Western Alliance Bancorporation (WAL) 10-K 25 Feb 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Jun. 30, 2021	Feb. 18, 2021
Entity Information [Line Items]
Document Annual Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, $0.0001 Par Value
Entity Address, Address Line One	One E. Washington Street, Suite 1400
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Incorporation, State or Country Code	DE
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	WESTERN ALLIANCE BANCORPORATION
City Area Code	602
Local Phone Number	389-3500
Entity Central Index Key	0001212545
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding			106,997,341
Entity Shell Company	false
Entity Public Float		$ 9,040
Entity File Number	001-32550
Entity Tax Identification Number	88-0365922
Entity Address, Postal Zip Code	85004
ICFR Auditor Attestation Flag	true
Auditor Location	Los Angeles, California
Auditor Name	RSM US LLP
Auditor Firm ID	49
Common Stock [Member]
Entity Information [Line Items]
Trading Symbol	WAL
Security Exchange Name	NYSE
Noncumulative Preferred Stock
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/400th Interest in a Share of 4.250% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series A
Trading Symbol	WAL PrA
Security Exchange Name	NYSE

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Assets:
Cash and due from banks	$ 166.2	$ 174.2
Interest-bearing deposits in other financial institutions	350.2	2,497.5
Cash, cash equivalents and restricted cash	516.4	2,671.7
Debt Securities, Available-for-sale	6,188.8	4,708.5
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,107.1	568.8
Debt Securities, Held-to-maturity, Allowance for Credit Loss	(5.2)	(6.8)
Debt Securities, Held-to-maturity, Net	1,101.9	562
Investment securities - equity	158.5	167.3
Investments in restricted stock, at cost	91.7	67
Financing Receivable, Held-for-Sale	5,635.1	0
Loans:
Loans and Leases Receivable, Net of Deferred Income	39,075.4	27,053
Less: allowance for credit losses	(252.5)	(278.9)
Loans and Leases Receivable, Net Amount, Total	38,822.9	26,774.1
Premises and equipment, net	181.9	134.1
Operating lease right of use asset	133	72.5
Bank owned life insurance	180.2	176.3
Goodwill and intangible assets, net	634.8	298.5
Deferred tax assets, net	20.9	31.3
Investments in LIHTC and renewable energy	631.3	405.6
Other assets	987.2	392.1
Total assets	55,982.6	36,461
Deposits:
Non-interest-bearing demand	21,353.4	13,463.3
Interest-bearing	26,258.6	18,467.2
Total deposits	47,612	31,930.5
Customer repurchase agreements	16.6	16
Other borrowings	1,501.9	21
Qualifying debt	895.8	548.7
Operating lease liability	142.8	79.9
Other liabilities	867.5	467.4
Total liabilities	51,020	33,047.5
Commitments and contingencies (Note 18)
Stockholders’ equity:
Common Stocks, Including Additional Paid in Capital	1,966.2	1,390.9
Treasury stock, at cost (2,003,873 shares at December 31, 2019 and 1,793,231 shares at December 31, 2018)	(86.8)	(71.1)
Accumulated other comprehensive income	15.7	92.3
Retained earnings	2,773	2,001.4
Total stockholders’ equity	4,962.6	3,413.5
Total liabilities and stockholders’ equity	55,982.6	36,461
Debt Securities, Available-for-sale, Amortized Cost	6,166.5	4,586.4
Debt Securities, Held-to-maturity, Fair Value	$ 1,146.4	$ 611.8
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	108,981,341	103,013,290
Treasury Stock, Shares	2,350,021	2,169,397
Servicing Asset	$ 698	$ 0
Preferred Stock, Value, Issued	$ 294.5	$ 0
Preferred Stock, Par or Stated Value Per Share	$ 0.0001
Preferred Stock, Liquidation Preference Per Share	$ 25
Preferred Stock, Shares Authorized	20,000,000
Preferred Stock, Shares Outstanding	12,000,000	0

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale, Amortized Cost	$ 6,166.5	$ 4,586.4
Debt Securities, Held-to-maturity, Fair Value	$ 1,146.4	$ 611.8
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	108,981,341	103,013,290

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest income:
Loans, including fees	$ 1,488,800	$ 1,144,300	$ 1,093,000
Investment securities	158,600	107,800	111,900
Dividends and other	11,300	9,700	20,100
Total interest income	1,658,700	1,261,800	1,225,000
Interest expense:
Deposits	47,500	70,400	158,400
Qualifying debt	33,100	23,900	23,400
Other borrowings	29,300	600	2,800
Total interest expense	109,900	94,900	184,600
Net interest income	1,548,800	1,166,900	1,040,400
(Recovery of) provision for credit losses	(21,400)	(123,600)	(19,300)
Net interest income after provision for (recovery of) credit losses	1,570,200	1,043,300	1,021,100
Non-interest income:
Service charges and fees	28,300	23,300	23,300
Income from equity investments	22,100	12,700	8,300
Fair value (loss) gain on assets measured at fair value, net	(1,300)	3,800	5,100
Other income	12,300	16,100	9,200
Total non-interest income	404,200	70,800	65,100
Non-interest expense:
Salaries and employee benefits	466,700	303,600	279,300
Legal, professional, and directors' fees	58,600	42,200	37,000
Occupancy	43,800	34,100	32,600
Deposit costs	29,800	18,500	31,700
Data processing	58,200	35,700	30,600
Insurance	23,000	13,300	11,900
Business development and marketing	13,500	9,600	11,200
Gain (Loss) on Extinguishment of Debt	5,900	0	0
Net (gain) loss on sales and valuations of repossessed and other assets	(3,500)	(1,500)	3,800
Other expense	57,800	36,100	43,900
Total non-interest expense	851,400	491,600	482,000
Income before provision for income taxes	1,123,000	622,500	604,200
Income tax expense	223,800	115,900	105,000
Net income	899,200	506,600	499,200
Preferred Stock Dividends, Income Statement Impact	3,500	0	0
Net income available to common stockholders	$ 895,700	$ 506,600	$ 499,200
Earnings per share:
Basic	$ 8.72	$ 5.06	$ 4.86
Diluted	$ 8.67	$ 5.04	$ 4.84
Weighted average number of common shares outstanding:
Basic	102,700	100,200	102,700
Diluted	103,300	100,500	103,100
Net gain on loan origination and sale activities	$ 326,200	$ 0	$ 0
Commercial banking related income	17,400	14,700	16,100
Gain on sales of investment securities	8,300	200	3,100
Gain on recovery from credit guarantees	7,200	0	0
Loan servicing fees, net	(16,300)	0	0
Expense Related to Distribution or Servicing and Underwriting Fees	53,500	0	0
Loan Processing Fee	28,800	0	0
Acquisition and restructure expenses	$ 15,300	$ 0	$ 0

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	$ (70,200)	$ 67,500	$ 61,000
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(69,000)	70,900	71,200
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	300	400
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax	22,400	(23,100)	(23,200)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	0	100	100
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Unrealized Gain (Loss) Arising During Period, Tax	300	1,100	3,200
Realized gain on sale of securities, tax	2,100	0	(700)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(6,400)	(200)	(2,400)
Net Income (Loss) Attributable to Parent	899,200	506,600	499,200
Other comprehensive income (loss), net:
OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax	(69,000)	70,900	71,200
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	300	400
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Unrealized Gain (Loss) Arising During Period, after Tax	(1,200)	(3,100)	(9,800)
Amount reclassified from accumulated other comprehensive income	6,400	200	2,400
Net other comprehensive (loss) income	(76,600)	67,300	58,600
Accumulated other comprehensive income	15,700	92,300	25,000
Comprehensive income	822,600	573,900	557,800
Realized gain on sale of securities, tax	2,100	0	(700)
Unrealized holding gains (losses) on AFS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(69,000)	70,900	71,200
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(6,400)	(200)	(2,300)
Other comprehensive income (loss), net:
Net other comprehensive (loss) income	(75,400)	70,700	68,900
Accumulated other comprehensive income	16,700	92,100	21,400
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1,200)	(3,100)	(9,800)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Other comprehensive income (loss), net:
Net other comprehensive (loss) income	(1,200)	(3,100)	(9,800)
Accumulated other comprehensive income	(700)	500	3,600
Impairment loss on securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	100
Other comprehensive income (loss), net:
Net other comprehensive (loss) income	0	0	(100)
Accumulated other comprehensive income	0	0	0
Supplemental Employee Retirement Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	(300)	(400)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Other comprehensive income (loss), net:
Net other comprehensive (loss) income	0	(300)	(400)
Accumulated other comprehensive income	$ (300)	$ (300)	$ 0

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Realized gain on sale of securities, tax	$ 2,100	$ 0	$ (700)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Accumulated (Deficit) [Member]
Beginning balance at Dec. 31, 2019	$ 3,016,700		$ 0	$ 1,374,100	$ (62,700)	$ 25,000	$ 1,680,300
Beginning balance, shares at Dec. 31, 2019			102,500,000
Net Income (Loss) Attributable to Parent	506,600						506,600
Restricted stock grants, net, shares			600,000
Restricted stock grants, net	$ 29,100			29,100
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	165,489		200,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 8,400				(8,400)
Stock Repurchased and Retired During Period, Shares	(2,100,000)		(2,100,000)
Stock Repurchased and Retired During Period, Value	$ (71,600)			(12,300)			(59,300)
Dividends, Common Stock, Cash	(101,300)						(101,300)
Other comprehensive (loss) income, net	67,300					67,300
Ending balance at Dec. 31, 2020	3,413,500		$ 0	1,390,900	(71,100)	92,300	2,001,400
Ending balance, shares at Dec. 31, 2020			100,800,000
Stock Repurchase Program, Authorized Amount	250,000
Net Income (Loss) Attributable to Parent	899,200						899,200
Restricted stock grants, net, shares			600,000
Restricted stock grants, net	$ 35,000			35,000
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	180,607		200,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	$ 15,700				15,700
Dividends, Preferred Stock, Cash	3,500						3,500
Dividends, Common Stock, Cash	(124,100)						(124,100)
Other comprehensive (loss) income, net	(76,600)					(76,600)
Ending balance at Dec. 31, 2021	4,962,600	$ 294,500	$ 0	1,966,200	$ (86,800)	$ 15,700	$ 2,773,000
Ending balance, shares at Dec. 31, 2021		12,000,000	106,600,000
Stock Issued During Period, Value, New Issues	$ 540,300	$ 294,500		$ 540,300
Stock Issued During Period, Shares, New Issues		12,000,000	5,400,000

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net Income (Loss) Attributable to Parent	$ 899.2	$ 506.6	$ 499.2
Adjustments to reconcile net income to cash (used in) provided by operating activities:
(Recovery of) provision for credit losses	(21.4)	(123.6)	(19.3)
Depreciation and amortization	33.7	22.9	18.5
Stock-based compensation	35.1	28.7	26.2
Deferred income taxes	42	(25.1)	(5.1)
Amortization of net premiums for investment securities	39.8	28.2	17.1
Amortization of tax credit investments	49.5	49.2	41.5
Amortization of operating lease right of use asset	16.3	11.7	10.5
Amortization of Deferred Loan Origination Fees, Net	(66.3)	(51.2)	(42.7)
Net (gains) losses on:
Fair value (loss) gain on assets measured at fair value, net	(1.3)	3.8	5.1
Changes in other assets and liabilities, net	(157.6)	(15)	138.4
Changes in other assets and liabilities, net
Net cash provided by operating activities	(2,654)	670.2	717.8
Investment securities - AFS
Purchases	(3,248.4)	(2,966.2)	(927.6)
Principal pay downs and maturities	1,634.1	1,515.5	785.7
Proceeds from sales	164.5	156.6	150.4
Purchases	(595.6)	(182.7)	(131.4)
Principal pay downs and maturities	54.9	17.4	21.6
Proceeds from sales	0	0	10
Purchases	(36.2)	(34.5)	(32.7)
Redemption of principal (reinvestment of dividends)	21	7.6	14.6
Proceeds from sales	4.4	0	0
Proceeds from bank owned life insurance, net	0	5.9	0
Net increase in loans HFI	(12,665)	(5,897.2)	(3,429)
Purchase of premises, equipment, and other assets, net	(69.4)	(26.8)	(33.8)
Net cash used in investing activities	(14,711.9)	(7,537.5)	(3,723)
Cash flows from financing activities:
Net increase in deposits	15,681.5	9,134	3,619
Net proceeds from issuance of long-term debt	1,055.7	221.9	0
Payments on long-term debt	(475.9)	(75)	0
Net (decrease) increase in short-term borrowings	(1,742.1)	4.3	(496.7)
Payment, Tax Withholding, Share-based Payment Arrangement	15.8	7.9	9.6
Common stock repurchases	0	71.6	120.2
Payments of Dividends	127.6	101.3	51.3
Net cash provided by financing activities	15,210.6	9,104.4	2,941.2
Net (decrease) increase in cash, cash equivalents, and restricted cash	(2,155.3)	2,237.1	(64)
Cash, cash equivalents, and restricted cash at beginning of period	2,671.7	434.6	498.6
Cash, cash equivalents, and restricted cash at end of period	516.4	2,671.7	434.6
Cash paid during the period for:
Interest	111.6	108.6	180.4
Income taxes, net	175.7	44.2	(23.4)
Other Significant Noncash Transaction, Description	294.1	(102.2)	36.6
Transfers of securitized LHFS to AFS securities	144.5	0	0
Payments for Origination and Purchases of Loans Held-for-sale	(59,569.6)	0	0
Proceeds from Sale and Collection of Loans Held-for-sale	56,647.7	0	0
Servicing Asset at Fair Value, Additions	(763.8)	0	0
Other operating activities, net	(16.3)	(9.4)	(5.1)
Servicing Asset at Fair Value, Period Increase (Decrease)	177.7	0	0
Proceeds from Sale of Mortgage Servicing Rights (MSR)	1,182.8	0	0
Purchase of other investments	(134.6)	(133.1)	(150.8)
Payments to Acquire Businesses, Net of Cash Acquired	(1,024.4)	0	0
Proceeds from issuance of common stock in offerings, net	540.3	0	0
Preferred Stock [Member]
Cash paid during the period for:
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 294.5	$ 0	$ 0

Statement of Financial Position

Statement of Financial Position, Unclassified - Deposit Based Operations	12 Months Ended
	Dec. 31, 2021
Statement of Financial Position [Abstract]
Deposits [Abstract]	10. DEPOSITS The table below summarizes deposits by type: December 31, 2021 2020 (in millions) Non-interest-bearing demand deposits $ 21,353.4 $ 13,463.3 Interest-bearing transaction accounts 6,924.0 4,396.4 Savings and money market accounts 17,278.6 12,413.4 Time certificates of deposit ($250,000 or more) 523.0 602.0 Other time deposits 1,533.0 1,055.4 Total deposits $ 47,612.0 $ 31,930.5 The summary of the contractual maturities for all time deposits as of December 31, 2021 is as follows: December 31, (in millions) 2022 $ 1,932.4 2023 102.2 2024 17.4 2025 2.9 2026 1.1 Total $ 2,056.0 WAB is a participant in the Promontory Interfinancial Network, a network that offers deposit placement services such as CDARS and ICS, which offer products that qualify large deposits for FDIC insurance. Federal banking law and regulation places restrictions on depository institutions regarding brokered deposits because of the general concern that these deposits are not relationship-based and are at a greater risk of being withdrawn, thus posing liquidity risk for institutions that gather brokered deposits in significant amounts. At December 31, 2021 and 2020, the Company had $729.2 million and $496.4 million, respectively, of reciprocal CDARS deposits and $1.8 billion and $1.3 billion, respectively, of ICS deposits. The Company also had $1.8 billion and $554.8 million of wholesale brokered deposits at December 31, 2021 and 2020, respectively. In addition, deposits for which the Company provides account holders with earnings credits or referral fees to taled $10.8 billion a

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2021
Deposit [Abstract]
Schedule Of Deposits Table [Text Block]	The table below summarizes deposits by type: December 31, 2021 2020 (in millions) Non-interest-bearing demand deposits $ 21,353.4 $ 13,463.3 Interest-bearing transaction accounts 6,924.0 4,396.4 Savings and money market accounts 17,278.6 12,413.4 Time certificates of deposit ($250,000 or more) 523.0 602.0 Other time deposits 1,533.0 1,055.4 Total deposits $ 47,612.0 $ 31,930.5
Scheduled Maturities Of Time Deposits Table [Text Block]	The summary of the contractual maturities for all time deposits as of December 31, 2021 is as follows: December 31, (in millions) 2022 $ 1,932.4 2023 102.2 2024 17.4 2025 2.9 2026 1.1 Total $ 2,056.0

Deposits (Details)

Deposits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Deposit [Abstract]
Non-interest-bearing demand	$ 21,353.4	$ 13,463.3
Certificates of Deposit, CDARS	729.2	496.4
Non-interest-bearing demand	10,800	5,900
Time Deposit Maturities, Next Twelve Months	1,932.4
Time Deposit Maturities, Year Two	102.2
Time Deposit Maturities, Year Three	17.4
Time Deposit Maturities, Year Four	2.9
Time Deposit Maturities, Year Five	1.1
Time Deposits	2,056
Interest Bearing Deposit Demand	6,924	4,396.4
Deposits, Savings Deposits	17,278.6	12,413.4
Time Deposits, $250,000 or more	523	602
Time Deposits, Less than $250,000	1,533	1,055.4
Total deposits	47,612	31,930.5
Deposits, ICS	1,800	1,300
Deposits, Wholesale	1,800	554.8
Deposits costs, deposits with earnings credits	$ 27.4	$ 17

Stockholders' Equity Treasury s

Stockholders' Equity Treasury shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Stockholders' Equity [Abstract]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	180,607	165,489	210,657
Equity, Class of Treasury Stock [Line Items]
Treasury Stock Acquired, Average Cost Per Share	$ 86.63	$ 50.80	$ 45.80

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Nature of operation WAL is a bank holding company headquartered in Phoenix, Arizona, incorporated under the laws of the state of Delaware. WAL provides a full spectrum of customized loan, deposit and treasury management capabilities, including blockchain-based offerings through its wholly-owned banking subsidiary, WAB. WAB operates the following full-service banking divisions: ABA, BON, FIB, Bridge, and TPB. The Company also serves business customers through a national platform of specialized financial services and has added to these capabilities with the acquisition of AmeriHome on April 7, 2021, which provides mortgage banking services. In addition, the Company has two non-bank subsidiaries, which are LVSP, which held and managed certain OREO properties, and CSI, a captive insurance company formed and licensed under the laws of the State of Arizona and established as part of the Company's overall enterprise risk management strategy. Basis of presentation The accounting and reporting policies of the Company are in accordance with GAAP and conform to practices within the financial services industry. The accounts of the Company and its consolidated subsidiaries are included in the Consolidated Financial Statements. Recent accounting pronouncements Convertible Debt and Derivatives and Hedging In August 2020, the FASB issued guidance within ASU 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) . The amendments in this update affect entities that issue convertible instruments and/or contracts indexed to and potentially settled in an entity’s own equity. The new ASU simplifies the convertible accounting framework through elimination of the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, the new guidance modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments to ASC Subtopics 470 and 815 are effective for interim and annual reporting periods beginning after December 15, 2021 and are not expected to have a material impact on the Company’s Consolidated Financial Statements. Reference Rate Reform In March 2020, the FASB issued guidance within ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting, in response to the scheduled discontinuation of LIBOR on December 31, 2021. Since the issuance of this guidance, the publication cessation of U.S. dollar LIBOR has been extended to June 30, 2023 . The amendments in this update provide optional guidance designed to provide relief from the accounting analysis and impacts that may otherwise be required for modifications to agreements (e.g., loans, debt securities, derivatives, borrowings) necessitated by reference rate reform. The following optional expedients for applying the requirements of certain ASC Topics or Industry Subtopics in the Codification are permitted for contracts that are modified because of reference rate reform and that meet certain scope guidance: 1) modifications of contracts within the scope of ASC Topics 310, Receivables , and 470, Debt , should be accounted for by prospectively adjusting the effective interest rate; 2) modifications of contracts within the scope of ASC Topic 842, Leases , should be accounted for as a continuation of the existing contracts with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required under this ASC Topic for modifications not accounted for as separate contracts; 3) modifications of contracts do not require an entity to reassess its original conclusion about whether that contract contains an embedded derivative that is clearly and closely related to the economic characteristics and risks of the host contract under ASC Subtopic 815-15, Derivatives and Hedging- Embedded Derivatives; and 4) for other ASC Topics or Industry Subtopics in the Codification, the amendments in this Update also include a general principle that permits an entity to consider contract modifications due to reference rate reform to be an event that does not require contract remeasurement at the modification date or reassessment of a previous accounting determination. In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope in order to clarify that certain optional expedients and exceptions in ASC Topic 848 apply to derivatives that are affected by the discounting transition. Specifically, certain provisions in ASC Topic 848, if elected by an entity, apply to derivative instruments that use an interest rate for margining, discount, or contract price alignment that is modified as a result of reference rate reform. The amendments in these updates are effective immediately for all entities and apply to contract modifications through December 31, 2022. The adoption of this accounting guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. Recently adopted accounting guidance Income Taxes In December 2019, the FASB issued guidance within ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in ASU 2019-12 are intended to reduce the cost and complexity of applying ASC 740. The amendments that are applicable to the Company address: 1) franchise and other taxes partially based on income; 2) step-up in basis of goodwill in a business combination; 3) allocation of tax expense in separate entity financial statements; and 4) interim recognition of enactment of tax laws or rate changes. The adoption of this guidance did not have a significant impact on the Company’s Consolidated Financial Statements. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management's estimates and judgments are ongoing and are based on experience, current and expected future conditions, third-party evaluations and various other assumptions that management believes are reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities, as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from those estimates and assumptions used in the Consolidated Financial Statements and related notes. Material estimates that are susceptible to significant changes in the near term, particularly to the extent that economic conditions worsen or persist longer than expected in an adverse state, relate to: 1) the determination of the allowance for credit losses; 2) certain assets and liabilities carried at fair value; and 3) accounting for income taxes. Principles of consolidation As of December 31, 2021, WAL has the following significant wholly-owned subsidiaries: WAB and eight unconsolidated subsidiaries used as business trusts in connection with the issuance of trust-preferred securities. WAB has the following significant wholly-owned subsidiaries: 1) WABT, which holds certain investment securities, municipal and nonprofit loans, and leases; 2) WA PWI, which holds interests in certain limited partnerships invested primarily in low income housing tax credits and small business investment corporations; 3) Helios Prime, which holds interests in certain limited partnerships invested in renewable energy projects; 4) BW Real Estate, Inc., which operates as a real estate investment trust and holds certain of WAB's real estate loans and related securities; and 5) Western Finance Company (formerly Western Alliance Equipment Finance), which purchases and originates equipment finance leases and provides mortgage banking services through its wholly-owned subsidiary, AmeriHome Mortgage. The Company does not have any other significant entities that should be consolidated. All significant intercompany balances and transactions have been eliminated in consolidation. Reclassifications Certain amounts in the Consolidated Income Statements for the prior periods have been reclassified to conform to the current presentation. The reclassifications have no effect on net income or stockholders’ equity as previously reported. Cash and cash equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks (including cash items in process of clearing), and federal funds sold. Cash flows from loans originated by the Company and customer deposit accounts are reported net. The Company maintains deposit accounts with other banks, which at times may exceed federally insured limits. The Company has not experienced any losses in such accounts. Business combinations Business combinations are accounted for under the acquisition method of accounting in accordance with ASC 805, Business Combinations . Under the acquisition method, the acquiring entity in a business combination recognizes all of the acquired assets and assumed liabilities at their estimated fair values as of the date of acquisition. Any excess of the purchase price over the fair value of net assets and other identifiable intangible assets acquired is recorded as goodwill. To the extent the fair value of net assets acquired, including identified intangible assets, exceeds the purchase price, a bargain purchase gain is recognized. Assets acquired and liabilities assumed from contingencies are also recognized at fair value if the fair value can be determined during the measurement period. Results of operations of an acquired business are included in the Consolidated Income Statement from the date of acquisition. Acquisition-related costs, including conversion and restructuring charges, are expensed as incurred. Investment securities Investment securities include debt and equity securities. Debt securities may be classified as HTM, AFS, or trading. The appropriate classification is initially decided at the time of purchase. Securities classified as HTM are those debt securities that the Company has both the intent and ability to hold to maturity regardless of changes in market conditions, liquidity needs, or general economic conditions. The sale of an HTM security within three months of its maturity date or after the majority of the principal outstanding has been collected is considered a maturity for purposes of classification and disclosure. Securities classified as AFS are debt securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity. Any decision to sell a security classified as AFS would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Company’s assets and liabilities, liquidity needs, decline in credit quality, and regulatory capital considerations. HTM securities are carried at amortized cost. AFS securities are carried at their estimated fair value, with unrealized holding gains and losses reported in OCI, net of tax. When AFS debt securities are sold, the unrealized gains or losses are reclassified from OCI to non-interest income. Trading securities are carried at their estimated fair value, with changes in fair value reported in earnings as part of non-interest income. Equity securities are carried at their estimated fair value, with changes in fair value reported in earnings as part of non-interest income. Interest income is recognized based on the coupon rate and includes the amortization of purchase premiums and the accretion of purchase discounts. Premiums and discounts on investment securities are generally amortized or accreted over the contractual life of the security using the interest method. For the Company's mortgage-backed securities, amortization or accretion of premiums or discounts are adjusted for anticipated prepayments. Gains and losses on the sale of investment securities are recorded on the trade date and determined using the specific identification method. A debt security is placed on nonaccrual status at the time its principal or interest payments become 90 days past due. Interest accrued but not received for a security placed on nonaccrual is reversed against interest income. Allowance for credit losses on investment securities On January 1, 2020, the Company adopted ASC Topic 326, Financial Instruments-Credit Losses, which replaced the legacy GAAP Other-than-Temporary Impairment model with a credit loss model. The credit loss model under ASC 326-20, applicable to HTM debt securities, requires recognition of lifetime expected credit losses through an allowance account at the time the security is purchased. The Company measures expected credit losses on its HTM debt securities on a collective basis by major security type. The Company's HTM securities portfolio consists of low income housing tax-exempt bonds and private label residential MBS. Low income housing tax-exempt bonds share similar risk characteristics with the Company's CRE, non-owner occupied or construction and land loan pools, given the similarity in underlying assets or collateral. Accordingly, expected credit losses on HTM securities are estimated using the same models and approaches as these loan pools, which utilize risk parameters (probability of default, loss given default, and exposure at default) in the measurement of expected credit losses. The historical data used to estimate probability of default and severity of loss in the event of default is derived or obtained from internal and external sources and adjusted for the expected effects of reasonable and supportable forecasts over the expected lives of the securities on those historical losses. Accrued interest receivable on HTM securities, which is included in other assets on the Consolidated Balance Sheet, is excluded from the estimate of expected credit losses. The credit loss model under ASC 326-30, applicable to AFS debt securities, requires recognition of credit losses through an allowance account with credit losses recognized once securities become impaired. For AFS debt securities, a decline in fair value due to credit loss results in recognition of an allowance for credit losses. Impairment may result from credit deterioration of the issuer or collateral underlying the security. An assessment to determine whether a decline in fair value resulted from a credit loss is performed at the individual security level. Among other factors, the Company considers: 1) the extent to which the fair value is less than the amortized cost basis; 2) the financial condition and near term prospects of the issuer, including consideration of relevant financial metrics or ratios of the issuer; 3) any adverse conditions related to an industry or geographic area of an issuer; 4) any changes to the rating of the security by a rating agency; and 5) any past due principal or interest payments from the issuer. If an assessment of the above factors indicates that a credit loss exists, the Company records an allowance for credit losses for the excess of the amortized cost basis over the present value of cash flows expected to be collected, limited to the amount that the security's fair value is less than its amortized cost basis. Subsequent changes in the allowance for credit losses are recorded as a provision for (or recovery of) credit loss expense. Interest accruals and amortization and accretion of premiums and discounts are suspended when the credit loss is recognized in earnings. Any interest received after the security has been placed on nonaccrual status is recognized on a cash basis. Accrued interest receivable on AFS debt securities, which is included in other assets on the Consolidated Balance Sheet, is excluded from the estimate of expected credit losses. For each AFS security in an unrealized loss position, the Company also considers: 1) its intent to retain the security until anticipated recovery of the security's fair value; and 2) whether it is more-likely-than not that the Company would be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the debt security is written down to its fair value and the write-down is charged against the allowance for credit losses with any incremental impairment recorded in earnings. Write-offs are made through reversal of the allowance for credit losses and a direct write-off of the amortized cost basis of the AFS security. The Company considers the following events to be indicators that a write-off should be taken: 1) bankruptcy of the issuer; 2) significant adverse event(s) affecting the issuer in which it is improbable for the issuer to make its remaining payments on the security; and 3) significant loss of value of the underlying collateral behind a security. Recoveries on debt securities, if any, are recorded in the period received. Restricted stock WAB is a member of the Federal Reserve System and, as part of its membership, is required to maintain stock in the FRB in a specified ratio to its capital. In addition, WAB is a member of the FHLB system and, accordingly, maintains an investment in capital stock of the FHLB based on the borrowing capacity used. These investments are considered equity securities with no actively traded market. Therefore, the shares are considered restricted investment securities. These investments are carried at cost, which is equal to the value at which they may be redeemed. The dividend income received from the stock is reported in interest income. The Company conducts a periodic review and evaluation of its restricted stock to determine if any impairment exists. No impairment has been recorded to date. Loans held for sale The Company began holding loans HFS in connection with the AmeriHome acquisition and continues to purchase and originate loans as part of its mortgage banking business. Loans HFS are reported at fair value or the lower of cost or fair value, depending on the acquisition source. The Company has elected to record loans purchased from correspondent sellers or originated directly to consumers at fair value to more timely reflect the Company's performance. Changes in fair value of loans HFS are reported in current period income as a component of Net gain on loan origination and sale activities in the Consolidated Income Statement. Alternatively, delinquent loans repurchased under the terms of the GNMA MBS program, referred to as EBO loans, are reported at the lower of cost or fair value. For EBO loans, the amount by which cost exceeds fair value is accounted for as a valuation allowance and any changes in the valuation allowance are included in Net gain on loan origination and sale activities in the Consolidated Income Statement. The Company recognizes a transfer of loans as a sale when it surrenders control over the transferred loans. Control is considered to be surrendered when the transferred loans have been legally isolated from the Company, the transferee has the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred loans, and the Company does not maintain effective control over the transferred loans through either an agreement that entitles or obligates the Company to repurchase or redeem the loans before their maturity or the ability to unilaterally cause the holder to return loans. If the transfer of loans qualifies as a sale, the Company derecognizes such loans and records the gain or loss as a component of Net gain on loan origination and sale activities in the Consolidated Income Statement. If the transfer of loans does not qualify as a sale, the proceeds from the transfer are accounted for as secured borrowings. Loan acquisition and origination fees on loans HFS consist of fees earned by the Company for purchasing and originating loans and are recognized at the time the loans are purchased or originated. These fees generally represent flat, per loan fee amounts and are included as part of Net gain on loan origination and sale activities in the Consolidated Income Statement. Recognition of interest income on non-government guaranteed or insured loans HFS is suspended and accrued unpaid interest receivable is reversed against interest income when loans become 90 days delinquent or when recovery of income and principal becomes doubtful. Loans return to accrual status when the principal and interest become current and it is probable that the amounts are fully collectible. For government guaranteed or insured loans HFS that are 90 days delinquent, the Company continues to recognize interest income at the debenture rate for FHA loans and at the note rate for VA and USDA loans, adjusted for probability of default. Loans held for investment Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at amortized cost. Amortized cost is the amount of unpaid principal, adjusted for unamortized net deferred fees and costs, premiums and discounts, and write-offs. In addition, the amortized cost of loans subject to a fair value hedge are adjusted for changes in value attributable to the effective portion of the hedged benchmark interest rate risk. The Company may also purchase loans or acquire loans through a business combination. At the purchase or acquisition date, loans are evaluated to determine whether there has been more than insignificant credit deterioration since origination. Loans that have experienced more than insignificant credit deterioration since origination are referred to as PCD loans. In its evaluation of whether a loan has experienced more than insignificant deterioration in credit quality since origination, the Company takes into consideration loan grades, loan-to-values greater than policy limits, past due and nonaccrual status, and TDR loans. The Company may also consider external credit rating agency ratings for borrowers and for non-commercial loans, FICO score or band, probability of default levels, and number of times past due. The initial estimate of credit losses on PCD loans is added to the purchase price on the acquisition date to establish the initial amortized cost basis of the loan; accordingly, the initial recognition of expected credit losses has no impact on net income. When the initial measurement of expected credit losses on PCD loans are calculated on a pooled loan basis, the expected credit losses are allocated to each loan within the pool. Any difference between the initial amortized cost basis and the unpaid principal balance of the loan represents a noncredit discount or premium, which is accreted (or amortized) into interest income over the life of the loan. Subsequent changes to the allowance for credit losses on PCD loans are recorded through the provision for credit losses. For purchased loans that are not deemed to have experienced more than insignificant credit deterioration since origination, any discounts or premiums included in the purchase price are accreted (or amortized) over the contractual life of the individual loan. For additional information, see "Note 5. Loans, Leases and Allowance for Credit Losses" of these Notes to Consolidated Financial Statements. In applying the effective yield method to loans, the Company generally applies the contractual method whereby loan fees collected for the origination of loans less direct loan origination costs (net of deferred loan fees), as well as premiums and discounts and certain purchase accounting adjustments, are amortized over the contractual life of the loan through interest income. If a loan has scheduled payments, the amortization of the net deferred fee is calculated using the interest method over the contractual life of the loan. If a loan does not have scheduled payments, such as a line of credit, the net deferred loan fee is recognized as interest income on a straight-line basis over the contractual life of the loan commitment. Commitment fees based on a percentage of a customer’s unused line of credit and fees related to standby letters of credit are recognized over the commitment period. When loans are repaid, any remaining unamortized balances of premiums, discounts, or net deferred fees are recognized as interest income. Conversely, with respect to loans originated under the PPP, the Company incorporates projected prepayments in calculating effective yield. As a result, net deferred fees are accreted into interest income faster than would be the case when applying the contractual method based upon the timing and amount of estimated forgiven loan balances. Nonaccrual loans When a borrower discontinues making payments as contractually required by the note, the Company must determine whether it is appropriate to continue to accrue interest. The Company ceases accruing interest income when the loan has become delinquent by more than 90 days or when management determines that the full repayment of principal and collection of interest according to contractual terms is no longer likely. Past due status is based on the contractual terms of the loan. The Company may decide to continue to accrue interest on certain loans more than 90 days delinquent if the loans are well secured by collateral and in the process of collection. For all HFI loan types, when a loan is placed on nonaccrual status, all interest accrued but uncollected is reversed against interest income in the period in which the status is changed, and the Company makes a loan-level decision to apply either the cash basis or cost recovery method. The Company may recognize income on a cash basis when a payment is received and only for those nonaccrual loans for which the collection of the remaining principal balance is not in doubt. Under the cost recovery method, subsequent payments received from the customer are applied to principal and generally no further interest income is recognized until the loan principal has been paid in full or until circumstances have changed such that payments are again consistently received as contractually required. Loans are returned to accrual status when all of the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Troubled Debt Restructured Loans A TDR loan is a loan on which the Company, for reasons related to a borrower’s financial difficulties, grants a concession to the borrower that the Company would not otherwise consider. In order to determine whether a borrower is experiencing financial difficulty, an evaluation is performed to assess the probability that the borrower will be in payment default on any of its debt in the foreseeable future without the modification. The evaluation is performed in accordance with the Company's internal underwriting policy. The loan terms that may be modified or restructured due to a borrower’s financial situation include, but are not limited to, a reduction in the stated interest rate, an extension of the maturity or renewal of the loan at an interest rate below current market, a reduction in the face amount of the debt, a reduction in the accrued interest, or deferral of interest payments. A TDR loan may be returned to accrual status when the loan is brought current, has performed in accordance with the contractual restructured terms for a reasonable period of time (generally six months), and the ultimate collectability of the total contractual restructured principal and interest is no longer in doubt. Consistent with regulatory guidance, a TDR loan that is subsequently modified in another restructuring agreement but has shown sustained performance and classification as a TDR, will be removed from TDR status provided that the modified terms were market-based at the time of modification. The CARES Act, signed into law on March 27, 2020, permitted financial institutions to suspend requirements under GAAP for loan modifications to borrowers affected by COVID-19 that would otherwise be characterized as TDRs and suspend any determination related thereto if (i) the loan modification was made between March 1, 2020 and December 31, 2020 and (ii) the applicable loan was not more than 30 days past due as of December 31, 2019. The Consolidated Appropriations Act, 2021 extended these provisions through January 1, 2022. In addition, federal bank regulatory authorities issued guidance to encourage financial institutions to make loan modifications for borrowers affected by COVID-19 and assured financial institutions that they will neither receive supervisory criticism for such prudent loan modifications, nor be required by examiners to automatically categorize COVID-19-related loan modifications as TDRs. The Company has been applying this guidance to qualifying loan modifications. Credit quality indicators Loans are regularly reviewed to assess credit quality indicators and to determine appropriate loan classification and grading in accordance with applicable bank regulations. The Company’s risk rating methodology assigns risk ratings ranging from 1 to 9, where a higher rating represents higher risk. The Company differentiates its loan segments based on shared risk characteristics for which expected credit losses are measured on a pool basis. The nine risk rating categories can generally be described by the following groupings for loans: "Pass" (grades 1 through 5): The Company has five pass risk ratings, which represent a level of credit quality that ranges from having no well-defined deficiency or weakness to some noted weakness; however, the risk of default on any loan classified as pass is expected to be remote. The five pass risk ratings are described below: Minimal risk. C onsist of loans that are fully secured either with cash held in a deposit account at the Bank or by readily marketable securities with an acceptable margin based on the type of security pledged. Low risk. Consist of loans with a high investment grade rating equivalent. Modest risk. Consist of loans where the credit facility greatly exceeds all policy requirements or with policy exceptions that are appropriately mitigated. A secondary source of repayment is verified and considered sustainable. Collateral coverage on these loans is sufficient to fully cover the debt as a tertiary source of repayment. Debt of the borrower is low relative to borrower’s financial strength and ability to pay. Average risk. Consist of loans where the credit facility meets or exceeds all policy requirements or with policy exceptions that are appropriately mitigated. A secondary source of repayment is available to service the debt. Collateral coverage is more than adequate to cover the debt. The borrower exhibits acceptable cash flow and moderate leverage. Acceptable risk. Consist of loans with an acceptable primary source of repayment, but a less than preferable secondary source of repayment. Cash flow is adequate to service debt, but there is minimal excess cash flow. Leverage is moderate or high. "Special mention" (grade 6): These are generally assets that possess potential weaknesses that warrant management's close attention. These loans may involve borrowers with adverse financial trends, higher debt-to-equity ratios, or weaker liquidity positions, but not to the degree of being considered a “problem loan” where risk of loss may be apparent. Loans in this category are usually performing as agreed, although there may be non-compliance with financial covenants. "Substandard" (grade 7): These assets are characterized by well-defined credit weaknesses and carry the distinct possibility that the Company will sustain some loss if such weakness or deficiency is not corrected. All loans 90 days or more past due and all loans on nonaccrual status are considered at least "Substandard," unless extraordinary circumstances would suggest otherwise. "Doubtful" (grade 8): These assets have all the weaknesses inherent in those classified as "Substandard" with the added characteristic that the weaknesses present make collection or liquidation in full, on the basis of currently existing facts, condition
Accounting Standards Update and Change in Accounting Principle	Recent accounting pronouncements Convertible Debt and Derivatives and Hedging In August 2020, the FASB issued guidance within ASU 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) . The amendments in this update affect entities that issue convertible instruments and/or contracts indexed to and potentially settled in an entity’s own equity. The new ASU simplifies the convertible accounting framework through elimination of the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, the new guidance modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments to ASC Subtopics 470 and 815 are effective for interim and annual reporting periods beginning after December 15, 2021 and are not expected to have a material impact on the Company’s Consolidated Financial Statements. Reference Rate Reform In March 2020, the FASB issued guidance within ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting, in response to the scheduled discontinuation of LIBOR on December 31, 2021. Since the issuance of this guidance, the publication cessation of U.S. dollar LIBOR has been extended to June 30, 2023 . The amendments in this update provide optional guidance designed to provide relief from the accounting analysis and impacts that may otherwise be required for modifications to agreements (e.g., loans, debt securities, derivatives, borrowings) necessitated by reference rate reform. The following optional expedients for applying the requirements of certain ASC Topics or Industry Subtopics in the Codification are permitted for contracts that are modified because of reference rate reform and that meet certain scope guidance: 1) modifications of contracts within the scope of ASC Topics 310, Receivables , and 470, Debt , should be accounted for by prospectively adjusting the effective interest rate; 2) modifications of contracts within the scope of ASC Topic 842, Leases , should be accounted for as a continuation of the existing contracts with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required under this ASC Topic for modifications not accounted for as separate contracts; 3) modifications of contracts do not require an entity to reassess its original conclusion about whether that contract contains an embedded derivative that is clearly and closely related to the economic characteristics and risks of the host contract under ASC Subtopic 815-15, Derivatives and Hedging- Embedded Derivatives; and 4) for other ASC Topics or Industry Subtopics in the Codification, the amendments in this Update also include a general principle that permits an entity to consider contract modifications due to reference rate reform to be an event that does not require contract remeasurement at the modification date or reassessment of a previous accounting determination. In January 2021, the FASB issued ASU 2021-01, Reference Rate Reform (Topic 848): Scope in order to clarify that certain optional expedients and exceptions in ASC Topic 848 apply to derivatives that are affected by the discounting transition. Specifically, certain provisions in ASC Topic 848, if elected by an entity, apply to derivative instruments that use an interest rate for margining, discount, or contract price alignment that is modified as a result of reference rate reform. The amendments in these updates are effective immediately for all entities and apply to contract modifications through December 31, 2022. The adoption of this accounting guidance is not expected to have a material impact on the Company's Consolidated Financial Statements. Recently adopted accounting guidance Income Taxes In December 2019, the FASB issued guidance within ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.
Credit Linked Notes	Credit linked notesCredit linked notes are structured to effectively transfer the risk of first losses on a reference pool of loans and are considered to be free standing credit enhancements. These notes are recorded at the amount of the proceeds received, net of debt issuance costs. In addition, as the credit guarantee component of these notes is considered to be free standing, the allowance for credit losses measured on the reference pool of loans in accordance with ASC 326 is not reduced by the credit guarantee. Rather, a contra debt balance equal to the estimated allowance for credit losses on the reference pool of loans is recorded, which reduces the carrying value of the notes. The initial contra debt balance and subsequent adjustments are recorded with a corresponding gain or loss on recovery from credit guarantees recognized in earnings.

Receivables, Loans, Notes Recei

Receivables, Loans, Notes Receivable, and Others	12 Months Ended
	Dec. 31, 2021
Receivables [Abstract]
Schedule of Held for Investment Loan Portfolio Composition of Loans, Leases and Allowance for Credit Losses	December 31, 2021 2020 (in millions) Warehouse lending $ 5,155.9 $ 4,340.2 Municipal & nonprofit 1,579.2 1,728.8 Tech & innovation 1,417.8 1,403.0 Equity fund resources 3,829.8 1,145.3 Other commercial and industrial 6,465.7 5,911.2 CRE - owner occupied 1,723.7 1,909.3 Hotel franchise finance 2,534.0 1,983.9 Other CRE - non-owner occupied 3,951.8 3,640.2 Residential 9,242.8 2,378.5 Construction and land development 3,005.8 2,429.4 Other 168.9 183.2 Total loans HFI 39,075.4 27,053.0 Allowance for credit losses (252.5) (278.9) Total loans HFI, net of allowance $ 38,822.9 $ 26,774.1
Impaired Loans by Loan Class	December 31, 2021 December 31, 2020 Number of Loans Recorded Investment Number of Loans Recorded Investment (dollars in millions) Tech & innovation 2 $ 2.1 4 $ 20.4 Other commercial and industrial 7 6.2 9 22.9 CRE - owner occupied 1 0.5 4 2.6 Hotel franchise finance — — 2 5.5 Other CRE - non-owner occupied 5 11.0 3 10.2 Construction and land development 1 1.0 — — Total 16 $ 20.8 22 $ 61.6
Average Investment in Impaired Loans by Loan Class	December 31, 2021 2020 Real Estate Collateral Other Collateral Total Real Estate Collateral Other Collateral Total (in millions) Tech & innovation $ — $ — $ — $ — $ 27.3 $ 27.3 Other commercial and industrial — 12.5 12.5 — 23.6 23.6 CRE - owner occupied 23.0 — 23.0 42.6 — 42.6 Hotel franchise finance 155.7 — 155.7 27.1 — 27.1 Other CRE - non-owner occupied 31.6 — 31.6 73.7 — 73.7 Construction and land development 3.9 — 3.9 1.5 — 1.5 Other — 0.1 0.1 — 0.4 0.4 Total $ 214.2 $ 12.6 $ 226.8 $ 144.9 $ 51.3 $ 196.2

Premises and Equipment (Notes)

Premises and Equipment (Notes)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	7. PREMISES AND EQUIPMENT The following is a summary of the major categories of premises and equipment: December 31, 2021 2020 (in millions) Bank premises $ 91.6 $ 92.0 Land and improvements 32.4 33.0 Furniture, fixtures, and equipment 99.6 68.2 Leasehold improvements 41.5 29.7 Construction in progress 42.7 17.4 Total 307.8 240.3 Accumulated depreciation and amortization (125.9) (106.2) Premises and equipment, net $ 181.9 $ 134.1

Other Borrowings

Other Borrowings	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Other Borrowings	11. OTHER BORROWINGS The following table summarizes the Company’s borrowings as of December 31, 2021 and 2020: December 31, 2021 2020 (in millions) Short-Term: Federal funds purchased $ 675.0 $ — FHLB advances — 5.0 Customer repurchase agreements 16.6 16.0 Secured borrowings 35.3 — Total short-term borrowings $ 726.9 $ 21.0 Long-Term: AmeriHome senior notes, net of fair value adjustment $ 317.9 $ — Credit linked notes, net of debt issuance costs 457.1 — Total long-term borrowings $ 775.0 $ — Total other borrowings $ 1,501.9 $ 21.0 Short-Term Borrowings Federal Funds Lines of Credit The Company maintains federal fund lines of credit totaling $2.8 billion as of December 31, 2021, which have rates comparable to the federal funds effective rate plus 0.10% to 0.20%. As of December 31, 2021, outstanding balances on the Company's federal fund lines of credit totaled $675.0 million. As of December 31, 2020, there were no outstanding balances on the Company's federal fund lines of credit. FHLB Advances The Company also maintains secured lines of credit with the FHLB and the FRB. The Company’s borrowing capacity is determined based on collateral pledged, generally consisting of investment securities and loans, at the time of the borrowing. The Company has a PPP lending facility with the FRB that allows the Company to pledge loans originated under the PPP in return for dollar for dollar funding from the FRB, which would provide up to $416.0 million in additional credit. The amount of available credit under the PPP lending facility will decline each period as these loans are paid down. At December 31, 2021, the Company had no amounts outstanding under its line of credit or its PPP lending facility with the FRB and had no borrowings under its lines of credit with the FHLB. As of December 31, 2021 and 2020, the Company had additional available credit with the FHLB of approximately $7.8 billion and $4.0 billion, respectively, and with the FRB of approximately $3.4 billion and $2.7 billion, respectively. Repurchase Agreements Other short-term borrowing sources available to the Company include customer repurchase agreements, which totaled $16.6 million and $16.0 million as of December 31, 2021 and 2020, respectively. The weighted average rate on customer repurchase agreements was 0.15% as of December 31, 2021 and 2020. Secured Borrowings Transfers of loans HFS not qualifying for sales accounting treatment, resulted in recognition of secured borrowings of $35.3 million at December 31, 2021. Warehouse Borrowings The Company assumed warehouse borrowing lines of credit as part of the AmeriHome acquisition, which are used to finance the acquisition of loans through the use of repurchase agreements. Repurchase agreements operate as financings under which the Company transfers loans to secure these borrowings. The borrowing amounts are based on the attributes of the collateralized loans and are defined in the repurchase agreement of each warehouse lender. The Company retains beneficial ownership of the transferred loans and will receive the loans from the lender upon full repayment of the borrowing. The repurchase agreements may require the Company to transfer additional assets to the lender in the event the estimated fair value of the existing transferred loans declines.

Qualifying Debt Qualifying Debt

Qualifying Debt Qualifying Debt (Notes)	12 Months Ended
	Dec. 31, 2021
Qualifying Debt Disclosure [Abstract]
Subordinated Borrowings Disclosure [Text Block]	12. QUALIFYING DEBT Subordinated Debt The Company's subordinated debt issuances are detailed in the tables below: December 31, 2021 Description Issuance Date Maturity Date Interest Rate Principal Debt Issuance Costs at Origination (in millions) WAL fixed-to-variable-rate (1) June 2021 June 15, 2031 3.00 % $ 600.0 $ 8.1 WAB fixed-to-variable-rate (2) May 2020 June 1, 2030 5.25 % 225.0 3.1 $ 825.0 $ 11.2 December 31, 2020 Description Issuance Date Maturity Date Interest Rate Principal Debt Issuance Costs at Origination (in millions) WAL fixed-rate (3) June 2016 July 1, 2056 6.25 % $ 175.0 $ 5.5 WAB fixed-to-variable-rate (4) June 2015 July 15, 2025 3.44 % 75.0 1.8 WAB fixed-to-variable-rate (2) May 2020 June 1, 2030 5.25 % 225.0 3.1 $ 475.0 $ 10.4 (1) Notes are redeemable, in whole or in part, beginning on June 15, 2026 at their principal amount plus accrued and unpaid interest. The notes also convert to a variable rate on this date, which is expected to be three-month SOFR plus 225 basis points. (2) Debt is redeemable, in whole or in part, on or after June 1, 2025 at its principal amount plus accrued and unpaid interest and has a fixed interest rate of 5.25% through June 1, 2025 and then converts to a variable rate per annum equal to three-month SOFR plus 512 basis points. (3) Debentures became redeemable on July 1, 2021 at their principal amount plus any accrued and unpaid interest. During the year ended December 31, 2021 the debentures were redeemed in full. (4) Debt became redeemable on July 15, 2020, at its principal amount plus accrued and unpaid interest. During the year ended December 31, 2021, the remaining $75 million was redeemed in full. The Company hedged the interest rate risk on its 2015 and 2016 subordinated debt issuance with fair value interest rate hedges (receive fixed/pay variable swaps). These hedges were terminated during the year ended December 31, 2021 in connection with the redemptions of these subordinated debentures. The carrying value of all subordinated debt issuances, which included the fair value of the related hedges, totaled $815.1 million and $469.8 million at December 31, 2021 and 2020, respectively. Junior Subordinated Debt The Company has formed or acquired through acquisition eight statutory business trusts, which exist for the exclusive purpose of issuing Cumulative Trust Preferred Securities. The Company's junior subordinated debt has contractual balances and maturity dates as follows: December 31, Name of Trust Maturity 2021 2020 At fair value (in millions) BankWest Nevada Capital Trust II 2033 $ 15.5 $ 15.5 Intermountain First Statutory Trust I 2034 10.3 10.3 First Independent Statutory Trust I 2035 7.2 7.2 WAL Trust No. 1 2036 20.6 20.6 WAL Statutory Trust No. 2 2037 5.2 5.2 WAL Statutory Trust No. 3 2037 7.7 7.7 Total contractual balance 66.5 66.5 FVO on junior subordinated debt 0.9 (0.6) Junior subordinated debt, at fair value $ 67.4 $ 65.9 At amortized cost Bridge Capital Holdings Trust I 2035 $ 12.4 $ 12.4 Bridge Capital Holdings Trust II 2036 5.1 5.1 Total contractual balance 17.5 17.5 Purchase accounting adjustment, net of accretion (1) (4.2) (4.5) Junior subordinated debt, at amortized cost $ 13.3 $ 13.0 Total junior subordinated debt $ 80.7 $ 78.9 (1) The purchase accounting adjustment is being accreted over the remaining life of the trusts, pursuant to accounting guidance. With the exception of debt issued by Bridge Capital Trust I and Bridge Capital Trust II, junior subordinated debt is recorded at fair value at each reporting date due to the FVO election made by the Company under ASC 825. The Company did not make the FVO election for the junior subordinated debt acquired as part of the Bridge acquisition. Accordingly, the carrying value of these trusts does not reflect the current fair value of the debt and includes a fair market value adjustment established at acquisition that is being accreted over the remaining life of the trusts. The carrying value of junior subordinated debt was $80.7 million and $78.9 million as of December 31, 2021 and 2020, respectively. The weighted average interest rate of all junior subordinated debt as of December 31, 2021 was 2.55%, which is equal to three-month LIBOR plus the contractual spread of 2.34%, compared to a weighted average interest rate of 2.58% at December 31, 2020. Subsequent to June 30, 2023, interest rates on the Company's junior subordinated debt will be based on SOFR. In the event of certain changes or amendments to regulatory requirements or federal tax rules, the debt is redeemable in whole. The obligations under these instruments are fully and unconditionally guaranteed by the Company and rank subordinate and junior in right of payment to all other liabilities of the Company. Based on guidance issued by the FRB, the Company's securities continue to qualify as Tier 1 Capital.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2021
Stockholders' Equity Note [Abstract]
Stockholder's Equity	13. STOCKHOLDERS' EQUITY Stock-Based Compensation Restricted Stock Awards The Incentive Plan, as amended, gives the BOD the authority to grant up to 11.8 million in stock awards consisting of unrestricted stock, stock units, dividend equivalent rights, stock options (incentive and non-qualified), stock appreciation rights, restricted stock, and performance and annual incentive awards. The Incentive Plan limits the maximum number of shares of common stock that may be awarded to any person eligible for an award to 300,000 per calendar year and also limits the total compensation (cash and stock) that can be awarded to a non-employee director to $600,000 in any calendar year. Stock awards available for grant at December 31, 2021 were 3.0 million. Restricted stock awards granted to employees generally vest over a 3-year period. Stock grants made to non-employee WAL directors in 2021 were fully vested on July 1, 2021. The Company estimates the compensation cost for stock grants based upon the grant date fair value. Stock compensation expense is recognized on a straight-line basis over the requisite service period for the entire award. Stock compensation expense related to restricted stock awards granted to employees are included in Salaries and employee benefits in the Consolidated Income Statement. For restricted stock awards granted to WAL directors, the related stock compensation expense is included in Legal, professional, and directors' fees. For the year ended December 31, 2021, the Company recognized $22.9 million in stock-based compensation expense related to these stock grants, compared to $20.3 million and $17.4 million during the years ended December 31, 2020 and 2019, respectively. In addition, the Company previously granted shares of restricted stock to certain members of executive management that had both performance and service conditions that affect vesting. There were no such grants made during the years ended December 31, 2021, 2020, and 2019, however expense was still being recognized through June 30, 2021 for a grant made in 2017 with a four-year vesting period. The Company recognized $0.6 million in stock-based compensation expense related to these performance-based restricted stock grants through June 30, 2021, the end of the vesting period, compared to $1.2 million and $1.9 million during the years ended December 31, 2020 and 2019, respectively. A summary of the status of the Company’s unvested shares of restricted stock and changes during the years then ended is presented below: December 31, 2021 2020 Shares Weighted Average Grant Date Fair Value Shares Weighted Average Grant Date Fair Value (in millions, except per share amounts) Balance, beginning of period 1.0 $ 50.12 1.0 $ 49.98 Granted 0.4 83.56 0.4 51.53 Vested (0.4) 53.50 (0.4) 51.86 Forfeited (0.1) 59.24 0.0 49.79 Balance, end of period 0.9 $ 63.53 1.0 $ 50.12 The total weighted average grant date fair value of all stock awards, including the performance-based restricted stock awards, granted during the years ended December 31, 2021, 2020, and 2019 was $35.4 million, $22.7 million, and $23.7 million, respectively. The total fair value of restricted stock that vested during the years ended December 31, 2021, 2020, and 2019 was $34.2 million, $19.6 million, and $21.3 million, respectively. As of December 31, 2021, there was $28.0 million of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the Incentive Plan. That cost is expected to be recognized over a weighted average period of 2.0 years. Performance Stock Units The Company grants performance stock units to members of its executive management that do not vest unless the Company achieves a specified cumulative EPS target and a TSR performance measure over a three-year performance period. The number of shares issued will vary based on the cumulative EPS target and relative TSR performance factor that is achieved. The Company estimates the cost of performance stock units based upon the grant date fair value and expected vesting percentage over the three-year performance period. For the year ended December 31, 2021, the Company recognized $10.4 million in stock-based compensation expense related to these performance stock units, compared to $7.1 million and $6.9 million in stock-based compensation expense for such units during the years ended December 31, 2020 and 2019, respectively. The three-year performance period for the 2019 grant ended on December 31, 2021, and the Company's cumulative EPS and TSR performance measure for the performance period exceeded the level required for a maximum award under the terms of the grant. As a result, 203,646 shares will become fully vested and distributed to executive management in the first quarter of 2022. The three-year performance period for the 2018 grant ended on December 31, 2020, and the Company's cumulative EPS and TSR performance measure for the performance period exceeded the level required for a maximum award under the terms of the grant. As a result, 152,418 shares became fully vested and were distributed to executive management in the first quarter of 2021. Preferred Stock On September 15, 2021, the Company entered into an underwriting agreement, pursuant to which the Company agreed to issue and sell an aggregate of 12,000,000 depositary shares, each representing a 1/400th ownership interest in a share of the Company’s 4.250% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Shares, Series A, par value $0.0001 per share, with a liquidation preference of $25 per depositary share (equivalent to $10,000 per share of Series A preferred stock). The Company received net proceeds of $294.5 million from the issuance of preferred stock during the year ended December 31, 2021. On December 14, 2021, the Company declared the first quarterly cash dividend of $0.29 per depositary share, for a total dividend payment to preferred shareholders of $3.5 million, paid on December 30, 2021. Common Stock Issuances Pursuant to ATM Distribution Agreement On June 3, 2021, the Company entered into a distribution agency agreement with J.P. Morgan Securities LLC, under which the Company may sell up to 4,000,000 shares of its common stock on the NYSE. The Company pays the distribution agents a mutually agreed rate, not to exceed 2% of the gross offering proceeds of the shares sold pursuant to the distribution agency agreement. The common stock will be sold at prevailing market prices at the time of the sale or at negotiated prices and, as a result, prices will vary. Sales under the ATM program are being made pursuant to a prospectus dated May 14, 2021 and a prospectus supplement filed with the SEC in an offering of shares from the Company's shelf registration statement on Form S-3 (No. 333-256120). On November 18, 2021, the distribution agency agreement was amended to add Piper Sandler & Co. as an agent with J.P. Morgan Securities LLC. During the year ended December 31, 2021, the Company sold 3.1 million shares under the ATM program at a weighted-average selling price of $106.41 per share for gross proceeds of $333.4 million. Total related offering costs were $2.3 million, of which $2.0 million relates to compensation costs paid to J.P. Morgan Securities LLC and Piper Sandler & Co. Registered Direct Offering The Company sold 2.3 million shares of its common stock in a registered direct offering during the year ended December 31, 2021. The shares were sold for $91.00 per share for aggregate net proceeds of $209.2 million. Common Stock Repurchase The Company's common stock repurchase program, which expired on December 31, 2020, authorized the Company to repurchase up to $250.0 million of its outstanding common stock. Effective April 17, 2020, the Company temporarily suspended its stock repurchase program. Prior to this decision and pursuant to the repurchase plan, the Company repurchased 2.1 million shares of its common stock at a weighted average price of $34.65 for a total payment of $71.6 million during the year ended December 31, 2020. There were no share repurchases during the year ended December 31, 2021. Cash Dividend on Common Shares During the year ended December 31, 2021, the Company declared and paid quarterly cash dividends of $0.25 per share for the first two quarters of the year and increased the quarterly cash dividend to $0.35 per share for the last two quarters of the year, for a total dividend payment to shareholders of $124.1 million. During the year ended December 31, 2020, the Company declared and paid a quarterly cash dividend of $0.25 per share, for a total dividend payment to shareholders of $101.3 million. Treasury Shares

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Accumulated Other Comprehensive Income	14. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table summarizes the changes in accumulated other comprehensive income (loss) by component, net of tax, for the periods indicated: Unrealized holding gains (losses) on AFS Unrealized holding gains (losses) on SERP Unrealized holding gains (losses) on junior subordinated debt Impairment loss on securities Total (in millions) Balance, December 31, 2018 $ (47.5) $ 0.4 $ 13.4 $ 0.1 $ (33.6) Other comprehensive income (loss) before reclassifications 71.2 (0.4) (9.8) — 61.0 Amounts reclassified from AOCI (2.3) — — (0.1) (2.4) Net current-period other comprehensive income (loss) 68.9 (0.4) (9.8) (0.1) 58.6 Balance, December 31, 2019 $ 21.4 $ — $ 3.6 $ — $ 25.0 Other comprehensive income (loss) before reclassifications 70.9 (0.3) (3.1) — 67.5 Amounts reclassified from accumulated other comprehensive income (0.2) — — — (0.2) Net current-period other comprehensive income (loss) 70.7 (0.3) (3.1) — 67.3 Balance, December 31, 2020 $ 92.1 $ (0.3) $ 0.5 $ — $ 92.3 Other comprehensive (loss) income before reclassifications (69.0) — (1.2) — (70.2) Amounts reclassified from AOCI (6.4) — — — (6.4) Net current-period other comprehensive (loss) income (75.4) — (1.2) — (76.6) Balance, December 31, 2021 $ 16.7 $ (0.3) $ (0.7) $ — $ 15.7 The following table presents reclassifications out of accumulated other comprehensive income: Year Ended December 31, Income Statement Classification 2021 2020 2019 (in millions) Gain on sales of AFS debt securities, net $ 8.5 $ 0.2 $ 3.1 Income tax expense (2.1) — (0.7) Net of tax $ 6.4 $ 0.2 $ 2.4

Derivatives and Hedging

Derivatives and Hedging	12 Months Ended
	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	15. DERIVATIVES AND HEDGING ACTIVITIES The Company is a party to various derivative instruments, including those derivative instruments assumed from the AmeriHome acquisition. Derivative instruments are contracts between two or more parties that have a notional amount and an underlying variable, require a small or no initial investment, and allow for the net settlement of positions. A derivative’s notional amount serves as the basis for the payment provision of the contract and takes the form of units, such as shares or dollars. A derivative’s underlying variable is a specified interest rate, security price, commodity price, foreign exchange rate, index, or other variable. The interaction between the notional amount and the underlying variable determines the number of units to be exchanged between the parties and influences the fair value of the derivative contract. The primary types of derivatives that the Company uses are interest rate swaps, forward purchase and sale commitments, and interest rate futures. Generally, these instruments are used to help manage the Company's exposure to interest rate risk related to IRLCs and its inventory of loans HFS and MSRs and also to meet client financing and hedging needs. Derivatives are recorded at fair value on the Consolidated Balance Sheets, after taking into account the effects of bilateral collateral and master netting agreements. These agreements allow the Company to settle all derivative contracts held with the same counterparty on a net basis, and to offset net derivative positions with related cash collateral, where applicable. As of December 31, 2021, 2020, and 2019, the Company does not have any outstanding cash flow hedges. Derivatives Designated in Hedge Relationships The Company utilizes derivatives that have been designated as part of a hedge relationship in accordance with the applicable accounting guidance to minimize the exposure to changes in benchmark interest rates and volatility of net interest income and EVE to interest rate fluctuations. The primary derivative instruments used to manage interest rate risk are interest rate swaps, which convert the contractual interest rate index of agreed-upon amounts of assets and liabilities (i.e., notional amounts) from either a fixed rate to a variable rate, or from a variable rate to a fixed rate. The Company has pay fixed/receive variable interest rate swaps designated as fair value hedges of certain fixed rate loans. As a result, the Company receives variable-rate interest payments in exchange for making fixed-rate payments over the lives of the contracts without exchanging the notional amounts. The variable-rate interest payments are based on LIBOR and will convert to SOFR upon the discontinuation of LIBOR in June 2023. The Company also has pay fixed/receive variable interest rate swaps, designated as fair value hedges using the last-of-layer method to manage the exposure to changes in fair value associated with fixed rate loans, resulting from changes in the designated benchmark interest rate (federal funds rate). These last-of-layer hedges provide the Company the ability to execute a fair value hedge of the interest rate risk associated with a portfolio of similar prepayable assets whereby the last dollar amount estimated to remain in the portfolio of assets is identified as the hedged item. Under these interest rate swap contracts, the Company receives a variable rate and pays a fixed rate on the outstanding notional amount. During the year ended December 31, 2021, the Company completed a partial discontinuation of one of its last-of-layer hedges, which reduced the total hedged amount on these hedges from $1.0 billion to $880.0 million. The $1.2 million cumulative basis adjustment on the discontinued portion was allocated across the remaining pool upon termination of the hedge and is being amortized over the remaining loan term. The Company had a receive fixed/pay variable interest rate swap, designated as a fair value hedge on its fixed rate $175.0 million subordinated debentures issued on June 16, 2016, which was terminated during the year ended December 31, 2021 in connection with the full redemption of the subordinated debentures. The Company paid a variable rate of three-month LIBOR plus 3.25% and received quarterly fixed payments of 6.25% to match the payments on the debt. Derivatives Not Designated in Hedge Relationships Management enters into certain foreign exchange derivative contracts and back-to-back interest rate swaps which are not designated as accounting hedges. Foreign exchange derivative contracts include spot, forward, forward window, and swap contracts. The purpose of these derivative contracts is to mitigate foreign currency risk on transactions entered into, or on behalf of customers. Contracts with customers, along with the related derivative trades that the Company places, are both remeasured at fair value, and are referred to as economic hedges since they economically offset the Company's exposure. The Company's back-to-back interest rate swaps are used to allow customers to manage long-term interest rate risk. As it relates to its mortgage banking business, the Company also uses derivative financial instruments to manage exposure to interest rate risk related to IRLCs, and its inventory of loans HFS and MSRs. The Company economically hedges the changes in fair value associated with changes in interest rates generally by utilizing forward sale commitments and interest rate futures. As of December 31, 2021 and 2020, the following amounts are reflected on the Consolidated Balance Sheets related to cumulative basis adjustments for fair value hedges: December 31, 2021 December 31, 2020 Carrying Value of Hedged Assets/(Liabilities) Cumulative Fair Value Hedging Adjustment (1) Carrying Value of Hedged Assets/(Liabilities) Cumulative Fair Value Hedging Adjustment (1) (in millions) Loans HFI, net of deferred loan fees and costs (2) $ 1,390.7 $ 38.5 $ 1,587.1 $ 85.5 Qualifying debt — — (247.6) (2.7) (1) Included in the carrying value of the hedged assets/(liabilities) (2) Includes last-of-layer derivative instruments, with $880.0 million designated as the hedged amount (from a closed portfolio of prepayable fixed rate loans with a carrying value of $1.4 billion and $1.9 billion as of December 31, 2021 and 2020, respectively). The cumulative basis adjustment included in the carrying value of these hedged items totaled $15.7 million and $0.6 million as of December 31, 2021 and 2020, respectively. The basis adjustment related to the discontinued portion was $1.0 million as of December 31, 2021. For the Company's derivative instruments that are designated and qualify as a fair value hedge, the gain or loss on the derivative instrument as well as the offsetting loss or gain on the hedged item attributable to the hedged risk are recognized in current earnings in the same line item as the offsetting loss or gain on the related interest rate swaps. For loans, the gain or loss on the hedged item is included in interest income and for subordinated debt, the gain or loss on the hedged items is included in interest expense, as shown in the table below. Year Ended December 31, 2021 2020 2019 Income Statement Classification Gain/(Loss) on Swaps Gain/(Loss) on Hedged Item Gain/(Loss) on Swaps Gain/(Loss) on Hedged Item Gain/(Loss) on Swaps Gain/(Loss) on Hedged Item (in millions) Interest income $ 44.8 $ (45.6) $ (32.2) $ 32.2 $ (30.3) $ 30.3 Interest expense (2.7) 2.7 3.1 (3.1) 19.3 (19.3) Fair Values, Volume of Activity, and Gain/Loss Information Related to Derivative Instruments The following table summarizes the fair value of the Company's derivative instruments on a gross basis as of December 31, 2021, 2020, and 2019. The change in the notional amounts of these derivatives from December 31, 2019 to December 31, 2021 indicates the volume of the Company's derivative transaction activity during these periods. The derivative asset and liability balances are presented on a gross basis, prior to the application of bilateral collateral and master netting agreements. Total derivative assets and liabilities are adjusted to take into account the impact of legally enforceable master netting agreements that allow the Company to settle all derivative contracts with the same counterparty on a net basis and to offset the net derivative position with the related cash collateral. Where master netting agreements are not in effect or are not enforceable under bankruptcy laws, the Company does not adjust those derivative amounts with counterparties. December 31, 2021 December 31, 2020 December 31, 2019 Fair Value Fair Value Fair Value Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities (in millions) Derivatives designated as hedging instruments: Fair value hedges Interest rate swaps (1) $ 1,382.8 $ 13.8 $ 54.5 $ 1,689.9 $ 3.3 $ 86.1 $ 863.0 $ 1.8 $ 55.5 Total $ 1,382.8 $ 13.8 $ 54.5 $ 1,689.9 $ 3.3 $ 86.1 $ 863.0 $ 1.8 $ 55.5 Derivatives not designated as hedging instruments (2): Foreign currency contracts $ 180.1 $ 0.2 $ 1.4 $ 119.2 $ 0.7 $ 1.2 $ 6.7 $ — $ — Forward purchase contracts 11,713.5 8.1 18.0 — — — — — — Forward sales contracts 17,358.5 15.8 17.7 — — — — — — Futures purchase contracts (3) 218,053.7 — — — — — — — — Futures sales contracts (3) 229,040.0 — — — — — — — — Interest rate lock commitments 3,033.2 11.0 1.6 — — — — — — Interest rate swaps 4.1 0.1 0.1 3.5 0.2 0.2 2.9 0.1 0.1 Total $ 479,383.1 $ 35.2 $ 38.8 $ 122.7 $ 0.9 $ 1.4 $ 9.6 $ 0.1 $ 0.1 Margin 1.2 6.5 — — — — — — Total, including margin $ 479,383.1 $ 36.4 $ 45.3 $ 122.7 $ 0.9 $ 1.4 $ 9.6 $ 0.1 $ 0.1 (1) Interest rate swap amounts include a notional amount of $880 million and $1.0 billion related to the last-of-layer hedges at December 31, 2021 and 2020, respectively. (2) Relate to economic hedging arrangements. (3) The Company enters into forward purchase and sales contracts that are subject to daily remargining and almost all of which are based on three-month LIBOR to hedge against its MSR valuation exposure. The notional amount on these contracts is substantial as these contracts have a duration of only 0.25 years and are intended to cover the longer duration of MSR hedges. The fair value of derivative contracts, after taking into account the effects of master netting agreements, is included in other assets or other liabilities on the Consolidated Balance Sheets, as summarized in the table below: December 31, 2021 December 31, 2020 December 31, 2019 Gross amount of recognized assets (liabilities) Gross offset Net assets (liabilities) Gross amount of recognized assets (liabilities) Gross offset Net assets (liabilities) Gross amount of recognized assets (liabilities) Gross offset Net assets (liabilities) (in millions) Derivatives subject to master netting arrangements: Assets Forward purchase contracts $ 7.9 $ — $ 7.9 $ — $ — $ — $ — $ — $ — Forward sales contracts 15.5 — 15.5 — — — — — — Interest rate swaps 13.8 — 13.8 3.3 — 3.3 1.8 — 1.8 Margin 1.2 — 1.2 — — — — — — Netting — (28.4) (28.4) — (0.6) (0.6) — — — $ 38.4 (28.4) $ 10.0 $ 3.3 $ (0.6) $ 2.7 $ 1.8 $ — $ 1.8 Liabilities Forward purchase contracts $ (17.7) $ — $ (17.7) $ — $ — $ — $ — $ — $ — Forward sales contracts (17.6) — (17.6) — — — — — — Interest rate swaps (54.5) — (54.5) (86.1) — (86.1) (55.5) — (55.5) Margin (6.5) — (6.5) — — — — — — Netting — 28.4 28.4 — 0.6 0.6 — — — $ (96.3) 28.4 $ (67.9) $ (86.1) $ 0.6 $ (85.5) $ (55.5) $ — $ (55.5) Derivatives not subject to master netting arrangements: Assets Foreign currency contracts $ 0.2 $ — $ 0.2 $ 0.7 $ — $ 0.7 $ — $ — $ — Forward purchase contracts 0.2 — 0.2 — — — — — — Forward sales contracts 0.3 — 0.3 — — — — — — Interest rate lock commitments 11.0 — 11.0 — — — — — — Interest rate swaps 0.1 — 0.1 0.2 — 0.2 0.1 — 0.1 $ 11.8 — $ 11.8 $ 0.9 $ — $ 0.9 $ 0.1 $ — $ 0.1 Liabilities Foreign currency contracts $ (1.4) $ — $ (1.4) $ (1.2) $ — $ (1.2) $ — $ — $ — Forward purchase contracts (0.3) — (0.3) — — — — — — Forward sales contracts (0.1) — (0.1) — — — — — — Interest rate lock commitments (1.6) — (1.6) — — — — — — Interest rate swaps (0.1) — (0.1) (0.2) — (0.2) (0.1) — (0.1) $ (3.5) — $ (3.5) $ (1.4) $ — $ (1.4) $ (0.1) $ — $ (0.1) Total derivatives and margin Assets $ 50.2 $ (28.4) $ 21.8 $ 4.2 $ (0.6) $ 3.6 $ 1.9 $ — $ 1.9 Liabilities $ (99.8) $ 28.4 $ (71.4) $ (87.5) $ 0.6 $ (86.9) $ (55.6) $ — $ (55.6) The following table summarizes the net gain (loss) on derivatives included in income: Year Ended December 31, 2021 (in millions) Net gain (loss) on loan origination and sale activities: Interest rate lock commitments $ 1.0 Forward contracts (52.2) Other contracts 1.4 Total gain $ (49.8) Net loan servicing revenue: Forward contracts $ (4.2) Options contracts (0.3) Futures contracts (23.9) Total (loss) gain $ (28.4) Counterparty Credit Risk Like other financial instruments, derivatives contain an element of credit risk. This risk is measured as the expected replacement value of the contracts. Management enters into bilateral collateral and master netting agreements that provide for the net settlement of all contracts with the same counterparty. Additionally, management monitors counterparty credit risk exposure on each contract to determine appropriate limits on the Company's total credit exposure across all product types, which may require the Company to post collateral to counterparties when these contracts are in a net liability position and conversely, for counterparties to post collateral to the Company when these contracts are in a net asset position. Management reviews the Company's collateral positions on a daily basis and exchanges collateral with counterparties in accordance with standard ISDA documentation and other related agreements. The Company generally posts or holds collateral in the form of cash deposits or highly rated securities issued by the U.S. Treasury or government-sponsored enterprises, such as GNMA, FNMA, and FHLMC. The total collateral pledged by the Company to counterparties for its derivatives designated as hedging instruments totaled $67.1 million, $117.8 million, and $52.5 million as of December 31, 2021, 2020, and 2019, respectively.

Earnings per Share (Notes)

Earnings per Share (Notes)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	16. EARNINGS PER SHARE Diluted EPS is based on the weighted average outstanding common shares during the period, including common stock equivalents. Basic EPS is based on the weighted average outstanding common shares during the period. The following table presents the calculation of basic and diluted EPS: Year Ended December 31, 2021 2020 2019 (in millions, except per share amounts) Weighted average shares - basic 102.7 100.2 102.7 Dilutive effect of stock awards 0.6 0.3 0.4 Weighted average shares - diluted 103.3 100.5 103.1 Net income available to common stockholders $ 895.7 $ 506.6 $ 499.2 Earnings per share - basic 8.72 5.06 4.86 Earnings per share - diluted 8.67 5.04 4.84

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	17. INCOME TAXES The provision for income taxes charged to operations consists of the following: Year Ended December 31, 2021 2020 2019 (in millions) Current $ 181.8 $ 141.0 $ 110.1 Deferred 42.0 (25.1) (5.1) Total tax provision $ 223.8 $ 115.9 $ 105.0 The reconciliation between the statutory federal income tax rate and the Company’s effective tax rate is summarized as follows: Year Ended December 31, 2021 2020 2019 (in millions) Income tax at statutory rate $ 235.8 $ 130.7 $ 126.9 Increase (decrease) resulting from: State income taxes, net of federal benefits 35.8 13.9 11.0 Tax-exempt income (25.6) (21.7) (19.6) Investment tax credits (15.9) (13.9) (15.0) Other, net (6.3) 6.9 1.7 Total tax provision $ 223.8 $ 115.9 $ 105.0 For the years ended December 31, 2021, 2020, and 2019 the Company's effective tax rate was 19.9%, 18.6%, and 17.4%, respectively. The increase in the effective tax rate from 2020 to 2021 is primarily due to an increase in pretax book income and state income taxes associated with the AmeriHome acquisition which were not fully offset by growth in permanent tax benefit items for the year. The increase in the effective tax rate from 2019 to 2020 is due primarily to tax expense associated with the surrender of BOLI, no valuation allowance release in 2020, and return to provision adjustments. The cumulative tax effects of the primary temporary differences are shown in the following table: December 31, 2021 2020 (in millions) Deferred tax assets: Allowance for credit losses $ 81.0 $ 84.6 Lease liability 38.6 21.1 Premises and equipment 10.0 — Accrued expenses 9.8 3.6 Passthrough income 9.1 8.4 Insurance premiums — 18.9 Other 34.9 29.1 Total gross deferred tax assets 183.4 165.7 Deferred tax asset valuation allowance — — Total deferred tax assets 183.4 165.7 Deferred tax liabilities: Mortgage servicing rights (57.6) — Right of use asset (36.0) (19.2) Deferred loan costs (15.5) (12.8) Leasing basis differences (12.3) (11.1) IRC section 50(d) income (7.7) (9.8) Estimated loss reserve (7.6) (17.5) Unearned premiums (7.2) (16.8) Insurance premiums (6.0) — Unrealized gain on AFS securities (5.7) (31.2) Premises and equipment — (7.6) Other (6.9) (8.4) Total deferred tax liabilities (162.5) (134.4) Deferred tax assets, net $ 20.9 $ 31.3 Deferred tax assets and liabilities are included in the Consolidated Financial Statements at currently enacted income tax rates applicable to the period in which the deferred tax assets or liabilities are expected to be reversed. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. Net deferred tax assets decreased $10.4 million to $20.9 million from December 31, 2020. The overall decrease in net deferred tax assets was due to an increase in deferred tax liabilities, not fully offset by an increase in deferred tax assets. The increase in deferred tax liabilities from December 31, 2020 is primarily attributable to an increase in mortgage servicing rights from AmeriHome operations and a decrease in deferred insurance premiums related to the Company’s insurance captive, which was in a deferred tax asset position in the prior year. These increases were offset in part by a decrease in deferred tax liabilities related to a decrease in the fair market value of AFS securities. The increase in deferred tax assets from December 31, 2020 is primarily attributable to a change in tax planning strategy pertaining to the depreciation election on premises and equipment, which was in a deferred tax liability position in the prior year. Although realization is not assured, the Company believes that the realization of the recognized net deferred tax asset of $20.9 million at December 31, 2021 is more-likely-than-not based on expectations as to future taxable income and based on available tax planning strategies that could be implemented if necessary to prevent a carryover from expiring. As of December 31, 2021 and 2020, the Company has no deferred tax valuation allowance. As of December 31, 2021, the Company’s gross federal NOL carryovers, all of which are subject to limitations under Section 382 of the IRC, totaled $41.1 million, for which a deferred tax asset of $4.5 million has been recorded, reflecting the expected benefit of these federal NOL carryovers remaining after application of the Section 382 limitation. The Company does not currently have any remaining state NOL carryovers. The Company files income tax returns in the U.S. federal jurisdiction and in various states. With few exceptions, the Company is no longer subject to U.S. federal, state, or local income tax examinations by tax authorities for years before 2017. When tax returns are filed, it is highly certain that most positions taken would be sustained upon examination by the taxing authorities, while others are subject to uncertainty about the merits of the position taken or the amount of the position that would be ultimately sustained. The benefit of a tax position is recognized in the Consolidated Financial Statements in the period in which, based on all available evidence, management believes it is more-likely-than-not that the position will be sustained upon examination, including the resolution of appeals or litigation processes, if any. Tax positions taken are not offset or aggregated with other positions. Tax positions that meet the more-likely-than-not recognition threshold are measured as the largest amount of tax benefit that is more than 50% likely of being realized upon settlement with the applicable taxing authority. The portion of the benefits associated with tax positions taken that exceeds the amount measured as described above is reflected as a liability for unrecognized tax benefits on the accompanying Consolidated Balance Sheets along with any associated interest and penalties payable to the taxing authorities upon examination. The total gross activity of unrecognized tax benefits related to the Company's uncertain tax positions are shown in the following table: December 31, 2021 2020 (in millions) Beginning balance $ 3.4 $ 1.7 Gross increases Tax positions in prior periods 0.8 — Current period tax positions 2.2 2.2 Gross decreases Tax positions in prior periods — — Settlements — (0.1) Lapse of statute of limitations — (0.4) Ending balance $ 6.4 $ 3.4 During the year ended December 31, 2021, the Company added a new position, which resulted in a tax detriment of $2.5 million, inclusive of interest and penalties. As of December 31, 2021 and 2020, the total amount of unrecognized tax benefits, net of associated deferred tax benefits, that would impact the effective tax rate, if recognized, is $5.1 million and $2.1 million, respectively. The Company does not anticipate that any unrecognized tax benefits will be resolved within the next 12 months. During the years ended December 31, 2021, 2020, and 2019, the Company recognized no additional amounts for interest and penalties. As of December 31, 2021 and 2020, the Company has no accrued liabilities for penalties and interest. LIHTC and renewable energy projects As discussed in "Note 1. Summary of Significant Accounting Policies," the Company holds ownership interests in limited partnerships and limited liability companies that invest in affordable housing and renewable energy projects. These investments are designed to generate a return primarily through the realization of federal tax credits and deductions. The limited liability entities are considered to be VIEs; however, as a limited partner, the Company is not the primary beneficiary and is not required to consolidate these entities. At December 31, 2021, the Company’s exposure to loss as a result of its involvement in these entities was limited to $676.5 million, which reflects the Company’s recorded investment in these projects, net of certain unfunded capital commitments, and previously recorded tax credits which remain subject to recapture by taxing authorities. During the years ended December 31, 2021, 2020, and 2019, the Company did not provide financial or other support to these entities that was not contractually required. Investments in LIHTC and renewable energy total $631.3 million and $405.6 million as of December 31, 2021 and 2020, respectively. Unfunded LIHTC and renewable energy obligations are included as part of Other liabilities on the Consolidated Balance Sheets and total $360.8 million and $151.7 million as of December 31, 2021 and 2020, respectively. For the years ended December 31, 2021, 2020, and 2019, $49.5 million, $49.2 million, and $41.5 million of amortization related to LIHTC investments was recognized as a component of income tax expense, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	18. COMMITMENTS AND CONTINGENCIES Unfunded Commitments and Letters of Credit The Company is party to financial instruments with off-balance sheet risk in the normal course of business to meet the financing needs of its customers. These financial instruments include commitments to extend credit and letters of credit. They involve, to varying degrees, elements of credit risk in excess of amounts recognized on the Consolidated Balance Sheets. Lines of credit are obligations to lend money to a borrower. Credit risk arises when the borrower's current financial condition may indicate less ability to pay than when the commitment was originally made. In the case of letters of credit, the risk arises from the potential failure of the customer to perform according to the terms of a contract. In such a situation, the third party might draw on the letter of credit to pay for completion of the contract and the Company would look to its customer to repay these funds with interest. To minimize the risk, the Company uses the same credit policies in making commitments and conditional obligations as it would for a loan to that customer. Letters of credit and financial guarantees are commitments issued by the Company to guarantee the performance of a customer to a third party in borrowing arrangements. The Company generally has recourse to recover from the customer any amounts paid under the guarantees. Typically, letters of credit issued have expiration dates within one year. A summary of the contractual amounts for unfunded commitments and letters of credit are as follows: December 31, 2021 2020 (in millions) Commitments to extend credit, including unsecured loan commitments of $1,199.8 at December 31, 2021 and $1,077.2 at December 31, 2020 $ 13,396.3 $ 9,425.2 Credit card commitments and financial guarantees 306.3 291.5 Letters of credit, including unsecured letters of credit of $12.9 at December 31, 2021 and $9.9 at December 31, 2020 198.1 186.9 Total $ 13,900.7 $ 9,903.6 The following table represents the contractual commitments for lines and letters of credit by maturity at December 31, 2021: Amount of Commitment Expiration per Period Total Amounts Committed Less Than 1 Year 1-3 Years 3-5 Years After 5 Years (in millions) Commitments to extend credit $ 13,396.3 $ 3,652.0 $ 6,235.1 $ 2,322.1 $ 1,187.0 Credit card commitments and financial guarantees 306.3 306.3 — — — Letters of credit 198.1 190.7 3.0 4.4 — Total $ 13,900.7 $ 4,149.0 $ 6,238.1 $ 2,326.5 $ 1,187.0 Commitments to extend credit are agreements to lend to a customer provided that there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. The Company enters into credit arrangements that generally provide for the termination of advances in the event of a covenant violation or other event of default. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the party. The commitments are collateralized by the same types of assets used as loan collateral. The Company has exposure to credit losses from unfunded commitments and letters of credit. As funds have not been disbursed on these commitments, they are not reported as loans outstanding. Credit losses related to these commitments are included in Other liabilities as a separate loss contingency and are not included in the allowance for credit losses reported in "Note 5. Loans, Leases and Allowance for Credit Losses" of these Consolidated Financial Statements. This loss contingency for unfunded loan commitments and letters of credit was $37.6 million and $37.0 million as of December 31, 2021 and 2020, respectively. Changes to this liability are adjusted through the provision for credit losses in the Consolidated Income Statement. Concentrations of Lending Activities The Company does not have a single external customer from which it derives 10% or more of its revenues. The Company monitors concentrations within three broad categories: industry, product, and collateral. The Company's loan portfolio includes significant credit exposure to the CRE market. As of December 31, 2021 and 2020, CRE related loans accounted for approximately 29% and 38% of total loans, respectively. Substantially all of these loans are secured by first liens with an initial loan-to-value ratio of generally not more than 75%. Approximately 23% and 28% of these CRE loans, excluding construction and land loans, were owner-occupied as of December 31, 2021 and 2020, respectively. Contingencies The Company is involved in various lawsuits of a routine nature that are being handled and defended in the ordinary course of the Company’s business. Expenses are being incurred in connection with these lawsuits, but in the opinion of management, based in part on consultation with outside legal counsel, the resolution of these lawsuits and associated defense costs will not have a material impact on the Company’s financial position, results of operations, or cash flows.

Fair Value Accounting

Fair Value Accounting	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Accounting	19. FAIR VALUE ACCOUNTING The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, the Company utilizes valuation techniques that are consistent with the market approach, the income approach, and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability. ASC 825 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under ASC 825 are described in "Note 1. Summary of Significant Accounting Policies" of these Notes to Consolidated Financial Statements. In general, fair value is based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon internally-developed models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and the Company’s creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. The Company’s valuation methodologies may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. While management believes the Company’s valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Furthermore, the reported fair value amounts have not been comprehensively revalued since the presentation dates, and therefore, estimates of fair value after the balance sheet date may differ significantly from the amounts presented herein. A more detailed description of the valuation methodologies used for assets and liabilities measured at fair value is set forth below. Under ASC 825, the Company elected the FVO treatment for junior subordinated debt issued by WAL. This election is irrevocable and results in the recognition of unrealized gains and losses on these items at each reporting date. These unrealized gains and losses are recognized as part of OCI rather than earnings. The Company did not elect FVO treatment for the junior subordinated debt assumed in the Bridge Capital Holdings acquisition. For the years ended December 31, 2021, 2020, and 2019, unrealized losses from fair value changes on junior subordinated debt were as follows: Year Ended December 31, 2021 2020 2019 (in millions) Unrealized losses $ (1.5) $ (4.2) $ (13.0) Changes included in OCI, net of tax (1.2) (3.1) (9.8) Fair value on a recurring basis Financial assets and financial liabilities measured at fair value on a recurring basis include the following: AFS debt securities: Securities classified as AFS are reported at fair value utilizing Level 1 and Level 2 inputs. For these securities, the Company obtains fair value measurements from an independent pricing service. The fair value measurements consider observable data that may include quoted prices in active markets, dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information, and the bond’s terms and conditions, among other things. Equity securities: Preferred stock and CRA investments are reported at fair value primarily utilizing Level 1 inputs. Independent pricing service: The Company's independent pricing service provides pricing information on the majority of the Company's Level 1 and Level 2 AFS debt securities. For a small subset of securities, other pricing sources are used, including observed prices on publicly-traded securities and dealer quotes. Management independently evaluates the fair value measurements received from the Company's third-party pricing service through multiple review steps. First, management reviews what has transpired in the marketplace with respect to interest rates, credit spreads, volatility, and mortgage rates, among other things, and develops an expectation of changes to the securities' valuations from the previous quarter. Then, management selects a sample of investment securities and compares the values provided by its primary third-party pricing service to the market values obtained from secondary sources, including other pricing services and safekeeping statements, and evaluates those with notable variances. In instances where there are discrepancies in pricing from various sources and management expectations, management may manually price securities using currently observed market data to determine whether they can develop similar prices or may utilize bid information from broker dealers. Any remaining discrepancies between management's review and the prices provided by the vendor are discussed with the vendor and/or the Company's other valuation advisors. Loans HFS : Government-insured or guaranteed and agency-conforming loans HFS are salable into active markets. Accordingly, the fair value of these loans is based on quoted market or contracted selling prices or a market price equivalent, which are categorized as Level 2 in the fair value hierarchy. The fair value of EBO loans, private label loans, and loans that are delinquent or have an underwriting defect are valued using Level 3 inputs since they lack active markets. Mortgage servicing rights : MSRs are measured based on valuation techniques using Level 3 inputs. The Company uses a discounted cash flow model that incorporates assumptions that market participants would use in estimating the fair value of servicing rights, including, but not limited to, option adjusted spread, conditional prepayment rate, servicing fee rate, recapture rate, and cost to service. Derivative financial instruments : Treasury futures and options, Eurodollar futures, and swap futures are measured based on valuation techniques using Level 1 inputs from exchange-provided daily settlement quotes. Forward purchase and sales contracts are measured based on valuation techniques using Level 2 inputs, such as quoted market price, contracted selling price, or market price equivalent. Interest rate swaps are reported at fair value utilizing Level 2 inputs. The Company obtains dealer quotations to value its interest rate swaps. IRLCs are measured based on valuation techniques that consider loan type, underlying loan amount, maturity date, note rate, loan program, and expected settlement date, with Level 3 inputs for the servicing release premium and pull-through rate. These measurements are adjusted at the loan level to consider the servicing release premium and loan pricing adjustment specific to each loan. The base value is then adjusted for the pull-through rate. The pull-through rate and servicing fee multiple are unobservable inputs based on historical experience. Junior subordinated debt: The Company estimates the fair value of its junior subordinated debt using a discounted cash flow model which incorporates the effect of the Company’s own credit risk in the fair value of the liabilities (Level 3). The Company’s cash flow assumptions are based on contractual cash flows as the Company anticipates that it will pay the debt according to its contractual terms. The fair value of assets and liabilities measured at fair value on a recurring basis was determined using the following inputs as of the periods presented: Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Fair Value (in millions) December 31, 2021 Available-for-sale debt securities CLO $ — $ 926.2 $ — $ 926.2 Commercial MBS issued by GSEs — 68.5 — 68.5 Corporate debt securities — 382.9 — 382.9 Private label residential MBS — 1,508.0 — 1,508.0 Residential MBS issued by GSEs — 1,993.4 — 1,993.4 Tax-exempt — 1,215.1 — 1,215.1 U.S. treasury securities 13.0 — — 13.0 Other 27.4 54.3 — 81.7 Total AFS debt securities $ 40.4 $ 6,148.4 $ — $ 6,188.8 Equity securities CRA investments $ 27.4 $ 17.2 $ — $ 44.6 Preferred stock 113.9 — — 113.9 Total equity securities $ 141.3 $ 17.2 $ — $ 158.5 Loans HFS $ — $ 3,894.2 $ 45.5 $ 3,939.7 Mortgage servicing rights — — 698.0 698.0 Derivative assets (1) — 39.2 11.0 50.2 Liabilities: Junior subordinated debt (2) $ — $ — $ 67.4 $ 67.4 Derivative liabilities (1) — 98.2 1.6 99.8 (1) See "Note 15. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $38.5 million as of December 31, 2021 for the effective portion of the hedge, which relates to the fair value of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment. Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Fair (in millions) December 31, 2020 Assets: Available-for-sale debt securities CLO $ — $ 146.9 $ — $ 146.9 Commercial MBS issued by GSEs — 84.6 — 84.6 Corporate debt securities — 270.2 — 270.2 Private label residential MBS — 1,476.9 — 1,476.9 Residential MBS issued by GSEs — 1,486.6 — 1,486.6 Tax-exempt — 1,187.4 — 1,187.4 Other 26.5 29.4 — 55.9 Total AFS debt securities $ 26.5 $ 4,682.0 $ — $ 4,708.5 Equity securities CRA investments $ 27.8 $ 25.6 $ — $ 53.4 Preferred stock 113.9 — — 113.9 Total equity securities $ 141.7 $ 25.6 $ — $ 167.3 Derivative assets (1) $ — $ 4.2 $ — $ 4.2 Liabilities: Junior subordinated debt (2) $ — $ — $ 65.9 $ 65.9 Derivative liabilities (1) — 87.5 — 87.5 (1) See "Note 15. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $85.5 million and the net carrying value of subordinated debt is decreased by $2.7 million as of December 31, 2020, which relates to the effective portion of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment. For the years ended December 31, 2021, 2020, and 2019, the change in Level 3 liabilities measured at fair value on a recurring basis included in OCI was as follows: Junior Subordinated Debt Year Ended December 31, 2021 2020 2019 (in millions) Beginning balance $ (65.9) $ (61.7) $ (48.7) Change in fair value (1) (1.5) (4.2) (13.0) Ending balance $ (67.4) $ (65.9) $ (61.7) (1) Unrealized gains/(losses) attributable to changes in the fair value of junior subordinated debt are recorded as part of OCI, net of tax, and totaled $(1.2) million, $(3.1) million, and $(9.8) million for the years ended December 31, 2021, 2020, and 2019, respectively. The significant unobservable inputs used in the fair value measurements of these Level 3 liabilities were as follows: December 31, 2021 Valuation Technique Significant Unobservable Inputs Input Value (in millions) Junior subordinated debt $ 67.4 Discounted cash flow Implied credit rating of the Company 2.61 % December 31, 2020 Valuation Technique Significant Unobservable Inputs Input Value (in millions) Junior subordinated debt $ 65.9 Discounted cash flow Implied credit rating of the Company 2.87 % The significant unobservable inputs used in the fair value measurement of the Company’s junior subordinated debt as of December 31, 2021 and 2020 was the implied credit risk for the Company. As of December 31, 2021 and 2020, the implied credit risk spread was calculated as the difference between the average of the 15-year 'BB' and 'BBB' rated financial indexes over the corresponding swap index. As of December 31, 2021, the Company estimates the discount rate at 2.61%, which represents an implied credit spread of 2.40% plus three-month LIBOR (0.21%). As of December 31, 2020, the Company estimated the discount rate at 2.87%, which was a 2.64% credit spread plus three-month LIBOR (0.24%). The change in Level 3 assets and liabilities measured at fair value on a recurring basis included in income was as follows: Year Ended December 31, 2021 Loans held for sale Mortgage servicing rights Net interest rate lock commitments (1) (in millions) Balance, December 31, 2020 $ — $ — $ — Acquired in AmeriHome acquisition 0.7 1,347.0 23.7 Purchases and additions 131.7 763.8 23,045.4 Settlement of interest rate lock commitments upon acquisition or origination of loans HFS — — (23,054.3) Sales and payments (93.4) (1,270.7) — Transfers from Level 2 to Level 3 7.3 — — Transfers from Level 3 to Level 2 (0.8) — — Change in fair value — (2.5) (5.4) Realization of cash flows — (139.6) — Balance, December 31, 2021 $ 45.5 $ 698.0 $ 9.4 Unrealized (losses) gains included in income related to assets held at period end $ 0.1 $ (19.5) $ 9.4 (1) Interest rate lock commitment asset and liability positions are presented net. The significant unobservable inputs used in the fair value measurements of these Level 3 assets and liabilities were as follows: December 31, 2021 Asset/liability Key inputs Range Weighted average Mortgage servicing rights: Option adjusted spread (in basis points) 553 - 735 600 Conditional prepayment rate (1) 9.9% - 20.7% 15.2 Recapture rate 20.0% - 20.0% 20 Servicing fee rate (in basis points) 25.0 - 50.0 29.5 Cost to service $84 - $91 86 Loans held for sale: Whole loan spread to TBA price (in basis points) (3.65) - (2.86) (3.3) Interest rate lock commitments: Servicing fee multiple 3.6 - 5.4 4.6 Pull-through rate 75% - 100% 90 (1) Lifetime total prepayment speed annualized. The following is a summary of the difference between the aggregate fair value and the aggregate UPB of loans HFS for which the fair value option has been elected: December 31, 2021 Fair value Unpaid principal balance Difference (in millions) Loans held for sale: Current through 89 days delinquent $ 3,937.5 $ 3,807.3 $ 130.2 90 days or more delinquent 2.2 2.2 — Total $ 3,939.7 $ 3,809.5 $ 130.2 Fair value on a nonrecurring basis Certain assets are measured at fair value on a nonrecurring basis. That is, the assets are not measured at fair value on an ongoing basis, but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of credit deterioration). The following table presents such assets carried on the Consolidated Balance Sheet by caption and by level within the ASC 825 hierarchy: Fair Value Measurements at the End of the Reporting Period Using Total Quoted Prices in Active Markets for Identical Assets Active Markets for Similar Assets Unobservable Inputs (in millions) As of December 31, 2021 Loans HFI $ 216.0 $ — $ — $ 216.0 Other assets acquired through foreclosure 11.7 — — 11.7 As of December 31, 2020 Loans HFI $ 187.3 $ — $ — $ 187.3 Other assets acquired through foreclosure 1.4 — — 1.4 For Level 3 assets measured at fair value on a nonrecurring basis as of December 31, 2021 and 2020, the significant unobservable inputs used in the fair value measurements were as follows: December 31, 2021 Valuation Technique(s) Significant Unobservable Inputs Range (in millions) Loans HFI $ 216.0 Collateral method Third party appraisal Costs to sell 6.0% to 10.0% Discounted cash flow method Discount rate Contractual loan rate 3.0% to 6.0% Scheduled cash collections Probability of default 0% to 20.0% Proceeds from non-real estate collateral Loss given default 0% to 70.0% Other assets acquired through foreclosure 11.7 Collateral method Third party appraisal Costs to sell 4.0% to 10.0% December 31, 2020 Valuation Technique(s) Significant Unobservable Inputs Range (in millions) Loans HFI $ 187.3 Collateral method Third party appraisal Costs to sell 4.0% to 10.0% Discounted cash flow method Discount rate Contractual loan rate 2.0% to 7.0% Scheduled cash collections Probability of default 0% to 20.0% Proceeds from non-real estate collateral Loss given default 0% to 70.0% Other assets acquired through foreclosure 1.4 Collateral method Third party appraisal Costs to sell 4.0% to 10.0% Loans HFI: Loans measured at fair value on a nonrecurring basis include collateral dependent loans. The specific reserves for these loans are based on collateral value, net of estimated disposition costs and other identified quantitative inputs. Collateral value is determined based on independent third-party appraisals or internally-developed discounted cash flow analyses. Appraisals may utilize a single valuation approach or a combination of approaches, including comparable sales and the income approach. Fair value is determined, where possible, using market prices derived from an appraisal or evaluation, which are considered to be Level 2. However, certain assumptions and unobservable inputs are often used by the appraiser, therefore qualifying the assets as Level 3 in the fair value hierarchy. In addition, when adjustments are made to an appraised value to reflect various factors such as the age of the appraisal or known changes in the market or the collateral, such valuation inputs are considered unobservable and the fair value measurement is categorized as a Level 3 measurement. Internal discounted cash flow analyses are also utilized to estimate the fair value of these loans, which considers internally-developed, unobservable inputs such as discount rates, default rates, and loss severity. Total Level 3 collateral dependent loans had an estimated fair value of $216.0 million and $187.3 million at December 31, 2021 and 2020, respectively, net of a specific valuation allowance of $10.8 million and $8.9 million at December 31, 2021 and 2020, respectively. Other assets acquired through foreclosure: Other assets acquired through foreclosure consist of properties acquired as a result of, or in-lieu-of, foreclosure. These assets are initially reported at the fair value determined by independent appraisals using appraised value less estimated cost to sell. Such properties are generally re-appraised every twelve months and there is risk for subsequent volatility. Costs relating to the development or improvement of the assets are capitalized and costs relating to holding the assets are charged to expense. Fair value is determined, where possible, using market prices derived from an appraisal or evaluation, which are considered to be Level 2. However, certain assumptions and unobservable inputs are often used by the appraiser, therefore qualifying the assets as Level 3 in the fair value hierarchy. When significant adjustments are based on unobservable inputs, such as when a current appraised value is not available or management determines the fair value of the collateral is further impaired below the appraised value and there is no observable market price, the resulting fair value measurement has been categorized as a Level 3 measurement. The Company had $11.7 million and $1.4 million of such assets at December 31, 2021 and 2020, respectively. Fair Value of Financial Instruments The estimated fair value of the Company’s financial instruments is as follows: December 31, 2021 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in millions) Financial assets: Investment securities: HTM $ 1,107.1 $ — $ 1,146.4 $ — $ 1,146.4 AFS 6,188.8 40.4 6,148.4 — 6,188.8 Equity securities 158.5 141.3 17.2 — 158.5 Derivative assets 50.2 — 39.2 11.0 50.2 Loans HFS 5,635.1 — 3,894.2 1,760.2 5,654.4 Loans HFI, net 38,822.9 — — 39,218.2 39,218.2 Mortgage servicing rights 698.0 — — 698.0 698.0 Accrued interest receivable 227.9 — 227.9 — 227.9 Financial liabilities: Deposits $ 47,612.0 $ — $ 47,615.5 $ — $ 47,615.5 Other borrowings 1,501.9 — 1,518.4 — 1,518.4 Qualifying debt 895.8 — 857.3 81.3 938.6 Derivative liabilities 99.8 — 98.2 1.6 99.8 Accrued interest payable 9.2 — 9.2 — 9.2 December 31, 2020 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in millions) Financial assets: Investment securities: HTM $ 568.8 $ — $ 611.8 $ — $ 611.8 AFS 4,708.5 26.5 4,682.0 — 4,708.5 Equity securities 167.3 141.7 25.6 — 167.3 Derivative assets 4.2 — 4.2 — 4.2 Loans HFI, net 26,774.1 — — 27,231.0 27,231.0 Accrued interest receivable 166.1 — 166.1 — 166.1 Financial liabilities: Deposits $ 31,930.5 $ — $ 31,935.9 $ — $ 31,935.9 Other borrowings 21.0 — 21.0 — 21.0 Qualifying debt 548.7 — 488.1 79.3 567.4 Derivative liabilities 87.5 — 87.5 — 87.5 Accrued interest payable 11.0 — 11.0 — 11.0 Interest rate risk The Company assumes interest rate risk (the risk to the Company’s earnings and capital from changes in interest rate levels) as a result of its normal operations. As a result, the fair values of the Company’s financial instruments, as well as its future net interest income, will change when interest rate levels change and that change may be either favorable or unfavorable to the Company. Interest rate risk exposure is measured using interest rate sensitivity analysis to determine the Company's change in EVE and net interest income resulting from hypothetical changes in interest rates. If potential changes to EVE and net interest income resulting from hypothetical interest rate changes are not within the limits established by the BOD, the BOD may direct management to adjust the asset and liability mix to bring interest rate risk within BOD-approved limits. WAB has an ALCO charged with managing interest rate risk within the BOD-approved limits. Limits are structured to preclude an interest rate risk profile that does not conform to both management and BOD risk tolerances without ALCO approval. There is also ALCO reporting at the Parent level for reviewing interest rate risk for the Company, which gets reported to the BOD and its Finance and Investment Committee. Fair value of commitments The estimated fair value of standby letters of credit outstanding at December 31, 2021 and 2020 approximates zero as there have been no significant changes in borrower creditworthiness. Loan commitments on which the committed interest rates are less than the current market rate are insignificant at December 31, 2021 and 2020.

Financial Services, Banking and

Financial Services, Banking and Thrift	12 Months Ended
	Dec. 31, 2021
Banking and Thrift, Other Disclosures [Abstract]
Summary of Actual Capital Amount and Ratio	The actual capital amounts and ratios for the Company and the Bank are presented in the following tables as of the periods indicated: Total Capital Tier 1 Capital Risk-Weighted Assets Tangible Average Assets Total Capital Ratio Tier 1 Capital Ratio Tier 1 Leverage Ratio Common Equity (dollars in millions) December 31, 2021 WAL $ 5,499.0 $ 4,444.3 $ 44,697.0 $ 56,972.9 12.3 % 9.9 % 7.8 % 9.1 % WAB 5,119.9 4,657.5 44,726.1 56,961.6 11.4 10.4 8.2 10.4 Well-capitalized ratios 10.0 8.0 5.0 6.5 Minimum capital ratios 8.0 6.0 4.0 4.5 December 31, 2020 WAL $ 3,872.0 $ 3,158.2 $ 31,015.4 $ 34,349.3 12.5 % 10.2 % 9.2 % 9.9 % WAB 3,619.4 3,078.2 31,140.6 34,367.0 11.6 9.9 9.0 9.9 Well-capitalized ratios 10.0 8.0 5.0 6.5 Minimum capital ratios 8.0 6.0 4.0 4.5
Regulatory Capital Requirements	20. REGULATORY CAPITAL REQUIREMENTS The Company and the Bank are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements could trigger certain mandatory or discretionary actions that, if undertaken, could have a direct material effect on the Company’s business and financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Company and the Bank must meet specific capital guidelines that involve quantitative measures of their assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. The capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. In connection with its adoption of CECL on January 1, 2020, the Company elected the five-year CECL transition option that delays the estimated impact on regulatory capital resulting from the adoption of CECL. As a result of this election, the estimated impact of CECL on regulatory capital relative to regulatory capital determined under the prior incurred loss methodology has been delayed for two years, followed by a three-year transition period to phase out the aggregate amount of capital benefit provided during the initial two-year delay. As a result, capital ratios and amounts as of December 31, 2021 exclude the impact of the increased allowance for credit losses related to the adoption of ASC 326. As of December 31, 2021 and 2020, the Company and the Bank's capital ratios exceeded the well-capitalized thresholds, as defined by the federal banking agencies. The actual capital amounts and ratios for the Company and the Bank are presented in the following tables as of the periods indicated: Total Capital Tier 1 Capital Risk-Weighted Assets Tangible Average Assets Total Capital Ratio Tier 1 Capital Ratio Tier 1 Leverage Ratio Common Equity (dollars in millions) December 31, 2021 WAL $ 5,499.0 $ 4,444.3 $ 44,697.0 $ 56,972.9 12.3 % 9.9 % 7.8 % 9.1 % WAB 5,119.9 4,657.5 44,726.1 56,961.6 11.4 10.4 8.2 10.4 Well-capitalized ratios 10.0 8.0 5.0 6.5 Minimum capital ratios 8.0 6.0 4.0 4.5 December 31, 2020 WAL $ 3,872.0 $ 3,158.2 $ 31,015.4 $ 34,349.3 12.5 % 10.2 % 9.2 % 9.9 % WAB 3,619.4 3,078.2 31,140.6 34,367.0 11.6 9.9 9.0 9.9 Well-capitalized ratios 10.0 8.0 5.0 6.5 Minimum capital ratios 8.0 6.0 4.0 4.5

Employee Benefit Plan (Notes)

Employee Benefit Plan (Notes)	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Employee Benefit Plans	21. EMPLOYEE BENEFIT PLANS The Company has a qualified 401(k) employee benefit plan for all eligible employees. Participants are able to defer between 1% and 75% (up to a maximum of $19,500 for those under 50 years of age and up to a maximum of $26,000 for those over 50 years of age in 2021) of their annual compensation. The Company may elect to match a discretionary amount each year, which was 100% of the first 5% of the participant’s compensation deferred into the plan during the year ended December 31, 2021. The Company’s contributions to this plan totaled $12.0 million, $7.1 million, and $6.2 million for the years ended December 31, 2021, 2020, and 2019, respectively. In addition, the Company has a SERP, which is an unfunded noncontributory defined benefit pension plan. The SERP provides retirement benefits to certain Bridge officers based on years of service and final average salary. The projected benefit obligation was $13.1 million as of December 31, 2021 and $13.6 million as of December 31, 2020, all of which was unfunded. Net periodic benefit cost totaled $1.1 million for each of the years ended December 31, 2021, 2020 and 2019.

Related Parties (Notes)

Related Parties (Notes)	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	22. RELATED PARTY TRANSACTIONS Principal stockholders, directors, and executive officers of the Company, their immediate family members, and companies they control or own more than a 10% interest in, are considered to be related parties. In the ordinary course of business, the Company engages in various related party transactions, including extending credit and bank service transactions. All related party transactions are subject to review and approval pursuant to the Company's related party transactions policy. Federal banking regulations require that any extensions of credit to insiders and their related interests not be offered on terms more favorable than would be offered to non-related borrowers of similar creditworthiness. The following table summarizes the aggregate activity for such loans: Year Ended December 31, 2021 2020 (in millions) Balance, beginning $ 3.3 $ 3.8 New loans — — Advances — — Repayments and other (3.3) (0.5) Balance, ending $ — $ 3.3 None of these loans are past due, on non-accrual status or have been restructured to provide a reduction or deferral of interest or principal because of deterioration in the financial position of the borrower. There were no loans to a related party that were considered classified loans at December 31, 2021 or 2020. The interest income associated with these loans was approximately $0.1 million for the year ended December 31, 2021 and $0.2 million for each of the years ended December 31, 2020 and 2019. Loan commitments outstanding with related parties totaled $7.0 million and $10.3 million at December 31, 2021 and 2020, respectively. The Company also accepts deposits from related parties, which totaled $101.3 million and $156.9 million at December 31, 2021 and 2020, respectively, with related interest expense of approximately $0.2 million during each of the years ended December 31, 2021 and 2020, and $0.3 million during the year ended December 31, 2019.

Parent Company (Notes)

Parent Company (Notes)	12 Months Ended
	Dec. 31, 2021
Parent Company Financial Information [Abstract]
Parent Company Financial Information	23. PARENT COMPANY FINANCIAL INFORMATION The condensed financial statements of the holding company are presented in the following tables: WESTERN ALLIANCE BANCORPORATION Condensed Balance Sheets December 31, 2021 2020 (in millions) ASSETS: Cash and cash equivalents $ 79.0 $ 55.5 Investment securities - AFS 0.5 5.1 Investment securities - equity 41.5 49.8 Investment in bank subsidiaries 5,433.6 3,493.5 Investment in non-bank subsidiaries 66.6 49.9 Other assets 22.5 18.0 Total assets $ 5,643.7 $ 3,671.8 LIABILITIES AND STOCKHOLDERS' EQUITY: Qualifying debt $ 673.0 $ 251.5 Accrued interest and other liabilities 8.0 6.8 Total liabilities 681.0 258.3 Total stockholders’ equity 4,962.7 3,413.5 Total liabilities and stockholders’ equity $ 5,643.7 $ 3,671.8 WESTERN ALLIANCE BANCORPORATION Condensed Income Statements Year Ended December 31, 2021 2020 2019 (in millions) Income: Dividends from subsidiaries $ 50.0 $ 160.0 $ 134.0 Interest income 3.2 3.1 2.8 Non-interest income 13.4 4.7 5.1 Total income 66.6 167.8 141.9 Expense: Interest expense 19.5 10.6 14.6 Non-interest expense 31.9 19.7 19.5 Total expense 51.4 30.3 34.1 Income before income taxes and equity in undistributed earnings of subsidiaries 15.2 137.5 107.8 Income tax benefit 7.4 4.5 5.7 Income before equity in undistributed earnings of subsidiaries 22.6 142.0 113.5 Equity in undistributed earnings of subsidiaries 876.6 364.6 385.7 Net income 899.2 506.6 499.2 Dividends on preferred stock 3.5 — — Net income available to common stockholders $ 895.7 $ 506.6 $ 499.2 Western Alliance Bancorporation Condensed Statements of Cash Flows Year Ended December 31, 2021 2020 2019 (in millions) Cash flows from operating activities: Net income $ 899.2 $ 506.6 $ 499.2 Adjustments to reconcile net income to net cash provided by operating activities: Equity in net undistributed earnings of subsidiaries (876.6) (364.6) (385.7) Junior subordinated debt change in fair value (0.1) — — Loss on extinguishment of debt 5.9 — — Other operating activities, net (1.4) 8.0 9.9 Net cash provided by operating activities 27.0 150.0 123.4 Cash flows from investing activities: Purchases of securities (16.0) (6.9) (10.8) Principal pay downs, calls, maturities, and sales proceeds of securities 28.6 7.7 19.0 Capital contributions to subsidiaries (1,139.3) — — Other investing activities, net — 1.2 — Net cash (used in) provided by investing activities (1,126.7) 2.0 8.2 Cash flows from financing activities: Net proceeds from issuance of subordinated debt 591.9 — — Common stock repurchases — (71.6) (120.2) Redemption of subordinated debt (176.0) — — Proceeds from issuance of common stock in offerings, net 540.3 — — Cash dividends paid on common and preferred stock (127.6) (101.3) (51.3) Proceeds from issuance of preferred stock, net 294.5 — — Other financing activities, net 0.1 0.5 0.1 Net cash provided by (used in) financing activities 1,123.2 (172.4) (171.4) Net increase (decrease) in cash and cash equivalents 23.5 (20.4) (39.8) Cash and cash equivalents at beginning of year 55.5 75.9 115.7 Cash and cash equivalents at end of year $ 79.0 $ 55.5 $ 75.9

Segments

Segments	12 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Segments	24. SEGMENTS The Company's reportable segments are aggregated with a focus on products and services offered and consist of three reportable segments: • Commercial segment: provides commercial banking and treasury management products and services to small and middle-market businesses, specialized banking services to sophisticated commercial institutions and investors within niche industries, as well as financial services to the real estate industry. • Consumer Related segment: offers consumer banking services, such as residential mortgage banking, and commercial banking services to enterprises in consumer-related sectors. • Corporate & Other segment: consists of the Company's investment portfolio, Corporate borrowings and other related items, income and expense items not allocated to our other reportable segments, and inter-segment eliminations. The Company's segment reporting process begins with the assignment of all loan and deposit accounts directly to the segments where these products are originated and/or serviced. Equity capital is assigned to each segment based on the risk profile of their assets and liabilities. With the exception of goodwill, which is assigned a 100% weighting, equity capital allocations ranged from 0% to 20% during the year. Any excess or deficient equity not allocated to segments based on risk is assigned to the Corporate & Other segment. Net interest income, provision for credit losses, and non-interest expense amounts are recorded in their respective segments to the extent that the amounts are directly attributable to those segments. Net interest income is recorded in each segment on a TEB with a corresponding increase in income tax expense, which is eliminated in the Corporate & Other segment. Further, net interest income of a reportable segment includes a funds transfer pricing process that matches assets and liabilities with similar interest rate sensitivity and maturity characteristics. Using this funds transfer pricing methodology, liquidity is transferred between users and providers. A net user of funds has lending/investing in excess of deposits/borrowings and a net provider of funds has deposits/borrowings in excess of lending/investing. A segment that is a user of funds is charged for the use of funds, while a provider of funds is credited through funds transfer pricing, which is determined based on the average life of the assets or liabilities in the portfolio. Residual funds transfer pricing mismatches are allocable to the Corporate & Other segment and presented as part of net interest income. The net income amount for each reportable segment is further derived by the use of expense allocations. Certain expenses not directly attributable to a specific segment are allocated across all segments based on key metrics, such as number of employees, number of transactions processed for loans and deposits, and average loan and deposit balances. These types of expenses include information technology, operations, human resources, finance, risk management, credit administration, legal, and marketing. Income taxes are applied to each segment based on the effective tax rate for the geographic location of the segment. Any difference in the corporate tax rate and the aggregate effective tax rates in the segments are adjusted in the Corporate & Other segment. The following is a summary of operating segment balance sheet information for the periods indicated: Consolidated Company Commercial Consumer Related Corporate & Other At December 31, 2021: (in millions) Assets: Cash, cash equivalents, and investment securities $ 8,057.3 $ 12.9 $ 82.4 $ 7,962.0 Loans held for sale 5,635.1 — 5,635.1 — Loans, net of deferred fees and costs 39,075.4 25,092.4 13,983.0 — Less: allowance for credit losses (252.5) (226.0) (26.5) — Total loans 38,822.9 24,866.4 13,956.5 — Other assets acquired through foreclosure, net 11.7 11.7 — — Goodwill and other intangible assets, net 634.8 294.7 340.1 — Other assets 2,820.8 253.8 1,278.1 1,288.9 Total assets $ 55,982.6 $ 25,439.5 $ 21,292.2 $ 9,250.9 Liabilities: Deposits $ 47,612.0 $ 30,466.8 $ 15,362.9 $ 1,782.3 Borrowings and qualifying debt 2,381.1 — 353.2 2,027.9 Other liabilities 1,026.9 233.4 138.2 655.3 Total liabilities 51,020.0 30,700.2 15,854.3 4,465.5 Allocated equity: 4,962.6 2,588.0 1,596.2 778.4 Total liabilities and stockholders' equity $ 55,982.6 $ 33,288.2 $ 17,450.5 $ 5,243.9 Excess funds provided (used) — 7,848.7 (3,841.7) (4,007.0) Consolidated Company Commercial Consumer Related Corporate At December 31, 2020: (in millions) Assets: Cash, cash equivalents, and investment securities $ 8,176.5 $ 12.0 $ 45.6 $ 8,118.9 Loans, net of deferred fees and costs 27,053.0 20,245.8 6,798.2 9.0 Less: allowance for loan losses (278.9) (263.4) (15.4) (0.1) Total loans 26,774.1 19,982.4 6,782.8 8.9 Other assets acquired through foreclosure, net 1.4 1.4 — — Goodwill and other intangible assets, net 298.5 296.1 2.4 — Other assets 1,210.5 257.0 96.6 856.9 Total assets $ 36,461.0 $ 20,548.9 $ 6,927.4 $ 8,984.7 Liabilities: Deposits $ 31,930.5 $ 21,448.0 $ 9,936.8 $ 545.7 Borrowings and qualifying debt 553.7 — — 553.7 Other liabilities 563.3 170.4 3.3 389.6 Total liabilities 33,047.5 21,618.4 9,940.1 1,489.0 Allocated equity: 3,413.5 1,992.2 579.1 842.2 Total liabilities and stockholders' equity $ 36,461.0 $ 23,610.6 $ 10,519.2 $ 2,331.2 Excess funds provided (used) — 3,061.7 3,591.8 (6,653.5) The following is a summary of operating segment income statement information for the periods indicated: Consolidated Company Commercial Consumer Related (1) Corporate & Other Year Ended December 31, 2021: (in millions) Net interest income $ 1,548.8 $ 1,181.7 $ 603.4 $ (236.3) (Recovery of) provision for credit losses (21.4) (30.6) 11.0 (1.8) Net interest income (expense) after provision for credit losses 1,570.2 1,212.3 592.4 (234.5) Non-interest income 404.2 65.1 317.6 21.5 Non-interest expense 851.4 415.9 413.9 21.6 Income (loss) before income taxes 1,123.0 861.5 496.1 (234.6) Income tax expense (benefit) 223.8 206.6 120.1 (102.9) Net income (loss) $ 899.2 $ 654.9 $ 376.0 $ (131.7) (1) Includes the financial results of AmeriHome following the acquisition on April 7, 2021, which contributed approximately 40% and 25% to net revenue and net income for the Consumer Related segment, respectively. Consolidated Company Commercial Consumer Related Corporate Year Ended December 31, 2020: (in millions) Net interest income $ 1,166.9 $ 999.7 $ 302.5 $ (135.3) Provision for (recovery of) credit losses 123.6 128.6 (9.0) 4.0 Net interest income (expense) after provision for credit losses 1,043.3 871.1 311.5 (139.3) Non-interest income 70.8 50.5 1.6 18.7 Non-interest expense 491.6 308.9 92.6 90.1 Income (loss) before income taxes 622.5 612.7 220.5 (210.7) Income tax expense (benefit) 115.9 147.6 52.3 (84.0) Net income (loss) $ 506.6 $ 465.1 $ 168.2 $ (126.7) Consolidated Company Commercial Consumer Related Corporate & Other Year Ended December 31, 2019: (in millions) Net interest income $ 1,040.4 $ 837.2 $ 209.0 $ (5.8) Provision for credit losses 19.3 11.1 7.4 0.8 Net interest income (expense) after provision for credit losses 1,021.1 826.1 201.6 (6.6) Non-interest income 65.1 50.4 1.4 13.3 Non-interest expense 482.0 320.6 96.7 64.7 Income (loss) before income taxes 604.2 555.9 106.3 (58.0) Income tax expense (benefit) 105.0 134.7 24.8 (54.5) Net income $ 499.2 $ 421.2 $ 81.5 $ (3.5)

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	On January 25, 2022, the Company completed the acquisition of Digital Settlement Technologies LLC, doing business as Digital Disbursements, a digital payments platform for the class action legal industry. The acquisition of Digital Disbursements is expected to extend the Company's digital payment efforts by providing a digital payments platform for the class action market and broader legal industry. Due to the limited time since the closing of the acquisition, the valuation efforts and related acquisition accounting are incomplete at the time of filing of these Consolidated Financial Statements. As a result, the Company is unable to provide amounts recognized as of the acquisition date for major classes of assets and liabilities acquired. The Company will record the assets acquired and liabilities assumed at their fair values as of the acquisition date.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Share-based Payment Arrangement [Policy Text Block]	Stock compensation plans The Company has the Incentive Plan, as amended, which is described more fully in "Note 13. Stockholders' Equity" of these Notes to Consolidated Financial Statements. Compensation expense on non-vested restricted stock awards is based on the fair value of the award on the measurement date which, for the Company, is the date of the grant and is recognized ratably over the service period of the award. Forfeitures are estimated at the time of the award grant and revised in subsequent periods if actual forfeitures differ from those estimates. The fair value of non-vested restricted stock awards is the market price of the Company’s stock on the date of grant. The Company's performance stock units have a cumulative EPS target and a TSR performance measure component. The TSR component is a market-based performance condition that is separately valued as of the date of the grant. A Monte Carlo valuation model is used to determine the fair value of the TSR performance metric, which simulates potential TSR outcomes over the performance period and determines the payouts that would occur in each scenario. The resulting fair value of the TSR component is based on the average of these results. Compensation expense related to the TSR component is based on the fair value determination on the date of the grant and is not subsequently revised based on actual performance. Compensation expense on the EPS component for these awards is based on the fair value (market price of the Company's stock on the date of the grant) of the award. Compensation expense related to both the TSR and EPS components is recognized ratably over the service period of the award.
Dividends	Dividends WAL is a legal entity separate and distinct from its subsidiaries. As a holding company with limited significant assets other than the capital stock of its subsidiaries, WAL's ability to pay dividends depends primarily upon the receipt of dividends or other capital distributions from its subsidiaries. The Company's subsidiaries' ability to pay dividends to WAL is subject to, among other things, their individual earnings, financial condition, and need for funds, as well as federal and state governmental policies and regulations applicable to WAL and each of those subsidiaries, which limit the amount that may be paid as dividends without prior approval. In addition, the terms and conditions of other securities the Company issues may restrict its ability to pay dividends to holders of the Company's common stock. For example, if any required payments on outstanding trust preferred securities are not made, WAL would be prohibited from paying cash dividends on its common stock. Preferred stock On September 22, 2021, the Company issued an aggregate of 12,000,000 depositary shares, each representing a 1/400th ownership interest in a share of the Company’s 4.250% Fixed-Rate Reset Non-Cumulative Perpetual Preferred Shares, Series A, par value $0.0001 per share, with a liquidation preference of $25 per Depositary Share (equivalent to $10,000 per share of Series A preferred stock). The Company's Series A preferred stock is perpetual preferred stock that is not subject to any mandatory redemption, resulting in classification as permanent equity. Dividends on preferred stock are recognized on the declaration date and are recorded as a reduction of retained earnings. Treasury shares The Company separately presents treasury shares, which represent shares surrendered to the Company equal in value to the statutory payroll tax withholding obligations arising from the vesting of employee restricted stock awards. Treasury shares are carried at cost. Common stock repurchases The Company has previously adopted common stock repurchase programs pursuant to which the Company has repurchased shares of its outstanding common stock, the most recent of which expired in December 2020. All shares repurchased under the plan were retired upon settlement. The Company has elected to allocate the excess of the repurchase price over the par value of its common stock between APIC and retained earnings. The portion allocated to APIC is limited to the amount of APIC that was recorded at the time the shares were initially issued, which was calculated on a last-in, first-out basis. Sales of common stock under ATM program On June 3, 2021, the Company entered into a distribution agency agreement with J.P. Morgan Securities LLC, under which the Company may sell up to 4,000,000 shares of its common stock on the NYSE. The Company pays the distribution agents a mutually agreed rate, not to exceed 2% of the gross offering proceeds of the shares sold pursuant to the distribution agency agreement. The common stock is sold at prevailing market prices at the time of the sale or at negotiated prices and, as a result, prices will vary. Any sales under the ATM program are made pursuant to a prospectus dated May 14, 2021 and a prospectus supplement filed with the SEC in an offering of shares from the Company's shelf registration statement on Form S-3 (No. 333-256120). On November 18, 2021, the distribution agency agreement was amended to add Piper Sandler & Co. as an agent with J.P. Morgan Securities LLC. See "Note 13. Stockholders' Equity" of these Notes to Consolidated Financial Statements for further discussion of this program.
Nature of Operation	Nature of operation WAL is a bank holding company headquartered in Phoenix, Arizona, incorporated under the laws of the state of Delaware. WAL provides a full spectrum of customized loan, deposit and treasury management capabilities, including blockchain-based offerings through its wholly-owned banking subsidiary, WAB.
Basis of Presentation	Basis of presentation The accounting and reporting policies of the Company are in accordance with GAAP and conform to practices within the financial services industry. The accounts of the Company and its consolidated subsidiaries are included in the Consolidated Financial Statements.
Use of Estimates	Use of estimatesThe preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management's estimates and judgments are ongoing and are based on experience, current and expected future conditions, third-party evaluations and various other assumptions that management believes are reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities, as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from those estimates and assumptions used in the Consolidated Financial Statements and related notes. Material estimates that are susceptible to significant changes in the near term, particularly to the extent that economic conditions worsen or persist longer than expected in an adverse state, relate to: 1) the determination of the allowance for credit losses; 2) certain assets and liabilities carried at fair value; and 3) accounting for income taxes.
Principles of Consolidation	Principles of consolidation As of December 31, 2021, WAL has the following significant wholly-owned subsidiaries: WAB and eight unconsolidated subsidiaries used as business trusts in connection with the issuance of trust-preferred securities. WAB has the following significant wholly-owned subsidiaries: 1) WABT, which holds certain investment securities, municipal and nonprofit loans, and leases; 2) WA PWI, which holds interests in certain limited partnerships invested primarily in low income housing tax credits and small business investment corporations; 3) Helios Prime, which holds interests in certain limited partnerships invested in renewable energy projects; 4) BW Real Estate, Inc., which operates as a real estate investment trust and holds certain of WAB's real estate loans and related securities; and 5) Western Finance Company (formerly Western Alliance Equipment Finance), which purchases and originates equipment finance leases and provides mortgage banking services through its wholly-owned subsidiary, AmeriHome Mortgage. The Company does not have any other significant entities that should be consolidated. All significant intercompany balances and transactions have been eliminated in consolidation.
Reclassifications	ReclassificationsCertain amounts in the Consolidated Income Statements for the prior periods have been reclassified to conform to the current presentation. The reclassifications have no effect on net income or stockholders’ equity as previously reported.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and cash equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks (including cash items in process of clearing), and federal funds sold. Cash flows from loans originated by the Company and customer deposit accounts are reported net. The Company maintains deposit accounts with other banks, which at times may exceed federally insured limits. The Company has not experienced any losses in such accounts.
Investment Securities	Investment securities Investment securities include debt and equity securities. Debt securities may be classified as HTM, AFS, or trading. The appropriate classification is initially decided at the time of purchase. Securities classified as HTM are those debt securities that the Company has both the intent and ability to hold to maturity regardless of changes in market conditions, liquidity needs, or general economic conditions. The sale of an HTM security within three months of its maturity date or after the majority of the principal outstanding has been collected is considered a maturity for purposes of classification and disclosure. Securities classified as AFS are debt securities that the Company intends to hold for an indefinite period of time, but not necessarily to maturity. Any decision to sell a security classified as AFS would be based on various factors, including significant movements in interest rates, changes in the maturity mix of the Company’s assets and liabilities, liquidity needs, decline in credit quality, and regulatory capital considerations. HTM securities are carried at amortized cost. AFS securities are carried at their estimated fair value, with unrealized holding gains and losses reported in OCI, net of tax. When AFS debt securities are sold, the unrealized gains or losses are reclassified from OCI to non-interest income. Trading securities are carried at their estimated fair value, with changes in fair value reported in earnings as part of non-interest income. Equity securities are carried at their estimated fair value, with changes in fair value reported in earnings as part of non-interest income. Interest income is recognized based on the coupon rate and includes the amortization of purchase premiums and the accretion of purchase discounts. Premiums and discounts on investment securities are generally amortized or accreted over the contractual life of the security using the interest method. For the Company's mortgage-backed securities, amortization or accretion of premiums or discounts are adjusted for anticipated prepayments. Gains and losses on the sale of investment securities are recorded on the trade date and determined using the specific identification method.
Restricted Stock	Restricted stockWAB is a member of the Federal Reserve System and, as part of its membership, is required to maintain stock in the FRB in a specified ratio to its capital. In addition, WAB is a member of the FHLB system and, accordingly, maintains an investment in capital stock of the FHLB based on the borrowing capacity used. These investments are considered equity securities with no actively traded market. Therefore, the shares are considered restricted investment securities. These investments are carried at cost, which is equal to the value at which they may be redeemed. The dividend income received from the stock is reported in interest income. The Company conducts a periodic review and evaluation of its restricted stock to determine if any impairment exists. No impairment has been recorded to date.
Loans, Interest and Fees from Loans	Loans held for investment Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at amortized cost. Amortized cost is the amount of unpaid principal, adjusted for unamortized net deferred fees and costs, premiums and discounts, and write-offs. In addition, the amortized cost of loans subject to a fair value hedge are adjusted for changes in value attributable to the effective portion of the hedged benchmark interest rate risk. The Company may also purchase loans or acquire loans through a business combination. At the purchase or acquisition date, loans are evaluated to determine whether there has been more than insignificant credit deterioration since origination. Loans that have experienced more than insignificant credit deterioration since origination are referred to as PCD loans. In its evaluation of whether a loan has experienced more than insignificant deterioration in credit quality since origination, the Company takes into consideration loan grades, loan-to-values greater than policy limits, past due and nonaccrual status, and TDR loans. The Company may also consider external credit rating agency ratings for borrowers and for non-commercial loans, FICO score or band, probability of default levels, and number of times past due. The initial estimate of credit losses on PCD loans is added to the purchase price on the acquisition date to establish the initial amortized cost basis of the loan; accordingly, the initial recognition of expected credit losses has no impact on net income. When the initial measurement of expected credit losses on PCD loans are calculated on a pooled loan basis, the expected credit losses are allocated to each loan within the pool. Any difference between the initial amortized cost basis and the unpaid principal balance of the loan represents a noncredit discount or premium, which is accreted (or amortized) into interest income over the life of the loan. Subsequent changes to the allowance for credit losses on PCD loans are recorded through the provision for credit losses. For purchased loans that are not deemed to have experienced more than insignificant credit deterioration since origination, any discounts or premiums included in the purchase price are accreted (or amortized) over the contractual life of the individual loan. For additional information, see "Note 5. Loans, Leases and Allowance for Credit Losses" of these Notes to Consolidated Financial Statements. In applying the effective yield method to loans, the Company generally applies the contractual method whereby loan fees collected for the origination of loans less direct loan origination costs (net of deferred loan fees), as well as premiums and discounts and certain purchase accounting adjustments, are amortized over the contractual life of the loan through interest income. If a loan has scheduled payments, the amortization of the net deferred fee is calculated using the interest method over the contractual life of the loan. If a loan does not have scheduled payments, such as a line of credit, the net deferred loan fee is recognized as interest income on a straight-line basis over the contractual life of the loan commitment. Commitment fees based on a percentage of a customer’s unused line of credit and fees related to standby letters of credit are recognized over the commitment period. When loans are repaid, any remaining unamortized balances of premiums, discounts, or net deferred fees are recognized as interest income. Conversely, with respect to loans originated under the PPP, the Company incorporates projected prepayments in calculating effective yield. As a result, net deferred fees are accreted into interest income faster than would be the case when applying the contractual method based upon the timing and amount of estimated forgiven loan balances. Nonaccrual loans When a borrower discontinues making payments as contractually required by the note, the Company must determine whether it is appropriate to continue to accrue interest. The Company ceases accruing interest income when the loan has become delinquent by more than 90 days or when management determines that the full repayment of principal and collection of interest according to contractual terms is no longer likely. Past due status is based on the contractual terms of the loan. The Company may decide to continue to accrue interest on certain loans more than 90 days delinquent if the loans are well secured by collateral and in the process of collection. For all HFI loan types, when a loan is placed on nonaccrual status, all interest accrued but uncollected is reversed against interest income in the period in which the status is changed, and the Company makes a loan-level decision to apply either the cash basis or cost recovery method. The Company may recognize income on a cash basis when a payment is received and only for those nonaccrual loans for which the collection of the remaining principal balance is not in doubt. Under the cost recovery method, subsequent payments received from the customer are applied to principal and generally no further interest income is recognized until the loan principal has been paid in full or until circumstances have changed such that payments are again consistently received as contractually required. Loans are returned to accrual status when all of the principal and interest amounts contractually due are brought current and future payments are reasonably assured. Troubled Debt Restructured Loans A TDR loan is a loan on which the Company, for reasons related to a borrower’s financial difficulties, grants a concession to the borrower that the Company would not otherwise consider. In order to determine whether a borrower is experiencing financial difficulty, an evaluation is performed to assess the probability that the borrower will be in payment default on any of its debt in the foreseeable future without the modification. The evaluation is performed in accordance with the Company's internal underwriting policy. The loan terms that may be modified or restructured due to a borrower’s financial situation include, but are not limited to, a reduction in the stated interest rate, an extension of the maturity or renewal of the loan at an interest rate below current market, a reduction in the face amount of the debt, a reduction in the accrued interest, or deferral of interest payments. A TDR loan may be returned to accrual status when the loan is brought current, has performed in accordance with the contractual restructured terms for a reasonable period of time (generally six months), and the ultimate collectability of the total contractual restructured principal and interest is no longer in doubt. Consistent with regulatory guidance, a TDR loan that is subsequently modified in another restructuring agreement but has shown sustained performance and classification as a TDR, will be removed from TDR status provided that the modified terms were market-based at the time of modification. The CARES Act, signed into law on March 27, 2020, permitted financial institutions to suspend requirements under GAAP for loan modifications to borrowers affected by COVID-19 that would otherwise be characterized as TDRs and suspend any determination related thereto if (i) the loan modification was made between March 1, 2020 and December 31, 2020 and (ii) the applicable loan was not more than 30 days past due as of December 31, 2019. The Consolidated Appropriations Act, 2021 extended these provisions through January 1, 2022. In addition, federal bank regulatory authorities issued guidance to encourage financial institutions to make loan modifications for borrowers affected by COVID-19 and assured financial institutions that they will neither receive supervisory criticism for such prudent loan modifications, nor be required by examiners to automatically categorize COVID-19-related loan modifications as TDRs. The Company has been applying this guidance to qualifying loan modifications. Credit quality indicators Loans are regularly reviewed to assess credit quality indicators and to determine appropriate loan classification and grading in accordance with applicable bank regulations. The Company’s risk rating methodology assigns risk ratings ranging from 1 to 9, where a higher rating represents higher risk. The Company differentiates its loan segments based on shared risk characteristics for which expected credit losses are measured on a pool basis. The nine risk rating categories can generally be described by the following groupings for loans: "Pass" (grades 1 through 5): The Company has five pass risk ratings, which represent a level of credit quality that ranges from having no well-defined deficiency or weakness to some noted weakness; however, the risk of default on any loan classified as pass is expected to be remote. The five pass risk ratings are described below: Minimal risk. C onsist of loans that are fully secured either with cash held in a deposit account at the Bank or by readily marketable securities with an acceptable margin based on the type of security pledged. Low risk. Consist of loans with a high investment grade rating equivalent. Modest risk. Consist of loans where the credit facility greatly exceeds all policy requirements or with policy exceptions that are appropriately mitigated. A secondary source of repayment is verified and considered sustainable. Collateral coverage on these loans is sufficient to fully cover the debt as a tertiary source of repayment. Debt of the borrower is low relative to borrower’s financial strength and ability to pay. Average risk. Consist of loans where the credit facility meets or exceeds all policy requirements or with policy exceptions that are appropriately mitigated. A secondary source of repayment is available to service the debt. Collateral coverage is more than adequate to cover the debt. The borrower exhibits acceptable cash flow and moderate leverage. Acceptable risk. Consist of loans with an acceptable primary source of repayment, but a less than preferable secondary source of repayment. Cash flow is adequate to service debt, but there is minimal excess cash flow. Leverage is moderate or high. "Special mention" (grade 6): These are generally assets that possess potential weaknesses that warrant management's close attention. These loans may involve borrowers with adverse financial trends, higher debt-to-equity ratios, or weaker liquidity positions, but not to the degree of being considered a “problem loan” where risk of loss may be apparent. Loans in this category are usually performing as agreed, although there may be non-compliance with financial covenants. "Substandard" (grade 7): These assets are characterized by well-defined credit weaknesses and carry the distinct possibility that the Company will sustain some loss if such weakness or deficiency is not corrected. All loans 90 days or more past due and all loans on nonaccrual status are considered at least "Substandard," unless extraordinary circumstances would suggest otherwise. "Doubtful" (grade 8): These assets have all the weaknesses inherent in those classified as "Substandard" with the added characteristic that the weaknesses present make collection or liquidation in full, on the basis of currently existing facts, conditions and values, highly questionable and improbable, but because of certain known factors that may work to the advantage and strengthening of the asset (for example, capital injection, perfecting liens on additional collateral and refinancing plans), classification as an estimated loss is deferred until a more precise status may be determined. Due to the high probability of loss, loans classified as "Doubtful" are placed on nonaccrual status. "Loss" (grade 9): These assets are considered uncollectible and having such little recoverable value that it is not practical to defer writing off the asset. This classification does not mean that the loan has absolutely no recovery or salvage value, but rather that it is not practicable or desirable to defer writing off the asset, even though partial recovery may be achieved in the future.
Allowance for Credit Losses	Allowance for credit losses on HFI loans On January 1, 2020, the Company adopted ASC Topic 326, which changed the impairment model for most financial assets carried at amortized cost from an incurred loss model to an expected loss model. The discussion below reflects the current expected credit loss model methodology. Prior to January 1, 2020, the allowance for credit losses on loans was based on incurred credit losses in accordance with accounting policies disclosed in "Note 1. Summary of Significant Accounting Policies" in the accompanying Notes to Consolidated Financial Statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2019. Credit risk is inherent in the business of extending loans and leases to borrowers and is continuously monitored by management and reflected within the allowance for credit losses. The allowance for credit losses is an estimate of life-of-loan losses for the Company's loans HFI. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of a loan to present the net amount expected to be collected on the loan. Accrued interest receivable on these loans, which is included in other assets on the Consolidated Balance Sheet, is excluded from the estimate of expected credit losses. Expected recoveries of amounts previously written off and expected to be written off are included in the valuation account and may not exceed the aggregate of amounts previously written off and expected to be written off. The Company formally re-evaluates and establishes the appropriate level of the allowance for credit losses on a quarterly basis. Determining the appropriateness of the allowance is complex and requires judgment by management about the effect of matters that are inherently uncertain. In future periods, evaluations of the overall loan portfolio or particular segments of the loan portfolio, in light of the factors and forecasts then prevailing, may result in significant changes in the allowance for credit losses and credit loss expense in those future periods. The allowance level is influenced by loan volumes, mix, loan performance metrics, asset quality characteristics, delinquency status, historical credit loss experience, and the inputs and assumptions in economic forecasts, such as macroeconomic inputs, length of reasonable and supportable forecast periods, and reversion methods. The methodology for estimating the amount of expected credit losses reported in the allowance for credit losses has two basic components: first, an asset-specific component involving individual loans that do not share similar risk characteristics with other loans and the measurement of expected credit losses for such individual loans and; second, a pooled component for estimated expected credit losses for loans that share similar risk characteristics. Loans that do not share risk characteristics with other loans Loans that do not share risk characteristics with other loans are evaluated on an individual basis. Loans evaluated individually are not included in the collective evaluation. These loans consist of loans with unique features or loans that no longer share risk characteristics with other pooled loans. The process for determining whether a loan should be evaluated on an individual basis begins with determination of credit rating. With the exception of residential loans, all accruing loans graded substandard or worse with a total commitment of $1.0 million or more are assigned a reserve based on an individual evaluation. For these loans, the allowance is based primarily on the fair value of the underlying collateral, utilizing independent third-party appraisals. Loans that share similar risk characteristics with other loans In estimating the component of the allowance for credit losses for loans that share similar risk characteristics with other loans, such loans are segregated into loan segments. The Company's primary portfolio segments align with the methodology applied in estimating the allowance for credit losses under CECL. Loans are designated into loan segments based on loans pooled by product types, business lines, and similar risk characteristics or areas of risk concentration. In determining the allowance for credit losses, the Company derives an estimate of expected credit losses primarily using an expected loss methodology that incorporates risk parameters (probability of default, loss given default, and exposure at default), which are derived from various vendor models, internally-developed statistical models, or non-statistical estimation approaches. Probability of default is projected in these models or estimation approaches using a single economic scenario and were developed to incorporate relevant information about past events, current conditions, and reasonable and supportable forecasts. With the exception of the Company's residential loan segment, the Company's PD models share a common definition of default, which include loans that are 90 days past due, on nonaccrual status, have a charge-off, or obligor bankruptcy. Input reversion is used for all loan segment models, except for the commercial and industrial and CRE, owner-occupied loan segments. Output reversion is used for the commercial and industrial and CRE, owner-occupied loan segments by incorporating, after the forecast period, a one-year linear reversion to the long-term reversion rate in year three through the remaining life of the loans within the respective segments. LGDs are typically derived from the Company's historical loss experience. However, for the residential, warehouse lending, and municipal and nonprofit loan segments, where the Company has either zero (or near zero) losses, or has a limited loss history through the last economic downturn, certain non-modeled methodologies are employed to estimate LGD. Factors utilized in calculating average LGD vary for each loan segment and are further described below. Exposure at default refers to the Company's exposure to loss at the time of borrower default. For revolving lines of credit, the Company incorporates an expectation of increased line utilization for a higher EAD on defaulted loans based on historical experience. For term loans, EAD is calculated using an amortization schedule based on contractual loan terms, adjusted for a prepayment rate assumption. Prepayment trends are sensitive to interest rates and the macroeconomic environment. Fixed rate loans are more influenced by interest rates, whereas variable rate loans are more influenced by the macroeconomic environment. After the quantitative expected loss estimates are calculated, management then adjusts these estimates to incorporate considerations of current trends and conditions that are not captured in the quantitative loss estimates, through the use of qualitative and/or environmental factors. The following provides credit quality indicators and risk elements most relevant in monitoring and measuring the allowance for credit losses on loans for each of the loan portfolio segments identified: Warehouse lending The warehouse lending portfolio segment consists of mortgage warehouse lines, MSR financing facilities, and note finance loans, which have a monitored borrowing base to mortgage companies and similar lenders and are primarily structured as commercial and industrial loans. The collateral for these loans is primarily comprised of residential whole loans and MSRs, with the borrowing base of these loans tightly monitored and controlled by the Company. The primary support for these loans takes the form of pledged collateral, with secondary support provided by the capacity of the financial institution. The collateral-driven nature of these loans distinguish them from traditional commercial and industrial loans. These loans are impacted by interest rate shocks, residential lending rates, prepayment assumptions, and general real estate stress. As a result of the unique loan characteristics, limited historical default and loss experience, and the collateral nature of this loan portfolio segment, the Company uses a non-modeled approach to estimate expected credit losses, leveraging grade information, grade migration history, and management judgment. Municipal and nonprofit The municipal and nonprofit portfolio segment consists of loans to local governments, government-operated utilities, special assessment districts, hospitals, schools and other nonprofits. These loans are generally, but not exclusively, entered into for the purpose of financing real estate investment or for refinancing existing debt and are primarily structured as commercial and industrial loans. Loans are supported by taxes or utility fees, and in some cases tax liens on real estate, operating revenue of the institution, or other collateral support the loans. While unemployment rates and the market valuation of residential properties have an effect on the tax revenues supporting these loans, these loans tend to be less cyclical in comparison to similar commercial loans due to reliance on diversified tax bases. The Company uses a non-modeled approach to estimate expected credit losses for this portfolio segment, leveraging grade information and historical municipal default rates. Tech & innovation The tech & innovation portfolio segment is comprised of commercial loans that are originated within this business line and are not collateralized by real estate. The source of repayment of these loans is generally expected to be the income that is generated from the business. Expected credit losses for this loan segment are estimated using both a vendor model and an internally-developed model. These models incorporate market level and company-specific factors such as financial statement variables, adjusted for the current stage of the credit cycle and for the Company's loan performance data such as delinquency, utilization, maturity, and size of the loan commitment under specific macroeconomic scenarios to produce a probability of default. Macroeconomic variables include the Dow Jones Index, credit spread between the BBB Bond Yield and 10-Year Treasury Bond Yield, unemployment rate, and CBOE VIX Index quarterly high. LGD and the prepayment rate assumption for EAD for this loan segment are driven by unemployment levels. Equity fund resources The equity fund resources portfolio segment is comprised of commercial loans to private equity and venture capital funds. The primary source of repayment of these loans is typically uncalled capital commitments from institutional investors and high net worth individuals. The models used to estimate expected credit losses for this loan segment are the same as those used for the tech & innovation portfolio segment. Other commercial and industrial The other commercial and industrial segment is comprised of commercial and industrial loans that are not originated within the Company's specialty business lines and are not collateralized by real estate. The models used to estimate expected credit losses for this loan segment are the same as those used for the tech & innovation portfolio segment. Commercial real estate, owner-occupied The CRE, owner-occupied portfolio segment is comprised of commercial loans that are collateralized by real estate, where the borrower has a business that occupies the property. These loans are typically entered into for the purpose of providing real estate finance or improvement. The primary source of repayment of these loans is the income generated by the business and where rental or sale of the property may provide secondary support for the loan. These loans are sensitive to general economic conditions as well as the market valuation of CRE properties. The probability of default estimate for this loan segment is modeled using the same model as the commercial and industrial loan segment. LGD for this loan segment is driven by property appreciation and the prepayment rate assumption for EAD is driven by unemployment levels. Hotel franchise finance The Hotel franchise finance segment is comprised of loans that are originated within this business line and are collateralized by real estate, where the owner is not the primary tenant. These loans are typically entered into for the purpose of financing or the improvement of commercial investment properties. The primary source of repayment of these loans are the rents paid by tenants and where the sale of the property may provide secondary support for the loan. These loans are sensitive to the market valuation of CRE properties, rental rates, and general economic conditions. The vendor model used to estimate expected credit losses for this loan segment projects probabilities of default and exposure at default based on multiple macroeconomic scenarios by modeling how macroeconomic conditions affect the commercial real estate market. Real estate market factors utilized in this model include vacancy rate, rental growth rate, net operating income growth rate, and commercial property price changes for each specific property type. The model then incorporates loan and property-level characteristics including debt coverage, leverage, collateral size, seasoning, and property type. LGD for this loan segment is derived from a non-modeled approach that is driven by property appreciation and the prepayment rate assumption for EAD is driven by the property appreciation for fixed rate loans and unemployment levels for variable rate loans. Other commercial real estate, non-owner occupied The other commercial real estate, non-owner occupied segment is comprised of loans that are not originated within the Company's specialty business lines and are collateralized by real estate, where the owner is not the primary tenant. The model used to estimate expected credit losses for this loan segment is the same as the model used for the Hotel franchise finance portfolio segment. Residential The residential loan portfolio segment is comprised of loans collateralized primarily by first liens on 1-4 residential family properties and home equity lines of credit that are collateralized by either first liens or junior liens on residential properties. The primary source of repayment of these loans is the value of the property and the capacity of the owner to make payments on the loan. Unemployment rates and the market valuation of residential properties will impact the ultimate repayment of these loans. The residential mortgage loan model is a vendor model that projects probability of default, loss given default severity, prepayment rate, and exposure at default to calculate expected losses. The model is intended to capture the borrower's payment behavior during the lifetime of the residential loan by incorporating loan level characteristics such as loan type, coupon, age, loan-to-value, and credit score and economic conditions such as Home Price Index, interest rate, and unemployment rate. A default event for residential loans is defined as 60 days or more past due, with property appreciation as the driver for LGD results. The prepayment rate assumption for exposure at default for residential loans is based on industry prepayment history. Probability of default for HELOCs is derived from an internally-developed model that projects PD by incorporating loan level information such as FICO score, lien position, balloon payments, and macroeconomic conditions such as property appreciation. LGD for this loan segment is driven by property appreciation and lien position. Exposure at default for HELOCs is calculated based on utilization rate assumptions using a non-modeled approach and also incorporates management judgment. Construction and land development The construction and land portfolio segment is comprised of loans collateralized by land or real estate, which are entered into for the purpose of real estate development. The primary source of repayment of these loans is the eventual sale or refinance of the completed project and where claims on the property provide secondary support for the loan. These loans are impacted by the market valuation of CRE and residential properties and general economic conditions that have a higher sensitivity to real estate markets compared to other real estate loans. Default risk of a property is driven by loan-specific drivers, including loan-to-value, maturity, origination date, and the MSA in which the property is located, among other items. The variables used in the internally-developed model include loan level drivers such as origination loan-to-value, loan maturity, and macroeconomic drivers such as property appreciation, MSA level unemployment rate, and national GDP growth. LGD for this loan segment is driven by property appreciation. The prepayment rate assumption for EAD is driven by the property appreciation for fixed rate loans and unemployment levels for variable rate loans. Other
Transfers and Servicing of Financial Assets, Transfers of Financial Assets, Sales, Policy [Policy Text Block]	Transfers of financial assets Transfers of financial assets are accounted for as sales when control over the assets has been surrendered. Control over transferred assets is deemed surrendered when the: 1) assets have been isolated from the Company; 2) transferee obtains the right to pledge or exchange the transferred assets; and 3) Company no longer maintains effective control over the transferred assets through an agreement to repurchase the transferred assets before maturity.
Property, Plant and Equipment, Policy [Policy Text Block]	Premises and equipment Premises and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is computed principally using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over the term of the lease or the estimated life of the improvement, whichever is shorter. Depreciation and amortization is computed using the following estimated lives: Years Bank premises 31 Furniture, fixtures, and equipment 3 - 10 Leasehold improvements (1) 3 - 10 (1) Depreciation is recorded over the lesser of the relevant 3 to 10-year term or the remaining life of the lease. Management periodically reviews premises and equipment in order to determine if facts and circumstances suggest that the value of an asset is not recoverable.
Lessee, Leases [Policy Text Block]	Leases (lessee) At inception, contracts are evaluated to determine whether the contract constitutes a lease agreement. For contracts that are determined to be an operating lease, a corresponding ROU asset and operating lease liability are recorded in separate line items on the Consolidated Balance Sheet. A ROU asset represents the Company’s right to use an underlying asset during the lease term and a lease liability represents the Company’s commitment to make contractually obligated lease payments. Operating lease ROU assets and liabilities are recognized at the commencement date of the lease and are based on the present value of lease payments over the lease term. The measurement of the operating lease ROU asset includes any lease payments made and is reduced by lease incentives that are paid or are payable to the Company. Variable lease payments that depend on an index or rate such as the Consumer Price Index are included in lease payments based on the rate in effect at the commencement date of the lease. Lease payments are recognized on a straight-line basis over the lease term as part of Occupancy expense in the Consolidated Income Statements. As the rate implicit in the lease is not readily determinable, the Company's incremental collateralized borrowing rate is used to determine the present value of lease payments. This rate gives consideration to the applicable FHLB collateralized borrowing rates and is based on information available at the commencement date. The Company has elected to apply the short-term lease measurement and recognition exemption to leases with an initial term of 12 months or less; therefore, these leases are not recorded on the Company’s Consolidated Balance Sheet, but rather, lease expense is recognized over the lease term on a straight-line basis. The Company’s lease agreements may include options to extend or terminate the lease. These options are included in the lease term when it is reasonably certain that the options will be exercised.
Goodwill and Intangible Assets, Policy [Policy Text Block]	Goodwill and other intangible assets The Company records as goodwill the excess of the purchase price in a business combination over the fair value of the identifiable net assets acquired in accordance with applicable guidance. The Company performs its annual goodwill and intangibles impairment tests as of October 1 each year, or more often if events or circumstances indicate that the carrying value may not be recoverable. The Company can first elect to assess, through qualitative factors, whether it is more likely than not that goodwill is impaired. If the qualitative assessment indicates potential impairment, a quantitative impairment test is performed. If, based on the quantitative test, a reporting unit's carrying amount exceeds its fair value, a goodwill impairment charge for this difference is recorded to current period earnings as part of non-interest expense. Prior to the acquisition of AmeriHome, the Company’s intangible assets consisted primarily of core deposit intangible assets that are being amortized over periods ranging from five to 10 years. See "Note 2. Mergers, Acquisitions and Dispositions" of these Notes to Consolidated Financial Statements for discussion of the intangible assets acquired as part of the AmeriHome acquisition. The Company considers the remaining useful lives of its intangible assets each reporting period, as required by ASC 350, Intangibles—Goodwill and Other , to determine whether events and circumstances warrant a revision to the remaining period of amortization. If the estimate of an intangible asset’s remaining useful life has changed, the remaining carrying amount of the intangible asset is amortized prospectively over the revised remaining useful life. The Company has not revised its estimates of the useful lives of its intangible assets during the years ended December 31, 2021, 2020, or 2019.
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	Low income housing and renewable energy tax credits The Company holds ownership interests in limited partnerships and limited liability companies that invest in affordable housing and renewable energy projects. These investments are designed to generate a return primarily through the realization of federal tax credits and deductions, which may be subject to recapture by taxing authorities if compliance requirements are not met. The Company accounts for its low income housing investments using the proportional amortization method. Renewable energy projects are accounted for under the deferral method, whereby the investment tax credits are reflected as an immediate reduction in income taxes payable and the carrying value of the asset in the period that the investment tax credits are claimed. See "Note 17. Income Taxes" of these Notes to Consolidated Financial Statements for further discussion. The Company evaluates its interests in these entities to determine whether it has a variable interest and whether it is required to consolidate these entities. A variable interest is an investment or other interest that will absorb portions of an entity's expected losses or receive portions of the entity's expected residual returns. If the Company determines that it has a variable interest in an entity, it evaluates whether such interest is in a VIE. A VIE is broadly defined as an entity where either: 1) the equity investors as a group, if any, lack the power through voting or similar rights to direct the activities of an entity that most significantly impact the entity's economic performance or 2) the equity investment at risk is insufficient to finance that entity's activities without additional subordinated financial support. The Company is required to consolidate any VIE when it is determined to be the primary beneficiary of the VIE's operations. A variable interest holder is considered to be the primary beneficiary of a VIE if it has both the power to direct the activities of a VIE that most significantly impact the entity's economic performance and has the obligation to absorb losses of, or the right to receive benefits from, the entity that could potentially be significant to the VIE. The Company’s assessment of whether it is the primary beneficiary of a VIE includes consideration of various factors such as: 1) the Company's ability to direct the activities that most significantly impact the entity's economic performance; 2) its form of ownership interest; 3) its representation on the entity's governing body; 4) the size and seniority of its investment; and 5) its ability and the rights of other investors to participate in policy making decisions and to replace the manager of and/or liquidate the entity. The Company is required to evaluate whether to consolidate a VIE both at inception and on an ongoing basis as changes in circumstances require reconsideration. The Company’s investments in qualified affordable housing and renewable energy projects meet the definition of a VIE as the entities are structured such that the limited partner investors lack substantive voting rights. The general partner or managing member has both the power to direct the activities that most significantly impact the economic performance of the entities and the obligation to absorb losses or the right to receive benefits that could be significant to the entities. Accordingly, as a limited partner, the Company is not the primary beneficiary and is not required consolidate these entities.
Derivative Financial Instruments	Derivative financial instruments The Company uses interest rate swaps to mitigate interest-rate risk associated with changes to the fair value of certain fixed-rate financial instruments (fair value hedges). The Company recognizes derivatives as assets or liabilities on the Consolidated Balance Sheet at their fair value in accordance with ASC 815, Derivatives and Hedging . The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and further, on the type of hedging relationship. Derivative instruments designated in a hedge relationship to mitigate exposure to changes in the fair value of an asset or liability attributable to a particular risk, such as interest rate risk, are considered fair value hedges. The Company documents its hedge relationships, including identification of the hedging instruments and the hedged items, as well as its risk management objectives and strategies for undertaking the hedge transaction after the derivative contract is executed. At inception, the Company performs a quantitative assessment to determine whether the derivatives used in hedging transactions are highly effective (as defined in the guidance) in offsetting changes in the fair value of the hedged item. Retroactive effectiveness is assessed, as well as the continued expectation that the hedge will remain effective prospectively. After the initial quantitative assessment is performed, on a quarterly basis, the Company performs a qualitative hedge effectiveness assessment. This assessment takes into consideration any adverse developments related to the counterparty's risk of default and any negative events or circumstances that affect the factors that originally enabled the Company to assess that it could reasonably support, qualitatively, an expectation that the hedging relationship was and will continue to be highly effective. The Company discontinues hedge accounting prospectively when it is determined that a hedge is no longer highly effective. When hedge accounting is discontinued on a fair value hedge that no longer qualifies as an effective hedge, the derivative instrument continues to be reported at fair value on the Consolidated Balance Sheet, but the carrying amount of the hedged item is no longer adjusted for future changes in fair value. The adjustment to the carrying amount of the hedged item that existed at the date hedge accounting is discontinued is amortized over the remaining life of the hedged item into earnings. Changes in the fair value of a derivative that is designated and qualifies as a fair value hedge, along with changes in the fair value of the hedged asset or liability that are attributable to the hedged risk, are recorded in the same line item as the offsetting loss or gain on the related interest rate swaps during the period of change. For loans, the gain or loss on the hedged item is included in interest income and for subordinated debt, the gain or loss on the hedged items is included in interest expense. Derivative instruments that are not designated as hedges, so called free-standing derivatives, are reported on the Consolidated Balance Sheet at fair value and the changes in fair value are recognized in earnings as non-interest income during the period of change. With the acquisition of AmeriHome, the Company's economic hedging volume has substantially increased. The Company enters into commitments to purchase mortgage loans that will be held for sale. These loan commitments, described as IRLCs, qualify as derivative instruments, except those that are originated rather than purchased, and intended for HFI classification. As of December 31, 2021, all IRLCs qualify as derivative instruments. Changes in fair value associated with changes in interest rates are economically hedged by utilizing forward sale commitments and interest rate futures. These hedging instruments are typically entered into contemporaneously with IRLCs. Loans that have been or will be purchased or originated may be used to satisfy the Company's forward sale commitments. In addition, derivative financial instruments are also used to economically hedge the Company's MSR portfolio. Changes in the fair value of derivative financial instruments that hedge IRLCs and loans HFS are included in Net gain on loan origination and sale activities in the Consolidated Income Statement. Changes in the fair value of derivative financial instruments that hedge MSRs are included in Net loan servicing revenue in the Consolidated Income Statement. The Company may in the normal course of business purchase a financial instrument or originate a loan that contains an embedded derivative instrument. Upon purchasing the instrument or originating the loan, the Company assesses whether the economic characteristics of the embedded derivative are clearly and closely related to the economic characteristics of the remaining component of the financial instrument (i.e., the host contract) and whether a separate instrument with the same terms as the embedded instrument would meet the definition of a derivative instrument. When it is determined that the embedded derivative possesses economic characteristics that are not clearly and closely related to the economic characteristics of the host contract and a separate instrument with the same terms would qualify as a derivative instrument, the embedded derivative is separated from the host contract and carried at fair value. However, in cases where the host contract is measured at fair value, with changes in fair value reported in current earnings, or the Company is unable to reliably identify and measure an embedded derivative for separation from its host contract, the entire contract is carried on the Consolidated Balance Sheet at fair value and is not designated as a hedging instrument.
Income Taxes	Income taxes The Company is subject to income taxes in the United States and files a consolidated federal income tax return with all of its subsidiaries, with the exception of BW Real Estate, Inc. Deferred income taxes are recorded to reflect the effects of temporary differences between the financial reporting carrying amounts of assets and liabilities and their income tax bases using enacted tax rates that are expected to be in effect when the taxes are actually paid or recovered. As changes in tax laws or rates are enacted, deferred tax assets and liabilities are adjusted through the provision for income taxes. Net deferred tax assets are recorded to the extent that these assets will more-likely-than-not be realized. In making these determinations, all available positive and negative evidence is considered, including scheduled reversals of deferred tax liabilities, tax planning strategies, projected future taxable income, and recent operating results. If it is determined that deferred income tax assets to be realized in the future are in excess of their net recorded amount, an adjustment to the valuation allowance will be recorded, which will reduce the Company's provision for income taxes. A tax benefit from an unrecognized tax benefit may be recognized when it is more-likely-than-not that the position will be sustained upon examination, including related appeals or litigation, based on technical merits. Income tax benefits must meet a more-likely-than-not recognition threshold at the effective date to be recognized. Interest and penalties related to unrecognized tax benefits are recognized as part of the provision for income taxes in the Consolidated Income Statement. Accrued interest and penalties are included in the related tax liability line with other liabilities on the Consolidated Balance Sheet. See "Note 17. Income Taxes" of these Notes to Consolidated Financial Statements for further discussion on income taxes.
Revenue [Policy Text Block]	Non-interest income Non-interest income includes revenue associated with mortgage banking and commercial banking activities, investment securities, equity investments, and bank owned life insurance. These non-interest income streams are primarily generated by different types of financial instruments held by the Company for which there is specific accounting guidance and therefore, are not within the scope of ASC 606, Revenue from Contracts with Customers . Non-interest income amounts within the scope of ASC 606 include service charges and fees, success fees related to equity investments, and debit and credit card interchange fees. Service charges and fees consist of fees earned from performance of account analysis, general account services, and other deposit account services. These fees are recognized as the related services are provided. Success fees are one-time fees detailed as part of certain loan agreements and are earned immediately upon occurrence of a triggering event. Card income includes fees earned from customer use of debit and credit cards, interchange income from merchants, and international charges. Card income is generally within the scope of ASC 310, Receivables
Off-Balance Sheet Instruments	Off-balance sheet instruments In the ordinary course of business, the Company enters into off-balance sheet financial instrument arrangements consisting of commitments to extend credit and standby letters of credit. Such financial instruments are recorded in the Consolidated Balance Sheets when funded. These off-balance sheet financial instruments impact, to varying degrees, elements of credit risk in excess of amounts recognized on the Consolidated Balance Sheet. Losses could be experienced when the Company is contractually obligated to make a payment under these instruments and must seek repayment from the borrower, which may not be as financially sound in the current period as they were when the commitment was originally made. Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract and, in certain instances, may be unconditionally cancelable. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. The Company enters into credit arrangements that generally provide for the termination of advances in the event of a covenant violation or other event of default. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. The Company evaluates each customer’s creditworthiness on a case-by-case basis. The amount of collateral obtained, if deemed necessary by the Company upon extension of credit, is based on management’s credit evaluation of the party. The commitments are collateralized by the same types of assets used as loan collateral. The Company also has off-balance sheet arrangements related to its derivative instruments. Derivative instruments are recognized in the Consolidated Balance Sheets at fair value and their notional values are carried off-balance sheet. See "Note 15. Derivatives and Hedging Activities" of these Notes to Consolidated Financial Statements for further discussion.
Fair Values of Financial Instruments	Fair values of financial instruments The Company uses fair value measurements to record fair value adjustments to certain assets and liabilities. ASC 820, Fair Value Measurement , establishes a framework for measuring fair value and a three-level valuation hierarchy for disclosure of fair value measurement, and also sets forth disclosure requirements for fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. The Company uses various valuation approaches, including market, income, and/or cost approaches. ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the factors market participants would consider in pricing the asset or liability developed based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs, as follows: • Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted 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 might include quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, prepayment speeds, volatilities, etc.) or model-based valuation techniques where all significant assumptions are observable, either directly or indirectly, in the market. • Level 3 - Valuation is generated from model-based techniques where one or more significant inputs are not observable, either directly or indirectly, in the market. These unobservable assumptions reflect the Company’s own estimates of assumptions that market participants would use in pricing the asset or liability. Valuation techniques may include use of matrix pricing, discounted cash flow models, and similar techniques. The availability of observable inputs varies based on the nature of the specific financial instrument. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. For disclosure purposes, the lowest level input that is significant to the fair value measurement determines the level in the fair value hierarchy within which the fair value measurement falls in its entirety. Fair value is a market-based measure considered from the perspective of a market participant who may purchase the asset or assume the liability, rather than an entity-specific measure. When market assumptions are available, ASC 820 requires that the Company consider the assumptions that market participants would use to estimate the fair value of the financial instrument at the measurement date. ASC 825, Financial Instruments , requires disclosure of fair value information about financial instruments, whether or not recognized in the balance sheet, for which it is practicable to estimate that value. Management uses its best judgment in estimating the fair value of the Company’s financial instruments; however, there are inherent limitations in any estimation technique. Therefore, for substantially all financial instruments, the fair value estimates presented herein are not necessarily indicative of the amounts the Company could have realized in a sales transaction at December 31, 2021 and 2020. The estimated fair value amounts for December 31, 2021 and 2020 have been measured as of period-end, and have not been re-evaluated or updated for purposes of these Consolidated Financial Statements subsequent to those dates. As such, the estimated fair values of these financial instruments subsequent to the reporting date may be different than the amounts reported at period-end. The information in "Note 19. Fair Value Accounting" of these Notes to Consolidated Financial Statements should not be interpreted as an estimate of the fair value of the entire Company since a fair value calculation is only required for a limited portion of the Company’s assets and liabilities. Due to the wide range of valuation techniques and the degree of subjectivity used in making the estimate, comparisons between the Company’s disclosures and those of other companies or banks may not be meaningful. The following methods and assumptions were used by the Company in estimating the fair value of its financial instruments: Cash, cash equivalents, and restricted cash The carrying amounts reported on the Consolidated Balance Sheet for cash and due from banks approximate their fair value. Investment securities The fair values of U.S. treasury and certain other debt securities as well as publicly-traded CRA investments and exchange-listed preferred stock are based on quoted market prices and are categorized as Level 1 in the fair value hierarchy. The fair values of debt securities are primarily determined based on matrix pricing. Matrix pricing is a mathematical technique that utilizes observable market inputs including, yield curves, credit ratings, and prepayment speeds. Fair values determined using matrix pricing are generally categorized as Level 2 in the fair value hierarchy. In addition to matrix pricing, the Company uses other pricing sources, including observed prices on publicly traded securities and dealer quotes, to estimate the fair value of debt securities, which are also categorized as Level 2 in the fair value hierarchy. Restricted stock Restricted stock consists of investments in the capital stock of the FRB and the FHLB. As no ready market exists for them and they have no quoted market value, the fair values of these investments have been categorized as Level 2 in the fair value hierarchy. Loans HFS Government-insured or guaranteed and agency-conforming loans HFS are salable into active markets. Accordingly, the fair value of these loans is based on quoted market or contracted selling prices or a market price equivalent, which are categorized as Level 2 in the fair value hierarchy. The fair value of non-agency loans HFS as well as certain loans that become nonsalable into active markets due to the identification of a defect is determined based on valuation techniques that utilize Level 3 inputs. Loans HFI The fair value of loans is estimated based on discounted cash flows using interest rates currently being offered for loans with similar terms to borrowers with similar credit quality and adjustments that the Company believes a market participant would consider in determining fair value based on a third-party independent valuation. As a result, the fair value for loans is categorized as Level 3 in the fair value hierarchy. Mortgage servicing rights The fair value of MSRs is estimated using a discounted cash flow model that incorporates assumptions that a market participant would use in estimating the fair value of servicing rights, including, but not limited to, option adjusted spread, conditional prepayment rate, servicing fee rate, and cost to service. As a result, the fair value for MSRs is categorized as Level 3 in the fair value hierarchy. Accrued interest receivable and payable The carrying amounts reported on the Consolidated Balance Sheet for accrued interest receivable and payable approximate their fair values. Derivative financial instruments All derivatives are recognized on the Consolidated Balance Sheets at fair value. The valuation methodologies used to estimate the fair value of derivative instruments varies by type. Treasury futures and options, Eurodollar futures, and swap futures are measured based on valuation techniques using Level 1 Inputs from exchange-provided daily settlement quotes. Interest rate swaps and forward purchase and sales contracts are measured based on valuation techniques using Level 2 inputs, such as quoted market price, contracted selling price, or market price equivalent. IRLCs are measured based on valuation techniques that consider loan type, underlying loan amount, maturity date, note rate, loan program, and expected settlement date, with Level 3 inputs for the servicing release premium and pull-through rate. These measurements are adjusted at the loan level to consider the servicing release premium and loan pricing adjustment specific to each loan. The base value is then adjusted for the pull-through rate. The pull-through rate and servicing fee multiple are unobservable inputs based on historical experience. Deposits The fair value disclosed for demand and savings deposits is by definition equal to the amount payable on demand at the reporting date (that is, their carrying amount), as these deposits do not have a contractual term. The carrying amount for variable rate deposit accounts approximates their fair value. Fair values for fixed rate certificates of deposit are estimated using a discounted cash flow calculation that applies interest rates currently being offered on certificates to a schedule of aggregated expected monthly maturities on these deposits. The fair value measurement of deposit liabilities is categorized as Level 2 in the fair value hierarchy. FHLB advances and customer repurchase agreements The fair values of the Company’s borrowings are estimated using discounted cash flow analyses, based on the market rates for similar types of borrowing arrangements. The carrying value of FHLB advances and customer repurchase agreements approximate their fair values due to their short durations and have been categorized as Level 2 in the fair value hierarchy. Credit linked notes The fair value of credit linked notes is based on observable inputs, when available, and as such credit linked notes are categorized as Level 2 liabilities. Because the notes are variable rate debt, the fair value approximates carrying value. Subordinated debt The fair value of subordinated debt is based on the market rate for the respective subordinated debt security. Subordinated debt has been categorized as Level 2 in the fair value hierarchy. Junior subordinated debt Junior subordinated debt is valued based on a discounted cash flow model which uses the Treasury Bond rates and the 'BB' and 'BBB' rated financial indexes as inputs. Junior subordinated debt has been categorized as Level 3 in the fair value hierarchy.
Life Insurance, Corporate or Bank Owned [Text Block]	Bank owned life insurance BOLI is carried at its cash surrender value with changes recorded in other non-interest income in the Consolidated Income Statements. The face amount of the underlying policies including death benefits was $462.5 million and $465.8 million as of December 31, 2021 and 2020, respectively. There are no loans offset against cash surrender values, and there are no restrictions as to the use of proceeds.
Credit Loss, Financial Instrument	Allowance for credit losses on investment securities On January 1, 2020, the Company adopted ASC Topic 326, Financial Instruments-Credit Losses, which replaced the legacy GAAP Other-than-Temporary Impairment model with a credit loss model. The credit loss model under ASC 326-20, applicable to HTM debt securities, requires recognition of lifetime expected credit losses through an allowance account at the time the security is purchased. The Company measures expected credit losses on its HTM debt securities on a collective basis by major security type. The Company's HTM securities portfolio consists of low income housing tax-exempt bonds and private label residential MBS. Low income housing tax-exempt bonds share similar risk characteristics with the Company's CRE, non-owner occupied or construction and land loan pools, given the similarity in underlying assets or collateral. Accordingly, expected credit losses on HTM securities are estimated using the same models and approaches as these loan pools, which utilize risk parameters (probability of default, loss given default, and exposure at default) in the measurement of expected credit losses. The historical data used to estimate probability of default and severity of loss in the event of default is derived or obtained from internal and external sources and adjusted for the expected effects of reasonable and supportable forecasts over the expected lives of the securities on those historical losses. Accrued interest receivable on HTM securities, which is included in other assets on the Consolidated Balance Sheet, is excluded from the estimate of expected credit losses. The credit loss model under ASC 326-30, applicable to AFS debt securities, requires recognition of credit losses through an allowance account with credit losses recognized once securities become impaired. For AFS debt securities, a decline in fair value due to credit loss results in recognition of an allowance for credit losses. Impairment may result from credit deterioration of the issuer or collateral underlying the security. An assessment to determine whether a decline in fair value resulted from a credit loss is performed at the individual security level. Among other factors, the Company considers: 1) the extent to which the fair value is less than the amortized cost basis; 2) the financial condition and near term prospects of the issuer, including consideration of relevant financial metrics or ratios of the issuer; 3) any adverse conditions related to an industry or geographic area of an issuer; 4) any changes to the rating of the security by a rating agency; and 5) any past due principal or interest payments from the issuer. If an assessment of the above factors indicates that a credit loss exists, the Company records an allowance for credit losses for the excess of the amortized cost basis over the present value of cash flows expected to be collected, limited to the amount that the security's fair value is less than its amortized cost basis. Subsequent changes in the allowance for credit losses are recorded as a provision for (or recovery of) credit loss expense. Interest accruals and amortization and accretion of premiums and discounts are suspended when the credit loss is recognized in earnings. Any interest received after the security has been placed on nonaccrual status is recognized on a cash basis. Accrued interest receivable on AFS debt securities, which is included in other assets on the Consolidated Balance Sheet, is excluded from the estimate of expected credit losses. For each AFS security in an unrealized loss position, the Company also considers: 1) its intent to retain the security until anticipated recovery of the security's fair value; and 2) whether it is more-likely-than not that the Company would be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the debt security is written down to its fair value and the write-down is charged against the allowance for credit losses with any incremental impairment recorded in earnings. Write-offs are made through reversal of the allowance for credit losses and a direct write-off of the amortized cost basis of the AFS security. The Company considers the following events to be indicators that a write-off should be taken: 1) bankruptcy of the issuer; 2) significant adverse event(s) affecting the issuer in which it is improbable for the issuer to make its remaining payments on the security; and 3) significant loss of value of the underlying collateral behind a security. Recoveries on debt securities, if any, are recorded in the period received. Off-balance sheet credit exposures, including unfunded loan commitments The Company maintains a separate allowance for credit losses on off-balance-sheet credit exposures, including unfunded loan commitments, financial guarantees, and letters of credit, which is classified in other liabilities on the Consolidated Balance Sheet. The allowance for credit losses on off-balance sheet credit exposures is adjusted through increases or decreases to the provision for credit loss expense. The estimate includes consideration of the likelihood that funding will occur, an estimate of exposure at default that is derived from utilization rate assumptions using a non-modeled approach, and PD and LGD estimates that are derived from the same models and approaches for the Company's other loan portfolio segments described in the Allowance for credit losses on HFI loans section within this note as these unfunded commitments share similar risk characteristics with these loan portfolio segments. No credit loss estimate is recorded for off-balance sheet credit exposures that are unconditionally cancellable by the Company or for undrawn amounts under such arrangements that may be drawn prior to the cancellation of the arrangement.
Business Combinations	Business combinations Business combinations are accounted for under the acquisition method of accounting in accordance with ASC 805, Business Combinations . Under the acquisition method, the acquiring entity in a business combination recognizes all of the acquired assets and assumed liabilities at their estimated fair values as of the date of acquisition. Any excess of the purchase price over the fair value of net assets and other identifiable intangible assets acquired is recorded as goodwill. To the extent the fair value of net assets acquired, including identified intangible assets, exceeds the purchase price, a bargain purchase gain is recognized. Assets acquired and liabilities assumed from contingencies are also recognized at fair value if the fair value can be determined during the measurement period. Results of operations of an acquired business are included in the Consolidated Income Statement from the date of acquisition. Acquisition-related costs, including conversion and restructuring charges, are expensed as incurred.
Financing Receivable, Held-for-sale	Loans held for sale The Company began holding loans HFS in connection with the AmeriHome acquisition and continues to purchase and originate loans as part of its mortgage banking business. Loans HFS are reported at fair value or the lower of cost or fair value, depending on the acquisition source. The Company has elected to record loans purchased from correspondent sellers or originated directly to consumers at fair value to more timely reflect the Company's performance. Changes in fair value of loans HFS are reported in current period income as a component of Net gain on loan origination and sale activities in the Consolidated Income Statement. Alternatively, delinquent loans repurchased under the terms of the GNMA MBS program, referred to as EBO loans, are reported at the lower of cost or fair value. For EBO loans, the amount by which cost exceeds fair value is accounted for as a valuation allowance and any changes in the valuation allowance are included in Net gain on loan origination and sale activities in the Consolidated Income Statement. The Company recognizes a transfer of loans as a sale when it surrenders control over the transferred loans. Control is considered to be surrendered when the transferred loans have been legally isolated from the Company, the transferee has the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred loans, and the Company does not maintain effective control over the transferred loans through either an agreement that entitles or obligates the Company to repurchase or redeem the loans before their maturity or the ability to unilaterally cause the holder to return loans. If the transfer of loans qualifies as a sale, the Company derecognizes such loans and records the gain or loss as a component of Net gain on loan origination and sale activities in the Consolidated Income Statement. If the transfer of loans does not qualify as a sale, the proceeds from the transfer are accounted for as secured borrowings. Loan acquisition and origination fees on loans HFS consist of fees earned by the Company for purchasing and originating loans and are recognized at the time the loans are purchased or originated. These fees generally represent flat, per loan fee amounts and are included as part of Net gain on loan origination and sale activities in the Consolidated Income Statement.
Credit Linked Notes	Credit linked notesCredit linked notes are structured to effectively transfer the risk of first losses on a reference pool of loans and are considered to be free standing credit enhancements. These notes are recorded at the amount of the proceeds received, net of debt issuance costs. In addition, as the credit guarantee component of these notes is considered to be free standing, the allowance for credit losses measured on the reference pool of loans in accordance with ASC 326 is not reduced by the credit guarantee. Rather, a contra debt balance equal to the estimated allowance for credit losses on the reference pool of loans is recorded, which reduces the carrying value of the notes. The initial contra debt balance and subsequent adjustments are recorded with a corresponding gain or loss on recovery from credit guarantees recognized in earnings.
Transfers and Servicing of Financial Assets, Servicing of Financial Assets, Policy	Mortgage servicing rights The Company acquired MSRs as part of the AmeriHome acquisition and continues to generate new MSRs from its mortgage banking business. When the Company sells mortgage loans in the secondary market and retains the right to service these loans, a servicing right asset is capitalized at the time of sale when the benefits of servicing are deemed to be greater than adequate compensation for performing the servicing activities. MSRs represent the then-current fair value of future net cash flows expected to be realized from performing servicing activities. The Company has elected to subsequently measure MSRs at fair value and report changes in fair value in current period income as a component of Net loan servicing revenue in the Consolidated Income Statement. The Company may in the ordinary course of business sell MSRs and will recognize, as of the trade date, a gain or loss on the sale equal to the difference between the carrying value of the transferred MSRs and the value of the assets received as consideration. The Company subsequently derecognizes MSRs when substantially all of the risks and rewards of ownership are irrevocably passed to the transferee and any protection provisions retained by the Company are minor and can be reasonably estimated, which typically occurs on the settlement date. Protection provisions are considered to be minor if the obligation created by such provisions is estimated to be no more than 10 percent of the sales price and the Company retains the risk of prepayment for no more than 120 days. The Company records an estimated liability for retained protection provisions as of the trade date and continues to remeasure this liability until settlement, with any changes in the estimated liability recorded in earnings. In addition, fees to transfer loans associated with the sold MSRs to a new servicer are also recorded on the settlement date. Gains or losses on sales of MSRs, net of retained protection provisions, and transfer fees are included in Net loan servicing revenue in the Consolidated Income Statement.

Investment Securities (Tables)

Investment Securities (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Carrying Amounts and Fair Values of Investment Securities	The carrying amounts and fair values of investment securities at December 31, 2021 and 2020 are summarized as follows: December 31, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Fair Value (in millions) Held-to-maturity Private label residential MBS $ 216.9 $ — $ (1.6) $ 215.3 Tax-exempt 890.2 43.2 (2.3) 931.1 Total HTM securities $ 1,107.1 $ 43.2 $ (3.9) $ 1,146.4 Available-for-sale debt securities CLO $ 926.0 $ 0.5 $ (0.3) $ 926.2 Commercial MBS issued by GSEs 68.2 0.9 (0.6) 68.5 Corporate debt securities 382.7 9.2 (9.0) 382.9 Private label residential MBS 1,528.7 3.5 (24.2) 1,508.0 Residential MBS issued by GSEs 2,027.5 7.3 (41.4) 1,993.4 Tax-exempt 1,145.1 71.2 (1.2) 1,215.1 U.S. treasury securities 13.0 — — 13.0 Other 75.3 11.0 (4.6) 81.7 Total AFS debt securities $ 6,166.5 $ 103.6 $ (81.3) $ 6,188.8 Equity securities CRA investments $ 45.1 $ — $ (0.5) $ 44.6 Preferred stock 107.1 7.7 (0.9) 113.9 Total equity securities $ 152.2 $ 7.7 $ (1.4) $ 158.5 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized (Losses) Fair Value (in millions) Held-to-maturity Tax-exempt $ 568.8 $ 43.0 $ — $ 611.8 Available-for-sale debt securities CLO $ 146.9 $ — $ — $ 146.9 Commercial MBS issued by GSEs 80.8 3.8 — 84.6 Corporate debt securities 271.1 4.8 (5.7) 270.2 Private label residential MBS 1,461.7 15.7 (0.5) 1,476.9 Residential MBS issued by GSEs 1,462.5 27.9 (3.8) 1,486.6 Tax-exempt 1,109.3 78.1 — 1,187.4 Other 54.1 7.3 (5.5) 55.9 Total AFS debt securities $ 4,586.4 $ 137.6 $ (15.5) $ 4,708.5 Equity securities CRA investments $ 53.1 $ 0.3 $ — $ 53.4 Preferred stock 107.0 7.3 (0.4) 113.9 Total equity securities $ 160.1 $ 7.6 $ (0.4) $ 167.3
Unrealized Losses and Fair Value of Investment Securities in Continuous Unrealized Loss Position	December 31, 2021 Less Than Twelve Months More Than Twelve Months Total Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (in millions) Available-for-sale debt securities CLO $ 0.3 $ 170.7 $ — $ — $ 0.3 $ 170.7 Commercial MBS issued by GSEs 0.6 19.5 — — 0.6 19.5 Corporate debt securities 9.0 107.0 — — 9.0 107.0 Private label residential MBS 24.2 1,250.0 — — 24.2 1,250.0 Residential MBS issued by GSEs 32.6 1,355.7 8.8 142.1 41.4 1,497.8 Tax-exempt 1.2 141.4 — — 1.2 141.4 Other — 2.0 4.6 27.4 4.6 29.4 Total AFS securities $ 67.9 $ 3,046.3 $ 13.4 $ 169.5 $ 81.3 $ 3,215.8 December 31, 2020 Less Than Twelve Months More Than Twelve Months Total Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value (in millions) Available-for-sale debt securities Corporate debt securities $ 0.1 $ 17.3 $ 5.6 $ 94.3 $ 5.7 $ 111.6 Private label residential MBS 0.5 149.7 — — 0.5 149.7 Residential MBS issued by GSEs 3.8 231.9 — — 3.8 231.9 Other — — 5.5 26.5 5.5 26.5 Total AFS securities $ 4.4 $ 398.9 $ 11.1 $ 120.8 $ 15.5 $ 519.7
Investment Securities by Credit Rating Type	December 31, 2021 AAA Split-rated AAA/AA+ AA+ to AA- A+ to A- BBB+ to BBB- BB+ and below Unrated Totals (in millions) Held-to-maturity Private label residential MBS $ — $ — $ — $ — $ — $ — $ 216.9 $ 216.9 Tax-exempt — — — — — — 890.2 890.2 Total HTM securities (1) $ — $ — $ — $ — $ — $ — $ 1,107.1 $ 1,107.1 Available-for-sale debt securities CLO $ 45.0 $ — $ 635.6 $ 245.6 $ — $ — $ — $ 926.2 Commercial MBS issued by GSEs — 68.5 — — — — — 68.5 Corporate debt securities — — — 45.3 318.7 18.9 — 382.9 Private label residential MBS 1,419.6 — 87.4 — 0.9 — 0.1 1,508.0 Residential MBS issued by GSEs — 1,993.4 — — — — — 1,993.4 Tax-exempt 43.2 40.4 469.1 628.9 — — 33.5 1,215.1 U.S. treasury securities — 13.0 — — — — — 13.0 Other — — 12.1 10.0 30.2 9.6 19.8 81.7 Total AFS securities (1) $ 1,507.8 $ 2,115.3 $ 1,204.2 $ 929.8 $ 349.8 $ 28.5 $ 53.4 $ 6,188.8 Equity securities CRA investments $ — $ 27.3 $ — $ — $ — $ — $ 17.3 $ 44.6 Preferred stock — — — — 79.3 20.2 14.4 113.9 Total equity securities (1) $ — $ 27.3 $ — $ — $ 79.3 $ 20.2 $ 31.7 $ 158.5 (1) Where ratings differ, the Company uses an average of the available ratings by major credit agencies. December 31, 2020 AAA Split-rated AAA/AA+ AA+ to AA- A+ to A- BBB+ to BBB- BB+ and below Unrated Totals (in millions) Held-to-maturity Tax-exempt (1) $ — $ — $ — $ — $ — $ — $ 568.8 $ 568.8 Available-for-sale debt securities CLO $ — $ — $ 139.6 $ 7.3 $ — $ — $ — $ 146.9 Commercial MBS issued by GSEs — 84.6 — — — — — 84.6 Corporate debt securities — — 19.2 28.1 194.5 28.4 — 270.2 Private label residential MBS 1,385.5 — 90.1 0.1 0.3 0.9 — 1,476.9 Residential MBS issued by GSEs — 1,486.6 — — — — — 1,486.6 Tax-exempt 44.3 57.3 454.7 599.3 — — 31.8 1,187.4 Other — — 12.3 — 29.1 6.9 7.6 55.9 Total AFS securities (1) $ 1,429.8 $ 1,628.5 $ 715.9 $ 634.8 $ 223.9 $ 36.2 $ 39.4 $ 4,708.5 Equity securities CRA investments $ — $ 27.8 $ — $ — $ — $ — $ 25.6 $ 53.4 Preferred stock — — — — 73.2 39.0 1.7 113.9 Total equity securities (1) $ — $ 27.8 $ — $ — $ 73.2 $ 39.0 $ 27.3 $ 167.3 (1) Where ratings differ, the Company uses an average of the available ratings by major credit agencies.
Gross Gains and (Losses) on Sales of Investment Securities	The following table presents gross gains and losses on sales of investment securities: Year Ended December 31, 2021 2020 2019 (in millions) Available-for-sale securities Gross gains $ 8.4 $ 0.4 $ 3.1 Gross losses — (0.2) — Net gains on AFS securities $ 8.4 $ 0.2 $ 3.1 Equity securities Gross gains $ 0.1 $ — $ — Gross losses (0.2) — — Net losses on equity securities $ (0.1) $ — $ —

Loans, Leases and Allowance for

Loans, Leases and Allowance for Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Loans by Risk Rating	Term Loan Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total December 31, 2021 2021 2020 2019 2018 2017 Prior (in millions) Warehouse lending Pass $ 242.6 $ 12.5 $ — $ — $ — $ — $ 4,900.8 $ 5,155.9 Special mention — — — — — — — — Classified — — — — — — — — Total $ 242.6 $ 12.5 $ — $ — $ — $ — $ 4,900.8 $ 5,155.9 Municipal & nonprofit Pass $ 129.5 $ 195.0 $ 101.2 $ 52.9 $ 219.3 $ 877.8 $ 3.5 $ 1,579.2 Special mention — — — — — — — — Classified — — — — — — — — Total $ 129.5 $ 195.0 $ 101.2 $ 52.9 $ 219.3 $ 877.8 $ 3.5 $ 1,579.2 Tech & innovation Pass $ 762.6 $ 157.1 $ 101.1 $ 6.1 $ — $ 0.6 $ 334.4 $ 1,361.9 Special mention 26.0 4.7 — — — — 8.1 38.8 Classified 3.0 5.2 7.5 — — — 1.4 17.1 Total $ 791.6 $ 167.0 $ 108.6 $ 6.1 $ — $ 0.6 $ 343.9 $ 1,417.8 Equity fund resources Pass $ 9.0 $ 1.7 $ — $ 0.3 $ 2.2 $ 0.2 $ 3,816.4 $ 3,829.8 Special mention — — — — — — — — Classified — — — — — — — — Total $ 9.0 $ 1.7 $ — $ 0.3 $ 2.2 $ 0.2 $ 3,816.4 $ 3,829.8 Other commercial and industrial Pass $ 2,910.8 $ 360.0 $ 387.1 $ 210.3 $ 80.2 $ 97.8 $ 2,306.0 $ 6,352.2 Special mention 5.4 26.7 22.0 17.6 0.1 — 15.0 86.8 Classified — 10.1 5.6 2.2 1.4 0.2 7.2 26.7 Total $ 2,916.2 $ 396.8 $ 414.7 $ 230.1 $ 81.7 $ 98.0 $ 2,328.2 $ 6,465.7 CRE - owner occupied Pass $ 417.2 $ 198.5 $ 220.1 $ 190.4 $ 278.0 $ 322.4 $ 55.6 $ 1,682.2 Special mention — — 0.3 10.1 — 1.5 0.4 12.3 Classified 2.2 2.6 1.0 4.6 8.0 10.7 0.1 29.2 Total $ 419.4 $ 201.1 $ 221.4 $ 205.1 $ 286.0 $ 334.6 $ 56.1 $ 1,723.7 Hotel franchise finance Pass $ 721.3 $ 205.3 $ 658.8 $ 332.2 $ 135.5 $ 63.5 $ 123.0 $ 2,239.6 Special mention — — 87.6 51.1 — — — 138.7 Classified 30.3 — 99.2 15.9 10.3 — — 155.7 Total $ 751.6 $ 205.3 $ 845.6 $ 399.2 $ 145.8 $ 63.5 $ 123.0 $ 2,534.0 Other CRE - non-owner occupied Pass $ 1,398.2 $ 754.8 $ 673.0 $ 278.8 $ 185.8 $ 283.5 $ 315.1 $ 3,889.2 Special mention 14.8 — 9.8 — — 1.7 — 26.3 Classified — — 4.2 4.5 0.3 16.4 10.9 36.3 Total $ 1,413.0 $ 754.8 $ 687.0 $ 283.3 $ 186.1 $ 301.6 $ 326.0 $ 3,951.8 Term Loan Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total December 31, 2021 2021 2020 2019 2018 2017 Prior (in millions) Residential Pass $ 7,459.3 $ 1,018.4 $ 395.5 $ 201.3 $ 41.6 $ 75.5 $ 36.1 $ 9,227.7 Special mention — — — — — — — — Classified 8.9 0.9 3.6 0.5 0.1 1.1 — 15.1 Total $ 7,468.2 $ 1,019.3 $ 399.1 $ 201.8 $ 41.7 $ 76.6 $ 36.1 $ 9,242.8 Construction and land development Pass $ 957.6 $ 632.3 $ 394.0 $ 112.2 $ 3.5 $ 0.1 $ 869.8 $ 2,969.5 Special mention — 22.5 — — 5.6 — — 28.1 Classified 1.0 4.3 0.6 — — — 2.3 8.2 Total $ 958.6 $ 659.1 $ 394.6 $ 112.2 $ 9.1 $ 0.1 $ 872.1 $ 3,005.8 Other Pass $ 15.7 $ 11.6 $ 3.7 $ 4.3 $ 4.4 $ 82.0 $ 46.4 $ 168.1 Special mention — — — — — 0.1 — 0.1 Classified — — 0.1 0.1 — 0.5 — 0.7 Total $ 15.7 $ 11.6 $ 3.8 $ 4.4 $ 4.4 $ 82.6 $ 46.4 $ 168.9 Total by Risk Category Pass $ 15,023.8 $ 3,547.2 $ 2,934.5 $ 1,388.8 $ 950.5 $ 1,803.4 $ 12,807.1 $ 38,455.3 Special mention 46.2 53.9 119.7 78.8 5.7 3.3 23.5 331.1 Classified 45.4 23.1 121.8 27.8 20.1 28.9 21.9 289.0 Total $ 15,115.4 $ 3,624.2 $ 3,176.0 $ 1,495.4 $ 976.3 $ 1,835.6 $ 12,852.5 $ 39,075.4 Term Loan Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total December 31, 2020 2020 2019 2018 2017 2016 Prior (in millions) Warehouse lending Pass $ 135.2 $ — $ 0.9 $ 1.6 $ 0.1 $ — $ 4,202.4 $ 4,340.2 Special mention — — — — — — — — Classified — — — — — — — — Total $ 135.2 $ — $ 0.9 $ 1.6 $ 0.1 $ — $ 4,202.4 $ 4,340.2 Municipal & nonprofit Pass $ 219.3 $ 156.6 $ 81.6 $ 231.2 $ 129.1 $ 905.6 $ 3.5 $ 1,726.9 Special mention — — — — — — — — Classified — — — 1.9 — — — 1.9 Total $ 219.3 $ 156.6 $ 81.6 $ 233.1 $ 129.1 $ 905.6 $ 3.5 $ 1,728.8 Tech & innovation Pass $ 595.5 $ 205.9 $ 76.4 $ — $ 0.9 $ — $ 481.7 $ 1,360.4 Special mention 10.7 4.6 — — — — — 15.3 Classified 25.2 2.0 — — — — 0.1 27.3 Total $ 631.4 $ 212.5 $ 76.4 $ — $ 0.9 $ — $ 481.8 $ 1,403.0 Equity fund resources Pass $ 14.2 $ 1.5 $ 0.5 $ 2.0 $ — $ — $ 1,127.1 $ 1,145.3 Special mention — — — — — — — — Classified — — — — — — — — Total $ 14.2 $ 1.5 $ 0.5 $ 2.0 $ — $ — $ 1,127.1 $ 1,145.3 Other commercial and industrial Pass $ 2,069.5 $ 819.8 $ 447.7 $ 250.7 $ 99.7 $ 114.6 $ 1,935.7 $ 5,737.7 Special mention 2.2 52.1 32.1 22.1 1.7 0.2 34.3 144.7 Classified 0.9 8.4 3.2 1.6 9.7 0.8 4.2 28.8 Total $ 2,072.6 $ 880.3 $ 483.0 $ 274.4 $ 111.1 $ 115.6 $ 1,974.2 $ 5,911.2 Term Loan Amortized Cost Basis by Origination Year Revolving Loans Amortized Cost Basis Total December 31, 2020 2020 2019 2018 2017 2016 Prior (in millions) CRE - owner occupied Pass $ 252.2 $ 307.1 $ 302.1 $ 402.4 $ 148.4 $ 323.5 $ 39.5 $ 1,775.2 Special mention 0.9 12.4 9.3 24.3 4.4 10.5 22.4 84.2 Classified 1.4 7.5 4.8 8.5 6.2 19.5 2.0 49.9 Total $ 254.5 $ 327.0 $ 316.2 $ 435.2 $ 159.0 $ 353.5 $ 63.9 $ 1,909.3 Hotel franchise finance Pass $ 161.6 $ 792.0 $ 464.1 $ 139.9 $ — $ 101.5 $ 162.6 $ 1,821.7 Special mention — 32.7 56.9 27.3 — 18.2 — 135.1 Classified 8.9 — — 12.6 2.1 3.5 — 27.1 Total $ 170.5 $ 824.7 $ 521.0 $ 179.8 $ 2.1 $ 123.2 $ 162.6 $ 1,983.9 Other CRE - non-owner occupied Pass $ 1,032.6 $ 912.5 $ 560.8 $ 384.3 $ 164.7 $ 208.4 $ 281.0 $ 3,544.3 Special mention 1.4 — 7.0 5.4 1.0 7.4 — 22.2 Classified 7.4 26.4 — 20.3 6.5 13.1 — 73.7 Total $ 1,041.4 $ 938.9 $ 567.8 $ 410.0 $ 172.2 $ 228.9 $ 281.0 $ 3,640.2 Residential Pass $ 759.5 $ 869.3 $ 402.0 $ 108.9 $ 113.8 $ 74.1 $ 39.5 $ 2,367.1 Special mention — — — — — — — — Classified — 4.4 5.9 1.1 — — — 11.4 Total $ 759.5 $ 873.7 $ 407.9 $ 110.0 $ 113.8 $ 74.1 $ 39.5 $ 2,378.5 Construction and land development Pass $ 677.8 $ 704.2 $ 429.6 $ 15.4 $ 1.2 $ 15.0 $ 537.4 $ 2,380.6 Special mention 8.5 0.4 38.0 — — — 0.4 47.3 Classified — — 1.5 — — — — 1.5 Total $ 686.3 $ 704.6 $ 469.1 $ 15.4 $ 1.2 $ 15.0 $ 537.8 $ 2,429.4 Other Pass $ 21.1 $ 15.6 $ 14.5 $ 5.8 $ 1.8 $ 75.8 $ 45.7 $ 180.3 Special mention — — 0.1 1.7 — 0.5 — 2.3 Classified — 0.1 0.2 — 0.1 0.2 — 0.6 Total $ 21.1 $ 15.7 $ 14.8 $ 7.5 $ 1.9 $ 76.5 $ 45.7 $ 183.2 Total by Risk Category Pass $ 5,938.5 $ 4,784.5 $ 2,780.2 $ 1,542.2 $ 659.7 $ 1,818.5 $ 8,856.1 $ 26,379.7 Special mention 23.7 102.2 143.4 80.8 7.1 36.8 57.1 451.1 Classified 43.8 48.8 15.6 46.0 24.6 37.1 6.3 222.2 Total $ 6,006.0 $ 4,935.5 $ 2,939.2 $ 1,669.0 $ 691.4 $ 1,892.4 $ 8,919.5 $ 27,053.0

Premises and Equipment (Tables)

Premises and Equipment (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	December 31, 2021 2020 (in millions) Bank premises $ 91.6 $ 92.0 Land and improvements 32.4 33.0 Furniture, fixtures, and equipment 99.6 68.2 Leasehold improvements 41.5 29.7 Construction in progress 42.7 17.4 Total 307.8 240.3 Accumulated depreciation and amortization (125.9) (106.2) Premises and equipment, net $ 181.9 $ 134.1

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	The following is a schedule of the Company's operating lease liabilities by contractual maturity as of December 31, 2021: (in millions) 2022 $ 15.1 2023 20.7 2024 22.7 2025 18.3 2026 19.3 Thereafter 60.2 Total lease payments $ 156.3 Less: imputed interest 13.5 Total present value of lease liabilities $ 142.8

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets (Tables) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)
Goodwill and Intangible Assets Amortization Schedule [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following is a summary of the Company's acquired intangible assets: December 31, 2021 December 31, 2020 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in millions) Subject to amortization Core deposit intangibles $ 14.6 $ 10.2 $ 4.4 $ 14.6 $ 8.8 $ 5.8 Customer relationship intangibles 2.5 0.6 1.9 2.5 0.1 2.4 Correspondent customer relationships 76.0 2.8 73.2 — — — Trade name - AmeriHome 9.5 0.4 9.1 — — — Operating licenses 55.5 1.0 54.5 — — — $ 158.1 $ 15.0 $ 143.1 $ 17.1 $ 8.9 $ 8.2 December 31, 2021 December 31, 2020 Gross Carrying Amount Impairment Net Carrying Amount Gross Carrying Amount Impairment Net Carrying Amount (in millions) Not subject to amortization Trade name - Bridge Bank $ 0.4 $ — $ 0.4 $ 0.4 $ — $ 0.4
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	Below is a summary of future estimated aggregate amortization expense: December 31, 2021 (in millions) 2022 $ 7.5 2023 7.4 2024 7.4 2025 6.6 2026 5.7 Thereafter 108.5 Total $ 143.1
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 7.5
Finite-Lived Intangible Assets, Amortization Expense, Year Two	7.4
Finite-Lived Intangible Assets, Amortization Expense, Year Three	7.4
Finite-Lived Intangible Assets, Amortization Expense, Year Four	6.6
Finite-Lived Intangible Assets, Amortization Expense, Year Five	5.7
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	$ 108.5

Other Borrowings (Tables)

Other Borrowings (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Company's Borrowings	The following table summarizes the Company’s borrowings as of December 31, 2021 and 2020: December 31, 2021 2020 (in millions) Short-Term: Federal funds purchased $ 675.0 $ — FHLB advances — 5.0 Customer repurchase agreements 16.6 16.0 Secured borrowings 35.3 — Total short-term borrowings $ 726.9 $ 21.0 Long-Term: AmeriHome senior notes, net of fair value adjustment $ 317.9 $ — Credit linked notes, net of debt issuance costs 457.1 — Total long-term borrowings $ 775.0 $ — Total other borrowings $ 1,501.9 $ 21.0

Qualifying Debt Junior Subordin

Qualifying Debt Junior Subordinated Debt Table (Tables)	12 Months Ended
	Dec. 31, 2021
Junior Subordinated Debt Table [Abstract]
Schedule of Subordinated Borrowing [Table Text Block]	December 31, Name of Trust Maturity 2021 2020 At fair value (in millions) BankWest Nevada Capital Trust II 2033 $ 15.5 $ 15.5 Intermountain First Statutory Trust I 2034 10.3 10.3 First Independent Statutory Trust I 2035 7.2 7.2 WAL Trust No. 1 2036 20.6 20.6 WAL Statutory Trust No. 2 2037 5.2 5.2 WAL Statutory Trust No. 3 2037 7.7 7.7 Total contractual balance 66.5 66.5 FVO on junior subordinated debt 0.9 (0.6) Junior subordinated debt, at fair value $ 67.4 $ 65.9 At amortized cost Bridge Capital Holdings Trust I 2035 $ 12.4 $ 12.4 Bridge Capital Holdings Trust II 2036 5.1 5.1 Total contractual balance 17.5 17.5 Purchase accounting adjustment, net of accretion (1) (4.2) (4.5) Junior subordinated debt, at amortized cost $ 13.3 $ 13.0 Total junior subordinated debt $ 80.7 $ 78.9

Stockholders' Equity Schedule o

Stockholders' Equity Schedule of Share-based Compensation Arrangements by Share-based Payment Award (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block]	A summary of the status of the Company’s unvested shares of restricted stock and changes during the years then ended is presented below: December 31, 2021 2020 Shares Weighted Average Grant Date Fair Value Shares Weighted Average Grant Date Fair Value (in millions, except per share amounts) Balance, beginning of period 1.0 $ 50.12 1.0 $ 49.98 Granted 0.4 83.56 0.4 51.53 Vested (0.4) 53.50 (0.4) 51.86 Forfeited (0.1) 59.24 0.0 49.79 Balance, end of period 0.9 $ 63.53 1.0 $ 50.12

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income	The following table summarizes the changes in accumulated other comprehensive income (loss) by component, net of tax, for the periods indicated: Unrealized holding gains (losses) on AFS Unrealized holding gains (losses) on SERP Unrealized holding gains (losses) on junior subordinated debt Impairment loss on securities Total (in millions) Balance, December 31, 2018 $ (47.5) $ 0.4 $ 13.4 $ 0.1 $ (33.6) Other comprehensive income (loss) before reclassifications 71.2 (0.4) (9.8) — 61.0 Amounts reclassified from AOCI (2.3) — — (0.1) (2.4) Net current-period other comprehensive income (loss) 68.9 (0.4) (9.8) (0.1) 58.6 Balance, December 31, 2019 $ 21.4 $ — $ 3.6 $ — $ 25.0 Other comprehensive income (loss) before reclassifications 70.9 (0.3) (3.1) — 67.5 Amounts reclassified from accumulated other comprehensive income (0.2) — — — (0.2) Net current-period other comprehensive income (loss) 70.7 (0.3) (3.1) — 67.3 Balance, December 31, 2020 $ 92.1 $ (0.3) $ 0.5 $ — $ 92.3 Other comprehensive (loss) income before reclassifications (69.0) — (1.2) — (70.2) Amounts reclassified from AOCI (6.4) — — — (6.4) Net current-period other comprehensive (loss) income (75.4) — (1.2) — (76.6) Balance, December 31, 2021 $ 16.7 $ (0.3) $ (0.7) $ — $ 15.7
Schedule of Reclassifications Out of Accumulated Other Comprehensive Income	The following table presents reclassifications out of accumulated other comprehensive income: Year Ended December 31, Income Statement Classification 2021 2020 2019 (in millions) Gain on sales of AFS debt securities, net $ 8.5 $ 0.2 $ 3.1 Income tax expense (2.1) — (0.7) Net of tax $ 6.4 $ 0.2 $ 2.4

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	12 Months Ended
	Dec. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position	December 31, 2021 December 31, 2020 December 31, 2019 Fair Value Fair Value Fair Value Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities Notional Derivative Assets Derivative Liabilities (in millions) Derivatives designated as hedging instruments: Fair value hedges Interest rate swaps (1) $ 1,382.8 $ 13.8 $ 54.5 $ 1,689.9 $ 3.3 $ 86.1 $ 863.0 $ 1.8 $ 55.5 Total $ 1,382.8 $ 13.8 $ 54.5 $ 1,689.9 $ 3.3 $ 86.1 $ 863.0 $ 1.8 $ 55.5 Derivatives not designated as hedging instruments (2): Foreign currency contracts $ 180.1 $ 0.2 $ 1.4 $ 119.2 $ 0.7 $ 1.2 $ 6.7 $ — $ — Forward purchase contracts 11,713.5 8.1 18.0 — — — — — — Forward sales contracts 17,358.5 15.8 17.7 — — — — — — Futures purchase contracts (3) 218,053.7 — — — — — — — — Futures sales contracts (3) 229,040.0 — — — — — — — — Interest rate lock commitments 3,033.2 11.0 1.6 — — — — — — Interest rate swaps 4.1 0.1 0.1 3.5 0.2 0.2 2.9 0.1 0.1 Total $ 479,383.1 $ 35.2 $ 38.8 $ 122.7 $ 0.9 $ 1.4 $ 9.6 $ 0.1 $ 0.1 Margin 1.2 6.5 — — — — — — Total, including margin $ 479,383.1 $ 36.4 $ 45.3 $ 122.7 $ 0.9 $ 1.4 $ 9.6 $ 0.1 $ 0.1

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table presents the calculation of basic and diluted EPS: Year Ended December 31, 2021 2020 2019 (in millions, except per share amounts) Weighted average shares - basic 102.7 100.2 102.7 Dilutive effect of stock awards 0.6 0.3 0.4 Weighted average shares - diluted 103.3 100.5 103.1 Net income available to common stockholders $ 895.7 $ 506.6 $ 499.2 Earnings per share - basic 8.72 5.06 4.86 Earnings per share - diluted 8.67 5.04 4.84

Income Taxes Provision (Tables)

Income Taxes Provision (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Expense Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	Year Ended December 31, 2021 2020 2019 (in millions) Current $ 181.8 $ 141.0 $ 110.1 Deferred 42.0 (25.1) (5.1) Total tax provision $ 223.8 $ 115.9 $ 105.0
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Year Ended December 31, 2021 2020 2019 (in millions) Income tax at statutory rate $ 235.8 $ 130.7 $ 126.9 Increase (decrease) resulting from: State income taxes, net of federal benefits 35.8 13.9 11.0 Tax-exempt income (25.6) (21.7) (19.6) Investment tax credits (15.9) (13.9) (15.0) Other, net (6.3) 6.9 1.7 Total tax provision $ 223.8 $ 115.9 $ 105.0
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	December 31, 2021 2020 (in millions) Deferred tax assets: Allowance for credit losses $ 81.0 $ 84.6 Lease liability 38.6 21.1 Premises and equipment 10.0 — Accrued expenses 9.8 3.6 Passthrough income 9.1 8.4 Insurance premiums — 18.9 Other 34.9 29.1 Total gross deferred tax assets 183.4 165.7 Deferred tax asset valuation allowance — — Total deferred tax assets 183.4 165.7 Deferred tax liabilities: Mortgage servicing rights (57.6) — Right of use asset (36.0) (19.2) Deferred loan costs (15.5) (12.8) Leasing basis differences (12.3) (11.1) IRC section 50(d) income (7.7) (9.8) Estimated loss reserve (7.6) (17.5) Unearned premiums (7.2) (16.8) Insurance premiums (6.0) — Unrealized gain on AFS securities (5.7) (31.2) Premises and equipment — (7.6) Other (6.9) (8.4) Total deferred tax liabilities (162.5) (134.4) Deferred tax assets, net $ 20.9 $ 31.3
Summary of Income Tax Contingencies [Table Text Block]	December 31, 2021 2020 (in millions) Beginning balance $ 3.4 $ 1.7 Gross increases Tax positions in prior periods 0.8 — Current period tax positions 2.2 2.2 Gross decreases Tax positions in prior periods — — Settlements — (0.1) Lapse of statute of limitations — (0.4) Ending balance $ 6.4 $ 3.4

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of Contractual Amounts for Unfunded Commitments and Letters of Credit	A summary of the contractual amounts for unfunded commitments and letters of credit are as follows: December 31, 2021 2020 (in millions) Commitments to extend credit, including unsecured loan commitments of $1,199.8 at December 31, 2021 and $1,077.2 at December 31, 2020 $ 13,396.3 $ 9,425.2 Credit card commitments and financial guarantees 306.3 291.5 Letters of credit, including unsecured letters of credit of $12.9 at December 31, 2021 and $9.9 at December 31, 2020 198.1 186.9 Total $ 13,900.7 $ 9,903.6
Contractual Obligation, Fiscal Year Maturity [Table Text Block]	Amount of Commitment Expiration per Period Total Amounts Committed Less Than 1 Year 1-3 Years 3-5 Years After 5 Years (in millions) Commitments to extend credit $ 13,396.3 $ 3,652.0 $ 6,235.1 $ 2,322.1 $ 1,187.0 Credit card commitments and financial guarantees 306.3 306.3 — — — Letters of credit 198.1 190.7 3.0 4.4 — Total $ 13,900.7 $ 4,149.0 $ 6,238.1 $ 2,326.5 $ 1,187.0

Fair Value Accounting (Tables)

Fair Value Accounting (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Gains and Losses from Fair Value Changes Included in Consolidated Statement of Operations	For the years ended December 31, 2021, 2020, and 2019, unrealized losses from fair value changes on junior subordinated debt were as follows: Year Ended December 31, 2021 2020 2019 (in millions) Unrealized losses $ (1.5) $ (4.2) $ (13.0) Changes included in OCI, net of tax (1.2) (3.1) (9.8)
Fair Value of Assets and Liabilities	The fair value of assets and liabilities measured at fair value on a recurring basis was determined using the following inputs as of the periods presented: Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Fair Value (in millions) December 31, 2021 Available-for-sale debt securities CLO $ — $ 926.2 $ — $ 926.2 Commercial MBS issued by GSEs — 68.5 — 68.5 Corporate debt securities — 382.9 — 382.9 Private label residential MBS — 1,508.0 — 1,508.0 Residential MBS issued by GSEs — 1,993.4 — 1,993.4 Tax-exempt — 1,215.1 — 1,215.1 U.S. treasury securities 13.0 — — 13.0 Other 27.4 54.3 — 81.7 Total AFS debt securities $ 40.4 $ 6,148.4 $ — $ 6,188.8 Equity securities CRA investments $ 27.4 $ 17.2 $ — $ 44.6 Preferred stock 113.9 — — 113.9 Total equity securities $ 141.3 $ 17.2 $ — $ 158.5 Loans HFS $ — $ 3,894.2 $ 45.5 $ 3,939.7 Mortgage servicing rights — — 698.0 698.0 Derivative assets (1) — 39.2 11.0 50.2 Liabilities: Junior subordinated debt (2) $ — $ — $ 67.4 $ 67.4 Derivative liabilities (1) — 98.2 1.6 99.8 (1) See "Note 15. Derivatives and Hedging Activities." In addition, the carrying value of loans is increased by $38.5 million as of December 31, 2021 for the effective portion of the hedge, which relates to the fair value of the hedges put in place to mitigate against fluctuations in interest rates. (2) Includes only the portion of junior subordinated debt that is recorded at fair value at each reporting period pursuant to the election of FVO treatment. Fair Value Measurements at the End of the Reporting Period Using: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Fair (in millions) December 31, 2020 Assets: Available-for-sale debt securities CLO $ — $ 146.9 $ — $ 146.9 Commercial MBS issued by GSEs — 84.6 — 84.6 Corporate debt securities — 270.2 — 270.2 Private label residential MBS — 1,476.9 — 1,476.9 Residential MBS issued by GSEs — 1,486.6 — 1,486.6 Tax-exempt — 1,187.4 — 1,187.4 Other 26.5 29.4 — 55.9 Total AFS debt securities $ 26.5 $ 4,682.0 $ — $ 4,708.5 Equity securities CRA investments $ 27.8 $ 25.6 $ — $ 53.4 Preferred stock 113.9 — — 113.9 Total equity securities $ 141.7 $ 25.6 $ — $ 167.3 Derivative assets (1) $ — $ 4.2 $ — $ 4.2 Liabilities: Junior subordinated debt (2) $ — $ — $ 65.9 $ 65.9 Derivative liabilities (1) — 87.5 — 87.5
Change in Level 3 Liabilities Measured at Fair Value on Recurring Basis	For the years ended December 31, 2021, 2020, and 2019, the change in Level 3 liabilities measured at fair value on a recurring basis included in OCI was as follows: Junior Subordinated Debt Year Ended December 31, 2021 2020 2019 (in millions) Beginning balance $ (65.9) $ (61.7) $ (48.7) Change in fair value (1) (1.5) (4.2) (13.0) Ending balance $ (67.4) $ (65.9) $ (61.7) (1) Unrealized gains/(losses) attributable to changes in the fair value of junior subordinated debt are recorded as part of OCI, net of tax, and totaled $(1.2) million, $(3.1) million, and $(9.8) million for the years ended December 31, 2021, 2020, and 2019, respectively. The significant unobservable inputs used in the fair value measurements of these Level 3 liabilities were as follows: December 31, 2021 Valuation Technique Significant Unobservable Inputs Input Value (in millions) Junior subordinated debt $ 67.4 Discounted cash flow Implied credit rating of the Company 2.61 %
Assets Measured at Fair Value on Nonrecurring Basis	The following table presents such assets carried on the Consolidated Balance Sheet by caption and by level within the ASC 825 hierarchy: Fair Value Measurements at the End of the Reporting Period Using Total Quoted Prices in Active Markets for Identical Assets Active Markets for Similar Assets Unobservable Inputs (in millions) As of December 31, 2021 Loans HFI $ 216.0 $ — $ — $ 216.0 Other assets acquired through foreclosure 11.7 — — 11.7 As of December 31, 2020 Loans HFI $ 187.3 $ — $ — $ 187.3 Other assets acquired through foreclosure 1.4 — — 1.4
Estimated Fair Value of Financial Instruments	The estimated fair value of the Company’s financial instruments is as follows: December 31, 2021 Carrying Amount Fair Value Level 1 Level 2 Level 3 Total (in millions) Financial assets: Investment securities: HTM $ 1,107.1 $ — $ 1,146.4 $ — $ 1,146.4 AFS 6,188.8 40.4 6,148.4 — 6,188.8 Equity securities 158.5 141.3 17.2 — 158.5 Derivative assets 50.2 — 39.2 11.0 50.2 Loans HFS 5,635.1 — 3,894.2 1,760.2 5,654.4 Loans HFI, net 38,822.9 — — 39,218.2 39,218.2 Mortgage servicing rights 698.0 — — 698.0 698.0 Accrued interest receivable 227.9 — 227.9 — 227.9 Financial liabilities: Deposits $ 47,612.0 $ — $ 47,615.5 $ — $ 47,615.5 Other borrowings 1,501.9 — 1,518.4 — 1,518.4 Qualifying debt 895.8 — 857.3 81.3 938.6 Derivative liabilities 99.8 — 98.2 1.6 99.8 Accrued interest payable 9.2 — 9.2 — 9.2

Related Parties (Tables)

Related Parties (Tables)	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]	The following table summarizes the aggregate activity for such loans: Year Ended December 31, 2021 2020 (in millions) Balance, beginning $ 3.3 $ 3.8 New loans — — Advances — — Repayments and other (3.3) (0.5) Balance, ending $ — $ 3.3

Parent Company (Tables)

Parent Company (Tables)	12 Months Ended
	Dec. 31, 2021
Parent Company Financial Information [Abstract]
Condensed Balance Sheet [Table Text Block]	WESTERN ALLIANCE BANCORPORA
Schedule Of Condensed Income Statement And Comprehensive Income Table [Text Block]	Condensed Income Statements Year Ended December 31, 2021 2020 2019 (in millions) Income: Dividends from subsidiaries $ 50.0 $ 160.0 $ 134.0 Interest income 3.2 3.1 2.8 Non-interest income 13.4 4.7 5.1 Total income 66.6 167.8 141.9 Expense: Interest expense 19.5 10.6 14.6 Non-interest expense 31.9 19.7 19.5 Total expense 51.4 30.3 34.1 Income before income taxes and equity in undistributed earnings of subsidiaries 15.2 137.5 107.8 Income tax benefit 7.4 4.5 5.7 Income before equity in undistributed earnings of subsidiaries 22.6 142.0 113.5 Equity in undistributed earnings of subsidiaries 876.6 364.6 385.7 Net income 899.2 506.6 499.2 Dividends on preferred stock 3.5 — — Net income available to common stockholders $ 895.7 $ 506.6 $ 499.2
Condensed Cash Flow Statement [Table Text Block]	Condensed Statements of Cash Flows Year Ended December 31, 2021 2020 2019 (in millions) Cash flows from operating activities: Net income $ 899.2 $ 506.6 $ 499.2 Adjustments to reconcile net income to net cash provided by operating activities: Equity in net undistributed earnings of subsidiaries (876.6) (364.6) (385.7) Junior subordinated debt change in fair value (0.1) — — Loss on extinguishment of debt 5.9 — — Other operating activities, net (1.4) 8.0 9.9 Net cash provided by operating activities 27.0 150.0 123.4 Cash flows from investing activities: Purchases of securities (16.0) (6.9) (10.8) Principal pay downs, calls, maturities, and sales proceeds of securities 28.6 7.7 19.0 Capital contributions to subsidiaries (1,139.3) — — Other investing activities, net — 1.2 — Net cash (used in) provided by investing activities (1,126.7) 2.0 8.2 Cash flows from financing activities: Net proceeds from issuance of subordinated debt 591.9 — — Common stock repurchases — (71.6) (120.2) Redemption of subordinated debt (176.0) — — Proceeds from issuance of common stock in offerings, net 540.3 — — Cash dividends paid on common and preferred stock (127.6) (101.3) (51.3) Proceeds from issuance of preferred stock, net 294.5 — — Other financing activities, net 0.1 0.5 0.1 Net cash provided by (used in) financing activities 1,123.2 (172.4) (171.4) Net increase (decrease) in cash and cash equivalents 23.5 (20.4) (39.8) Cash and cash equivalents at beginning of year 55.5 75.9 115.7 Cash and cash equivalents at end of year $ 79.0 $ 55.5 $ 75.9

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2021
Segment Reporting [Abstract]
Operating Segment Information	The following is a summary of operating segment balance sheet information for the periods indicated: Consolidated Company Commercial Consumer Related Corporate & Other At December 31, 2021: (in millions) Assets: Cash, cash equivalents, and investment securities $ 8,057.3 $ 12.9 $ 82.4 $ 7,962.0 Loans held for sale 5,635.1 — 5,635.1 — Loans, net of deferred fees and costs 39,075.4 25,092.4 13,983.0 — Less: allowance for credit losses (252.5) (226.0) (26.5) — Total loans 38,822.9 24,866.4 13,956.5 — Other assets acquired through foreclosure, net 11.7 11.7 — — Goodwill and other intangible assets, net 634.8 294.7 340.1 — Other assets 2,820.8 253.8 1,278.1 1,288.9 Total assets $ 55,982.6 $ 25,439.5 $ 21,292.2 $ 9,250.9 Liabilities: Deposits $ 47,612.0 $ 30,466.8 $ 15,362.9 $ 1,782.3 Borrowings and qualifying debt 2,381.1 — 353.2 2,027.9 Other liabilities 1,026.9 233.4 138.2 655.3 Total liabilities 51,020.0 30,700.2 15,854.3 4,465.5 Allocated equity: 4,962.6 2,588.0 1,596.2 778.4 Total liabilities and stockholders' equity $ 55,982.6 $ 33,288.2 $ 17,450.5 $ 5,243.9 Excess funds provided (used) — 7,848.7 (3,841.7) (4,007.0) Consolidated Company Commercial Consumer Related Corporate At December 31, 2020: (in millions) Assets: Cash, cash equivalents, and investment securities $ 8,176.5 $ 12.0 $ 45.6 $ 8,118.9 Loans, net of deferred fees and costs 27,053.0 20,245.8 6,798.2 9.0 Less: allowance for loan losses (278.9) (263.4) (15.4) (0.1) Total loans 26,774.1 19,982.4 6,782.8 8.9 Other assets acquired through foreclosure, net 1.4 1.4 — — Goodwill and other intangible assets, net 298.5 296.1 2.4 — Other assets 1,210.5 257.0 96.6 856.9 Total assets $ 36,461.0 $ 20,548.9 $ 6,927.4 $ 8,984.7 Liabilities: Deposits $ 31,930.5 $ 21,448.0 $ 9,936.8 $ 545.7 Borrowings and qualifying debt 553.7 — — 553.7 Other liabilities 563.3 170.4 3.3 389.6 Total liabilities 33,047.5 21,618.4 9,940.1 1,489.0 Allocated equity: 3,413.5 1,992.2 579.1 842.2 Total liabilities and stockholders' equity $ 36,461.0 $ 23,610.6 $ 10,519.2 $ 2,331.2 Excess funds provided (used) — 3,061.7 3,591.8 (6,653.5) The following is a summary of operating segment income statement information for the periods indicated: Consolidated Company Commercial Consumer Related (1) Corporate & Other Year Ended December 31, 2021: (in millions) Net interest income $ 1,548.8 $ 1,181.7 $ 603.4 $ (236.3) (Recovery of) provision for credit losses (21.4) (30.6) 11.0 (1.8) Net interest income (expense) after provision for credit losses 1,570.2 1,212.3 592.4 (234.5) Non-interest income 404.2 65.1 317.6 21.5 Non-interest expense 851.4 415.9 413.9 21.6 Income (loss) before income taxes 1,123.0 861.5 496.1 (234.6) Income tax expense (benefit) 223.8 206.6 120.1 (102.9) Net income (loss) $ 899.2 $ 654.9 $ 376.0 $ (131.7) (1) Includes the financial results of AmeriHome following the acquisition on April 7, 2021, which contributed approximately 40% and 25% to net revenue and net income for the Consumer Related segment, respectively. Consolidated Company Commercial Consumer Related Corporate Year Ended December 31, 2020: (in millions) Net interest income $ 1,166.9 $ 999.7 $ 302.5 $ (135.3) Provision for (recovery of) credit losses 123.6 128.6 (9.0) 4.0 Net interest income (expense) after provision for credit losses 1,043.3 871.1 311.5 (139.3) Non-interest income 70.8 50.5 1.6 18.7 Non-interest expense 491.6 308.9 92.6 90.1 Income (loss) before income taxes 622.5 612.7 220.5 (210.7) Income tax expense (benefit) 115.9 147.6 52.3 (84.0) Net income (loss) $ 506.6 $ 465.1 $ 168.2 $ (126.7) Consolidated Company Commercial Consumer Related Corporate & Other Year Ended December 31, 2019: (in millions) Net interest income $ 1,040.4 $ 837.2 $ 209.0 $ (5.8) Provision for credit losses 19.3 11.1 7.4 0.8 Net interest income (expense) after provision for credit losses 1,021.1 826.1 201.6 (6.6) Non-interest income 65.1 50.4 1.4 13.3 Non-interest expense 482.0 320.6 96.7 64.7 Income (loss) before income taxes 604.2 555.9 106.3 (58.0) Income tax expense (benefit) 105.0 134.7 24.8 (54.5) Net income $ 499.2 $ 421.2 $ 81.5 $ (3.5)

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)Subsidiary	Dec. 31, 2020USD ($)	Jan. 01, 2020USD ($)	Dec. 31, 2019USD ($)
Significant Of Accounting Policies [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 462.5	$ 465.8
Number Of Unconsolidated Subsidiaries | Subsidiary	8
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 5.2	6.8	$ 2.7
Loans and Leases Receivable, Allowance	252.5	278.9
Deferred tax assets, net	20.9	31.3
Off-Balance Sheet, Credit Loss, Liability	37.6	37		$ 9
Retained Earnings (Accumulated Deficit)	$ (2,773)	$ (2,001.4)
Cumulative Effect, Period of Adoption, Adjustment [Member]
Significant Of Accounting Policies [Line Items]
Off-Balance Sheet, Credit Loss, Liability			$ 15.1

Business Combinations and Asset

Business Combinations and Asset Acquisitions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Apr. 07, 2021
Business Combination and Asset Acquisition [Abstract]
Payments to Acquire Businesses, Gross	$ 1,231,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents			$ 207,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Held for Sale			3,552,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Servicing Assets			1,347,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			11,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Right of use Asset			18,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			141,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Eligible for Repurchase			2,744,700,000
Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Assets			6,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			236,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets			8,265,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt			3,633,900,000
Business Combination, Recognized Identifiable Asset Acquired and Liability Assumed, Lease Obligation			18,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liability for Loans Eligible for Repurchase			2,744,700,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other			151,100,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities			6,548,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net			1,717,000,000
Business Combination, Elimination of Pre-existing debt and other	686,800,000
Business Combination, Consideration Transferred	1,918,400,000
Goodwill and intangible assets, net	491,300,000	$ 289,900,000	201,400,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount			185,000,000
Business Acquisition, Pro Forma Interest Income	1,679,900,000	1,322,600,000
Business Acquisition, Pro Forma Non-interest Income	470,500,000	902,700,000
Business Acquisition, Pro Forma Net Income (Loss)	909,700,000	$ 931,200,000
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			141,000,000
Business Combination, Acquisition Related Costs	3,400,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Servicing Right Asset	$ 29.3
Customer Relationships
Business Combination and Asset Acquisition [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			76,000,000
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			76,000,000
Finite-Lived Intangible Asset, Useful Life	20 years
Finite-Lived Intangible Asset, Useful Life	20 years
License
Business Combination and Asset Acquisition [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			55,500,000
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			55,500,000
Finite-Lived Intangible Asset, Useful Life	40 years
Finite-Lived Intangible Asset, Useful Life	40 years
Trade Names
Business Combination and Asset Acquisition [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			9,500,000
Acquired Finite-Lived Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			$ 9,500,000
Finite-Lived Intangible Asset, Useful Life	20 years
Finite-Lived Intangible Asset, Useful Life	20 years

Investment Securities - Carryin

Investment Securities - Carrying Amounts and Fair Values of Investment Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	$ 158,500	$ 167,300
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,107,100	568,800
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	43,200	43,000
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(3,900)	0
Debt Securities, Held-to-maturity, Fair Value	1,146,400	611,800
Debt Securities, Available-for-sale, Amortized Cost	6,166,500	4,586,400
Equity Securities, FV-NI, Cost	152,200	160,100
Equity securities, FV-NI, Accumulated Gross Unrealized Gain, Before Tax	7,700	7,600
Equity securities, FV-NI, Accumulated Gross Unrealized Loss, Before Tax	1,400	400
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	103,600	137,600
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(81,300)	(15,500)
Debt Securities, Available-for-sale	6,188,800	4,708,500
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	13,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0
Debt Securities, Available-for-sale	13,000
Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	382,700	271,100
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	9,200	4,800
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(9,000)	(5,700)
Debt Securities, Available-for-sale	382,900	270,200
Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	113,900	113,900
Equity Securities, FV-NI, Cost	107,100	107,000
Equity securities, FV-NI, Accumulated Gross Unrealized Gain, Before Tax	7,700	7,300
Equity securities, FV-NI, Accumulated Gross Unrealized Loss, Before Tax	900	400
Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	2,027,500	1,462,500
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	7,300	27,900
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(41,400)	(3,800)
Debt Securities, Available-for-sale	1,993,400	1,486,600
Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	890,200	568,800
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	43,200
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(2,300)
Debt Securities, Held-to-maturity, Fair Value	931,100
Debt Securities, Available-for-sale, Amortized Cost	1,145,100	1,109,300
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	71,200	78,100
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,200)	0
Debt Securities, Available-for-sale	1,215,100	1,187,400
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	68,200	80,800
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	900	3,800
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(600)	0
Debt Securities, Available-for-sale	68,500	84,600
Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	216,900
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(1,600)
Debt Securities, Held-to-maturity, Fair Value	215,300
Debt Securities, Available-for-sale, Amortized Cost	1,528,700	1,461,700
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,500	15,700
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(24,200)	(500)
Debt Securities, Available-for-sale	1,508,000	1,476,900
CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	44,600	53,400
Equity Securities, FV-NI, Cost	45,100	53,100
Equity securities, FV-NI, Accumulated Gross Unrealized Gain, Before Tax	0	300
Equity securities, FV-NI, Accumulated Gross Unrealized Loss, Before Tax	500	0
Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	926,000	146,900
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	500	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(300)	0
Debt Securities, Available-for-sale	926,200	146,900
Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	75,300	54,100
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	11,000	7,300
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(4,600)	(5,500)
Debt Securities, Available-for-sale	81,700	55,900
AAA [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	1,507,800	1,429,800
AAA [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0
AAA [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
AAA [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
AAA [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
AAA [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Debt Securities, Available-for-sale	43,200	44,300
AAA [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
AAA [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	1,419,600	1,385,500
AAA [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
AAA [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	45,000	0
AAA [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Split-rated AAA/AA Plus [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	27,300	27,800
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	2,115,300	1,628,500
Split-rated AAA/AA Plus [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	13,000
Split-rated AAA/AA Plus [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Split-rated AAA/AA Plus [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
Split-rated AAA/AA Plus [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	1,993,400	1,486,600
Split-rated AAA/AA Plus [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Debt Securities, Available-for-sale	40,400	57,300
Split-rated AAA/AA Plus [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	68,500	84,600
Split-rated AAA/AA Plus [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	0	0
Split-rated AAA/AA Plus [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	27,300	27,800
Split-rated AAA/AA Plus [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Split-rated AAA/AA Plus [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
AA Plus to AA- [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	1,204,200	715,900
AA Plus to AA- [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0
AA Plus to AA- [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	19,200
AA Plus to AA- [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
AA Plus to AA- [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
AA Plus to AA- [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Debt Securities, Available-for-sale	469,100	454,700
AA Plus to AA- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
AA Plus to AA- [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	87,400	90,100
AA Plus to AA- [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
AA Plus to AA- [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	635,600	139,600
AA Plus to AA- [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	12,100	12,300
A Plus to A- [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	929,800	634,800
A Plus to A- [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0
A Plus to A- [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	45,300	28,100
A Plus to A- [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
A Plus to A- [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
A Plus to A- [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Debt Securities, Available-for-sale	628,900	599,300
A Plus to A- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
A Plus to A- [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	0	100
A Plus to A- [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
A Plus to A- [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	245,600	7,300
A Plus to A- [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	10,000	0
BBB Plus to BBB- [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	79,300	73,200
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	349,800	223,900
BBB Plus to BBB- [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0
BBB Plus to BBB- [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	318,700	194,500
BBB Plus to BBB- [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	79,300	73,200
BBB Plus to BBB- [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
BBB Plus to BBB- [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Debt Securities, Available-for-sale	0	0
BBB Plus to BBB- [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
BBB Plus to BBB- [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	900	300
BBB Plus to BBB- [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
BBB Plus to BBB- [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
BBB Plus to BBB- [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	30,200	29,100
BB Plus and below [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	20,200	39,000
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	28,500	36,200
BB Plus and below [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0
BB Plus and below [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	18,900	28,400
BB Plus and below [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	20,200	39,000
BB Plus and below [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
BB Plus and below [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Debt Securities, Available-for-sale	0	0
BB Plus and below [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
BB Plus and below [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0
Debt Securities, Available-for-sale	0	900
BB Plus and below [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	0	0
BB Plus and below [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
BB Plus and below [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	9,600	6,900
Corporate Credit Quality Indicator Unrated [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	31,700	27,300
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,107,100
Debt Securities, Available-for-sale	53,400	39,400
Corporate Credit Quality Indicator Unrated [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0
Corporate Credit Quality Indicator Unrated [Member] | Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Corporate Credit Quality Indicator Unrated [Member] | Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	14,400	1,700
Corporate Credit Quality Indicator Unrated [Member] | Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Corporate Credit Quality Indicator Unrated [Member] | Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	890,200	568,800
Debt Securities, Available-for-sale	33,500	31,800
Corporate Credit Quality Indicator Unrated [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Corporate Credit Quality Indicator Unrated [Member] | Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	216,900
Debt Securities, Available-for-sale	100	0
Corporate Credit Quality Indicator Unrated [Member] | CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	17,300	25,600
Corporate Credit Quality Indicator Unrated [Member] | Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	0	0
Corporate Credit Quality Indicator Unrated [Member] | Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	$ 19,800	$ 7,600

Investment Securities - Additio

Investment Securities - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)positions	Dec. 31, 2020USD ($)positions
Investment Identifier [Line Items]
Securities with carrying amounts were pledged	$ 2,200	$ 778
Debt Securities, Held-to-maturity, Credit Loss Expense (Reversal)	$ (1.6)	$ 4.1
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions | positions	179	49
Accrued Investment Income Receivable	$ 3	$ 2

Investment Securities - Unreali

Investment Securities - Unrealized Losses and Fair Value of Investment Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 67.9	$ 4.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	3,046.3	398.9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	13.4	11.1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	169.5	120.8
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	81.3	15.5
Debt Securities, Available-for-sale, Unrealized Loss Position	3,215.8	519.7
Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1.2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	141.4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1.2
Debt Securities, Available-for-sale, Unrealized Loss Position	141.4
Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9	0.1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	107	17.3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	5.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	94.3
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	9	5.7
Debt Securities, Available-for-sale, Unrealized Loss Position	107	111.6
Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	32.6	3.8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,355.7	231.9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	8.8	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	142.1	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	41.4	3.8
Debt Securities, Available-for-sale, Unrealized Loss Position	1,497.8	231.9
Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	24.2	0.5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,250	149.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	24.2	0.5
Debt Securities, Available-for-sale, Unrealized Loss Position	1,250	149.7
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	19.5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	0.6
Debt Securities, Available-for-sale, Unrealized Loss Position	19.5
Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0.3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	170.7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	0.3
Debt Securities, Available-for-sale, Unrealized Loss Position	170.7
Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	2	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4.6	5.5
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	27.4	26.5
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	4.6	5.5
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 29.4	$ 26.5

Investment Securities - Amortiz

Investment Securities - Amortized Cost and Fair Value of Investment Securities by Contractual Maturities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost	$ 40,700
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value	40,700
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost	18,100
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value	18,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Amortized Cost	831,400
Debt Securities, Held-to-Maturity, Amortized Cost, after Allowance for Credit Loss, Maturity, without Single Maturity Date	216,900
Debt Securities, Held-to-maturity, Maturity, without Single Maturity Date, Fair Value	215,300
Securities available for sale, Due in one year or less, Amortized Cost	14,000
Securities available for sale, Due in one year or less, Estimated Fair Value	14,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value	872,400
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,107,100	$ 568,800
Debt Securities, Held-to-maturity, Fair Value	1,146,400	611,800
Securities available for sale, After one year through five years, Amortized Cost	119,200
Securities available for sale, After five years through ten years, Amortized Cost	760,400
Securities available for sale, After ten years, Amortized Cost	1,648,500
Securities available for sale, Mortgage backed securities, Amortized Cost	3,624,400
Debt Securities, Available-for-sale, Amortized Cost	6,166,500	4,586,400
Securities available for sale, After one year through five years, Estimated Fair Value	115,800
Securities available for sale, After five years through ten years, Estimated Fair Value	765,200
Securities available for sale, After ten years, Estimated Fair Value	1,723,900
Securities available for sale, Mortgage backed securities, Estimated Fair Value	3,569,900
Debt Securities, Available-for-sale	$ 6,188,800	$ 4,708,500

Investment Securities - Investm

Investment Securities - Investment Securities by Credit Rating Type (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	$ 1,107.1	$ 568.8
Investment securities - equity	158.5	167.3
Debt Securities, Available-for-sale	6,188.8	4,708.5
Residential mortgage-backed securities issued by GSEs
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	1,993.4	1,486.6
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	68.5	84.6
Private label residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	216.9
Debt Securities, Available-for-sale	1,508	1,476.9
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	13
Preferred Stock [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	113.9	113.9
Corporate debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	382.9	270.2
CRA investments [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - equity	44.6	53.4
Collateralized Loan Obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	926.2	146.9
Nontaxable Municipal Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	890.2	568.8
Debt Securities, Available-for-sale	1,215.1	1,187.4
Other Security Investments
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	$ 81.7	$ 55.9

Investment Securities - Gross G

Investment Securities - Gross Gains and (Losses) on Sales of Investments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Gain (Loss) on Securities [Line Items]
Equity Securities, FV-NI, Realized Loss	$ 0.2	$ 0	$ 0
Debt Securities, Available-for-sale, Realized Gain (Loss)	8.4	0.2	3.1
Gross gains	8.4	0.4	3.1
Gross (losses)	0	(0.2)	0
Equity Securities, FV-NI, Realized Gain	0.1	0	0
Equity Securities, FV-NI, Realized Gain (Loss)	$ (0.1)	$ 0	$ 0

Investments Securities Investme

Investments Securities Investment Securities - Allowance for Credit Losses - HTM (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 5.2	$ 6.8	$ 2.7
Debt Securities, Held-to-maturity, Credit Loss Expense (Reversal)	(1.6)	4.1
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Writeoff	0	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Recovery	0	0
Accrued Investment Income Receivable	$ 3	$ 2

Loans Held For Sale (Details)

Loans Held For Sale (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	$ 5,635.1	$ 0
Pledged Assets Separately Reported, Loans Pledged as Collateral, at Fair Value	0
MSR capitalized upon sale of loan	763.8
Proceeds from Sale of Mortgage Loans Held-for-sale	(465.3)
Provision for and change in estimate of liability for losses under representations and warranties	(0.6)
Change in fair value of loans held for sale	(0.3)
Unrealized Gain (Loss) on Derivatives	(69.9)
Derivative Instruments Not Designated as Hedging Instruments, Gain	20.1
Gain (Loss) on Sales of Loans, Net	247.8
Loan acquisition and origination fees	78.4
Net gain on loan origination and sale activities	326.2	$ 0	$ 0
Non-agency
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	62.8
Purchased from Ginnie Mae
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	1,692.8
Purchased from correspondent seller
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	1,396.6
Loans Insured or Guaranteed by US Government Authorities
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	3,089.4
US Government Agency Insured Loans
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	$ 2,482.9

Loans, Leases and Allowance f_2

Loans, Leases and Allowance for Credit Losses - Schedule of Held for Investment Loan Portfolio Composition of Loans, Leases and Allowance for Credit Losses (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 39,075.4	$ 27,053
Loans and Leases Receivable, Allowance	(252.5)	(278.9)
Loans, net	38,822.9	26,774.1
Net deferred loan fees and costs	(85.7)	(75.4)
Receivable with Imputed Interest, Premium	184.8	26
Financing Receivable, Held-for-Sale	5,635.1	0
Tech & Innovation [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,417.8	1,403
Other commercial and industrial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,465.7	5,911.2
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,723.7	1,909.3
Hotel franchise finance [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,534	1,983.9
Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,951.8	3,640.2
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	9,242.8	2,378.5
Construction And Land Development Land [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Warehouse lending [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Municipal and nonprofit [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,728.8
Other, loan segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	168.9	183.2
Equity fund resources
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 3,829.8	$ 1,145.3

Loans, Leases and Allowance f_3

Loans, Leases and Allowance for Credit Losses - Summary of Recorded Investment in Nonaccrual Loans and Loans Past Due 90 Days Still Accruing Interest by Loan Class (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	$ 38.9	$ 104.9
Nonaccrual with an Allowance for Credit Loss	33.7	10.3
Total Nonaccrual	72.6	115.2
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Impaired, Interest Lost on Nonaccrual Loans	5.3	5	$ 2.2
Financing Receivable, Held-for-Sale	5,635.1	0
Loans and Leases Receivable, Net of Deferred Income	39,075.4	27,053
Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	2.1	9.6
Nonaccrual with an Allowance for Credit Loss	11.2	3.9
Total Nonaccrual	13.3	13.5
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Net of Deferred Income	1,417.8	1,403
Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	12.7	10.9
Nonaccrual with an Allowance for Credit Loss	3.4	6.3
Total Nonaccrual	16.1	17.2
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Net of Deferred Income	6,465.7	5,911.2
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	11.6	34.5
Nonaccrual with an Allowance for Credit Loss	1.4	0
Total Nonaccrual	13	34.5
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Net of Deferred Income	1,723.7	1,909.3
Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,534	1,983.9
Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	11.3	36.5
Nonaccrual with an Allowance for Credit Loss	1.8	0
Total Nonaccrual	13.1	36.5
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Net of Deferred Income	3,951.8	3,640.2
Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0	11.4
Nonaccrual with an Allowance for Credit Loss	15.1	0
Total Nonaccrual	15.1	11.4
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Net of Deferred Income	9,242.8	2,378.5
Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	1
Nonaccrual with an Allowance for Credit Loss	0
Total Nonaccrual	1
Loans Past Due 90 Days or More and Still Accruing	0
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss		1.9
Nonaccrual with an Allowance for Credit Loss		0
Total Nonaccrual		1.9
Loans Past Due 90 Days or More and Still Accruing		0
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,728.8
Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0.2	0.1
Nonaccrual with an Allowance for Credit Loss	0.2	0.1
Total Nonaccrual	0.4	0.2
Loans Past Due 90 Days or More and Still Accruing	0	0
Loans and Leases Receivable, Net of Deferred Income	168.9	183.2
Construction And Land Development Land [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Nonaccrual with No Allowance for Credit Loss	0
Nonaccrual with an Allowance for Credit Loss	0.6
Total Nonaccrual	0.6
Loans Past Due 90 Days or More and Still Accruing	0
Loans and Leases Receivable, Net of Deferred Income	3,829.8	1,145.3
Financial Asset, Not Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	39,022.9	27,041.8
Financial Asset, Not Past Due | Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	1,417.8	1,403
Financial Asset, Not Past Due | Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	6,465.7	5,911
Financial Asset, Not Past Due | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	1,723.7	1,909.3
Financial Asset, Not Past Due | Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	2,534	1,983.9
Financial Asset, Not Past Due | Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	3,951.8	3,640.2
Financial Asset, Not Past Due | Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	9,190.4	2,368
Financial Asset, Not Past Due | Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	3,005.8	2,429.4
Financial Asset, Not Past Due | Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	5,155.9	4,340.2
Financial Asset, Not Past Due | Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	1,579.2	1,728.8
Financial Asset, Not Past Due | Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	168.8	182.7
Financial Asset, Not Past Due | Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	3,829.8	1,145.3
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	50.8	9.7
Financial Asset, 30 to 59 Days Past Due [Member] | Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0.2
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	50.7	9.1
Financial Asset, 30 to 59 Days Past Due [Member] | Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0.1	0.4
Financial Asset, 30 to 59 Days Past Due [Member] | Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	1.7	1.5
Financial Asset, 60 to 89 Days Past Due [Member] | Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	1.7	1.4
Financial Asset, 60 to 89 Days Past Due [Member] | Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0.1
Financial Asset, 60 to 89 Days Past Due [Member] | Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Loans Past Due 90 Days or More and Still Accruing	0	0
Financial Asset, Past Due
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	52.5	11.2
Financial Asset, Past Due | Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0.2
Financial Asset, Past Due | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	52.4	10.5
Financial Asset, Past Due | Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0	0
Financial Asset, Past Due | Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	0.1	0.5
Financial Asset, Past Due | Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Gross	$ 0	$ 0

Contractual Aging of Loan Portf

Contractual Aging of Loan Portfolio by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 39,075.4	$ 27,053
Financing Receivable, Year One, Originated, Current Fiscal Year	15,115.4	6,006
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,624.2	4,935.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3,176	2,939.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,495.4	1,669
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	976.3	691.4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,835.6	1,892.4
Financing Receivable, Revolving	12,852.5	8,919.5
Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	38,455.3	26,379.7
Financing Receivable, Year One, Originated, Current Fiscal Year	15,023.8	5,938.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,547.2	4,784.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,934.5	2,780.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,388.8	1,542.2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	950.5	659.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,803.4	1,818.5
Financing Receivable, Revolving	12,807.1	8,856.1
Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	331.1	451.1
Financing Receivable, Year One, Originated, Current Fiscal Year	46.2	23.7
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	53.9	102.2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	119.7	143.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	78.8	80.8
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	5.7	7.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3.3	36.8
Financing Receivable, Revolving	23.5	57.1
Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	289	222.2
Financing Receivable, Year One, Originated, Current Fiscal Year	45.4	43.8
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	23.1	48.8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	121.8	15.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	27.8	46
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	20.1	24.6
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	28.9	37.1
Financing Receivable, Revolving	21.9	6.3
Tech & Innovation [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,417.8	1,403
Financing Receivable, Year One, Originated, Current Fiscal Year	791.6	631.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	167	212.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	108.6	76.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6.1	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.6	0
Financing Receivable, Revolving	343.9	481.8
Tech & Innovation [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,361.9	1,360.4
Financing Receivable, Year One, Originated, Current Fiscal Year	762.6	595.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	157.1	205.9
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	101.1	76.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6.1	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.6	0
Financing Receivable, Revolving	334.4	481.7
Tech & Innovation [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	38.8	15.3
Financing Receivable, Year One, Originated, Current Fiscal Year	26	10.7
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.7	4.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	8.1	0
Tech & Innovation [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	17.1	27.3
Financing Receivable, Year One, Originated, Current Fiscal Year	3	25.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	5.2	2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	7.5	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	1.4	0.1
Other commercial and industrial [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,465.7	5,911.2
Financing Receivable, Year One, Originated, Current Fiscal Year	2,916.2	2,072.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	396.8	880.3
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	414.7	483
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	230.1	274.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	81.7	111.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	98	115.6
Financing Receivable, Revolving	2,328.2	1,974.2
Other commercial and industrial [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,352.2	5,737.7
Financing Receivable, Year One, Originated, Current Fiscal Year	2,910.8	2,069.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	360	819.8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	387.1	447.7
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	210.3	250.7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	80.2	99.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	97.8	114.6
Financing Receivable, Revolving	2,306	1,935.7
Other commercial and industrial [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	86.8	144.7
Financing Receivable, Year One, Originated, Current Fiscal Year	5.4	2.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	26.7	52.1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	22	32.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	17.6	22.1
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0.1	1.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0.2
Financing Receivable, Revolving	15	34.3
Other commercial and industrial [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	26.7	28.8
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0.9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	10.1	8.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	5.6	3.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2.2	1.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1.4	9.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.2	0.8
Financing Receivable, Revolving	7.2	4.2
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,723.7	1,909.3
Financing Receivable, Year One, Originated, Current Fiscal Year	419.4	254.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	201.1	327
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	221.4	316.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	205.1	435.2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	286	159
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	334.6	353.5
Financing Receivable, Revolving	56.1	63.9
Commercial Real Estate Owner Occupied [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,682.2	1,775.2
Financing Receivable, Year One, Originated, Current Fiscal Year	417.2	252.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	198.5	307.1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	220.1	302.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	190.4	402.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	278	148.4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	322.4	323.5
Financing Receivable, Revolving	55.6	39.5
Commercial Real Estate Owner Occupied [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	12.3	84.2
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0.9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	12.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0.3	9.3
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	10.1	24.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	4.4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1.5	10.5
Financing Receivable, Revolving	0.4	22.4
Commercial Real Estate Owner Occupied [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	29.2	49.9
Financing Receivable, Year One, Originated, Current Fiscal Year	2.2	1.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2.6	7.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1	4.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.6	8.5
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	8	6.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	10.7	19.5
Financing Receivable, Revolving	0.1	2
Hotel franchise finance [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,534	1,983.9
Financing Receivable, Year One, Originated, Current Fiscal Year	751.6	170.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	205.3	824.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	845.6	521
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	399.2	179.8
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	145.8	2.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	63.5	123.2
Financing Receivable, Revolving	123	162.6
Hotel franchise finance [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,239.6	1,821.7
Financing Receivable, Year One, Originated, Current Fiscal Year	721.3	161.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	205.3	792
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	658.8	464.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	332.2	139.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	135.5	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	63.5	101.5
Financing Receivable, Revolving	123	162.6
Hotel franchise finance [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	138.7	135.1
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	32.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	87.6	56.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	51.1	27.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	18.2
Financing Receivable, Revolving	0	0
Hotel franchise finance [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	155.7	27.1
Financing Receivable, Year One, Originated, Current Fiscal Year	30.3	8.9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	99.2	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	15.9	12.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	10.3	2.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	3.5
Financing Receivable, Revolving	0	0
Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,951.8	3,640.2
Financing Receivable, Year One, Originated, Current Fiscal Year	1,413	1,041.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	754.8	938.9
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	687	567.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	283.3	410
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	186.1	172.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	301.6	228.9
Financing Receivable, Revolving	326	281
Other Commercial Real Estate Non owner Occupied [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,889.2	3,544.3
Financing Receivable, Year One, Originated, Current Fiscal Year	1,398.2	1,032.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	754.8	912.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	673	560.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	278.8	384.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	185.8	164.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	283.5	208.4
Financing Receivable, Revolving	315.1	281
Other Commercial Real Estate Non owner Occupied [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	26.3	22.2
Financing Receivable, Year One, Originated, Current Fiscal Year	14.8	1.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	9.8	7
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	5.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1.7	7.4
Financing Receivable, Revolving	0	0
Other Commercial Real Estate Non owner Occupied [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	36.3	73.7
Financing Receivable, Year One, Originated, Current Fiscal Year	0	7.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	26.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4.2	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.5	20.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0.3	6.5
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	16.4	13.1
Financing Receivable, Revolving	10.9	0
Residential Real Estate [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	9,242.8	2,378.5
Financing Receivable, Year One, Originated, Current Fiscal Year	7,468.2	759.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,019.3	873.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	399.1	407.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	201.8	110
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	41.7	113.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	76.6	74.1
Financing Receivable, Revolving	36.1	39.5
Residential Real Estate [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	9,227.7	2,367.1
Financing Receivable, Year One, Originated, Current Fiscal Year	7,459.3	759.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,018.4	869.3
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	395.5	402
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	201.3	108.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	41.6	113.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	75.5	74.1
Financing Receivable, Revolving	36.1	39.5
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Residential Real Estate [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	15.1	11.4
Financing Receivable, Year One, Originated, Current Fiscal Year	8.9	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.9	4.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3.6	5.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0.5	1.1
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0.1	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1.1	0
Financing Receivable, Revolving	0	0
Construction and land development [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Warehouse lending [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Financing Receivable, Year One, Originated, Current Fiscal Year	242.6	135.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	12.5	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	4,900.8	4,202.4
Warehouse lending [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Financing Receivable, Year One, Originated, Current Fiscal Year	242.6	135.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	12.5	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	4,900.8	4,202.4
Warehouse lending [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Warehouse lending [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Municipal and nonprofit [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,728.8
Financing Receivable, Year One, Originated, Current Fiscal Year	129.5	219.3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	195	156.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	101.2	81.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	52.9	233.1
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	219.3	129.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	877.8	905.6
Financing Receivable, Revolving	3.5	3.5
Municipal and nonprofit [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,726.9
Financing Receivable, Year One, Originated, Current Fiscal Year	129.5	219.3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	195	156.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	101.2	81.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	52.9	231.2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	219.3	129.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	877.8	905.6
Financing Receivable, Revolving	3.5	3.5
Municipal and nonprofit [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Municipal and nonprofit [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	1.9
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Other, loan segment [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	168.9	183.2
Financing Receivable, Year One, Originated, Current Fiscal Year	15.7	21.1
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	11.6	15.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3.8	14.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.4	7.5
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4.4	1.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	82.6	76.5
Financing Receivable, Revolving	46.4	45.7
Other, loan segment [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	168.1	180.3
Financing Receivable, Year One, Originated, Current Fiscal Year	15.7	21.1
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	11.6	15.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3.7	14.5
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.3	5.8
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4.4	1.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	82	75.8
Financing Receivable, Revolving	46.4	45.7
Other, loan segment [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0.1	2.3
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.1	0.5
Financing Receivable, Revolving	0	0
Other, loan segment [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0.7	0.6
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0.1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0.1	0.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0.1	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.5	0.2
Financing Receivable, Revolving	0	0
Construction And Land Development Land [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Financing Receivable, Year One, Originated, Current Fiscal Year	958.6	686.3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	659.1	704.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	394.6	469.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	112.2	15.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	9.1	1.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.1	15
Financing Receivable, Revolving	872.1	537.8
Construction And Land Development Land [Member] | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,969.5	2,380.6
Financing Receivable, Year One, Originated, Current Fiscal Year	957.6	677.8
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	632.3	704.2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	394	429.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	112.2	15.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3.5	1.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.1	15
Financing Receivable, Revolving	869.8	537.4
Construction And Land Development Land [Member] | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	28.1	47.3
Financing Receivable, Year One, Originated, Current Fiscal Year	0	8.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	22.5	0.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	38
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	5.6	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0.4
Construction And Land Development Land [Member] | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	8.2	1.5
Financing Receivable, Year One, Originated, Current Fiscal Year	1	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.3	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0.6	1.5
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	2.3	0
Equity fund resources
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,829.8	1,145.3
Financing Receivable, Year One, Originated, Current Fiscal Year	9	14.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.7	1.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.5
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0.3	2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2.2	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.2	0
Financing Receivable, Revolving	3,816.4	1,127.1
Equity fund resources | Pass [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,829.8	1,145.3
Financing Receivable, Year One, Originated, Current Fiscal Year	9	14.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1.7	1.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.5
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0.3	2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2.2	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.2	0
Financing Receivable, Revolving	3,816.4	1,127.1
Equity fund resources | Special Mention [Member]
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Equity fund resources | Classified
Financing Receivable, Nonaccrual [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	$ 0	$ 0

Loans, Leases and Allowance f_4

Loans, Leases and Allowance for Credit Losses - Loans by Risk Rating (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 15,115.4	$ 6,006
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,624.2	4,935.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3,176	2,939.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,495.4	1,669
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	976.3	691.4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,835.6	1,892.4
Financing Receivable, Revolving	12,852.5	8,919.5
Loans and Leases Receivable, Net of Deferred Income	39,075.4	27,053
Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	15,023.8	5,938.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,547.2	4,784.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,934.5	2,780.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,388.8	1,542.2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	950.5	659.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,803.4	1,818.5
Financing Receivable, Revolving	12,807.1	8,856.1
Loans and Leases Receivable, Net of Deferred Income	38,455.3	26,379.7
Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	46.2	23.7
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	53.9	102.2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	119.7	143.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	78.8	80.8
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	5.7	7.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3.3	36.8
Financing Receivable, Revolving	23.5	57.1
Loans and Leases Receivable, Net of Deferred Income	331.1	451.1
Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	45.4	43.8
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	23.1	48.8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	121.8	15.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	27.8	46
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	20.1	24.6
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	28.9	37.1
Financing Receivable, Revolving	21.9	6.3
Loans and Leases Receivable, Net of Deferred Income	289	222.2
Tech & Innovation [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	791.6	631.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	167	212.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	108.6	76.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6.1	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.6	0
Financing Receivable, Revolving	343.9	481.8
Loans and Leases Receivable, Net of Deferred Income	1,417.8	1,403
Tech & Innovation [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	762.6	595.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	157.1	205.9
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	101.1	76.4
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6.1	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.6	0
Financing Receivable, Revolving	334.4	481.7
Loans and Leases Receivable, Net of Deferred Income	1,361.9	1,360.4
Tech & Innovation [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	26	10.7
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.7	4.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	8.1	0
Loans and Leases Receivable, Net of Deferred Income	38.8	15.3
Tech & Innovation [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	3	25.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	5.2	2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	7.5	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	1.4	0.1
Loans and Leases Receivable, Net of Deferred Income	17.1	27.3
Other commercial and industrial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	2,916.2	2,072.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	396.8	880.3
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	414.7	483
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	230.1	274.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	81.7	111.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	98	115.6
Financing Receivable, Revolving	2,328.2	1,974.2
Loans and Leases Receivable, Net of Deferred Income	6,465.7	5,911.2
Other commercial and industrial [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	2,910.8	2,069.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	360	819.8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	387.1	447.7
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	210.3	250.7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	80.2	99.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	97.8	114.6
Financing Receivable, Revolving	2,306	1,935.7
Loans and Leases Receivable, Net of Deferred Income	6,352.2	5,737.7
Other commercial and industrial [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	5.4	2.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	26.7	52.1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	22	32.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	17.6	22.1
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0.1	1.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0.2
Financing Receivable, Revolving	15	34.3
Loans and Leases Receivable, Net of Deferred Income	86.8	144.7
Other commercial and industrial [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0.9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	10.1	8.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	5.6	3.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2.2	1.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1.4	9.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.2	0.8
Financing Receivable, Revolving	7.2	4.2
Loans and Leases Receivable, Net of Deferred Income	26.7	28.8
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	419.4	254.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	201.1	327
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	221.4	316.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	205.1	435.2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	286	159
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	334.6	353.5
Financing Receivable, Revolving	56.1	63.9
Loans and Leases Receivable, Net of Deferred Income	1,723.7	1,909.3
Commercial Real Estate Owner Occupied [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	417.2	252.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	198.5	307.1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	220.1	302.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	190.4	402.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	278	148.4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	322.4	323.5
Financing Receivable, Revolving	55.6	39.5
Loans and Leases Receivable, Net of Deferred Income	1,682.2	1,775.2
Commercial Real Estate Owner Occupied [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0.9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	12.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0.3	9.3
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	10.1	24.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	4.4
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1.5	10.5
Financing Receivable, Revolving	0.4	22.4
Loans and Leases Receivable, Net of Deferred Income	12.3	84.2
Commercial Real Estate Owner Occupied [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	2.2	1.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2.6	7.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1	4.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.6	8.5
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	8	6.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	10.7	19.5
Financing Receivable, Revolving	0.1	2
Loans and Leases Receivable, Net of Deferred Income	29.2	49.9
Hotel franchise finance [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	751.6	170.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	205.3	824.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	845.6	521
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	399.2	179.8
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	145.8	2.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	63.5	123.2
Financing Receivable, Revolving	123	162.6
Loans and Leases Receivable, Net of Deferred Income	2,534	1,983.9
Hotel franchise finance [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	721.3	161.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	205.3	792
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	658.8	464.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	332.2	139.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	135.5	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	63.5	101.5
Financing Receivable, Revolving	123	162.6
Loans and Leases Receivable, Net of Deferred Income	2,239.6	1,821.7
Hotel franchise finance [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	32.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	87.6	56.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	51.1	27.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	18.2
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	138.7	135.1
Hotel franchise finance [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	30.3	8.9
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	99.2	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	15.9	12.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	10.3	2.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	3.5
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	155.7	27.1
Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,413	1,041.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	754.8	938.9
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	687	567.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	283.3	410
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	186.1	172.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	301.6	228.9
Financing Receivable, Revolving	326	281
Loans and Leases Receivable, Net of Deferred Income	3,951.8	3,640.2
Other Commercial Real Estate Non owner Occupied [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,398.2	1,032.6
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	754.8	912.5
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	673	560.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	278.8	384.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	185.8	164.7
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	283.5	208.4
Financing Receivable, Revolving	315.1	281
Loans and Leases Receivable, Net of Deferred Income	3,889.2	3,544.3
Other Commercial Real Estate Non owner Occupied [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	14.8	1.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	9.8	7
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	5.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1.7	7.4
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	26.3	22.2
Other Commercial Real Estate Non owner Occupied [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	7.4
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	26.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4.2	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.5	20.3
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0.3	6.5
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	16.4	13.1
Financing Receivable, Revolving	10.9	0
Loans and Leases Receivable, Net of Deferred Income	36.3	73.7
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	7,468.2	759.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,019.3	873.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	399.1	407.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	201.8	110
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	41.7	113.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	76.6	74.1
Financing Receivable, Revolving	36.1	39.5
Loans and Leases Receivable, Net of Deferred Income	9,242.8	2,378.5
Residential Real Estate [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	7,459.3	759.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,018.4	869.3
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	395.5	402
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	201.3	108.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	41.6	113.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	75.5	74.1
Financing Receivable, Revolving	36.1	39.5
Loans and Leases Receivable, Net of Deferred Income	9,227.7	2,367.1
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	0	0
Residential Real Estate [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	8.9	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0.9	4.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3.6	5.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0.5	1.1
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0.1	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1.1	0
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	15.1	11.4
Construction And Land Development Land [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	958.6	686.3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	659.1	704.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	394.6	469.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	112.2	15.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	9.1	1.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.1	15
Financing Receivable, Revolving	872.1	537.8
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Construction And Land Development Land [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	957.6	677.8
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	632.3	704.2
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	394	429.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	112.2	15.4
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3.5	1.2
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.1	15
Financing Receivable, Revolving	869.8	537.4
Loans and Leases Receivable, Net of Deferred Income	2,969.5	2,380.6
Construction And Land Development Land [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	8.5
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	22.5	0.4
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	38
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	5.6	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0.4
Loans and Leases Receivable, Net of Deferred Income	28.1	47.3
Construction And Land Development Land [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4.3	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0.6	1.5
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	2.3	0
Loans and Leases Receivable, Net of Deferred Income	8.2	1.5
Warehouse lending [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	242.6	135.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	12.5	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	4,900.8	4,202.4
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Warehouse lending [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	242.6	135.2
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	12.5	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.9
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.6
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	4,900.8	4,202.4
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Warehouse lending [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	0	0
Warehouse lending [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	0	0
Municipal and nonprofit [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	129.5	219.3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	195	156.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	101.2	81.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	52.9	233.1
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	219.3	129.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	877.8	905.6
Financing Receivable, Revolving	3.5	3.5
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,728.8
Municipal and nonprofit [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	129.5	219.3
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	195	156.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	101.2	81.6
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	52.9	231.2
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	219.3	129.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	877.8	905.6
Financing Receivable, Revolving	3.5	3.5
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,726.9
Municipal and nonprofit [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	0	0
Municipal and nonprofit [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.9
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0	0
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	0	1.9
Other, loan segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	15.7	21.1
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	11.6	15.7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3.8	14.8
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.4	7.5
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4.4	1.9
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	82.6	76.5
Financing Receivable, Revolving	46.4	45.7
Loans and Leases Receivable, Net of Deferred Income	168.9	183.2
Other, loan segment [Member] | Pass [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	15.7	21.1
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	11.6	15.6
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3.7	14.5
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4.3	5.8
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4.4	1.8
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	82	75.8
Financing Receivable, Revolving	46.4	45.7
Loans and Leases Receivable, Net of Deferred Income	168.1	180.3
Other, loan segment [Member] | Special Mention [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0	0.1
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0	1.7
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.1	0.5
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	0.1	2.3
Other, loan segment [Member] | Classified
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0	0.1
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0.1	0.2
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0.1	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0	0.1
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0.5	0.2
Financing Receivable, Revolving	0	0
Loans and Leases Receivable, Net of Deferred Income	$ 0.7	$ 0.6

Loans, Leases and Allowance f_5

Loans, Leases and Allowance for Credit Losses - Troubled Debt Restructurings (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)SecurityLoan	Dec. 31, 2020USD ($)SecurityLoan
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	16	22
Troubled debt restructured loans	$ 20.8	$ 61.6
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend	$ 0	$ 0.6
Number of Loans | SecurityLoan	9	17
Post-Modification Outstanding Recorded Investment	$ 12.5	$ 37.3
Reserves allocated to customers whose loan terms modified in troubled debt restructurings	$ 0	$ 2.7
Number of Loans | SecurityLoan	1	3
Recorded Investment	$ 2.1	$ 5.8
Financing Receivable, CARES Act Modification	152.8
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down	$ 2
Tech & Innovation [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	2	4
Troubled debt restructured loans	$ 2.1	$ 20.4
Other commercial and industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	7	9
Troubled debt restructured loans	$ 6.2	$ 22.9
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	1	4
Troubled debt restructured loans	$ 0.5	$ 2.6
Hotel franchise finance [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	0	2
Troubled debt restructured loans	$ 0	$ 5.5
Other Commercial Real Estate Non owner Occupied [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	5	3
Troubled debt restructured loans	$ 11	$ 10.2
Residential Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans in Forbearance	$ 22.2
Construction and land development [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing Receivable, Troubled Debt Restructured Loans, Number of Outstanding Contracts | SecurityLoan	1	0
Troubled debt restructured loans	$ 1	$ 0

Loans, Leases and Allowance f_6

Loans, Leases and Allowance for Credit Loans, Leases and Allowance for Credit Losses - Collateral Dependent Loans (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	$ 226.8	$ 196.2
Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	214.2	144.9
Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	12.6	51.3
Tech & Innovation [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	27.3
Tech & Innovation [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Tech & Innovation [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	27.3
Other commercial and industrial [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	12.5	23.6
Other commercial and industrial [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Other commercial and industrial [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	12.5	23.6
Commercial Real Estate Owner Occupied [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	23	42.6
Commercial Real Estate Owner Occupied [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	23	42.6
Commercial Real Estate Owner Occupied [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Hotel franchise finance [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	155.7	27.1
Hotel franchise finance [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	155.7	27.1
Hotel franchise finance [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Other Commercial Real Estate Non owner Occupied [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	31.6	73.7
Other Commercial Real Estate Non owner Occupied [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	31.6	73.7
Other Commercial Real Estate Non owner Occupied [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Construction and land development [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	3.9	1.5
Construction and land development [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	3.9	1.5
Construction and land development [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Other, loan segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.1	0.4
Other, loan segment [Member] | Real Estate Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0	0
Other, loan segment [Member] | Other Collateral [Member]
Loans and Leases Receivable Disclosure [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	$ 0.1	$ 0.4

Loans, Leases and Allowance f_7

Loans, Leases and Allowance for Credit Losses - Allowances for Credit Losses (Detail) Valuation - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	$ (20.5)	$ (106.5)
Financing Receivable, Allowance for Credit Loss, Writeoff	11.6	20.4
Financing Receivable, Allowance for Credit Loss, Recovery	(5.7)	(5.9)
Financing Receivable, Collectively Evaluated for Impairment	38,812.3	26,787.4
Financing Receivable, Individually Evaluated for Impairment	(263.1)	(265.6)
Loans and Leases Receivable, Net of Deferred Income	39,075.4	27,053
Loans and Leases Receivable, Allowance	252.5	278.9
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	236.4	267.7
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	16.1	11.2
Financing Receivable, Allowance for Credit Loss	252.5	278.9	$ 186.9
Off-Balance Sheet, Credit Loss, Liability	37.6	37		$ 9
Off-Balance Sheet, Credit Loss, Liability, Change in Method, Credit Loss Expense (Reversal)	0.6	12.9
Interest Receivable	197.6	142.1
Cumulative Effect, Period of Adoption, Adjustment [Member]
Valuation Allowance [Line Items]
Off-Balance Sheet, Credit Loss, Liability			15.1
Tech & Innovation [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(6.2)	(23.5)
Financing Receivable, Allowance for Credit Loss, Writeoff	2	11.1
Financing Receivable, Allowance for Credit Loss, Recovery	(0.5)	0
Financing Receivable, Collectively Evaluated for Impairment	1,400.8	1,375.8
Financing Receivable, Individually Evaluated for Impairment	(17)	(27.2)
Loans and Leases Receivable, Net of Deferred Income	1,417.8	1,403
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	22.9	29.5
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2.8	3.9
Financing Receivable, Allowance for Credit Loss	25.7	33.4	21
Other commercial and industrial [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(14)	(1.8)
Financing Receivable, Allowance for Credit Loss, Writeoff	7.4	6.4
Financing Receivable, Allowance for Credit Loss, Recovery	(2.3)	(3.5)
Financing Receivable, Collectively Evaluated for Impairment	6,442.7	5,883.1
Financing Receivable, Individually Evaluated for Impairment	(23)	(28.1)
Loans and Leases Receivable, Net of Deferred Income	6,465.7	5,911.2
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	101.1	90.3
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2.5	4.4
Financing Receivable, Allowance for Credit Loss	103.6	94.7	95.8
Commercial Real Estate Owner Occupied [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(8)	(8.3)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0.2
Financing Receivable, Allowance for Credit Loss, Recovery	0	(0.1)
Financing Receivable, Collectively Evaluated for Impairment	1,699.3	1,857.9
Financing Receivable, Individually Evaluated for Impairment	(24.4)	(51.4)
Loans and Leases Receivable, Net of Deferred Income	1,723.7	1,909.3
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	10.6	18.6
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	10.6	18.6	10.4
Hotel franchise finance [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(2.1)	(29.2)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0
Financing Receivable, Allowance for Credit Loss, Recovery	(0.3)	0
Financing Receivable, Collectively Evaluated for Impairment	2,378.3	1,927
Financing Receivable, Individually Evaluated for Impairment	(155.7)	(56.9)
Loans and Leases Receivable, Net of Deferred Income	2,534	1,983.9
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	30.7	40.4
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	10.8	2.9
Financing Receivable, Allowance for Credit Loss	41.5	43.3	14.1
Other Commercial Real Estate Non owner Occupied [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(22.5)	(29.8)
Financing Receivable, Allowance for Credit Loss, Writeoff	2	2.1
Financing Receivable, Allowance for Credit Loss, Recovery	(1.5)	(1.7)
Financing Receivable, Collectively Evaluated for Impairment	3,917.3	3,553.6
Financing Receivable, Individually Evaluated for Impairment	(34.5)	(86.6)
Loans and Leases Receivable, Net of Deferred Income	3,951.8	3,640.2
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	16.9	39.9
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	16.9	39.9	10.5
Residential Real Estate [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(11.2)	(3.1)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0.3
Financing Receivable, Allowance for Credit Loss, Recovery	(0.5)	(0.4)
Financing Receivable, Collectively Evaluated for Impairment	9,242.8	2,367.1
Financing Receivable, Individually Evaluated for Impairment	0	(11.4)
Loans and Leases Receivable, Net of Deferred Income	9,242.8	2,378.5
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	12.5	0.8
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	12.5	0.8	3.8
Construction and land development [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(9.5)	(15.7)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0
Financing Receivable, Allowance for Credit Loss, Recovery	0	(0.1)
Financing Receivable, Collectively Evaluated for Impairment	2,997.6	2,427.9
Financing Receivable, Individually Evaluated for Impairment	(8.2)	(1.5)
Loans and Leases Receivable, Net of Deferred Income	3,005.8	2,429.4
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	12.5	22
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	12.5	22	6.2
Warehouse lending [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(0.4)	(3.2)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0
Financing Receivable, Allowance for Credit Loss, Recovery	0	0
Financing Receivable, Collectively Evaluated for Impairment	5,155.9	4,340.2
Financing Receivable, Individually Evaluated for Impairment	0	0
Loans and Leases Receivable, Net of Deferred Income	5,155.9	4,340.2
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	3	3.4
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	3	3.4	0.2
Municipal and nonprofit [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(2.2)	(1.5)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0
Financing Receivable, Allowance for Credit Loss, Recovery	0	0
Financing Receivable, Collectively Evaluated for Impairment	1,579.2	1,726.9
Financing Receivable, Individually Evaluated for Impairment	0	(1.9)
Loans and Leases Receivable, Net of Deferred Income	1,579.2	1,728.8
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	13.7	15.9
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	13.7	15.9	17.4
Other, loan segment [Member]
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(2.5)	(0.9)
Financing Receivable, Allowance for Credit Loss, Writeoff	0.2	0.3
Financing Receivable, Allowance for Credit Loss, Recovery	(0.6)	(0.1)
Financing Receivable, Collectively Evaluated for Impairment	168.6	182.6
Financing Receivable, Individually Evaluated for Impairment	(0.3)	(0.6)
Loans and Leases Receivable, Net of Deferred Income	168.9	183.2
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2.9	5
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	2.9	5	6.1
Equity fund resources
Valuation Allowance [Line Items]
Provision for Loan and Lease Losses	(7.7)	(0.5)
Financing Receivable, Allowance for Credit Loss, Writeoff	0	0
Financing Receivable, Allowance for Credit Loss, Recovery	0	0
Financing Receivable, Collectively Evaluated for Impairment	3,829.8	1,145.3
Financing Receivable, Individually Evaluated for Impairment	0	0
Loans and Leases Receivable, Net of Deferred Income	3,829.8	1,145.3
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	9.6	1.9
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Financing Receivable, Allowance for Credit Loss	$ 9.6	$ 1.9	$ 1.4

Loans, Leases and Allowance f_8

Loans, Leases and Allowance for Credit Losses Loan Purchases and Sales (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Purchase	$ 12,300	$ 2,700
Financing Receivable, Sale	551.2	77.3
Loans and Leases Receivable, Gain (Loss) on Sales, Net	7.2	1.7
Financing Receivable, Purchase
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Purchase	8,800	1,600
Financing Receivable, Syndication
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Purchase	$ 3,500	$ 1,100

Transfers and Servicing (Detail

Transfers and Servicing (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Apr. 07, 2021
Transfers and Servicing [Abstract]
Servicing Asset at Fair Value, Amount	$ 698	$ 0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Servicing Assets				$ 1,347
Servicing Asset at Fair Value, Additions	763.8	$ 0	$ 0
Servicing Asset at Fair Value, Disposals	(1,270.7)
Servicing Asset at Fair Value, Changes in Fair Value Resulting from Changes in Valuation Inputs or Changes in Assumptions	(2.5)
Servicing Asset at Fair Value, Other Changes in Fair Value	(139.6)
Continuing Involvement with Transferred Financial Assets, Principal Amount Outstanding	54,347.6
MSR Sales, UPB of underlying loans	97,200
MSR Loan Sales, Receivable	82.5
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	138.9
Servicing advances, net	81.6
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 basis point Adverse Interest Rate Change	(61.6)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 basis point Favorable Interest Rate Change	39.9
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 basis point Discount Rate Increase	(13.3)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 50 basis point Discount Rate Decrease	13.8
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 1 Percent Increase in Prepayment Speed	(21.5)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 1 Percent Decrease in Prepayment Speed	23.8
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Increase Cost of Service	(9.6)
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Decrease Cost of Service	9.6
Servicing Assets at Fair Value [Line Items]
Servicing Asset at Fair Value, Disposals	1,270.7
Servicing Contracts
Transfers and Servicing [Abstract]
Servicing Asset at Fair Value, Disposals	(1,300)
Servicing Assets at Fair Value [Line Items]
Servicing Asset at Fair Value, Disposals	$ 1,300

Premises and Equipment (Details

Premises and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Land and Land Improvements	$ 32.4	$ 33
Furniture Fixtures And Equipment Gross	99.6	68.2
Leasehold Improvements, Gross	41.5	29.7
Construction in Progress, Gross	42.7	17.4
Property, Plant and Equipment, Gross	307.8	240.3
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(125.9)	(106.2)
Premises and equipment, net	181.9	134.1
Buildings and Improvements, Gross	91.6	92
Depreciation	$ 20.7	$ 15.2	$ 13.5
Operating Lease, Weighted Average Discount Rate, Percent	2.14%	2.80%	3.08%
Operating Lease, Weighted Average Remaining Lease Term	7 years 6 months	7 years 8 months 12 days	8 years 4 months 24 days
Lease, Cost	$ 18.8	$ 14	$ 12.9
Lessee, operating lease, other cost	$ 3.8	$ 3.9	$ 4

Leases (Details)

Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Payments	$ 16.3	$ 13	$ 12.4
Lessee, operating lease, leases not yet commenced, aggregated commitment	36.9
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	15.1
Operating lease right of use asset	133	72.5
Operating lease liability	$ 142.8	$ 79.9
Operating Lease, Weighted Average Discount Rate, Percent	2.14%	2.80%	3.08%
Operating Lease, Weighted Average Remaining Lease Term	7 years 6 months	7 years 8 months 12 days	8 years 4 months 24 days
Lessee, Operating Lease, Liability, Payments, Due Year Two	$ 20.7
Lessee, Operating Lease, Liability, Payments, Due Year Three	22.7
Lessee, Operating Lease, Liability, Payments, Due Year Four	18.3
Lessee, Operating Lease, Liability, Payments, Due Year Five	19.3
Lessee, Operating Lease, Liability, Payments, Due after Year Five	60.2
Lessee, Operating Lease, Liability, Payments, Due	156.3
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	13.5
Lease, Cost	18.8	$ 14	$ 12.9
Lessee, operating lease, other cost	3.8	3.9	4
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 76.7	$ 11.8	$ 43.7
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	7 years 6 months	7 years 8 months 12 days	8 years 4 months 24 days

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Apr. 07, 2021
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 158.1	$ 17.1
Finite-Lived Trade Names, Gross	0.4	0.4
Trade Name, Impaired, Accumulated Impairment Loss	0	0
Finite-Lived Intangible Assets, Accumulated Amortization	15	8.9
Indefinite-Lived Trade Names	0.4	0.4
Finite-Lived Intangible Assets, Net	143.1	8.2
Goodwill and intangible assets, net	$ 491.3	289.9		$ 201.4
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	26 years 2 months 12 days
Amortization of Intangible Assets	$ 6.1	1.6	$ 1.6
Core Deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	14.6	14.6
Finite-Lived Intangible Assets, Accumulated Amortization	10.2	8.8
Finite-Lived Intangible Assets, Net	4.4	5.8
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	2.5	2.5
Finite-Lived Intangible Assets, Accumulated Amortization	0.6	0.1
Finite-Lived Intangible Assets, Net	1.9	2.4
Correspondent relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	76	0
Finite-Lived Intangible Assets, Accumulated Amortization	2.8	0
Finite-Lived Intangible Assets, Net	73.2	0
Trade Names
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	9.5	0
Finite-Lived Intangible Assets, Accumulated Amortization	0.4	0
Finite-Lived Intangible Assets, Net	9.1	0
License
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	55.5	0
Finite-Lived Intangible Assets, Accumulated Amortization	1	0
Finite-Lived Intangible Assets, Net	$ 54.5	$ 0

Other Borrowings - Company's Bo

Other Borrowings - Company's Borrowings (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jun. 16, 2016
Short Term
Federal Funds Purchased	$ 675,000,000	$ 0
FHLB advances	0	5,000,000
Short-term Debt	726,900,000	21,000,000
Customer repurchase agreements	16,600,000	16,000,000
Long Term
Other Short-term Borrowings	35,300,000	0
Senior Notes	317,900,000	0
Notes Payable	457,100,000	0
Long-term Debt	775,000,000	0
Other borrowings	1,501,900,000	$ 21,000,000
Credit Linked Notes Maturing December 2024 [Member]
Long Term
Debt Instrument, Face Amount	242,000,000
Debt Issuance Cost	2,900,000
Credit Linked Notes Maturing July 2059
Long Term
Debt Instrument, Face Amount	227,600,000
Debt Issuance Cost	$ 2,800,000
Subordinated Debt [Member] | Subordinated Debentures Maturing June 2031
Long Term
Debt Instrument, Interest Rate, Stated Percentage	3.00%
Debt Instrument, Face Amount	$ 600,000,000
Debt Issuance Cost	$ 8,100,000
Subordinated Debt [Member] | Subordinated Debentures Maturing June 2030 [Member]
Long Term
Debt Instrument, Interest Rate, Stated Percentage	5.25%	5.25%
Debt Instrument, Face Amount	$ 225,000,000	$ 225,000,000
Debt Issuance Cost	3,100,000	$ 3,100,000
Subordinated Debt [Member] | Subordinated Debentures Maturing July 2056 [Member]
Long Term
Debt Instrument, Interest Rate, Stated Percentage		6.25%	6.25%
Debt Instrument, Face Amount		$ 175,000,000	$ 175,000,000
Debt Issuance Cost		$ 5,500,000
Subordinated Debt [Member] | Subordinated Debentures Maturing July 2025 [Member]
Long Term
Debt Instrument, Interest Rate, Stated Percentage		3.44%
Debt Instrument, Face Amount		$ 75,000,000
Debt Issuance Cost		1,800,000
Payments on long-term debt	75,000,000
Federal Home Loan Bank Advances [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 7,800,000,000	$ 4,000,000,000

Other Borrowings - Additional I

Other Borrowings - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt [Line Items]
FHLB advances	$ 0	$ 5
Other Short-term Borrowings	35.3	0
Subordinated Long-term Debt, Noncurrent	815.1	469.8
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	80.7	78.9
FHLB advances	$ 0	5
Senior Notes
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Debt Instrument, Face Amount	$ 300
Credit Linked Notes Maturing December 2024 [Member]
Debt [Line Items]
Debt Instrument, Face Amount	242
Debt Issuance Cost	$ 2.9
Debt Instrument, Interest Rate Terms	LIBOR plus 5.50%
Federal Home Loan Bank Advances [Member]
Debt [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 7,800	4,000
FRB [Member]
Debt [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	3,400	$ 2,700
Unsecured Credit Facility [Member]
Debt [Line Items]
Secured borrowing credit line	2,800
Warehouse Agreement Borrowings
Debt [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity	$ 1,000

Qualifying Debt Subordinated De

Qualifying Debt Subordinated Debt Details (Details) - Subordinated Debt [Member] - USD ($)	Dec. 31, 2020	Jun. 16, 2016
Subordinated Debentures Maturing July 2056 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 175,000,000	$ 175,000,000
Debt Issuance Cost	$ 5,500,000
Debt Instrument, Interest Rate, Stated Percentage	6.25%	6.25%
Subordinated Debentures Maturing July 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 75,000,000
Debt Issuance Cost	$ 1,800,000
Debt Instrument, Interest Rate, Stated Percentage	3.44%

Qualifying Debt Junior Subord_2

Qualifying Debt Junior Subordinated Debt (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 67.4	$ 65.9
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	80.7	78.9
Unrealized gain or loss on junior subordinated debt [Line Items]	(0.9)	(0.6)
Business Combination, Fair Market Value Adjustment on Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	(4.2)	(4.5)
BankWest Nevada Capital Trust II [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	15.5	15.5
Intermountain First Statutory Trust I [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	10.3	10.3
First Independent Capital Trust I [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	7.2	7.2
WAL Trust No. 1 [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	20.6	20.6
WAL Statutory Trust No. 2 [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	5.2	5.2
WAL Statutory Trust No. 3 [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	7.7	7.7
Bridge Capital Trust I [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	12.4	12.4
Bridge Capital Trust II [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	$ 5.1	$ 5.1
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time	2.55%	2.58%
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 67.4	$ 65.9
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	66.5	66.5
Bridge Capital Holdings [Member]
Debt Instrument [Line Items]
Junior Subordinated Debenture Owed to Unconsolidated Subsidiary Trust	17.5	17.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Junior Subordinated Debt	$ 13.3	$ 13

Qualifying Debt Supplemental Sc

Qualifying Debt Supplemental Schedule - Adoption of ASU 2016-01 (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncement, Early Adoption [Line Items]
Accumulated other comprehensive income	$ 15,700	$ 92,300	$ 25,000	$ (33,600)
Retained earnings	2,773,000	2,001,400
Non-interest income	404,200	70,800	65,100
Income tax expense	223,800	115,900	105,000
Net Income (Loss) Attributable to Parent	899,200	506,600	499,200
Net income available to common stockholders	$ 895,700	$ 506,600	$ 499,200
Basic	$ 8.72	$ 5.06	$ 4.86
Diluted	$ 8.67	$ 5.04	$ 4.84

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	11,800,000	11,800,000
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 28	$ 28
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term		2 years
Common Stock, Shares, Issued	108,981,341	108,981,341	103,013,290
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		400,000	400,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	900,000	900,000	1,000,000	1,000,000
Weighted Average Selling Price Per Share			$ 34.65
Stock Repurchase Program, Authorized Amount			$ 250
Stock Repurchased and Retired During Period, Shares			2,100,000
Stock Issued During Period, Value, New Issues		$ 540.3
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs		2.3
Proceeds from issuance of common stock in offerings, net		$ 540.3	$ 0	$ 0
ATM Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues		3,100,000
Stock Issued During Period, Value, New Issues		$ 333.4
Shares Issued, Price Per Share	$ 106.41	$ 106.41
Registered Direct Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues		2,300,000
Shares Issued, Price Per Share	$ 91	$ 91
Proceeds from issuance of common stock in offerings, net		$ 209.2
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Repurchased and Retired During Period, Shares			2,100,000	2,800,000
Stock Issued During Period, Shares, New Issues		5,400,000
Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues		12,000,000
Stock Issued During Period, Value, New Issues	$ 294.5	$ 294.5
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense		10.4	$ 7.1	$ 6.9
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense		$ 22.9	$ 20.3	$ 17.4
Grant year 2019 | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	203,646	203,646

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Unvested Shares of Restricted Stock and Changes (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	400,000	400,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	900,000	1,000,000	1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 63.53	$ 50.12	$ 49.98
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(400,000)	(400,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 53.50	$ 51.86
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(100,000)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 59.24	$ 49.79
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Aggregate Intrinsic Value	$ 35.4	$ 22.7	$ 23.7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	34.2	19.6	21.3
Share-based Payment Arrangement, Expense	22.9	20.3	17.4
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 10.4	7.1	6.9
Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0
Share-based Payment Arrangement, Expense	$ 0.6	$ 1.2	$ 1.9

Stockholders' Equity Share-Base

Stockholders' Equity Share-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	3,000,000
Stock Repurchased and Retired During Period, Value		$ 71,600	$ 120,200
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 83.56	$ 51.53
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	400,000	400,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	900,000	1,000,000	1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	400,000	400,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Aggregate Intrinsic Value	$ 35,400	$ 22,700	$ 23,700
Share-based Payment Arrangement, Expense	22,900	20,300	17,400
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	10,400	$ 7,100	6,900
2017 [Member] [Domain] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		152,418
Executive Officer [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 600	$ 1,200	$ 1,900
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0

Stockholders' Equity Common Sto

Stockholders' Equity Common Stock Repurchase (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Common Stock Repurchase [Abstract]
Stock Repurchase Program, Authorized Amount	$ 250,000
Stock Repurchased and Retired During Period, Shares	2,100,000
Weighted Average Selling Price Per Share	$ 34.65
Stock Repurchased and Retired During Period, Value	$ 71,600	$ 120,200

Stockholders' Equity Dividend (

Stockholders' Equity Dividend (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Dividends [Abstract]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.35	$ 0.25		$ 0.25
Dividends			$ 124,100	$ 101,300	$ 51,300
Preferred Stock, Dividends, Per Share, Cash Paid			$ 0.29

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income - Summary of Changes in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	$ 15.7	$ 92.3	$ 25
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	0	0.3	0.4
Beginning balance	92.3	25	(33.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(70.2)	67.5	61
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(6.4)	(0.2)	(2.4)
Other comprehensive (loss) income, net	(76.6)	67.3	58.6
Ending balance	15.7	92.3	25
Unrealized holding gains (losses) on AFS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	16.7	92.1	21.4
Beginning balance	92.1	21.4	(47.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(69)	70.9	71.2
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(6.4)	(0.2)	(2.3)
Other comprehensive (loss) income, net	(75.4)	70.7	68.9
Ending balance	16.7	92.1	21.4
Accumulated Gain (Loss), Financial Liability, Fair Value Option, Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	(0.7)	0.5	3.6
Beginning balance	0.5	3.6	13.4
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(1.2)	(3.1)	(9.8)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Other comprehensive (loss) income, net	(1.2)	(3.1)	(9.8)
Ending balance	(0.7)	0.5	3.6
Impairment loss on securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	0	0	0
Beginning balance	0	0	0.1
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0.1
Other comprehensive (loss) income, net	0	0	(0.1)
Ending balance	0	0	0
Supplemental Employee Retirement Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income	(0.3)	(0.3)	0
Beginning balance	(0.3)	0	0.4
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	(0.3)	(0.4)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0
Other comprehensive (loss) income, net	0	(0.3)	(0.4)
Ending balance	$ (0.3)	$ (0.3)	$ 0

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income - Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Realized gains on sales of investment securities	$ 8,500	$ 200	$ 3,100
Amount reclassified from accumulated other comprehensive income	(2,100)	0	700
Amount reclassified from accumulated other comprehensive income	$ 6,400	$ 200	2,400
Income Tax Expense [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amount reclassified from accumulated other comprehensive income			$ (700)

Derivatives and Hedging Fair Va

Derivatives and Hedging Fair Value of Derivative Contracts (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Hedged Liability, Fair Value Hedge	$ 0	$ 247.6
Hedged Asset, Fair Value Hedge	1,390.7	1,587.1
Derivative Asset, Fair Value, Gross Asset	38.4	3.3	$ 1.8
Derivative Liability, Fair Value, Gross Liability	96.3	86.1	55.5
Prepayable Financial Asset Closed Portfolio, Last-of-Layer, Amortized Cost	1,400	1,900
Hedged Asset, Fair Value Hedge, Last-of-Layer, Cumulative Increase (Decrease)	15.7	0.6
Hedged Asset, Fair Value Hedge, Last-of-Layer, Amount	880
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	13.8	3.3	1.8
Derivative Liability, Fair Value, Gross Liability	54.5	86.1	55.5
Forward purchase contracts
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	7.9	0	0
Derivative Liability, Fair Value, Gross Liability	17.7	0	0
Forward sales contracts
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	15.5	0	0
Derivative Liability, Fair Value, Gross Liability	17.6	0	0
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,382.8	1,689.9	863
Derivative Asset, Fair Value, Gross Asset	13.8	3.3	1.8
Derivative Liability, Fair Value, Gross Liability	54.5	86.1	55.5
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	1,382.8	1,689.9	863
Derivative Asset, Fair Value, Gross Asset	13.8	3.3	1.8
Derivative Liability, Fair Value, Gross Liability	54.5	86.1	55.5
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	479,383.1	122.7	9.6
Derivative Asset, Fair Value, Gross Asset	35.2	0.9	0.1
Derivative Liability, Fair Value, Gross Liability	38.8	1.4	0.1
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	4.1	3.5	2.9
Derivative Asset, Fair Value, Gross Asset	0.1	0.2	0.1
Derivative Liability, Fair Value, Gross Liability	0.1	0.2	0.1
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	180.1	119.2	6.7
Derivative Asset, Fair Value, Gross Asset	0.2	0.7	0
Derivative Liability, Fair Value, Gross Liability	1.4	1.2	0
Not Designated as Hedging Instrument [Member] | Forward purchase contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	11,713.5	0	0
Derivative Asset, Fair Value, Gross Asset	8.1	0	0
Derivative Liability, Fair Value, Gross Liability	18	0	0
Not Designated as Hedging Instrument [Member] | Forward sales contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	17,358.5	0	0
Derivative Asset, Fair Value, Gross Asset	15.8	0	0
Derivative Liability, Fair Value, Gross Liability	17.7	0	0
Not Designated as Hedging Instrument [Member] | Futures purchase contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	218,053.7	0	0
Derivative Asset, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	0	0	0
Not Designated as Hedging Instrument [Member] | Futures sales contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	229,040	0	0
Derivative Asset, Fair Value, Gross Asset	0	0	0
Derivative Liability, Fair Value, Gross Liability	0	0	0
Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	3,033.2	0	0
Derivative Asset, Fair Value, Gross Asset	11	0	0
Derivative Liability, Fair Value, Gross Liability	$ 1.6	$ 0	$ 0

Derivatives and Hedging Pre-Tax

Derivatives and Hedging Pre-Tax Net Gains (Losses) on Fair Value Hedges (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	$ (45.6)	$ 32.2	$ 30.3
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	44.8	(32.2)	(30.3)
Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge	2.7	(3.1)	(19.3)
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ (2.7)	$ 3.1	$ 19.3

Derivatives and Hedging Additio

Derivatives and Hedging Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jun. 16, 2016
Derivative [Line Items]
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	$ 38,500,000	$ 85,500,000
Derivative Asset, Fair Value, Gross Asset	38,400,000	3,300,000	$ 1,800,000
Derivative Liability, Fair Value, Gross Liability	96,300,000	86,100,000	55,500,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	10,000,000	2,700,000	1,800,000
Derivative Netting Adjustments, Assets	(28,400,000)	(600,000)	0
Derivative Asset, Collateral, Obligation to Return Cash, Offset	1,200,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	(67,900,000)	(85,500,000)	(55,500,000)
Derivative Netting Adjustments, Liabilities	28,400,000	600,000	0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	(6,500,000)
Derivative Asset, Not Subject to Master Netting Arrangement	11,800,000	900,000	100,000
Derivative Liability, Not Subject to Master Netting Arrangement	(3,500,000)	(1,400,000)	(100,000)
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	50,200,000	4,200,000	1,900,000
Derivative Asset, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election	21,800,000	3,600,000	1,900,000
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(99,800,000)	(87,500,000)	(55,600,000)
Derivative Liability, Fair Value, Offset Against Collateral, Net of Not Subject to Master Netting Arrangement, Policy Election	(71,400,000)	(86,900,000)	(55,600,000)
Derivative, Collateral, Right to Reclaim Securities	67,100,000	117,800,000	52,500,000
Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	49,800,000
Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	28,400,000
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,800,000	3,300,000	1,800,000
Derivative Liability, Fair Value, Gross Liability	54,500,000	86,100,000	55,500,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	13,800,000	3,300,000	1,800,000
Derivative Netting Adjustments, Assets		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(54,500,000)	(86,100,000)	(55,500,000)
Derivative Netting Adjustments, Liabilities		0	0
Derivative Asset, Not Subject to Master Netting Arrangement	100,000	200,000	100,000
Derivative Liability, Not Subject to Master Netting Arrangement	(100,000)	(200,000)	(100,000)
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	200,000	700,000	0
Derivative Liability, Not Subject to Master Netting Arrangement	(1,400,000)	(1,200,000)	0
Forward purchase contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	7,900,000	0	0
Derivative Liability, Fair Value, Gross Liability	17,700,000	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	7,900,000	0	0
Derivative Netting Adjustments, Assets		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(17,700,000)	0	0
Derivative Netting Adjustments, Liabilities		0	0
Derivative Asset, Not Subject to Master Netting Arrangement	200,000
Derivative Liability, Not Subject to Master Netting Arrangement	(300,000)
Forward sales contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	15,500,000	0	0
Derivative Liability, Fair Value, Gross Liability	17,600,000	0	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	15,500,000	0	0
Derivative Netting Adjustments, Assets		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral	(17,600,000)	0	0
Derivative Netting Adjustments, Liabilities		$ 0	0
Derivative Asset, Not Subject to Master Netting Arrangement	300,000
Derivative Liability, Not Subject to Master Netting Arrangement	(100,000)
Interest Rate Lock Commitments
Derivative [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	11,000,000
Derivative Liability, Not Subject to Master Netting Arrangement	(1,600,000)
Interest Rate Lock Commitments | Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,000,000)
Forward Contracts | Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	52,200,000
Forward Contracts | Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	4,200,000
Other Contract | Net gain on loan origination and sale activities
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1,400,000)
Swaption | Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(300,000)
Future | Loan servicing fees, net
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	23,900,000
Subordinated Debentures Maturing July 2025 [Member] | Subordinated Debt [Member]
Derivative [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.44%
Debt Instrument, Face Amount		$ 75,000,000
Subordinated Debentures Maturing July 2056 [Member] | Subordinated Debt [Member]
Derivative [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.25%		6.25%
Debt Instrument, Face Amount		$ 175,000,000		$ 175,000,000
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,800,000	3,300,000	1,800,000
Derivative Liability, Fair Value, Gross Liability	54,500,000	86,100,000	55,500,000
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	13,800,000	3,300,000	1,800,000
Derivative Liability, Fair Value, Gross Liability	54,500,000	86,100,000	55,500,000
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	35,200,000	900,000	100,000
Derivative Liability, Fair Value, Gross Liability	38,800,000	1,400,000	100,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	100,000	200,000	100,000
Derivative Liability, Fair Value, Gross Liability	100,000	200,000	100,000
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	200,000	700,000	0
Derivative Liability, Fair Value, Gross Liability	1,400,000	1,200,000	0
Not Designated as Hedging Instrument [Member] | Forward purchase contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	8,100,000	0	0
Derivative Liability, Fair Value, Gross Liability	18,000,000	0	0
Not Designated as Hedging Instrument [Member] | Forward sales contracts
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	15,800,000	0	0
Derivative Liability, Fair Value, Gross Liability	17,700,000	0	0
Not Designated as Hedging Instrument [Member] | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	11,000,000	0	0
Derivative Liability, Fair Value, Gross Liability	$ 1,600,000	$ 0	$ 0

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Anti-dilutive stock options outstanding that were not included in computation of diluted earnings per common share	0
Basic	102,700	100,200	102,700
Dilutive Effect Of Stock Options Restricted Stock And Equity Settled Awards	600	300	400
Diluted	103,300	100,500	103,100
Net income available to common stockholders	$ 895,700	$ 506,600	$ 499,200
Earnings (loss) per share - basic	$ 8.72	$ 5.06	$ 4.86
Diluted	$ 8.67	$ 5.04	$ 4.84

Income Taxes Provision for Inco

Income Taxes Provision for Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	19.90%	18.60%	17.40%
Current Income Tax Expense (Benefit)	$ 181.8	$ 141	$ 110.1
Deferred Income Tax Expense (Benefit)	42	(25.1)	(5.1)
Income tax benefit	$ 223.8	$ 115.9	$ 105

Income Taxes Reconciliation bet

Income Taxes Reconciliation between Statutory Federal Income Tax and Company's Effective Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 235.8	$ 130.7	$ 126.9
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	35.8	13.9	11
Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount	(25.6)	21.7	(19.6)
Income Tax Reconciliation Low Income Housing And Other Tax Credits	(15.9)	(13.9)	(15)
Income Tax Reconciliation Tax On Earnings Other Than Statutory Tax Rate	(6.3)	6.9	1.7
Income tax benefit	$ 223.8	$ 115.9	$ 105
Effective Income Tax Rate Reconciliation, Percent	19.90%	18.60%	17.40%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Percent	19.90%	18.60%	17.40%
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 5.1	$ 2.1
Decreased deferred tax assets net	10.4
Recognized net deferred tax asset	20.9	31.3
Operating Loss Carryforwards, Valuation Allowance	0	0
Deferred Tax Liabilities, Insurance Premiums	(6)	$ 0
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	4.5
Operating Loss Carryforwards	$ 41.1

Income Taxes Income Taxes - Cum

Income Taxes Income Taxes - Cumulative Tax Effects of Primary Differences (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Deferred Tax Liabilities, Property, Plant and Equipment	$ 0	$ 7.6
Deferred Tax Liabilities, Deferred Expense, Reserves and Accruals	(7.6)	(17.5)
Deferred Tax Liabilities, Insurance Premiums	(6)	0
Deferred Tax Liabilities, Tax Deferred Income	(7.7)	(9.8)
Deferred Tax Liabilities, Mortgage Servicing Rights	(57.6)	0
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	5.1	2.1
Deferred Tax Assets, Net of Valuation Allowance	183.4	165.7
Deferred Tax Liabilities, Leasing Arrangements	(36)	(19.2)
Deferred Tax Liabilities, Tax Deferred Income	(5.7)	(31.2)
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Provision for Loan Losses	81	84.6
Deferred Tax Assets, Leasing Arrangements	38.6	21.1
Deferred Tax Assets, Other	34.9	29.1
Deferred Tax Assets, Gross	183.4	165.7
Deferred Tax Liabilities, Deferred Expense, Deferred Financing Costs	(15.5)	(12.8)
Deferred Tax Liabilities, Unearned Premiums	(7.2)	(16.8)
Deferred Tax Liabilities, Leasing Basis Differences	(12.3)	(11.1)
Deferred Tax Liabilities, Other	(6.9)	(8.4)
Deferred Tax Liabilities, Gross	(162.5)	(134.4)
Deferred tax assets, net	20.9	31.3
Deferred Tax Assets, Valuation Allowance	0	0
Deferred Tax Assets, Insurance Premiums	0	18.9
Deferred Tax Assets, Passthrough Income	9.1	8.4
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities	9.8	3.6
Deferred Tax Assets, Property, Plant and Equipment	$ 10	$ 0

Income Taxes - Low Income Housi

Income Taxes - Low Income Housing Tax Credit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 676.5
Amortization of tax credit investments	49.5	$ 49.2	$ 41.5
Investments in LIHTC and renewable energy	631.3	405.6
Investment-related Liabilities	$ 360.8	$ 151.7

Income Taxes Gross Activity of

Income Taxes Gross Activity of Unrecognized Tax Benefits Related to Uncertain Tax Positions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Income Tax Penalties Expense	$ 0
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	5,100,000	$ 2,100,000
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	800,000	0
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	2,200,000	2,200,000
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	0	0
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0	(100,000)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	0	(400,000)
Unrecognized Tax Benefits	$ 6,400,000	$ 3,400,000	$ 1,700,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Letters of credit expiration period	1 year
Percentage of first liens initial loan to value ratio	75.00%
Percent of commercial real estate loans owner occupied	23.00%	28.00%
Off-Balance Sheet, Credit Loss, Liability	$ 37.6	$ 37		$ 9
Cumulative Effect, Period of Adoption, Adjustment [Member]
Loss Contingencies [Line Items]
Off-Balance Sheet, Credit Loss, Liability			$ 15.1
Commercial Real Estate Portfolio Segment [Member] | Loans Receivable [Member] | Credit Concentration Risk [Member]
Loss Contingencies [Line Items]
Percent of commercial real estate related loans	29.00%	38.00%
Unfunded Loan Commitment [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual	$ 37.6	$ 37

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Contractual Amounts for Unfunded Commitments and Letters of Credit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Other Commitments [Line Items]
Total amount	$ 13,900,700	$ 9,903,600
Percent of commercial real estate loans owner occupied	23.00%	28.00%
Unfunded Loan Commitment [Member]
Other Commitments [Line Items]
Loss Contingency Accrual	$ 37,600	$ 37,000
Standby letters of credit [Member]
Other Commitments [Line Items]
Total amount	198,100	186,900
Unsecured Letters Of Credit	12,900	9,900
Credit card guarantees [Member]
Other Commitments [Line Items]
Total amount	306,300	291,500
Commitments to extend credit [Member]
Other Commitments [Line Items]
Total amount	13,396,300	9,425,200
Unsecured Loan Commitments	$ 1,199,800	$ 1,077,200
Loans Receivable [Member] | Credit Concentration Risk [Member] | Commercial Real Estate Portfolio Segment [Member]
Other Commitments [Line Items]
Concentration Risk, Percentage	29.00%	38.00%

Commitments and Contingencies_3

Commitments and Contingencies - Contractual Commitments for Lines and Letters of Credit by Maturity (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Loss Contingencies [Line Items]
Total Amount Committed	$ 13,900.7	$ 9,903.6
Other Commitment, Due in Next Twelve Months	4,149
Other Commitment, Due in Second and Third Year	6,238.1
Other Commitment, Due in Fourth and Fifth Year	2,326.5
Other Commitment, Due after Fifth Year	1,187
Commitments to extend credit [Member]
Loss Contingencies [Line Items]
Total Amount Committed	13,396.3	9,425.2
Other Commitment, Due in Next Twelve Months	3,652
Other Commitment, Due in Second and Third Year	6,235.1
Other Commitment, Due in Fourth and Fifth Year	2,322.1
Other Commitment, Due after Fifth Year	1,187
Credit card guarantees [Member]
Loss Contingencies [Line Items]
Total Amount Committed	306.3	291.5
Other Commitment, Due in Next Twelve Months	306.3
Other Commitment, Due in Second and Third Year	0
Other Commitment, Due in Fourth and Fifth Year	0
Other Commitment, Due after Fifth Year	0
Standby letters of credit [Member]
Loss Contingencies [Line Items]
Total Amount Committed	198.1	$ 186.9
Other Commitment, Due in Next Twelve Months	190.7
Other Commitment, Due in Second and Third Year	3
Other Commitment, Due in Fourth and Fifth Year	4.4
Other Commitment, Due after Fifth Year	$ 0

Commitments and Contingencies C

Commitments and Contingencies Concentration of Lending Activities (Details)	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Percent of commercial real estate loans owner occupied	23.00%	28.00%

Fair Value Accounting - Gains a

Fair Value Accounting - Gains and Losses from Fair Value Changes Included in Consolidated Statement of Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Unrealized Gain (Loss) Arising During Period, after Tax	$ (1.2)	$ (3.1)	$ (9.8)
Junior Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ (1.5)	$ (4.2)	$ (13)

Fair Value Accounting - Fair Va

Fair Value Accounting - Fair Value of Assets and Liabilities (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Hedged Asset, Fair Value Hedge, Cumulative Increase (Decrease)	$ 38,500,000	$ 85,500,000
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	0	(2,700,000)
Investment securities - equity	158,500,000	167,300,000
Subordinated Debt Obligations, Fair Value Disclosure	67,400,000	65,900,000
Debt Securities, Available-for-sale	6,188,800,000	4,708,500,000
Servicing Asset at Fair Value, Amount	698,000,000	0
Debt Securities, Available-for-sale, Amortized Cost	6,166,500,000	4,586,400,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	103,600,000	137,600,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(81,300,000)	(15,500,000)
Other Security Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	81,700,000	55,900,000
Debt Securities, Available-for-sale, Amortized Cost	75,300,000	54,100,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	11,000,000	7,300,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(4,600,000)	(5,500,000)
Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	926,200,000	146,900,000
Debt Securities, Available-for-sale, Amortized Cost	926,000,000	146,900,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	500,000	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(300,000)	0
Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	68,500,000	84,600,000
Debt Securities, Available-for-sale, Amortized Cost	68,200,000	80,800,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	900,000	3,800,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(600,000)	0
Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	382,900,000	270,200,000
Debt Securities, Available-for-sale, Amortized Cost	382,700,000	271,100,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	9,200,000	4,800,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(9,000,000)	(5,700,000)
Private label residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,508,000,000	1,476,900,000
Debt Securities, Available-for-sale, Amortized Cost	1,528,700,000	1,461,700,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,500,000	15,700,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(24,200,000)	(500,000)
Residential mortgage-backed securities issued by GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,993,400,000	1,486,600,000
Debt Securities, Available-for-sale, Amortized Cost	2,027,500,000	1,462,500,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	7,300,000	27,900,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(41,400,000)	(3,800,000)
Nontaxable Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,215,100,000	1,187,400,000
Debt Securities, Available-for-sale, Amortized Cost	1,145,100,000	1,109,300,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	71,200,000	78,100,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,200,000)	0
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	13,000,000
Debt Securities, Available-for-sale, Amortized Cost	13,000,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	158,500,000	167,300,000
Loans Held-for-sale, Fair Value Disclosure	3,939,700,000
Derivative Liability	99,800,000	87,500,000
Derivative Asset	50,200,000	4,200,000
Debt Securities, Available-for-sale	6,188,800,000	4,708,500,000
Servicing Asset at Fair Value, Amount	698,000,000
Fair Value, Recurring [Member] | Other Security Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	81,700,000	55,900,000
Fair Value, Recurring [Member] | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	926,200,000	146,900,000
Fair Value, Recurring [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	68,500,000	84,600,000
Fair Value, Recurring [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	382,900,000	270,200,000
Fair Value, Recurring [Member] | Private label residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,508,000,000	1,476,900,000
Fair Value, Recurring [Member] | Residential mortgage-backed securities issued by GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,993,400,000	1,486,600,000
Fair Value, Recurring [Member] | Nontaxable Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,215,100,000	1,187,400,000
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	13,000,000
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	141,300,000	141,700,000
Loans Held-for-sale, Fair Value Disclosure	0
Derivative Liability	0	0
Derivative Asset	0	0
Subordinated Debt Obligations, Fair Value Disclosure	0	0
Debt Securities, Available-for-sale	40,400,000	26,500,000
Servicing Asset at Fair Value, Amount	0
Fair Value, Recurring [Member] | Level 1 [Member] | Other Security Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	27,400,000	26,500,000
Fair Value, Recurring [Member] | Level 1 [Member] | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Private label residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Residential mortgage-backed securities issued by GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Nontaxable Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 1 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	13,000,000
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	17,200,000	25,600,000
Loans Held-for-sale, Fair Value Disclosure	3,894,200,000
Derivative Liability	98,200,000	87,500,000
Derivative Asset	39,200,000	4,200,000
Subordinated Debt Obligations, Fair Value Disclosure	0	0
Debt Securities, Available-for-sale	6,148,400,000	4,682,000,000
Servicing Asset at Fair Value, Amount	0
Fair Value, Recurring [Member] | Level 2 [Member] | Other Security Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	54,300,000	29,400,000
Fair Value, Recurring [Member] | Level 2 [Member] | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	926,200,000	146,900,000
Fair Value, Recurring [Member] | Level 2 [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	68,500,000	84,600,000
Fair Value, Recurring [Member] | Level 2 [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	382,900,000	270,200,000
Fair Value, Recurring [Member] | Level 2 [Member] | Private label residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,508,000,000	1,476,900,000
Fair Value, Recurring [Member] | Level 2 [Member] | Residential mortgage-backed securities issued by GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,993,400,000	1,486,600,000
Fair Value, Recurring [Member] | Level 2 [Member] | Nontaxable Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	1,215,100,000	1,187,400,000
Fair Value, Recurring [Member] | Level 2 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	0	0
Loans Held-for-sale, Fair Value Disclosure	45,500,000
Derivative Liability	1,600,000	0
Derivative Asset	11,000,000	0
Subordinated Debt Obligations, Fair Value Disclosure	67,400,000	65,900,000
Debt Securities, Available-for-sale	0	0
Servicing Asset at Fair Value, Amount	698,000,000
Fair Value, Recurring [Member] | Level 3 [Member] | Other Security Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Commercial Mortgage Backed Securities Issued By US Government Sponsored Enterprise [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Private label residential mortgage-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Residential mortgage-backed securities issued by GSEs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Nontaxable Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Level 3 [Member] | US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Available-for-sale	0
Fair Value, Recurring [Member] | CRA investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	44,600,000	53,400,000
Fair Value, Recurring [Member] | CRA investments [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	27,400,000	27,800,000
Fair Value, Recurring [Member] | CRA investments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	17,200,000	25,600,000
Fair Value, Recurring [Member] | CRA investments [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	0	0
Fair Value, Recurring [Member] | Preferred Stock [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	113,900,000	113,900,000
Fair Value, Recurring [Member] | Preferred Stock [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	113,900,000	113,900,000
Fair Value, Recurring [Member] | Preferred Stock [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	0	0
Fair Value, Recurring [Member] | Preferred Stock [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - equity	0	0
Junior Subordinated Debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 67,400,000	$ 65,900,000
Junior subordinated debt, Significant Unobservable Inputs	Implied credit rating of the Company	Implied credit rating of the Company
Valuation Technique, Discounted Cash Flow [Member] | Junior Subordinated Debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Discounted cash flow	Discounted cash flow

Fair Value Accounting - Change

Fair Value Accounting - Change in Level 3 Liabilities Measured at Fair Value on Recurring Basis (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Unrealized Gain (Loss) Arising During Period, after Tax	$ (1.2)	$ (3.1)	$ (9.8)
Junior subordinated debt	(67.4)	(65.9)
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt	$ (67.4)	$ (65.9)
Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Discounted cash flow method	Discounted cash flow method
Other Assets [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Collateral method	Collateral method
Junior Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)	$ (1.5)	$ (4.2)	(13)
Debt Instrument, Measurement Input	0.0261	0.0287
Debt Instrument, Basis Spread on Variable Rate	2.40%	2.64%
Percentage Of Basis Spread On Variable Rate	0.21%	0.24%
Junior Subordinated Debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Implied credit rating of the Company	Implied credit rating of the Company
Junior subordinated debt	$ (67.4)	$ (65.9)
Junior Subordinated Debt [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	(65.9)	(61.7)	48.7
Closing balance	$ (67.4)	$ (65.9)	$ (61.7)
Collateral Method [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Collateral method	Collateral method
Third Party Appraisal [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Third party appraisal	Third party appraisal
Third Party Appraisal [Member] | Other Assets [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Third party appraisal	Third party appraisal
Discount Rate [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Discount rate	Discount rate
Scheduled Cash Collections [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Scheduled cash collections	Scheduled cash collections
Proceeds from Non-Real Estate Collateral [Member] | Loans and Finance Receivables [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Proceeds from non-real estate collateral	Proceeds from non-real estate collateral

Fair Value Accounting - Assets

Fair Value Accounting - Assets Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	$ 11.7	$ 1.4
Collateral Dependent Loans, Net of Allowance	216	187.3
Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	0	0
Collateral Dependent Loans, Net of Allowance	0	0
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	0	0
Collateral Dependent Loans, Net of Allowance	0	0
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	11.7	1.4
Collateral Dependent Loans, Net of Allowance	$ 216	$ 187.3
Loans and Finance Receivables [Member] | Third Party Appraisal [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 3 Fair Value Measurement Inputs	Costs to sell	Costs to sell
Loans and Finance Receivables [Member] | Discount Rate [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 3 Fair Value Measurement Inputs	Contractual loan rate	Contractual loan rate
Loans and Finance Receivables [Member] | Scheduled Cash Collections [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 3 Fair Value Measurement Inputs	Probability of default	Probability of default
Loans and Finance Receivables [Member] | Proceeds from Non-Real Estate Collateral [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 3 Fair Value Measurement Inputs	Loss given default	Loss given default
Other Assets [Member] | Third Party Appraisal [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Level 3 Fair Value Measurement Inputs	Costs to sell	Costs to sell

Fair Value Accounting - Estimat

Fair Value Accounting - Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	$ 1,107,100	$ 568,800
Financial assets
Accrued Investment Income Receivable	3,000	2,000
Investment securities - equity	158,500	167,300
Loans, net	38,822,900	26,774,100
Financial liabilities
Total deposits	47,612,000	31,930,500
Customer repurchases	16,600	16,000
FHLB and FRB advances	0	5,000
Junior subordinated debt	67,400	65,900
Financing Receivable, Held-for-Sale	5,635,100	0
Servicing Asset	698,000	0
Debt Securities, Available-for-sale	6,188,800	4,708,500
Fair Value, Nonrecurring [Member]
Financial liabilities
Repossessed Assets	11,700	1,400
Fair Value, Nonrecurring [Member] | Level 1 [Member]
Financial liabilities
Repossessed Assets	0	0
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Financial liabilities
Repossessed Assets	0	0
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Financial liabilities
Repossessed Assets	11,700	1,400
Fair Value, Nonrecurring [Member] | Carrying Amount [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,107,100	568,800
Financial assets
Loans, net	38,822,900	26,774,100
Financial liabilities
Total deposits	47,612,000	31,930,500
Other Borrowings Fair Value Disclosure	1,501,900	21,000
Junior subordinated debt	895,800	548,700
Fair Value, Nonrecurring [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,146,400	611,800
Financial assets
Loans, net	39,218,200	27,231,000
Financial liabilities
Total deposits	47,615,500	31,935,900
Other Borrowings Fair Value Disclosure	1,518,400	21,000
Junior subordinated debt	938,600	567,400
Fair Value, Nonrecurring [Member] | Fair Value [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Financial assets
Loans, net	0	0
Financial liabilities
Total deposits	0	0
Other Borrowings Fair Value Disclosure	0	0
Junior subordinated debt	0	0
Fair Value, Nonrecurring [Member] | Fair Value [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	1,146,400	611,800
Financial assets
Loans, net	0	0
Financial liabilities
Total deposits	47,615,500	31,935,900
Other Borrowings Fair Value Disclosure	1,518,400	21,000
Junior subordinated debt	857,300	488,100
Fair Value, Nonrecurring [Member] | Fair Value [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities - HTM, at amortized cost; fair value of $516,261 at December 31, 2019 and $298,648 at December 31, 2018	0	0
Financial assets
Loans, net	39,218,200	27,231,000
Financial liabilities
Total deposits	0	0
Other Borrowings Fair Value Disclosure	0	0
Junior subordinated debt	81,300	79,300
Fair Value, Recurring [Member]
Financial assets
Investment securities - equity	158,500	167,300
Derivative Asset	50,200	4,200
Financial liabilities
Derivative Liability	99,800	87,500
Debt Securities, Available-for-sale	6,188,800	4,708,500
Fair Value, Recurring [Member] | Level 1 [Member]
Financial assets
Investment securities - equity	141,300	141,700
Derivative Asset	0	0
Financial liabilities
Junior subordinated debt	0	0
Derivative Liability	0	0
Debt Securities, Available-for-sale	40,400	26,500
Fair Value, Recurring [Member] | Level 2 [Member]
Financial assets
Investment securities - equity	17,200	25,600
Derivative Asset	39,200	4,200
Financial liabilities
Junior subordinated debt	0	0
Derivative Liability	98,200	87,500
Debt Securities, Available-for-sale	6,148,400	4,682,000
Fair Value, Recurring [Member] | Level 3 [Member]
Financial assets
Investment securities - equity	0	0
Derivative Asset	11,000	0
Financial liabilities
Junior subordinated debt	67,400	65,900
Derivative Liability	1,600	0
Debt Securities, Available-for-sale	0	0
Fair Value, Recurring [Member] | Carrying Amount [Member]
Financial assets
Accrued Investment Income Receivable	227,900	166,100
Investment securities - equity	158,500	167,300
Derivative Asset	50,200	4,200
Financial liabilities
Interest Payable, Current	9,200	11,000
Derivative Liability	99,800	87,500
Financing Receivable, Held-for-Sale	5,635,100
Servicing Asset	698,000
Debt Securities, Available-for-sale	6,188,800	4,708,500
Fair Value, Recurring [Member] | Fair Value [Member]
Financial assets
Accrued Investment Income Receivable	227,900	166,100
Investment securities - equity	158,500	167,300
Derivative Asset	50,200	4,200
Financial liabilities
Interest Payable, Current	9,200	11,000
Derivative Liability	99,800	87,500
Financing Receivable, Held-for-Sale	5,654,400
Servicing Asset	698,000
Debt Securities, Available-for-sale	6,188,800	4,708,500
Fair Value, Recurring [Member] | Fair Value [Member] | Level 1 [Member]
Financial assets
Accrued Investment Income Receivable	0	0
Investment securities - equity	141,300	141,700
Derivative Asset	0	0
Financial liabilities
Interest Payable, Current	0	0
Derivative Liability	0	0
Financing Receivable, Held-for-Sale	0
Servicing Asset	0
Debt Securities, Available-for-sale	40,400	26,500
Fair Value, Recurring [Member] | Fair Value [Member] | Level 2 [Member]
Financial assets
Accrued Investment Income Receivable	227,900	166,100
Investment securities - equity	17,200	25,600
Derivative Asset	39,200	4,200
Financial liabilities
Interest Payable, Current	9,200	11,000
Derivative Liability	98,200	87,500
Financing Receivable, Held-for-Sale	3,894,200
Servicing Asset	0
Debt Securities, Available-for-sale	6,148,400	4,682,000
Fair Value, Recurring [Member] | Fair Value [Member] | Level 3 [Member]
Financial assets
Accrued Investment Income Receivable	0	0
Investment securities - equity	0	0
Derivative Asset	11,000	0
Financial liabilities
Interest Payable, Current	0	0
Derivative Liability	1,600	0
Financing Receivable, Held-for-Sale	1,760,200
Servicing Asset	698,000
Debt Securities, Available-for-sale	0	0
CRA investments [Member] | Fair Value, Recurring [Member]
Financial assets
Investment securities - equity	44,600	53,400
CRA investments [Member] | Fair Value, Recurring [Member] | Level 1 [Member]
Financial assets
Investment securities - equity	27,400	27,800
CRA investments [Member] | Fair Value, Recurring [Member] | Level 2 [Member]
Financial assets
Investment securities - equity	17,200	25,600
CRA investments [Member] | Fair Value, Recurring [Member] | Level 3 [Member]
Financial assets
Investment securities - equity	0	0
Preferred Stock [Member] | Fair Value, Recurring [Member]
Financial assets
Investment securities - equity	113,900	113,900
Preferred Stock [Member] | Fair Value, Recurring [Member] | Level 1 [Member]
Financial assets
Investment securities - equity	113,900	113,900
Preferred Stock [Member] | Fair Value, Recurring [Member] | Level 2 [Member]
Financial assets
Investment securities - equity	0	0
Preferred Stock [Member] | Fair Value, Recurring [Member] | Level 3 [Member]
Financial assets
Investment securities - equity	$ 0	$ 0

Fair Value Accounting - Additio

Fair Value Accounting - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021USD ($)percent	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Apr. 07, 2021USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Comprehensive Income (Loss), Financial Liability, Fair Value Option, Unrealized Gain (Loss) Arising During Period, after Tax	$ (1,200,000)	$ (3,100,000)	$ (9,800,000)
Subordinated Debt Obligations, Fair Value Disclosure	67,400,000	65,900,000
Other assets acquired through foreclosure	11,700,000	1,400,000
Collateral Dependent Loans, Allowance	(10,800,000)	(8,900,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 0
Fair Value, Option, Loans Held as Assets, Current Through 89 Days	3,937,500,000
Fair Value, Option, Loans Held as Assets, UPB, Current Through 89 Days	3,807,300,000
Fair Value, Option, Loans Held as Assets, Current Through 89 days, Aggregate Difference	130,200,000
Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due	2,200,000
Fair Value, Option, Loans Held as Assets, UPB, 90 Days or More Past Due	2,200,000
Fair Value, Option, Loans Held as Assets, 90 Days or More Past Due, Aggregate Difference	0
Fair Value, Option, Loans Held as Assets	3,939,700,000
Fair Value, Option, Loans Held as Assets, Aggregate Difference	$ 130,200,000
Minimum [Member] | Option Adjusted Spread
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	553
Minimum [Member] | Conditional Prepayment Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	0.099
Minimum [Member] | Recapture Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	0.200
Minimum [Member] | Servicing Fee Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	25
Minimum [Member] | Cost to Service
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	84
Minimum [Member] | Whole loan spread to TBA price in basis points
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Measurement Input | percent	(3.65)
Minimum [Member] | Servicing Fee Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Measurement Input | percent	3.6
Minimum [Member] | Pull-through Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Measurement Input | percent	0.75
Maximum [Member] | Option Adjusted Spread
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	735
Maximum [Member] | Conditional Prepayment Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	0.207
Maximum [Member] | Recapture Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	0.200
Maximum [Member] | Servicing Fee Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	50
Maximum [Member] | Cost to Service
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	91
Maximum [Member] | Whole loan spread to TBA price in basis points
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Measurement Input | percent	(2.86)
Maximum [Member] | Servicing Fee Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Measurement Input | percent	5.4
Maximum [Member] | Pull-through Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Measurement Input | percent	1
Weighted Average | Option Adjusted Spread
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	600
Weighted Average | Conditional Prepayment Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	15.2
Weighted Average | Recapture Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	20
Weighted Average | Servicing Fee Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	29.5
Weighted Average | Cost to Service
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset, Measurement Input | percent	86
Weighted Average | Whole loan spread to TBA price in basis points
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Measurement Input | percent	(3.3)
Weighted Average | Servicing Fee Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Measurement Input | percent	4.6
Weighted Average | Pull-through Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Measurement Input | percent	90
Loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 45,500,000			$ 700,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	131,700,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(93,400,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	7,300,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3	(800,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	0
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	100,000
Servicing Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	698,000,000			1,347,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	763,800,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(1,270,700,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(2,500,000)
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	(19,500,000)
Realization of cash flows	(139,600,000)
Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	9,400,000			$ 23,700,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	23,045,400,000
IRLC, Settlements upon Acquisition or Origination	(23,054,300,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(5,400,000)
Fair Value, Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss)	$ 9,400,000
Junior Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.40%	2.64%
Percentage Of Basis Spread On Variable Rate	0.21%	0.24%
Junior Subordinated Debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 67,400,000	$ 65,900,000
Junior subordinated debt, Significant Unobservable Inputs	Implied credit rating of the Company	Implied credit rating of the Company
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	$ 11,700,000	$ 1,400,000
Collateral Dependent Loans, Net of Allowance	216,000,000	187,300,000
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Repossessed Assets	11,700,000	1,400,000
Collateral Dependent Loans, Net of Allowance	216,000,000	187,300,000
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Option, Loans Held as Assets, UPB	3,809,500,000
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Subordinated Debt Obligations, Fair Value Disclosure	$ 67,400,000	$ 65,900,000
Valuation Technique, Discounted Cash Flow [Member] | Junior Subordinated Debt [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Significant Unobservable Inputs	Discounted cash flow	Discounted cash flow

Fair Value Accounting Additiona

Fair Value Accounting Additional Details (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Other Repossessed Assets	$ 11.7	$ 1.4

Regulatory Capital Requirements

Regulatory Capital Requirements - Summary of Actual Capital Amount and Ratio (Detail)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Required to be Well Capitalized to Risk Weighted Assets	0.100	0.100
Capital Required for Capital Adequacy to Risk Weighted Assets	0.080	0.080
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.080	0.080
Tier 1 Capital Ratio	0.060	0.060
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	0.050	0.050
Common Equity Tier One Capital Required to be Well-Capitalized	$ 0.065	$ 0.065
Tier 1 Leverage Ratio	0.040	0.040
Common Equity Tier One Capital Required for Capital Adequacy	$ 0.045	$ 0.045
Consolidated Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	5,499,000,000	3,872,000,000
Tier 1 Capital	4,444,300,000	3,158,200,000
Risk-Weighted Assets	44,697,000,000	31,015,400,000
Tangible Average Assets	$ 56,972,900,000	$ 34,349,300,000
Capital to Risk Weighted Assets	0.123	0.125
Tier One Risk Based Capital to Risk Weighted Assets	0.099	0.102
Tier One Leverage Capital to Average Assets	0.078	0.092
Common Equity Tier One Capital Ratio	0.091	0.099
Western Alliance Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital	$ 5,119,900,000	$ 3,619,400,000
Tier 1 Capital	4,657,500,000	3,078,200,000
Risk-Weighted Assets	44,726,100,000	31,140,600,000
Tangible Average Assets	$ 56,961,600,000	$ 34,367,000,000
Capital to Risk Weighted Assets	0.114	0.116
Tier One Risk Based Capital to Risk Weighted Assets	0.104	0.099
Tier One Leverage Capital to Average Assets	0.082	0.090
Common Equity Tier One Capital Ratio	0.104	0.099

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Initial Percentage Of Discretionary Deferred Compensation	5.00%
Defined Contribution Plan Age Of Participants	50 years
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount	$ 19,500
Defined Contribution Plan Percentage Of Discretionary Deferred Compensation	100.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 12,000,000	$ 7,100,000	$ 6,200,000
Defined Benefit Plan, Benefit Obligation	13,100,000	13,600,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 1,100,000	$ 1,100,000	$ 1,100,000
Minimum [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Initial Percentage Of Discretionary Deferred Compensation	1.00%
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan Initial Percentage Of Discretionary Deferred Compensation	75.00%

Related Parties (Details)

Related Parties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Loans and Leases Receivable, Related Parties	$ 0	$ 3.3	$ 3.8
Origination of Notes Receivable from Related Parties	0	0
Loans and Leases Receivable Advances, Related Parties	0	0
Loans and Leases Receivable Repayments, Related Parties	(3.3)	(0.5)
Related Party Deposit Liabilities	101.3	156.9
Interest Expense, Related Party	0.2	0.2	0.3
Related Party Transaction, Expenses from Transactions with Related Party	1	1	1
Interest Income, Related Party	0.1	0.2	$ 0.2
Loan and Leases Receivable, Commitment Outstanding, Related Parties	$ 7	$ 10.3

Parent Company Parent Company B

Parent Company Parent Company Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	$ 516.4	$ 2,671.7		$ 434.6	$ 498.6
Debt Securities, Available-for-sale	6,188.8	4,708.5
Investment securities - equity	158.5	167.3
Other assets	987.2	392.1
Total assets	55,982.6	36,461
Qualifying debt	895.8	548.7
Total liabilities	51,020	33,047.5
Total stockholders’ equity	4,962.6	3,413.5	$ 2,991.8	3,016.7		$ 2,613.7
Total liabilities and stockholders’ equity	55,982.6	36,461
Consolidated Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents	79	55.5		$ 75.9	$ 115.7
Debt Securities, Available-for-sale	0.5	5.1
Investment securities - equity	41.5	49.8
Investment in bank subsidiaries	5,433.6	3,493.5
Investment in non-bank subsidiaries	66.6	49.9
Other assets	22.5	18
Total assets	5,643.7	3,671.8
Qualifying debt	673	251.5
Accrued interest and other liabilities	8	6.8
Total liabilities	681	258.3
Total stockholders’ equity	4,962.7	3,413.5
Total liabilities and stockholders’ equity	$ 5,643.7	$ 3,671.8

Parent Company Parent Company C

Parent Company Parent Company Condensed Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Non-interest income	$ 404,200	$ 70,800	$ 65,100
Interest expense	109,900	94,900	184,600
Non-interest expense	851,400	491,600	482,000
Income before income taxes and equity in undistributed earnings of subsidiaries		622,500	604,200
Income tax benefit	(223,800)	(115,900)	(105,000)
Net income	899,200	506,600	499,200
Preferred Stock Dividends, Income Statement Impact	3,500	0	0
Net income available to common stockholders	895,700	506,600	499,200
Consolidated Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from subsidiaries	50,000	160,000	134,000
Interest income	3,200	3,100	2,800
Non-interest income	13,400	4,700	5,100
Total income	66,600	167,800	141,900
Interest expense	19,500	10,600	14,600
Non-interest expense	31,900	19,700	19,500
Total expense	51,400	30,300	34,100
Income before income taxes and equity in undistributed earnings of subsidiaries	15,200	137,500	107,800
Income tax benefit	7,400	4,500	5,700
Income before equity in undistributed earnings of subsidiaries	22,600	142,000	113,500
Equity in undistributed earnings of subsidiaries	876,600	364,600	385,700
Net income	$ 899,200	$ 506,600	$ 499,200

Parent Company Parent Company_2

Parent Company Parent Company Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Payments of Dividends	$ 127.6	$ 101.3	$ 51.3
Net Income (Loss) Attributable to Parent	899.2	506.6	499.2
Gain (Loss) on Extinguishment of Debt	5.9	0	0
Other operating activities, net	16.3	9.4	5.1
Net cash provided by operating activities	(2,654)	670.2	717.8
Net cash used in investing activities	(14,711.9)	(7,537.5)	(3,723)
Payments for Repurchase of Common Stock	0	(71.6)	(120.2)
Proceeds from issuance of common stock in offerings, net	540.3	0	0
Net cash provided by financing activities	15,210.6	9,104.4	2,941.2
Net increase (decrease) in cash and cash equivalents	(2,155.3)	2,237.1	(64)
Cash and cash equivalents	516.4	2,671.7	434.6	$ 498.6
Interest	111.6	108.6	180.4
Change in unrealized gain (loss) on junior subordinated debt, net of tax	(1.2)	(3.1)	(9.8)
Consolidated Company [Member]
Condensed Financial Statements, Captions [Line Items]
Payments of Dividends	127.6	101.3	51.3
Proceeds from Issuance of Preferred Stock and Preference Stock	294.5	0	0
Net Income (Loss) Attributable to Parent	899.2	506.6	499.2
Equity in net undistributed earnings of subsidiaries	(876.6)	(364.6)	(385.7)
Increase (Decrease) in Other Current Liabilities	(0.1)	0	0
Gain (Loss) on Extinguishment of Debt	5.9	0	0
Other operating activities, net	(1.4)	8	9.9
Net cash provided by operating activities	27	150	123.4
Purchases of securities	(16)	(6.9)	(10.8)
Proceeds from Maturities, Prepayments and Calls of Other Investments	28.6	7.7	19
Capital contributions to subsidiaries	(1,139.3)	0	0
Other investing activities, net	0	1.2	0
Net cash used in investing activities	(1,126.7)	2	8.2
Net proceeds from issuance of long-term debt	591.9	0	0
Payments for Repurchase of Common Stock	0	(71.6)	(120.2)
Repayments of Other Debt	(176)	0	0
Proceeds from issuance of common stock in offerings, net	540.3	0	0
Proceeds from exercise of common stock options	0.1	0.5	0.1
Net cash provided by financing activities	1,123.2	(172.4)	(171.4)
Net increase (decrease) in cash and cash equivalents	23.5	(20.4)	(39.8)
Cash and cash equivalents	$ 79	$ 55.5	$ 75.9	$ 115.7

Segments - Operating Segment In

Segments - Operating Segment Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2020	Jan. 01, 2018
Operating Statistics [Line Items]
Service charges and fees	$ 28.3	$ 23.3	$ 23.3
Total assets	55,982.6	36,461
Cash, Cash Equivalents and Investment Securities	8,057.3	8,176.5
Financing Receivable, Held-for-Sale	5,635.1	0
Loans and Leases Receivable, Net of Deferred Income	39,075.4	27,053
Loans and Leases Receivable, Allowance	(252.5)	(278.9)
Loans, net	38,822.9	26,774.1
Loans and Leases Receivable Including Held for Sale, Net	38,822.9	26,774.1
Goodwill and intangible assets, net	634.8	298.5
Other Assets Segment	2,820.8	1,210.5
Total deposits	47,612	31,930.5
Total stockholders’ equity	4,962.6	3,413.5	3,016.7	$ 2,991.8	$ 2,613.7
Net interest income	1,548.8	1,166.9	1,040.4
Provision for Loan, Lease, and Other Losses	(21.4)	(123.6)	(19.3)
Net interest income after provision for (recovery of) credit losses	1,570.2	1,043.3	1,021.1
Non-interest income	404.2	70.8	65.1
Non-interest expense	(851.4)	(491.6)	(482)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	1,123	622.5	604.2
Income before income taxes and equity in undistributed earnings of subsidiaries		622.5	604.2
Income tax expense	223.8	115.9	105
Other Repossessed Assets	11.7	1.4
Other liabilities	1,026.9	563.3
Total liabilities	51,020	33,047.5
Total liabilities and stockholders’ equity	55,982.6	36,461
Excess Funds Provided by (Used in) Segment Basis	0	0
Other borrowings	2,381.1	553.7
Net income	899.2	506.6	499.2
Operating Segments [Member] | Commercial Segment
Operating Statistics [Line Items]
Total assets	25,439.5	20,548.9
Cash, Cash Equivalents and Investment Securities	12.9	12
Financing Receivable, Held-for-Sale	0
Loans and Leases Receivable, Net of Deferred Income	25,092.4	20,245.8
Loans and Leases Receivable, Allowance	226	263.4
Loans and Leases Receivable Including Held for Sale, Net	24,866.4	19,982.4
Goodwill and intangible assets, net	294.7	296.1
Other Assets Segment	253.8	257
Total deposits	30,466.8	21,448
Total stockholders’ equity	2,588	1,992.2
Net interest income	1,181.7	999.7	837.2
Provision for Loan, Lease, and Other Losses	(30.6)	(128.6)	(11.1)
Net interest income after provision for (recovery of) credit losses	1,212.3	871.1	826.1
Non-interest income	65.1	50.5	50.4
Non-interest expense	(415.9)	(308.9)	(320.6)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	861.5
Income before income taxes and equity in undistributed earnings of subsidiaries		612.7	555.9
Income tax expense	206.6	147.6	134.7
Other Repossessed Assets	11.7	1.4
Other liabilities	233.4	170.4
Total liabilities	30,700.2	21,618.4
Total liabilities and stockholders’ equity	33,288.2	23,610.6
Excess Funds Provided by (Used in) Segment Basis	(7,848.7)	(3,061.7)
Other borrowings	0	0
Net income	654.9	465.1	421.2
Operating Segments [Member] | Consumer Related Segment
Operating Statistics [Line Items]
Total assets	21,292.2	6,927.4
Cash, Cash Equivalents and Investment Securities	82.4	45.6
Financing Receivable, Held-for-Sale	5,635.1
Loans and Leases Receivable, Net of Deferred Income	13,983	6,798.2
Loans and Leases Receivable, Allowance	26.5	15.4
Loans and Leases Receivable Including Held for Sale, Net	13,956.5	6,782.8
Goodwill and intangible assets, net	340.1	2.4
Other Assets Segment	1,278.1	96.6
Total deposits	15,362.9	9,936.8
Total stockholders’ equity	1,596.2	579.1
Net interest income	603.4	302.5	209
Provision for Loan, Lease, and Other Losses	(11)	(9)	(7.4)
Net interest income after provision for (recovery of) credit losses	592.4	311.5	201.6
Non-interest income	317.6	1.6	1.4
Non-interest expense	(413.9)	(92.6)	(96.7)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	496.1
Income before income taxes and equity in undistributed earnings of subsidiaries		220.5	106.3
Income tax expense	120.1	52.3	24.8
Other Repossessed Assets	0	0
Other liabilities	138.2	3.3
Total liabilities	15,854.3	9,940.1
Total liabilities and stockholders’ equity	17,450.5	10,519.2
Excess Funds Provided by (Used in) Segment Basis	(3,841.7)	(3,591.8)
Other borrowings	353.2	0
Net income	376	168.2	81.5
Corporate & Other
Operating Statistics [Line Items]
Total assets	9,250.9	8,984.7
Cash, Cash Equivalents and Investment Securities	7,962	8,118.9
Financing Receivable, Held-for-Sale	0
Loans and Leases Receivable, Net of Deferred Income	0	9
Loans and Leases Receivable, Allowance	0	0.1
Loans and Leases Receivable Including Held for Sale, Net	0	8.9
Goodwill and intangible assets, net	0	0
Other Assets Segment	1,288.9	856.9
Total deposits	1,782.3	545.7
Total stockholders’ equity	778.4	842.2
Net interest income	(236.3)	(135.3)	(5.8)
Provision for Loan, Lease, and Other Losses	1.8	(4)	(0.8)
Net interest income after provision for (recovery of) credit losses	(234.5)	(139.3)	(6.6)
Non-interest income	21.5	18.7	13.3
Non-interest expense	(21.6)	(90.1)	(64.7)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(234.6)
Income before income taxes and equity in undistributed earnings of subsidiaries		(210.7)	(58)
Income tax expense	(102.9)	(84)	(54.5)
Other Repossessed Assets	0	0
Other liabilities	655.3	389.6
Total liabilities	4,465.5	1,489
Total liabilities and stockholders’ equity	5,243.9	2,331.2
Excess Funds Provided by (Used in) Segment Basis	4,007	6,653.5
Other borrowings	2,027.9	553.7
Net income	$ (131.7)	$ (126.7)	$ (3.5)

Revenue from Contracts with Cus

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Service charges and fees	$ 28.3	$ 23.3	$ 23.3
Non-interest income	404.2	70.8	65.1
Disaggregation of Revenue [Line Items]
Service charges and fees	28.3	23.3	23.3
Non-interest income	404.2	70.8	65.1
Revenue from Contracts with Customers	37.6	29.9	31.1
Operating Segments [Member] | Commercial Segment
Revenue from Contract with Customer [Abstract]
Non-interest income	65.1	50.5	50.4
Disaggregation of Revenue [Line Items]
Non-interest income	65.1	50.5	50.4
Operating Segments [Member] | Consumer Related Segment
Revenue from Contract with Customer [Abstract]
Non-interest income	317.6	1.6	1.4
Disaggregation of Revenue [Line Items]
Non-interest income	317.6	1.6	1.4
Corporate & Other
Revenue from Contract with Customer [Abstract]
Non-interest income	21.5	18.7	13.3
Disaggregation of Revenue [Line Items]
Non-interest income	$ 21.5	$ 18.7	$ 13.3

Quarterly Financial Data (Detai

Quarterly Financial Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Data Disclosure [Abstract]
Net income available to common stockholders	$ 895,700	$ 506,600	$ 499,200

Uncategorized Items - wal-20211

Label	Element	Value
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	$ 26,300,000
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	9,600,000
AOCI Attributable to Parent [Member]
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	25,000,000
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	(33,600,000)
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	58,600,000
Common Stock [Member]
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	0
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	$ 0
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	600,000
Shares, Issued	us-gaap_SharesIssued	102,500,000
Shares, Issued	us-gaap_SharesIssued	104,900,000
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation	us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation	200,000
Treasury Stock [Member]
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	$ 62,700,000
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	(53,100,000)
Share-based Payment Arrangement, Decrease for Tax Withholding Obligation	us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation	9,600,000
Additional Paid-in Capital [Member]
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	1,417,700,000
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	1,374,100,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	26,300,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	69,900,000
Retained Earnings [Member]
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	1,655,400,000
Stockholders' Equity Attributable to Parent	us-gaap_StockholdersEquity	1,282,700,000
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	499,200,000
Dividends, Common Stock, Cash	us-gaap_DividendsCommonStockCash	51,300,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	$ 50,300,000