Allowance for Credit Losses - Amortized Cost of Loans by Estimated LTV and FICO Bands (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	$ 1,074,728	$ 4,696,852
Fiscal Year before Current Fiscal Year	4,657,598	1,736,838
Two Years before Current Fiscal Year	1,608,350	2,322,876
Three Years before Current Fiscal Year	2,154,680	1,254,797
Four Years before Current Fiscal Year	1,121,305	1,143,567
Prior	2,873,255	2,014,563
Revolving	1,241,092	1,121,488
Revolving Converted to Term During the Period	2,747	4,916
Total	14,733,755	14,295,897
Investor loans secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	690,589	3,088,930
Fiscal Year before Current Fiscal Year	3,083,122	1,320,289
Two Years before Current Fiscal Year	1,208,893	1,681,360
Three Years before Current Fiscal Year	1,546,339	865,841
Four Years before Current Fiscal Year	775,029	717,023
Prior	1,848,076	1,304,033
Revolving	10,140	10,152
Revolving Converted to Term During the Period	0	0
Total	9,162,188	8,987,628
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	2,774,650	2,771,137
Investor loans secured by real estate | CRE non-owner-occupied | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	80,360	366,617
Fiscal Year before Current Fiscal Year	370,848	141,752
Two Years before Current Fiscal Year	138,963	184,553
Three Years before Current Fiscal Year	182,092	171,879
Four Years before Current Fiscal Year	166,633	130,679
Prior	592,412	533,990
Revolving	9,854	9,866
Revolving Converted to Term During the Period	0	0
Total	1,541,162	1,539,336
Investor loans secured by real estate | CRE non-owner-occupied | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	88,510	277,092
Fiscal Year before Current Fiscal Year	238,821	91,539
Two Years before Current Fiscal Year	90,596	155,908
Three Years before Current Fiscal Year	154,776	86,933
Four Years before Current Fiscal Year	54,175	79,043
Prior	250,482	172,713
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	877,360	863,228
Investor loans secured by real estate | CRE non-owner-occupied | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	7,556	64,619
Fiscal Year before Current Fiscal Year	60,735	36,653
Two Years before Current Fiscal Year	27,529	58,350
Three Years before Current Fiscal Year	56,266	131,975
Four Years before Current Fiscal Year	130,804	5,662
Prior	27,166	25,446
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	310,056	322,705
Investor loans secured by real estate | CRE non-owner-occupied | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	232
Fiscal Year before Current Fiscal Year	229	0
Two Years before Current Fiscal Year	0	36,229
Three Years before Current Fiscal Year	36,128	4,818
Four Years before Current Fiscal Year	4,335	3,004
Prior	5,380	1,585
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	46,072	45,868
Investor loans secured by real estate | Multifamily
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	6,041,085	5,891,934
Investor loans secured by real estate | Multifamily | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	111,585	397,562
Fiscal Year before Current Fiscal Year	409,021	226,129
Two Years before Current Fiscal Year	197,947	285,520
Three Years before Current Fiscal Year	256,819	181,826
Four Years before Current Fiscal Year	169,113	197,276
Prior	449,182	279,880
Revolving	286	286
Revolving Converted to Term During the Period	0	0
Total	1,593,953	1,568,479
Investor loans secured by real estate | Multifamily | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	209,094	932,115
Fiscal Year before Current Fiscal Year	944,247	416,712
Two Years before Current Fiscal Year	367,310	510,840
Three Years before Current Fiscal Year	466,705	219,710
Four Years before Current Fiscal Year	194,097	185,773
Prior	348,010	198,802
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	2,529,463	2,463,952
Investor loans secured by real estate | Multifamily | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	142,824	906,910
Fiscal Year before Current Fiscal Year	896,113	306,272
Two Years before Current Fiscal Year	303,401	391,686
Three Years before Current Fiscal Year	353,096	41,174
Four Years before Current Fiscal Year	36,716	94,142
Prior	134,308	67,964
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	1,866,458	1,808,148
Investor loans secured by real estate | Multifamily | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	2,491	24,121
Fiscal Year before Current Fiscal Year	29,993	3,014
Two Years before Current Fiscal Year	3,000	11,459
Three Years before Current Fiscal Year	5,766	2,737
Four Years before Current Fiscal Year	0	1,838
Prior	9,961	8,186
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	51,211	51,355
Investor loans secured by real estate | Construction and land
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	303,811	277,640
Investor loans secured by real estate | Construction and land | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	46,203	116,575
Fiscal Year before Current Fiscal Year	129,135	95,293
Two Years before Current Fiscal Year	79,651	26,501
Three Years before Current Fiscal Year	10,675	4,172
Four Years before Current Fiscal Year	4,155	3,857
Prior	7,389	3,559
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	277,208	249,957
Investor loans secured by real estate | Construction and land | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	2,957
Fiscal Year before Current Fiscal Year	3,850	2,428
Two Years before Current Fiscal Year	0	5,095
Three Years before Current Fiscal Year	8,916	6,650
Four Years before Current Fiscal Year	4,872	0
Prior	0	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	17,638	17,130
Investor loans secured by real estate | Construction and land | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	8,960
Three Years before Current Fiscal Year	8,965	1,593
Four Years before Current Fiscal Year	0	0
Prior	0	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	8,965	10,553
Investor loans secured by real estate | Construction and land | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	0	0
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	42,642	46,917
Investor loans secured by real estate | SBA secured by real estate | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	1,966	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	632
Four Years before Current Fiscal Year	1,469	693
Prior	2,908	2,159
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	6,343	3,484
Investor loans secured by real estate | SBA secured by real estate | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	2,399
Three Years before Current Fiscal Year	2,392	1,950
Four Years before Current Fiscal Year	1,941	1,903
Prior	4,307	3,595
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	8,640	9,847
Investor loans secured by real estate | SBA secured by real estate | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	130
Fiscal Year before Current Fiscal Year	130	0
Two Years before Current Fiscal Year	0	2,767
Three Years before Current Fiscal Year	2,654	3,630
Four Years before Current Fiscal Year	3,113	4,444
Prior	7,158	4,346
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	13,055	15,317
Investor loans secured by real estate | SBA secured by real estate | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	497
Two Years before Current Fiscal Year	496	1,093
Three Years before Current Fiscal Year	1,089	6,162
Four Years before Current Fiscal Year	3,606	8,709
Prior	9,413	1,808
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	14,604	18,269
Business loans secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	281,024	1,015,804
Fiscal Year before Current Fiscal Year	994,405	312,168
Two Years before Current Fiscal Year	306,308	352,224
Three Years before Current Fiscal Year	342,773	218,944
Four Years before Current Fiscal Year	192,883	259,808
Prior	722,605	533,240
Revolving	4,719	8,099
Revolving Converted to Term During the Period	0	292
Total	2,844,717	2,700,579
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	68,466	69,184
Business loans secured by real estate | SBA secured by real estate | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	1,040	4,333
Fiscal Year before Current Fiscal Year	2,508	590
Two Years before Current Fiscal Year	589	1,821
Three Years before Current Fiscal Year	1,646	1,123
Four Years before Current Fiscal Year	962	4,512
Prior	17,411	14,850
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	24,156	27,229
Business loans secured by real estate | SBA secured by real estate | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	452
Fiscal Year before Current Fiscal Year	724	555
Two Years before Current Fiscal Year	555	199
Three Years before Current Fiscal Year	199	954
Four Years before Current Fiscal Year	1,454	1,524
Prior	9,264	8,497
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	12,196	12,181
Business loans secured by real estate | SBA secured by real estate | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	1,082
Fiscal Year before Current Fiscal Year	1,178	328
Two Years before Current Fiscal Year	327	3,478
Three Years before Current Fiscal Year	3,465	5,208
Four Years before Current Fiscal Year	647	4,853
Prior	7,823	2,793
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	13,440	17,742
Business loans secured by real estate | SBA secured by real estate | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	5,067	512
Fiscal Year before Current Fiscal Year	3,042	891
Two Years before Current Fiscal Year	886	1,833
Three Years before Current Fiscal Year	1,823	3,902
Four Years before Current Fiscal Year	3,585	2,535
Prior	4,271	2,359
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	18,674	12,032
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	2,391,984	2,251,014
Business loans secured by real estate | CRE owner-occupied | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	121,356	400,857
Fiscal Year before Current Fiscal Year	401,001	95,504
Two Years before Current Fiscal Year	109,427	107,766
Three Years before Current Fiscal Year	104,982	87,779
Four Years before Current Fiscal Year	79,468	134,184
Prior	450,860	347,926
Revolving	4,719	6,738
Revolving Converted to Term During the Period	0	292
Total	1,271,813	1,181,046
Business loans secured by real estate | CRE owner-occupied | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	59,295	214,798
Fiscal Year before Current Fiscal Year	202,766	67,639
Two Years before Current Fiscal Year	52,624	60,192
Three Years before Current Fiscal Year	63,290	32,283
Four Years before Current Fiscal Year	29,886	35,513
Prior	107,522	80,347
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	515,383	490,772
Business loans secured by real estate | CRE owner-occupied | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	60,334	188,022
Fiscal Year before Current Fiscal Year	190,253	78,589
Two Years before Current Fiscal Year	105,172	112,217
Three Years before Current Fiscal Year	103,746	41,874
Four Years before Current Fiscal Year	35,344	12,241
Prior	32,545	25,460
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	527,394	458,403
Business loans secured by real estate | CRE owner-occupied | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	9,217	49,367
Fiscal Year before Current Fiscal Year	36,626	31,737
Two Years before Current Fiscal Year	754	9,627
Three Years before Current Fiscal Year	9,569	5,774
Four Years before Current Fiscal Year	5,054	8,158
Prior	16,174	16,130
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	77,394	120,793
Business loans secured by real estate | Franchise real estate secured
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	384,267	380,381
Business loans secured by real estate | Franchise real estate secured | 55% and below
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	17,475	32,189
Fiscal Year before Current Fiscal Year	39,481	16,889
Two Years before Current Fiscal Year	16,725	8,954
Three Years before Current Fiscal Year	14,418	12,469
Four Years before Current Fiscal Year	12,385	9,163
Prior	23,380	14,552
Revolving	0	1,361
Revolving Converted to Term During the Period	0	0
Total	123,864	95,577
Business loans secured by real estate | Franchise real estate secured | >55-65%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	47,521
Fiscal Year before Current Fiscal Year	45,789	3,603
Two Years before Current Fiscal Year	11,986	10,270
Three Years before Current Fiscal Year	3,995	7,442
Four Years before Current Fiscal Year	7,313	4,749
Prior	12,726	9,349
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	81,809	82,934
Business loans secured by real estate | Franchise real estate secured | >65-75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	1,792	39,409
Fiscal Year before Current Fiscal Year	33,932	13,991
Two Years before Current Fiscal Year	5,426	32,743
Three Years before Current Fiscal Year	32,540	11,289
Four Years before Current Fiscal Year	9,235	29,641
Prior	35,728	9,768
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	118,653	136,841
Business loans secured by real estate | Franchise real estate secured | Greater than 75%
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	5,448	37,262
Fiscal Year before Current Fiscal Year	37,105	1,852
Two Years before Current Fiscal Year	1,837	3,124
Three Years before Current Fiscal Year	3,100	8,847
Four Years before Current Fiscal Year	7,550	12,735
Prior	4,901	1,209
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	59,941	65,029
Retail loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	324
Fiscal Year before Current Fiscal Year	319	239
Two Years before Current Fiscal Year	219	54
Three Years before Current Fiscal Year	41	51
Four Years before Current Fiscal Year	41	2,019
Prior	57,033	70,237
Revolving	27,482	28,033
Revolving Converted to Term During the Period	0	0
Total	85,135	100,957
Retail loans | Single family residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	79,978	95,292
Retail loans | Single family residential | Greater than 740
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	313
Fiscal Year before Current Fiscal Year	309	211
Two Years before Current Fiscal Year	194	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	1,446
Prior	30,820	40,605
Revolving	18,657	17,553
Revolving Converted to Term During the Period	0	0
Total	49,980	60,128
Retail loans | Single family residential | >680 - 740
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	32
Four Years before Current Fiscal Year	31	103
Prior	5,410	7,602
Revolving	4,278	5,579
Revolving Converted to Term During the Period	0	0
Total	9,719	13,316
Retail loans | Single family residential | >580 - 680
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	450
Prior	6,651	6,989
Revolving	755	756
Revolving Converted to Term During the Period	0	0
Total	7,406	8,195
Retail loans | Single family residential | Less than 580
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	9
Prior	12,842	13,612
Revolving	31	32
Revolving Converted to Term During the Period	0	0
Total	12,873	13,653
Retail loans | Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	5,157	5,665
Retail loans | Consumer | Greater than 740
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	7
Fiscal Year before Current Fiscal Year	7	28
Two Years before Current Fiscal Year	25	32
Three Years before Current Fiscal Year	26	19
Four Years before Current Fiscal Year	10	9
Prior	929	944
Revolving	1,847	2,196
Revolving Converted to Term During the Period	0	0
Total	2,844	3,235
Retail loans | Consumer | >680 - 740
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	4
Fiscal Year before Current Fiscal Year	3	0
Two Years before Current Fiscal Year	0	17
Three Years before Current Fiscal Year	11	0
Four Years before Current Fiscal Year	0	2
Prior	330	431
Revolving	1,852	1,859
Revolving Converted to Term During the Period	0	0
Total	2,196	2,313
Retail loans | Consumer | >580 - 680
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	5
Three Years before Current Fiscal Year	4	0
Four Years before Current Fiscal Year	0	0
Prior	51	54
Revolving	46	42
Revolving Converted to Term During the Period	0	0
Total	101	101
Retail loans | Consumer | Less than 580
Financing Receivable, Allowance for Credit Loss [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	0
Revolving	16	16
Revolving Converted to Term During the Period	0	0
Total	$ 16	$ 16