Allowance for Credit Losses - Allocation of Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	$ 268,018	$ 35,698
Charge-offs	(1,952)	(1,436)
Recoveries	618	92
Provision for Credit Losses	315	25,382
Ending ACL Balance	266,999	115,422
Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		55,686
Provision for Credit Losses	25,400
Investor loans secured by real estate | CRE non-owner-occupied
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	49,176	1,899
Charge-offs	(154)	(387)
Recoveries	0	0
Provision for Credit Losses	(3,477)	5,961
Ending ACL Balance	45,545	15,896
Investor loans secured by real estate | CRE non-owner-occupied | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		8,423
Investor loans secured by real estate | Multifamily
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	62,534	729
Charge-offs	0	0
Recoveries	0	0
Provision for Credit Losses	17,281	4,819
Ending ACL Balance	79,815	14,722
Investor loans secured by real estate | Multifamily | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		9,174
Investor loans secured by real estate | Construction and land
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	12,435	4,484
Charge-offs	0	0
Recoveries	0	0
Provision for Credit Losses	828	4,862
Ending ACL Balance	13,263	9,222
Investor loans secured by real estate | Construction and land | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		(124)
Investor loans secured by real estate | SBA secured by real estate
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	5,159	1,915
Charge-offs	(265)	0
Recoveries	0	0
Provision for Credit Losses	247	421
Ending ACL Balance	5,141	935
Investor loans secured by real estate | SBA secured by real estate | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		(1,401)
Business loans secured by real estate | SBA secured by real estate
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	6,567	2,119
Charge-offs	(98)	(315)
Recoveries	0	71
Provision for Credit Losses	(18)	(38)
Ending ACL Balance	6,451	4,044
Business loans secured by real estate | SBA secured by real estate | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		2,207
Business loans secured by real estate | CRE owner-occupied
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	50,517	2,781
Charge-offs	0	0
Recoveries	15	12
Provision for Credit Losses	(8,938)	3,834
Ending ACL Balance	41,594	26,793
Business loans secured by real estate | CRE owner-occupied | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		20,166
Business loans secured by real estate | Franchise real estate secured
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	11,451	592
Charge-offs	0	0
Recoveries	0	0
Provision for Credit Losses	(575)	1,712
Ending ACL Balance	10,876	7,503
Business loans secured by real estate | Franchise real estate secured | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		5,199
Commercial loans | Commercial and industrial
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	46,964	13,857
Charge-offs	(1,279)	(490)
Recoveries	601	5
Provision for Credit Losses	(2,913)	2,283
Ending ACL Balance	43,373	15,742
Commercial loans | Commercial and industrial | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		87
Commercial loans | Franchise non-real estate secured
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	20,525	5,816
Charge-offs	(156)	0
Recoveries	0	0
Provision for Credit Losses	(1,466)	1,586
Ending ACL Balance	18,903	16,616
Commercial loans | Franchise non-real estate secured | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		9,214
Commercial loans | SBA non-real estate secured
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	995	445
Charge-offs	0	(236)
Recoveries	2	4
Provision for Credit Losses	(107)	85
Ending ACL Balance	890	516
Commercial loans | SBA non-real estate secured | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		218
Retail loans | Single family residential
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	1,204	655
Charge-offs	0	0
Recoveries	0	0
Provision for Credit Losses	(382)	(59)
Ending ACL Balance	822	1,137
Retail loans | Single family residential | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		541
Retail loans | Consumer
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance	491	406
Charge-offs	0	(8)
Recoveries	0	0
Provision for Credit Losses	(165)	(84)
Ending ACL Balance	$ 326	2,296
Retail loans | Consumer | Cumulative effect of the change in accounting principle
Allocation of allowance as well as the activity in allowance
Beginning ACL Balance		$ 1,982