Loans Held for Investment - Internal Risk Grading System under ASC 326 (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	$ 2,351,732	$ 4,696,852
Fiscal Year before Current Fiscal Year	4,488,246	1,736,838
Two Years before Current Fiscal Year	1,470,747	2,322,876
Three Years before Current Fiscal Year	1,973,635	1,254,797
Four Years before Current Fiscal Year	987,932	1,143,567
Prior	2,545,199	2,014,563
Revolving	1,277,291	1,121,488
Revolving Converted to Term During the Period	3,913	4,916
Total	15,098,695
Total	15,047,608	14,295,897
Fair value hedging relationships	(51,087)	(5,298)
Investor loans secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,521,418	3,088,930
Fiscal Year before Current Fiscal Year	3,051,298	1,320,289
Two Years before Current Fiscal Year	1,083,783	1,681,360
Three Years before Current Fiscal Year	1,407,348	865,841
Four Years before Current Fiscal Year	668,128	717,023
Prior	1,614,677	1,304,033
Revolving	5,594	10,152
Revolving Converted to Term During the Period	488	0
Total	9,352,734
Total	9,352,734	8,987,628
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,788,715
Total	2,788,715	2,771,137
Investor loans secured by real estate | CRE non-owner-occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	407,555	708,560
Fiscal Year before Current Fiscal Year	647,131	269,944
Two Years before Current Fiscal Year	229,618	393,097
Three Years before Current Fiscal Year	370,339	387,923
Four Years before Current Fiscal Year	331,235	218,388
Prior	754,385	730,736
Revolving	5,333	9,353
Revolving Converted to Term During the Period	0	0
Total	2,745,596
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	7,585	0
Prior	6,359	0
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	13,944
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	25,773	0
Four Years before Current Fiscal Year	0	0
Prior	2,914	2,998
Revolving	0	513
Revolving Converted to Term During the Period	488	0
Total	29,175
Total		29,288
Investor loans secured by real estate | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Total	6,188,086
Total	6,188,086	5,891,934
Investor loans secured by real estate | Multifamily | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,012,086	2,260,708
Fiscal Year before Current Fiscal Year	2,245,091	952,127
Two Years before Current Fiscal Year	809,115	1,199,505
Three Years before Current Fiscal Year	976,171	444,904
Four Years before Current Fiscal Year	314,160	479,029
Prior	821,575	554,067
Revolving	261	286
Revolving Converted to Term During the Period	0	0
Total	6,178,459
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	2,799	543
Four Years before Current Fiscal Year	0	0
Prior	754	765
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	9,627
Total		1,308
Investor loans secured by real estate | Construction and land
Financing Receivable, Credit Quality Indicator [Line Items]
Total	331,734
Total	331,734	277,640
Investor loans secured by real estate | Construction and land | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	95,161	119,532
Fiscal Year before Current Fiscal Year	152,872	97,721
Two Years before Current Fiscal Year	44,555	40,556
Three Years before Current Fiscal Year	26,790	12,415
Four Years before Current Fiscal Year	5,063	3,857
Prior	7,293	3,559
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	331,734
Total		277,640
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	44,199
Total	44,199	46,917
Investor loans secured by real estate | SBA secured by real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	6,616	130
Fiscal Year before Current Fiscal Year	130	497
Two Years before Current Fiscal Year	495	6,259
Three Years before Current Fiscal Year	5,476	9,074
Four Years before Current Fiscal Year	7,653	12,070
Prior	15,870	9,198
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	36,240
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	2,432	3,679
Prior	5,527	2,166
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	7,959
Total		8,188
Business loans secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	558,800
Fiscal Year before Current Fiscal Year	919,863
Two Years before Current Fiscal Year	297,889
Three Years before Current Fiscal Year	317,673
Four Years before Current Fiscal Year	177,786
Prior	664,890
Revolving	4,720
Revolving Converted to Term During the Period	0
Total	2,941,621
Total	2,941,621	2,700,579
Business loans secured by real estate | CRE non-owner-occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year		1,015,804
Fiscal Year before Current Fiscal Year		312,168
Two Years before Current Fiscal Year		352,224
Three Years before Current Fiscal Year		218,944
Four Years before Current Fiscal Year		259,808
Prior		533,240
Revolving		8,099
Revolving Converted to Term During the Period		292
Total		2,700,579
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Total	67,191
Total	67,191	69,184
Business loans secured by real estate | SBA secured by real estate | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	8,493	6,379
Fiscal Year before Current Fiscal Year	7,265	2,364
Two Years before Current Fiscal Year	2,342	7,331
Three Years before Current Fiscal Year	6,507	9,125
Four Years before Current Fiscal Year	5,214	10,734
Prior	30,616	24,627
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	60,437
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	1,377	2,690
Prior	5,377	3,810
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	6,754
Total		8,562
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,486,747
Total	2,486,747	2,251,014
Business loans secured by real estate | CRE owner-occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	506,736	853,044
Fiscal Year before Current Fiscal Year	760,398	273,469
Two Years before Current Fiscal Year	255,275	287,249
Three Years before Current Fiscal Year	255,040	161,636
Four Years before Current Fiscal Year	131,615	187,130
Prior	551,125	464,271
Revolving	4,720	6,738
Revolving Converted to Term During the Period	0	292
Total	2,464,909
Total		2,233,829
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	4,655	2,553
Three Years before Current Fiscal Year	2,479	6,074
Four Years before Current Fiscal Year	4,761	2,966
Prior	9,943	5,592
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	21,838
Total		17,185
Business loans secured by real estate | Franchise real estate secured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	387,683
Total	387,683	380,381
Business loans secured by real estate | Franchise real estate secured | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	43,571	156,381
Fiscal Year before Current Fiscal Year	152,200	36,335
Two Years before Current Fiscal Year	35,617	55,091
Three Years before Current Fiscal Year	53,647	40,047
Four Years before Current Fiscal Year	34,819	56,288
Prior	67,829	34,878
Revolving	0	1,361
Revolving Converted to Term During the Period	0	0
Total	387,683
Total		380,381
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	271,514	591,794
Fiscal Year before Current Fiscal Year	516,770	104,142
Two Years before Current Fiscal Year	88,872	289,238
Three Years before Current Fiscal Year	248,584	169,961
Four Years before Current Fiscal Year	141,980	164,717
Prior	211,878	107,053
Revolving	1,239,236	1,075,204
Revolving Converted to Term During the Period	3,425	4,624
Total	2,722,259
Total	2,722,259	2,506,733
Commercial loans | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,295,421
Total	2,295,421	2,103,112
Commercial loans | Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	194,470	425,683
Fiscal Year before Current Fiscal Year	361,430	79,635
Two Years before Current Fiscal Year	65,403	200,234
Three Years before Current Fiscal Year	170,883	117,471
Four Years before Current Fiscal Year	100,744	123,345
Prior	152,008	70,789
Revolving	1,232,369	1,032,053
Revolving Converted to Term During the Period	2,801	3,371
Total	2,280,108
Total		2,052,581
Commercial loans | Commercial and industrial | 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	323	146
Three Years before Current Fiscal Year	0	0
Four Years before Current Fiscal Year	0	0
Prior	0	152
Revolving	530	14,814
Revolving Converted to Term During the Period	0	178
Total	853
Total		15,290
Commercial loans | Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	893	1,772
Fiscal Year before Current Fiscal Year	2,122	0
Two Years before Current Fiscal Year	0	14
Three Years before Current Fiscal Year	3,527	2,683
Four Years before Current Fiscal Year	674	863
Prior	1,687	1,150
Revolving	5,557	27,684
Revolving Converted to Term During the Period	0	1,075
Total	14,460
Total		35,241
Commercial loans | Franchise non-real estate secured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	415,830
Total	415,830	392,576
Commercial loans | Franchise non-real estate secured | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	74,199	163,865
Fiscal Year before Current Fiscal Year	152,765	23,943
Two Years before Current Fiscal Year	22,624	85,206
Three Years before Current Fiscal Year	72,220	45,061
Four Years before Current Fiscal Year	37,442	23,672
Prior	41,084	31,163
Revolving	780	0
Revolving Converted to Term During the Period	0	0
Total	401,114
Total		372,910
Commercial loans | Franchise 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	1,589
Three Years before Current Fiscal Year	0	3,627
Four Years before Current Fiscal Year	2,151	13,346
Prior	12,565	1,104
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	14,716
Total		19,666
Commercial loans | SBA non-real estate secured
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11,008
Total	11,008	11,045
Commercial loans | SBA non-real estate secured | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	1,952	474
Fiscal Year before Current Fiscal Year	453	564
Two Years before Current Fiscal Year	522	1,292
Three Years before Current Fiscal Year	1,817	666
Four Years before Current Fiscal Year	732	2,806
Prior	3,955	2,148
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	9,431
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	137	339
Four Years before Current Fiscal Year	237	685
Prior	579	547
Revolving	0	653
Revolving Converted to Term During the Period	624	0
Total	1,577
Total		2,300
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	324
Fiscal Year before Current Fiscal Year	315	239
Two Years before Current Fiscal Year	203	54
Three Years before Current Fiscal Year	30	51
Four Years before Current Fiscal Year	38	2,019
Prior	53,754	70,237
Revolving	27,741	28,033
Revolving Converted to Term During the Period	0	0
Total	82,081
Total	82,081	100,957
Retail loans | Single family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total	77,951
Total	77,951	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	306	211
Two Years before Current Fiscal Year	181	0
Three Years before Current Fiscal Year	0	32
Four Years before Current Fiscal Year	29	2,008
Prior	52,537	68,759
Revolving	24,854	23,920
Revolving Converted to Term During the Period	0	0
Total	77,907
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	44	49
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	44
Total		49
Retail loans | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total	4,130
Total	4,130	5,665
Retail loans | Consumer | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Current Fiscal Year	0	11
Fiscal Year before Current Fiscal Year	9	28
Two Years before Current Fiscal Year	22	49
Three Years before Current Fiscal Year	27	19
Four Years before Current Fiscal Year	9	11
Prior	1,173	1,394
Revolving	2,887	4,113
Revolving Converted to Term During the Period	0	0
Total	4,127
Total		5,625
Retail loans | Consumer | 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	5
Three Years before Current Fiscal Year	3	0
Four Years before Current Fiscal Year	0	0
Prior	0	35
Revolving	0	0
Revolving Converted to Term During the Period	0	0
Total	$ 3
Total		$ 40