Loans and Leases Receivable and Allowance for Credit Losses on Loans and Leases - Schedule of Loans and Leases Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans receivable, mortgage warehouse, at fair value	$ 1,755,758	$ 2,284,325
Loans receivable, PPP	2,195,902	3,250,008
Loans and leases receivable	10,118,855	9,018,298
Allowance for credit losses on loans and leases	(145,847)	(137,804)	$ (128,736)	$ (144,176)
Total loans and leases receivable, net of allowance for credit losses on loans and leases	13,924,668	14,414,827
Deferred (fees) costs and unamortized (discounts) premiums, net	(22,800)	(52,000)
Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	1,705,027	1,486,308
Allowance for credit losses on loans and leases	(7,437)	(4,477)	(8,026)	(12,620)
Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	161,024	198,981
Allowance for credit losses on loans and leases	(939)	(692)	(4,103)	(5,871)
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	466,423	334,730
Allowance for credit losses on loans and leases	(4,685)	(2,383)	(3,209)	(3,977)
Manufactured housing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	50,669	52,861
Allowance for credit losses on loans and leases	(4,342)	(4,278)	(4,800)	(5,190)
Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	1,897,706	1,744,475
Allowance for credit losses on loans and leases	(107,883)	(103,849)	$ (83,539)	$ (75,315)
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	7,704,057	6,886,232
Commercial | Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	1,705,027	1,486,308
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	3,995,802	3,424,783
Commercial | Commercial real estate owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	701,893	654,922
Commercial | Commercial real estate non-owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	1,140,311	1,121,238
Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	161,024	198,981
Commercial | Direct Finance Equipment Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	150,700	146,500
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	2,414,798	2,132,066
Consumer | Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	466,423	334,730
Consumer | Manufactured housing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	50,669	52,861
Consumer | Installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable	$ 1,897,706	$ 1,744,475