Loans and Leases Receivable and Allowance for Credit Losses on Loans and Leases - Schedule of Allowance for Credit Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 139,656	$ 156,530	$ 130,924	$ 137,804
Allowance for credit losses on FDIC PCD loans, net of charge-offs			2,576
Charge-offs	(30,020)	(21,484)	(69,713)	(45,935)
Recoveries	12,522	2,987	18,000	6,731
Provision (benefit) for credit losses on loans and leases	17,055	(7,836)	57,426	31,597
Ending balance	139,213	130,197	139,213	130,197
Commercial and industrial, including specialty lending
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	29,092	11,081	17,582	12,702
Allowance for credit losses on FDIC PCD loans, net of charge-offs			2,576
Charge-offs	(9,008)	(2,657)	(9,600)	(3,235)
Recoveries	6,034	76	6,439	1,129
Provision (benefit) for credit losses on loans and leases	(1,132)	6,631	7,989	4,535
Ending balance	24,986	15,131	24,986	15,131
Commercial and industrial, including specialty lending | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(9,008)		(9,600)
Multifamily
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	15,400	9,765	14,541	4,477
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	(1,999)	0	(3,447)	(1,990)
Recoveries	0	0	0	337
Provision (benefit) for credit losses on loans and leases	2,469	4,479	4,776	11,420
Ending balance	15,870	14,244	15,870	14,244
Multifamily | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(1,999)		(3,447)
Commercial real estate owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	10,215	4,745	6,454	3,213
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	(39)	0	(39)	0
Recoveries	0	0	34	49
Provision (benefit) for credit losses on loans and leases	187	1,475	3,914	2,958
Ending balance	10,363	6,220	10,363	6,220
Commercial real estate owner occupied | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	(39)		(39)
Commercial real estate non-owner occupied
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	13,495	8,880	11,219	6,210
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	0	(4,862)	(4,527)	(5,025)
Recoveries	0	31	27	43
Provision (benefit) for credit losses on loans and leases	2,324	7,283	9,100	10,104
Ending balance	15,819	11,332	15,819	11,332
Commercial real estate non-owner occupied | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		(4,527)
Construction
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	2,639	1,179	1,913	692
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	0	0	0	0
Recoveries	0	10	116	226
Provision (benefit) for credit losses on loans and leases	491	425	1,101	696
Ending balance	3,130	1,614	3,130	1,614
Construction | Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	0		0
Residential real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6,846	5,578	6,094	2,383
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	(42)	0	(69)	(4)
Recoveries	29	13	34	58
Provision (benefit) for credit losses on loans and leases	(31)	(138)	743	3,016
Ending balance	6,802	5,453	6,802	5,453
Manufactured housing
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4,338	4,080	4,430	4,278
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision (benefit) for credit losses on loans and leases	(258)	402	(350)	204
Ending balance	4,080	4,482	4,080	4,482
Installment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	57,631	111,222	68,691	103,849
Allowance for credit losses on FDIC PCD loans, net of charge-offs			0
Charge-offs	(18,932)	(13,965)	(52,031)	(35,681)
Recoveries	6,459	2,857	11,350	4,889
Provision (benefit) for credit losses on loans and leases	13,005	(28,393)	30,153	(1,336)
Ending balance	$ 58,163	$ 71,721	$ 58,163	$ 71,721