Loans Held for Investment - Internal Risk Grading System under ASC 326 (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	$ 2,878,292	$ 4,696,852
Fiscal Year before Current Fiscal Year	4,350,441	1,736,838
Two Years before Current Fiscal Year	1,438,521	2,322,876
Three Years before Current Fiscal Year	1,871,484	1,254,797
Four Years before Current Fiscal Year	920,886	1,143,567
Prior	2,364,115	2,014,563
Revolving	1,149,463	1,121,488
Revolving Converted to Term During the Period	3,733	4,916
Total	14,976,935
Total	14,908,811	14,295,897
Fair value hedging relationships	(68,124)	(5,298)
Investor loans secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,855,166	3,088,930
Fiscal Year before Current Fiscal Year	3,003,157	1,320,289
Two Years before Current Fiscal Year	1,059,676	1,681,360
Three Years before Current Fiscal Year	1,328,120	865,841
Four Years before Current Fiscal Year	630,423	717,023
Prior	1,509,640	1,304,033
Revolving	388	10,152
Revolving Converted to Term During the Period	475	0
Total	9,387,045
Total	9,387,045	8,987,628
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,771,272
Total	2,771,272	2,771,137
Investor loans secured by real estate | CRE non-owner-occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	500,592	708,560
Fiscal Year before Current Fiscal Year	619,259	269,944
Two Years before Current Fiscal Year	223,908	393,097
Three Years before Current Fiscal Year	362,597	387,923
Four Years before Current Fiscal Year	318,172	218,388
Prior	711,998	730,736
Revolving	0	9,353
Revolving Converted to Term During the Period	0	0
Total	2,736,526
Total		2,718,001
Investor loans secured by real estate | CRE non-owner-occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	16,166
Three Years before Current Fiscal Year	0	7,682
Four Years before Current Fiscal Year	7,537	0
Prior	3,965	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	11,502
Total		23,848
Investor loans secured by real estate | CRE non-owner-occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	25,777
Three Years before Current Fiscal Year	16,393	0
Four Years before Current Fiscal Year	194	0
Prior	6,182	2,998
Revolving	0	513
Revolving Converted to Term During the Period	475	0
Total	23,244
Total		29,288
Investor loans secured by real estate | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,199,581
Total	6,199,581	5,891,934
Investor loans secured by real estate | Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,193,692	2,260,708
Fiscal Year before Current Fiscal Year	2,225,146	952,127
Two Years before Current Fiscal Year	796,705	1,199,505
Three Years before Current Fiscal Year	922,115	444,904
Four Years before Current Fiscal Year	292,670	479,029
Prior	759,311	554,067
Revolving	388	286
Revolving Converted to Term During the Period	0	0
Total	6,190,027
Total		5,890,626
Investor loans secured by real estate | Multifamily | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	6,074	0
Two Years before Current Fiscal Year	0	0
Three Years before Current Fiscal Year	2,732	543
Four Years before Current Fiscal Year	0	0
Prior	748	765
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	9,554
Total		1,308
Investor loans secured by real estate | Construction and land
Financing Receivable, Credit Quality Indicator [Line Items]
Total	373,194
Total	373,194	277,640
Investor loans secured by real estate | Construction and land | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	154,286	119,532
Fiscal Year before Current Fiscal Year	152,548	97,721
Two Years before Current Fiscal Year	38,569	40,556
Three Years before Current Fiscal Year	18,817	12,415
Four Years before Current Fiscal Year	1,853	3,857
Prior	7,121	3,559
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	373,194
Total		277,640
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	42,998
Total	42,998	46,917
Investor loans secured by real estate | SBA secured by real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	6,596	130
Fiscal Year before Current Fiscal Year	130	497
Two Years before Current Fiscal Year	494	6,259
Three Years before Current Fiscal Year	5,466	9,074
Four Years before Current Fiscal Year	7,575	12,070
Prior	14,833	9,198
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	35,094
Total		37,228
Investor loans secured by real estate | SBA secured by real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year		0
Fiscal Year before Current Fiscal Year		0
Two Years before Current Fiscal Year		0
Three Years before Current Fiscal Year		957
Four Years before Current Fiscal Year		0
Prior		544
Revolving		0
Revolving Converted to Term During the Period		0
Total		1,501
Investor loans secured by real estate | SBA secured by real estate | Substandard
Financing Receivable, Credit Quality Indicator [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	2,343
Four Years before Current Fiscal Year	2,422	3,679
Prior	5,482	2,166
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	7,904
Total		8,188
Business loans secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	657,576	1,015,804
Fiscal Year before Current Fiscal Year	892,203	312,168
Two Years before Current Fiscal Year	294,316	352,224
Three Years before Current Fiscal Year	308,706	218,944
Four Years before Current Fiscal Year	165,877	259,808
Prior	600,812	533,240
Revolving	5,510	8,099
Revolving Converted to Term During the Period	0	292
Total	2,925,000
Total	2,925,000	2,700,579
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	64,002
Total	64,002	69,184
Business loans secured by real estate | SBA secured by real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	10,015	6,379
Fiscal Year before Current Fiscal Year	7,038	2,364
Two Years before Current Fiscal Year	2,332	7,331
Three Years before Current Fiscal Year	6,486	9,125
Four Years before Current Fiscal Year	4,968	10,734
Prior	27,076	24,627
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	57,915
Total		60,560
Business loans secured by real estate | SBA secured by real estate | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year		0
Fiscal Year before Current Fiscal Year		0
Two Years before Current Fiscal Year		0
Three Years before Current Fiscal Year		0
Four Years before Current Fiscal Year		0
Prior		62
Revolving		0
Revolving Converted to Term During the Period		0
Total		62
Business loans secured by real estate | SBA secured by real estate | Substandard
Financing Receivable, Credit Quality Indicator [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	2,062
Four Years before Current Fiscal Year	1,362	2,690
Prior	4,725	3,810
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	6,087
Total		8,562
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,477,530
Total	2,477,530	2,251,014
Business loans secured by real estate | CRE owner-occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	589,994	853,044
Fiscal Year before Current Fiscal Year	737,861	273,469
Two Years before Current Fiscal Year	252,950	287,249
Three Years before Current Fiscal Year	248,513	161,636
Four Years before Current Fiscal Year	121,626	187,130
Prior	489,097	464,271
Revolving	5,510	6,738
Revolving Converted to Term During the Period	0	292
Total	2,445,551
Total		2,233,829
Business loans secured by real estate | CRE owner-occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0
Fiscal Year before Current Fiscal Year	0
Two Years before Current Fiscal Year	504
Three Years before Current Fiscal Year	0
Four Years before Current Fiscal Year	0
Prior	9,393
Revolving	0
Revolving Converted to Term During the Period	0
Total	9,897
Business loans secured by real estate | CRE owner-occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	4,656	2,553
Three Years before Current Fiscal Year	2,442	6,074
Four Years before Current Fiscal Year	4,718	2,966
Prior	10,266	5,592
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	22,082
Total		17,185
Business loans secured by real estate | Franchise real estate secured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	383,468
Total	383,468	380,381
Business loans secured by real estate | Franchise real estate secured | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	56,586	156,381
Fiscal Year before Current Fiscal Year	147,304	36,335
Two Years before Current Fiscal Year	33,874	55,091
Three Years before Current Fiscal Year	45,173	40,047
Four Years before Current Fiscal Year	33,203	56,288
Prior	60,255	34,878
Revolving	0	1,361
Revolving Converted to Term During the Period	0	0
Total	376,395
Total		380,381
Business loans secured by real estate | Franchise real estate secured | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	981
Fiscal Year before Current Fiscal Year	0
Two Years before Current Fiscal Year	0
Three Years before Current Fiscal Year	6,092
Four Years before Current Fiscal Year	0
Prior	0
Revolving	0
Revolving Converted to Term During the Period	0
Total	7,073
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	365,550	591,794
Fiscal Year before Current Fiscal Year	454,771	104,142
Two Years before Current Fiscal Year	84,332	289,238
Three Years before Current Fiscal Year	234,645	169,961
Four Years before Current Fiscal Year	124,563	164,717
Prior	201,860	107,053
Revolving	1,116,974	1,075,204
Revolving Converted to Term During the Period	3,258	4,624
Total	2,585,953
Total	2,585,953	2,506,733
Commercial loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,164,623
Total	2,164,623	2,103,112
Commercial loans | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	251,964	425,683
Fiscal Year before Current Fiscal Year	306,145	79,635
Two Years before Current Fiscal Year	61,872	200,234
Three Years before Current Fiscal Year	161,641	117,471
Four Years before Current Fiscal Year	90,096	123,345
Prior	149,371	70,789
Revolving	1,107,645	1,032,053
Revolving Converted to Term During the Period	2,601	3,371
Total	2,131,335
Total		2,052,581
Commercial loans | Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	15,375	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	146
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	152
Revolving	3,764	14,814
Revolving Converted to Term During the Period	0	178
Total	19,139
Total		15,290
Commercial loans | Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,437	1,772
Fiscal Year before Current Fiscal Year	1,132	0
Two Years before Current Fiscal Year	0	14
Three Years before Current Fiscal Year	4,899	2,683
Four Years before Current Fiscal Year	615	863
Prior	1,230	1,150
Revolving	4,786	27,684
Revolving Converted to Term During the Period	50	1,075
Total	14,149
Total		35,241
Commercial loans | Franchise non-real estate secured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	409,773
Total	409,773	392,576
Commercial loans | Franchise non-real estate secured | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	91,787	163,865
Fiscal Year before Current Fiscal Year	146,650	23,943
Two Years before Current Fiscal Year	19,005	85,206
Three Years before Current Fiscal Year	64,017	45,061
Four Years before Current Fiscal Year	32,914	23,672
Prior	35,933	31,163
Revolving	779	0
Revolving Converted to Term During the Period	0	0
Total	391,085
Total		372,910
Commercial loans | Franchise non-real estate secured | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,775	0
Fiscal Year before Current Fiscal Year	400	0
Two Years before Current Fiscal Year	2,983	1,589
Three Years before Current Fiscal Year	2,276	3,627
Four Years before Current Fiscal Year	0	13,346
Prior	11,254	1,104
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	18,688
Total		19,666
Commercial loans | SBA non-real estate secured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11,557
Total	11,557	11,045
Commercial loans | SBA non-real estate secured | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	3,212	474
Fiscal Year before Current Fiscal Year	444	564
Two Years before Current Fiscal Year	472	1,292
Three Years before Current Fiscal Year	1,679	666
Four Years before Current Fiscal Year	707	2,806
Prior	3,723	2,148
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	10,237
Total		7,950
Commercial loans | SBA non-real estate secured | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year		0
Fiscal Year before Current Fiscal Year		0
Two Years before Current Fiscal Year		681
Three Years before Current Fiscal Year		114
Four Years before Current Fiscal Year		0
Prior		0
Revolving		0
Revolving Converted to Term During the Period		0
Total		795
Commercial loans | SBA non-real estate secured | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	0
Fiscal Year before Current Fiscal Year	0	0
Two Years before Current Fiscal Year	0	76
Three Years before Current Fiscal Year	133	339
Four Years before Current Fiscal Year	231	685
Prior	349	547
Revolving	0	653
Revolving Converted to Term During the Period	607	0
Total	1,320
Total		2,300
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	324
Fiscal Year before Current Fiscal Year	310	239
Two Years before Current Fiscal Year	197	54
Three Years before Current Fiscal Year	13	51
Four Years before Current Fiscal Year	23	2,019
Prior	51,803	70,237
Revolving	26,591	28,033
Revolving Converted to Term During the Period	0	0
Total	78,937
Total	78,937	100,957
Retail loans | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total	75,176
Total	75,176	95,292
Retail loans | Single family residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	313
Fiscal Year before Current Fiscal Year	303	211
Two Years before Current Fiscal Year	178	0
Three Years before Current Fiscal Year	0	32
Four Years before Current Fiscal Year	23	2,008
Prior	50,648	68,759
Revolving	23,982	23,920
Revolving Converted to Term During the Period	0	0
Total	75,134
Total		95,243
Retail loans | Single family residential | Substandard
Financing Receivable, Credit Quality Indicator [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	42	49
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	42
Total		49
Retail loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	3,761
Total	3,761	5,665
Retail loans | Consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	11
Fiscal Year before Current Fiscal Year	7	28
Two Years before Current Fiscal Year	19	49
Three Years before Current Fiscal Year	13	19
Four Years before Current Fiscal Year	0	11
Prior	1,113	1,394
Revolving	2,609	4,113
Revolving Converted to Term During the Period	0	0
Total	$ 3,761
Total		5,625
Retail loans | Consumer | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year		0
Fiscal Year before Current Fiscal Year		0
Two Years before Current Fiscal Year		5
Three Years before Current Fiscal Year		0
Four Years before Current Fiscal Year		0
Prior		35
Revolving		0
Revolving Converted to Term During the Period		0
Total		$ 40