (as a percent)	18.00%
Community banking
Segment profit:
Segment profit	$ 121,801	34,589
Segment profit, Change in Contribution	$ 87,212
Segment profit, Change in Contribution (as a percent)	252.00%
Segment assets:
Segment assets	$ 37,102,603	31,499,899
Segment assets, Change in Contribution	$ 5,602,704
Segment assets, Change in Contribution (as a percent)	18.00%
Specialty finance
Segment profit:
Segment profit	$ 23,903	22,133
Segment profit, Change in Contribution	$ 1,770
Segment profit, Change in Contribution (as a percent)	8.00%
Segment assets:
Segment assets	$ 7,174,269	6,133,548
Segment assets, Change in Contribution	$ 1,040,721
Segment assets, Change in Contribution (as a percent)	17.00%
Wealth management
Segment profit:
Segment profit	$ 7,444	6,090
Segment profit, Change in Contribution	$ 1,354
Segment profit, Change in Contribution (as a percent)	22.00%
Segment assets:
Segment assets	$ 1,405,330	1,166,400
Segment assets, Change in Contribution	$ 238,930
Segment assets, Change in Contribution (as a percent)	20.00%
Operating Segments
Net interest income:
Net interest income	$ 255,837	255,339
Net interest income, Change in Contribution	$ 498
Net interest income, Change in Contribution (as a percent)	0.00%
Provision for credit losses:
Provision for credit losses	$ (45,347)	52,961
Provision for credit losses, Change in Contribution	$ (98,308)
Provision for credit losses, Change in Contribution (as a percent)	(186.00%)
Non-interest income:
Non-interest income	$ 200,628	126,441
Non-interest income, Change in Contribution	$ 74,187
Non-interest income, Change in Contribution (as a percent)	59.00%
Net revenue:
Net revenue	$ 456,465	381,780
Net revenue, Change in Contribution	$ 74,685
Net revenue, Change in Contribution (as a percent)	20.00%
Operating Segments | Community banking
Net interest income:
Net interest income	$ 203,489	206,835
Net interest income, Change in Contribution	$ (3,346)
Net interest income, Change in Contribution (as a percent)	(2.00%)
Provision for credit losses:
Provision for credit losses	$ (46,572)	51,677
Provision for credit losses, Change in Contribution	$ (98,249)
Provision for credit losses, Change in Contribution (as a percent)	(190.00%)
Non-interest income:
Non-interest income	$ 147,268	81,003
Non-interest income, Change in Contribution	$ 66,265
Non-interest income, Change in Contribution (as a percent)	82.00%
Net revenue:
Net revenue	$ 350,757	287,838
Net revenue, Change in Contribution	$ 62,919
Net revenue, Change in Contribution (as a percent)	22.00%
Operating Segments | Specialty finance
Net interest income:
Net interest income	$ 44,899	40,712
Net interest income, Change in Contribution	$ 4,187
Net interest income, Change in Contribution (as a percent)	10.00%
Provision for credit losses:
Provision for credit losses	$ 1,225	1,284
Provision for credit losses, Change in Contribution	$ (59)
Provision for credit losses, Change in Contribution (as a percent)	(5.00%)
Non-interest income:
Non-interest income	$ 23,109	21,308
Non-interest income, Change in Contribution	$ 1,801
Non-interest income, Change in Contribution (as a percent)	8.00%
Net revenue:
Net revenue	$ 68,008	62,020
Net revenue, Change in Contribution	$ 5,988
Net revenue, Change in Contribution (as a percent)	10.00%
Operating Segments | Wealth management
Net interest income:
Net interest income	$ 7,449	7,792
Net interest income, Change in Contribution	$ (343)
Net interest income, Change in Contribution (as a percent)	(4.00%)
Provision for credit losses:
Provision for credit losses	$ 0	0
Provision for credit losses, Change in Contribution	$ 0
Provision for credit losses, Change in Contribution (as a percent)	0.00%
Non-interest income:
Non-interest income	$ 30,251	24,130
Non-interest income, Change in Contribution	$ 6,121
Non-interest income, Change in Contribution (as a percent)	25.00%
Net revenue:
Net revenue	$ 37,700	31,922
Net revenue, Change in Contribution	$ 5,778
Net revenue, Change in Contribution (as a percent)	18.00%
Intersegment Eliminations
Net interest income:
Net interest income	$ 6,058	6,104
Net interest income, Change in Contribution	$ (46)
Net interest income, Change in Contribution (as a percent)	(1.00%)
Provision for credit losses:
Provision for credit losses	$ 0	0
Provision for credit losses, Change in Contribution	$ 0
Provision for credit losses, Change in Contribution (as a percent)	0.00%
Non-interest income:
Non-interest income	$ (14,122)	(13,199)
Non-interest income, Change in Contribution	$ (923)
Non-interest income, Change in Contribution (as a percent)	7.00%
Net revenue:
Net revenue	$ (8,064)	$ (7,095)
Net revenue, Change in Contribution	$ (969)
Net revenue, Change in Contribution (as a percent)	14.00%

Derivative Financial Instrume_3

Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Derivative [Line Items]
Derivative assets	$ 253,509	$ 278,423	$ 301,368
Derivative liabilities	200,758	288,465	367,620
Interest Rate Contract
Derivative [Line Items]
Derivative assets	206,236	229,387	259,986
Derivative liabilities	196,091	275,843	329,590
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	50,541	8,182	0
Derivative liabilities	40,730	54,235	73,397
Designated as Hedging Instrument | Interest Rate Contract | Cash Flow Hedging
Derivative [Line Items]
Derivative assets	50,420	8,182	0
Derivative liabilities	31,161	39,715	57,274
Designated as Hedging Instrument | Interest Rate Contract | Fair Value Hedging
Derivative [Line Items]
Derivative assets	121	0	0
Derivative liabilities	9,569	14,520	16,123
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	202,968	270,241	301,368
Derivative liabilities	160,028	234,230	294,223
Not Designated as Hedging Instrument | Interest Rate Contract
Derivative [Line Items]
Derivative assets	155,695	221,205	259,986
Derivative liabilities	155,361	221,608	256,193
Not Designated as Hedging Instrument | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative assets	44,313	48,925	39,816
Derivative liabilities	1,342	0	1,105
Not Designated as Hedging Instrument | Forward Commitments to Sell Mortgage Loans
Derivative [Line Items]
Derivative assets	2,920	0	1,514
Derivative liabilities	3,283	12,510	36,872
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative assets	40	111	52
Derivative liabilities	$ 42	$ 112	$ 53

Derivative Financial Instrume_4

Derivative Financial Instruments (Narrative) (Detail)	3 Months Ended
	Mar. 31, 2021USD ($)derivative_instrument	Dec. 31, 2020derivative_instrument	Mar. 31, 2020derivative_instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount to be reclassified from accumulated other comprehensive income to interest expense in the next twelve months	$ 19,900,000
Net derivative liability position, aggregate fair value	131,400,000
Interest Rate Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	1,000,000,000
Interest Rate Contract, Qualified Borrowers | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	9,000,000,000
Forward Commitments to Sell Mortgage Loans | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	2,300,000,000
Interest Rate Lock Commitments | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	1,100,000,000
Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount	$ 3,800,000
Covered Call Options | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instrument	0	0	0
Mortgage banking derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Number of derivative instruments held | derivative_instrument	0
Cash Flow Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instrument	27
Cash Flow Hedging | Interest Rate Collar | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instrument	1
Fair Value Hedging | Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives held | derivative_instrument	17
Notional amount	$ 167,500,000

Derivative Financial Instrume_5

Derivative Financial Instruments (Schedule Of Cash Flow Hedging Instruments) (Detail) - Cash Flow Hedging - Designated as Hedging Instrument	Mar. 31, 2021USD ($)
October 2021
Derivative [Line Items]
Notional	$ 25,000,000
Fair Value - Asset (Liability)	(286,000)
November 2021
Derivative [Line Items]
Notional	20,000,000
Fair Value - Asset (Liability)	(287,000)
December 2021
Derivative [Line Items]
Notional	165,000,000
Fair Value - Asset (Liability)	(2,614,000)
March 2022
Derivative [Line Items]
Notional	500,000,000
Fair Value - Asset (Liability)	(220,000)
May 2022
Derivative [Line Items]
Notional	370,000,000
Fair Value - Asset (Liability)	(7,884,000)
June 2022
Derivative [Line Items]
Notional	160,000,000
Fair Value - Asset (Liability)	(3,652,000)
July 2022
Derivative [Line Items]
Notional	230,000,000
Fair Value - Asset (Liability)	(5,359,000)
August 2022
Derivative [Line Items]
Notional	235,000,000
Fair Value - Asset (Liability)	(5,944,000)
March 2023
Derivative [Line Items]
Notional	250,000,000
Fair Value - Asset (Liability)	(300,000)
April 2024
Derivative [Line Items]
Notional	250,000,000
Fair Value - Asset (Liability)	598,000
July 2027
Derivative [Line Items]
Notional	1,000,000,000
Fair Value - Asset (Liability)	49,823,000
September 2023
Derivative [Line Items]
Notional	96,429,000
Fair Value - Asset (Liability)	(4,616,000)
Total Cash Flow Hedges
Derivative [Line Items]
Notional	3,301,429,000
Fair Value - Asset (Liability)	$ 19,259,000

Derivative Financial Instrume_6

Derivative Financial Instruments (Rollforward Of Amounts In Accumulated Other Comprehensive Income Related To Interest Rate Swaps Designated As Cash Flow Hedges) (Detail) - Interest Rate Contract - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Unrealized loss at beginning of period	$ (31,533)	$ (17,943)
Amount reclassified from accumulated other comprehensive income to interest expense on deposits, other borrowings and junior subordinated debentures	6,696	1,090
Amount of income (loss) recognized in other comprehensive income	44,096	(39,783)
Unrealized gain (loss) at end of period	$ 19,259	$ (56,636)

Derivative Financial Instrume_7

Derivative Financial Instruments (Schedule of Carrying Amount of Hedged Assets/(Liabilities)) (Detail) - Interest Rate Swap - Designated as Hedging Instrument $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Loans, net of unearned income
Derivative [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	$ 175,605
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	9,262
Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued	(157)
Available-for-sale debt securities
Derivative [Line Items]
Carrying Amount of the Hedged Assets/(Liabilities)	1,303
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	94
Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued	0
Interest and fees on loans
Derivative [Line Items]
Location of (Loss)/Gain Recognized in Income on Derivative	(13)
Interest income - investment securities
Derivative [Line Items]
Location of (Loss)/Gain Recognized in Income on Derivative	$ 0

Derivative Financial Instrume_8

Derivative Financial Instruments (Summary Amounts Included In Consolidated Statement Of Income Related To Derivatives) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest rate swaps and caps | Trading gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	$ 428	$ (428)
Mortgage banking derivatives | Mortgage banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	(17,479)	17,267
Foreign exchange contracts | Trading gains (losses), net
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	(5)	(4)
Covered call options | Fees from covered call options
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	0	2,292
Derivative contract held as economic hedge on MSRs | Mortgage banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on derivative instruments	0	$ 4,160
Interest Rate Swap | Loans, net of unearned income | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Asset, Fair Value Hedge	175,605
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	9,262
Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued	(157)
Interest Rate Swap | Available-for-sale Securities [Member] | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Asset, Fair Value Hedge	1,303
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount of the Hedged Assets/(Liabilities)	94
Cumulative Amount of Fair Value Hedging Adjustment Remaining for any Hedged Assets (Liabilities) for which Hedge Accounting has been Discontinued	$ 0

Derivative Financial Instrume_9

Derivative Financial Instruments (Summary of Interest Rate Derivatives and Offsetting Positions) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Derivative Assets
Derivative assets	$ 253,509	$ 278,423	$ 301,368
Derivative Liabilities
Gross Amounts Recognized	200,758	288,465	367,620
Interest rate derivatives
Derivative Assets
Derivative assets	206,236	229,387	259,986
Less: Amounts offset in the Statements of Condition	0	0	0
Net amount presented in the Statements of Condition	206,236	229,387	259,986
Offsetting Derivative Positions	(60,593)	(8,647)	(1,048)
Collateral Posted	0	0	0
Net Credit Exposure	145,643	220,740	258,938
Derivative Liabilities
Gross Amounts Recognized	196,091	275,843	329,590
Less: Amounts offset in the Statements of Condition	0	0	0
Net amount presented in the Statements of Condition	196,091	275,843	329,590
Offsetting Derivative Positions	(60,593)	(8,647)	(1,048)
Collateral Posted	(125,818)	(266,832)	(328,542)
Net Credit Exposure	$ 9,680	$ 364	$ 0

Fair Values of Assets and Lia_3

Fair Values of Assets and Liabilities (Narrative) (Detail) $ in Thousands	Mar. 31, 2021USD ($)	Mar. 31, 2021	Mar. 31, 2021$ / shares	Dec. 31, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 2,430,749			$ 3,055,839	$ 3,570,959
Loans held-for-investment	51,916				142,267
MSRs	124,316			92,081	73,504	$ 85,638
Individually assessed loans - foreclosure probable and collateral-dependent	124,404				188,740
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	2,430,749			3,055,839	3,570,959
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	1,200,000			1,200,000	618,700
Portion at Other than Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	36,600
Non-performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale, at fair value	115,200			134,100	358
Appraisal adjustment - cost of sale | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, measurement input		0.10
Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	51,916			55,134	142,267
MSRs	124,316			92,081	73,504
Mortgage loans held-for-sale, at fair value	1,260,193			1,272,090	656,934
Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	87,757
Other real estate owned	15,813
Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-investment	6,408			10,280	9,568
MSRs	124,316			92,081	73,504
Derivative assets	25,600
Mortgage loans held-for-sale, at fair value	0			0	0
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Weighted Average of Inputs | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		0.0988
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Weighted Average of Inputs | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.0238
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Weighted Average of Inputs | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.0988
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Minimum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		0.03
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Minimum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.02
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Minimum | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.03
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Maximum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		0.19
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Maximum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.03
Level 3 | Measured at fair value on a recurring basis: | Discount rate | Maximum | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.19
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Weighted Average of Inputs | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.0026
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Minimum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0
Level 3 | Measured at fair value on a recurring basis: | Credit discount | Maximum | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.03
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Loans held-for-investment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.1299
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Weighted Average of Inputs | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		0.1299
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Weighted Average of Inputs | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.1299
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Minimum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		0.06
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Minimum | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.06
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Maximum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		0.92
Level 3 | Measured at fair value on a recurring basis: | Constant prepayment rate (CPR) | Maximum | Mortgage servicing rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate		0.92
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Weighted Average of Inputs | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		76	76
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Minimum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares			70
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing | Maximum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares			200
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Weighted Average of Inputs | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input		354	354
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Minimum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares			200
Level 3 | Measured at fair value on a recurring basis: | Cost of servicing - delinquent | Maximum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs, measurement input | $ / shares			1,000
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Weighted Average of Inputs | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, measurement input		0.8639
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Minimum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, measurement input		0.14
Level 3 | Measured at fair value on a recurring basis: | Pull-through rate | Maximum | Discounted cash flows
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, measurement input		1
Level 3 | Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	87,757
Other real estate owned	15,813
Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	148,300			146,910	146,609
Municipal Securities | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	148,300			146,910	146,609
Municipal Securities | Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	101,748			109,876	113,267
U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	81,526			84,513	368,643
U.S. Government agencies | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	81,526			84,513	368,643
U.S. Government agencies | Level 3 | Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 1,784			$ 1,966	$ 2,457

Fair Values of Assets and Lia_4

Fair Values of Assets and Liabilities (Summary of Balances of Assets and Liabilities Measured at Fair Value On A Recurring Basis) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 2,430,749	$ 3,055,839	$ 3,570,959
Equity securities with readily determinable fair value	90,338	90,862	47,310
Loans held-for-investment	51,916		142,267
MSRs	124,316	92,081	73,504	$ 85,638
U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	65,001	304,971	121,670
U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	81,526	84,513	368,643
Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	148,300	146,910	146,609
Measured at fair value on a recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	951	671	2,257
Equity securities with readily determinable fair value	90,338	90,862	47,310
Mortgage loans held-for-sale, at fair value	1,260,193	1,272,090	656,934
Loans held-for-investment	51,916	55,134	142,267
MSRs	124,316	92,081	73,504
Nonqualified deferred compensation assets	15,891	15,398	12,253
Derivative assets	253,509	278,423	301,368
Total financial assets	4,227,863	4,860,498	4,806,852
Derivative liabilities	200,758	288,465	367,620
Measured at fair value on a recurring basis: | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	65,001	304,971	121,670
Measured at fair value on a recurring basis: | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	81,526	84,513	368,643
Measured at fair value on a recurring basis: | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	148,300	146,910	146,609
Measured at fair value on a recurring basis: | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	92,349	91,405	101,018
Measured at fair value on a recurring basis: | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,043,573	2,428,040	2,833,019
Measured at fair value on a recurring basis: | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	0	0	0
Equity securities with readily determinable fair value	82,272	82,796	39,244
Mortgage loans held-for-sale, at fair value	0	0	0
Loans held-for-investment	0	0	0
MSRs	0	0	0
Nonqualified deferred compensation assets	0	0	0
Derivative assets	0	0	0
Total financial assets	147,273	387,767	160,914
Derivative liabilities	0	0	0
Measured at fair value on a recurring basis: | Level 1 | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	65,001	304,971	121,670
Measured at fair value on a recurring basis: | Level 1 | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 1 | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 1 | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 1 | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	951	671	2,257
Equity securities with readily determinable fair value	8,066	8,066	8,066
Mortgage loans held-for-sale, at fair value	1,260,193	1,272,090	656,934
Loans held-for-investment	45,508	44,854	132,699
MSRs	0	0	0
Nonqualified deferred compensation assets	15,891	15,398	12,253
Derivative assets	227,875	230,332	261,552
Total financial assets	3,820,700	4,210,437	4,407,326
Derivative liabilities	200,758	288,465	367,620
Measured at fair value on a recurring basis: | Level 2 | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 2 | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	79,742	82,547	366,186
Measured at fair value on a recurring basis: | Level 2 | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	46,552	37,034	33,342
Measured at fair value on a recurring basis: | Level 2 | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	92,349	91,405	101,018
Measured at fair value on a recurring basis: | Level 2 | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	2,043,573	2,428,040	2,833,019
Measured at fair value on a recurring basis: | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account securities	0	0	0
Equity securities with readily determinable fair value	0	0	0
Mortgage loans held-for-sale, at fair value	0	0	0
Loans held-for-investment	6,408	10,280	9,568
MSRs	124,316	92,081	73,504
Nonqualified deferred compensation assets	0	0	0
Derivative assets	25,634	48,091	39,816
Total financial assets	259,890	262,294	238,612
Derivative liabilities	0	0	0
Measured at fair value on a recurring basis: | Level 3 | U.S. Treasury
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 3 | U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	1,784	1,966	2,457
Measured at fair value on a recurring basis: | Level 3 | Municipal Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	101,748	109,876	113,267
Measured at fair value on a recurring basis: | Level 3 | Corporate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0	0
Measured at fair value on a recurring basis: | Level 3 | Mortgage-backed
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 0	$ 0	$ 0

Fair Values of Assets and Lia_5

Fair Values of Assets and Liabilities (Summary of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Loans held-for- investment
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 10,280	$ 9,620
Net Income	(530)	(78)
Other comprehensive income (loss)	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(3,918)	(96)
Net transfers into/(out of) Level 3	576	122
Ending Balance	6,408	9,568
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	92,081	85,638
Net Income	32,235	(12,134)
Other comprehensive income (loss)	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into/(out of) Level 3	0	0
Ending Balance	124,316	73,504
Derivative assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	48,091	2,631
Net Income	(22,457)	37,185
Other comprehensive income (loss)	0	0
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	0	0
Net transfers into/(out of) Level 3	0	0
Ending Balance	25,634	39,816
Municipal Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	109,876	111,950
Net Income	0	0
Other comprehensive income (loss)	(2,068)	(1,249)
Purchases	0	5,875
Issuances	0	0
Sales	0	0
Settlements	(6,060)	(3,309)
Net transfers into/(out of) Level 3	0	0
Ending Balance	101,748	113,267
U.S. Government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,966	2,646
Net Income	0	0
Other comprehensive income (loss)	(24)	(32)
Purchases	0	0
Issuances	0	0
Sales	0	0
Settlements	(158)	(157)
Net transfers into/(out of) Level 3	0	0
Ending Balance	$ 1,784	$ 2,457

Fair Values of Assets and Lia_6

Fair Values of Assets and Liabilities (Summary of Assets Measured at Fair Value on a Nonrecurring Basis) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	$ 124,404	$ 188,740
Fair value losses - individually assessed loans - foreclosure probable and collateral-dependent	12,548
Fair value losses - other real estate owned	170
Fair value losses	12,718
Measured at fair value on a non-recurring basis:
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	87,757
Other real estate owned	15,813
Total financial assets	103,570
Measured at fair value on a non-recurring basis: | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	0
Other real estate owned	0
Total financial assets	0
Measured at fair value on a non-recurring basis: | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	0
Other real estate owned	0
Total financial assets	0
Measured at fair value on a non-recurring basis: | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Individually assessed loans - foreclosure probable and collateral-dependent	87,757
Other real estate owned	15,813
Total financial assets	$ 103,570

Fair Values of Assets and Lia_7

Fair Values of Assets and Liabilities (Schedule of Valuation Techniques and Significant Unobservable Inputs Used to Measure Both Recurring and Non-Recurring) (Detail) $ in Thousands	Mar. 31, 2021USD ($)	Mar. 31, 2021	Mar. 31, 2021$ / shares	Dec. 31, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	$ 2,430,749			$ 3,055,839	$ 3,570,959
Loans held-for-investment	51,916				142,267
MSRs	124,316			92,081	73,504	$ 85,638
Individually assessed loans - foreclosure probable and collateral-dependent	124,404				188,740
Municipal Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	148,300			146,910	146,609
U.S. Government agencies
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	81,526			84,513	368,643
Measured at fair value on a recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment	51,916			55,134	142,267
MSRs	124,316			92,081	73,504
Derivative assets	253,509			278,423	301,368
Measured at fair value on a recurring basis: | Municipal Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	148,300			146,910	146,609
Measured at fair value on a recurring basis: | U.S. Government agencies
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	81,526			84,513	368,643
Measured at fair value on a non-recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	15,813
Individually assessed loans - foreclosure probable and collateral-dependent	87,757
Level 3 | Measured at fair value on a recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment	6,408			10,280	9,568
MSRs	124,316			92,081	73,504
Derivative assets	25,634			48,091	39,816
Level 3 | Measured at fair value on a recurring basis: | Municipal Securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	101,748			109,876	113,267
Level 3 | Measured at fair value on a recurring basis: | U.S. Government agencies
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Available-for-sale securities, at fair value	1,784			$ 1,966	$ 2,457
Level 3 | Measured at fair value on a non-recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other real estate owned	15,813
Individually assessed loans - foreclosure probable and collateral-dependent	$ 87,757
Discount rate | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.02
MSRs, measurement input		0.03
Discount rate | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.03
MSRs, measurement input		0.19
Discount rate | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.0238
MSRs, measurement input		0.0988
Credit discount | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0
Credit discount | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.03
Credit discount | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.0026
Constant prepayment rate (CPR) | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.1299
Constant prepayment rate (CPR) | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input		0.06
Constant prepayment rate (CPR) | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input		0.92
Constant prepayment rate (CPR) | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-investment, measurement input		0.1299
MSRs, measurement input		0.1299
Cost of servicing | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares			70
Cost of servicing | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares			200
Cost of servicing | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input		76	76
Cost of servicing - delinquent | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares			200
Cost of servicing - delinquent | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input | $ / shares			1,000
Cost of servicing - delinquent | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
MSRs, measurement input		354	354
Pull-through rate | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input		0.14
Pull-through rate | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input		1
Pull-through rate | Discounted cash flows | Level 3 | Measured at fair value on a recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives, measurement input		0.8639
Appraisal adjustment - cost of sale | Appraisal value | Level 3 | Measured at fair value on a non-recurring basis:
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans—collateral based, measurement input		0.10
Other real estate owned, measurement input		0.10
Appraisal adjustment - cost of sale | Appraisal value | Level 3 | Measured at fair value on a non-recurring basis: | Weighted Average of Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Impaired loans—collateral based, measurement input		0.1000
Other real estate owned, measurement input		0.1000

Fair Values of Assets and Lia_8

Fair Values of Assets and Liabilities (Summary Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing deposits with banks	$ 3,348,794	$ 4,802,527	$ 1,943,743
Available-for-sale securities	2,430,749	3,055,839	3,570,959
Held-to-maturity securities	2,121,065	593,767	879,192
Equity securities with readily determinable fair value	90,338	90,862	47,310
FHLB and FRB stock, at cost	135,881	135,588	134,546
Brokerage customer receivables	19,056	17,436	16,293
Mortgage loans held-for-sale, at fair value	1,260,193	1,272,090	656,934
Loans held-for-investment	33,171,233	32,079,073	27,807,321
Accrued interest receivable and other	1,230,362	1,351,455	1,460,168
FHLB advances	1,228,436	1,228,429	1,174,894
Other borrowings	516,877	518,928	487,503
Subordinated notes	436,595	436,506	436,179
Junior subordinated debentures	253,566	253,566	253,566
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	426,377	322,474	349,427
Interest-bearing deposits with banks	3,348,794	4,802,527	1,943,743
Available-for-sale securities	2,430,749	3,055,839	3,570,959
Held-to-maturity securities	2,166,419	579,138	865,376
Trading account securities	951	671	2,257
Equity securities with readily determinable fair value	90,338	90,862	47,310
FHLB and FRB stock, at cost	135,881	135,588	134,546
Brokerage customer receivables	19,056	17,436	16,293
Mortgage loans held-for-sale, at fair value	1,260,193	1,272,090	656,934
Nonqualified deferred compensation assets	15,891	15,398	12,253
Derivative assets	253,509	278,423	301,368
Accrued interest receivable and other	281,020	272,339	275,499
Total financial assets	43,600,411	42,921,858	35,983,286
Non-maturity deposits	33,061,502	32,116,023	26,071,881
Deposits with stated maturities	4,811,150	4,976,628	5,389,779
FHLB advances	1,228,436	1,228,429	1,174,894
Other borrowings	516,877	518,928	487,503
Subordinated notes	436,595	436,506	436,179
Junior subordinated debentures	253,566	253,566	253,566
Derivative liabilities	200,758	288,465	367,620
Accrued interest payable	19,940	15,645	27,696
Total financial liabilities	40,528,824	39,834,190	34,209,118
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	426,377	322,474	349,427
Interest-bearing deposits with banks	3,348,794	4,802,527	1,943,743
Available-for-sale securities	2,430,749	3,055,839	3,570,959
Held-to-maturity securities	2,121,065	593,767	879,192
Trading account securities	951	671	2,257
Equity securities with readily determinable fair value	90,338	90,862	47,310
FHLB and FRB stock, at cost	135,881	135,588	134,546
Brokerage customer receivables	19,056	17,436	16,293
Mortgage loans held-for-sale, at fair value	1,260,193	1,272,090	656,934
Nonqualified deferred compensation assets	15,891	15,398	12,253
Derivative assets	253,509	278,423	301,368
Accrued interest receivable and other	281,020	272,339	275,499
Total financial assets	43,502,500	42,784,231	35,801,537
Non-maturity deposits	33,061,502	32,116,023	26,071,881
Deposits with stated maturities	4,801,257	4,969,849	5,394,523
FHLB advances	1,121,269	1,172,315	1,130,327
Other borrowings	516,877	518,928	487,503
Subordinated notes	458,832	473,093	487,745
Junior subordinated debentures	208,132	204,713	224,523
Derivative liabilities	200,758	288,465	367,620
Accrued interest payable	19,940	15,645	27,696
Total financial liabilities	40,388,567	39,759,031	34,191,818
Loans held-for-investment, at fair value | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-investment	51,916	55,134	142,267
Loans held-for-investment, at fair value | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-investment	51,916	55,134	142,267
Loans held-for-investment, at amortized cost | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-investment	33,119,317	32,023,939	27,665,054
Loans held-for-investment, at amortized cost | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held-for-investment	$ 33,066,760	$ 31,871,683	$ 27,469,489

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	May 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares approved for issuance (in shares)			5,485,000
Shares available for future grants (in shares)	951,000
Number of stock options granted	0	0
Stock-based compensation expense	$ 2.9	$ (2.8)
Aggregate intrinsic value of options exercised	6.6	2.7
Cash received from option exercises	$ 9	$ 3.7
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term	7 years
Stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	5 years
Restricted shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Restricted shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	5 years
LTIP awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Term	7 years
LTIP awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance based award payouts	0.00%
LTIP awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of performance based award payouts	150.00%
Performance-based stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Performance period	3 years

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans (Summary Of Stock Option Activity) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Common Shares
Common Shares, Outstanding at beginning of the period (in shares)	520,663	755,332
Common Shares, Granted (in shares)	0	0
Common Shares, Exercised (in shares)	(208,579)	(94,653)
Common Shares, Forfeited or canceled (in shares)	(590)	0
Common Shares, Outstanding at end of the period (in shares)	311,494	660,679
Common Shares, Exercisable (in shares)	309,945	650,456
Weighted Average Strike Price
Weighted Average Strike Price, Outstanding at beginning of period (usd per share)	$ 42.47	$ 42.43
Weighted Average Strike Price, Granted (usd per share)	0	0
Weighted Average Strike Price, Exercised (usd per share)	42.96	38.69
Weighted Average Strike Price, Forfeited or canceled (usd per share)	46.86	0
Weighted Average Strike Price, Outstanding at end of period (usd per share)	42.14	42.97
Weighted Average Strike Price, Exercisable (usd per share)	$ 42.11	$ 42.95
Remaining Contractual Term, Outstanding	1 year 9 months 18 days	2 years 6 months
Remaining Contractual Term, Exercisable	1 year 9 months 18 days	2 years 4 months 24 days
Intrinsic Value, Outstanding	$ 10,485	$ 0
Intrinsic Value, Exercisable	$ 10,441	$ 1

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans (Summary Of Plans' Restricted Share And Performance-Vested Stock Award Activity) (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Restricted shares
Common Shares
Outstanding Beginning of the Period (in shares)	234,794	144,328
Granted (in shares)	257,189	99,963
Vested and issued (in shares)	(7,104)	(9,633)
Expired, canceled or forfeited (in shares)	(849)	(3,538)
Outstanding End of the Period (in shares)	484,030	231,120
Vested, but deferred (in shares)	94,348	92,244
Weighted Average Grant-Date Fair Value
Beginning Weighted Average Grant-Date Fair Value (usd per share)	$ 59.02	$ 60.37
Weighted Average Grant-Date Fair Value, Granted (usd per share)	62.79	64.10
Weighted Average Grant-Date Fair Value, Vested and issued (usd per share)	78.13	75.69
Weighted Average Grant-Date Fair Value, Expired, canceled or forfeited (usd per share)	63.44	81.89
Ending Weighted Average Grant-Date Fair Value (usd per share)	60.73	61.02
Weighted Average Grant-Date Fair Value, Vested, but deferred (usd per share)	$ 52.21	$ 52.23
Performance-based stock
Common Shares
Outstanding Beginning of the Period (in shares)	482,608	465,515
Granted (in shares)	206,465	166,547
Added by performance factor at vesting (in shares)	0	48,831
Vested and issued (in shares)	0	(180,596)
Expired, canceled or forfeited (in shares)	(125,622)	(6,071)
Outstanding End of the Period (in shares)	563,451	494,226
Vested, but deferred (in shares)	34,748	34,166
Weighted Average Grant-Date Fair Value
Beginning Weighted Average Grant-Date Fair Value (usd per share)	$ 71.15	$ 74.37
Weighted Average Grant-Date Fair Value, Granted (usd per share)	58.85	64.10
Weighted Average Grant-Date Fair Value, Added by performance factor at vesting (usd per share)	0	72.59
Weighted Average Grant-Date Fair Value, Vested and issued (usd per share)	0	72.59
Weighted Average Grant-Date Fair Value, Expired, canceled or forfeited (usd per share)	87.88	73.66
Ending Weighted Average Grant-Date Fair Value (usd per share)	62.91	71.39
Weighted Average Grant-Date Fair Value, Vested, but deferred (usd per share)	$ 43.28	$ 43.27

Shareholders' Equity And Earn_3

Shareholders' Equity And Earnings Per Share (Components Of Other Comprehensive Income (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance	$ 4,115,995	$ 3,691,250
Other comprehensive (loss) income during the period, net of tax, before reclassifications	(9,994)	26,692
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	4,758	440
Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax	(42)	(57)
Total other comprehensive (loss) income	(5,278)	27,075
Balance	4,252,511	3,700,393
Accumulated Unrealized Gains (Losses) on Securities
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance	70,737	14,982
Other comprehensive (loss) income during the period, net of tax, before reclassifications	(44,519)	67,007
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	(154)	(359)
Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax	(42)	(57)
Total other comprehensive (loss) income	(44,715)	66,591
Balance	26,022	81,573
Accumulated Unrealized (Losses) Gains on Derivative Instruments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance	(23,090)	(13,141)
Other comprehensive (loss) income during the period, net of tax, before reclassifications	32,345	(29,170)
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	4,912	799
Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax	0	0
Total other comprehensive (loss) income	37,257	(28,371)
Balance	14,167	(41,512)
Accumulated Foreign Currency Translation Adjustments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance	(32,265)	(36,519)
Other comprehensive (loss) income during the period, net of tax, before reclassifications	2,180	(11,145)
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	0	0
Amount reclassified from accumulated other comprehensive income (loss) related to amortization of unrealized gains on investment securities transferred to held-to-maturity from available-for-sale, net of tax	0	0
Total other comprehensive (loss) income	2,180	(11,145)
Balance	(30,085)	(47,664)
Accumulated other comprehensive (loss) income
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance	15,382	(34,678)
Total other comprehensive (loss) income	(5,278)	27,075
Balance	$ 10,104	$ (7,603)

Shareholders' Equity And Earn_4

Shareholders' Equity And Earnings Per Share (Other Comprehensive Income Reclassified from AOCI) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income before taxes	$ 206,859	$ 87,083
Income tax expense	(53,711)	(24,271)
Interest on deposits	27,944	67,435
Interest on junior subordinated debentures	2,704	2,811
Net income	153,148	62,812
Reclassification Out of Accumulated Other Comprehensive Income | Accumulated Unrealized Losses on Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Gains (losses) on investment securities, net	210	491
Income before taxes	210	491
Income tax expense	(56)	(132)
Net income	154	359
Reclassification Out of Accumulated Other Comprehensive Income | Accumulated Unrealized Gains on Derivative Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Income before taxes	(6,696)	(1,090)
Income tax expense	1,784	291
Interest on deposits	4,897	559
Interest on other borrowings	669	292
Interest on junior subordinated debentures	1,130	239
Net income	$ (4,912)	$ (799)

Shareholders' Equity And Earn_5

Shareholders' Equity And Earnings Per Share (Computation Of Basic And Diluted Earnings Per Common Share) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income	$ 153,148	$ 62,812
Less: Preferred stock dividends	6,991	2,050
Net income applicable to common shares	$ 146,157	$ 60,762
Weighted average common shares outstanding (in shares)	56,904	57,620
Effect of dilutive potential common shares
Common stock equivalents (in shares)	681	575
Average common shares and dilutive common shares (in shares)	57,585	58,195
Net income per common share:
Basic (usd per share)	$ 2.57	$ 1.05
Diluted (usd per share)	$ 2.54	$ 1.04

Shareholders' Equity And Earn_6

Shareholders' Equity And Earnings Per Share (Narrative) (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			3 Months Ended
	May 31, 2020	Jan. 31, 2020	Jun. 30, 2015	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2015
Temporary Equity [Line Items]
Cash dividends declared per common share (usd per share)		$ 0.31		$ 0.31	$ 0.28
Common stock dividends per share declared annualized (usd per share)		$ 1.24
Series D Preferred Stock
Temporary Equity [Line Items]
Sale of stock (in shares)			5,000,000
Preferred stock, liquidation value per share (usd per share)				25	25	$ 25	$ 25
Sale of stock, proceeds			$ 125
Preferred stock, dividend rate, percentage			6.50%
Series E Preferred Stock
Temporary Equity [Line Items]
Sale of stock (in shares)	11,500
Preferred stock, liquidation value per share (usd per share)	$ 25,000			$ 25,000	$ 25,000	$ 25,000
Preferred stock, dividend rate, percentage	6.875%
Depositary Shares
Temporary Equity [Line Items]
Sale of stock (in shares)	11,500,000
Sale of stock, proceeds	$ 287.5
London Interbank Offered Rate (LIBOR) | Series D Preferred Stock
Temporary Equity [Line Items]
Preferred stock, dividend rate, percentage, variable spread			4.06%

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event $ in Millions	Apr. 23, 2021USD ($)branch
Subsequent Event [Line Items]
Number of branches sold | branch	3
Deposits disposed | $	$ 77.4

Uncategorized Items - wtfc-2021

Label	Element	Value
Accounting Standards Update [Extensible List]	us-gaap_AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201613Member