Loans Held for Investment - Delinquencies (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	$ 13,044,395	$ 13,318,571
Basis adjustment associated with fair value hedge
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	13,044,395	13,318,571
Basis adjustment associated with fair value hedge	32,324	29,551
Current
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	13,032,217	13,308,517
30-59
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,983	2,484
60-89
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	974	1,294
90+
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	9,221	6,276
Investor loans secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	8,390,158	8,576,026
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,309,252	2,421,772
Investor loans secured by real estate | Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	5,558,966	5,645,310
Investor loans secured by real estate | Construction and land
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	486,734	472,544
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	35,206	36,400
Investor loans secured by real estate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	8,388,961	8,575,194
Investor loans secured by real estate | Current | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,308,852	2,421,360
Investor loans secured by real estate | Current | Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	5,558,966	5,645,310
Investor loans secured by real estate | Current | Construction and land
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	486,734	472,544
Investor loans secured by real estate | Current | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	34,409	35,980
Investor loans secured by real estate | 30-59
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 30-59 | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 30-59 | Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 30-59 | Construction and land
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 30-59 | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 60-89
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	381	0
Investor loans secured by real estate | 60-89 | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 60-89 | Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 60-89 | Construction and land
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 60-89 | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	381	0
Investor loans secured by real estate | 90+
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	816	832
Investor loans secured by real estate | 90+ | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	400	412
Investor loans secured by real estate | 90+ | Multifamily
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 90+ | Construction and land
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Investor loans secured by real estate | 90+ | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	416	420
Business loans secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,492,726	2,546,589
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	48,426	50,741
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,149,362	2,191,334
Business loans secured by real estate | Franchise real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	294,938	304,514
Business loans secured by real estate | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,487,806	2,541,505
Business loans secured by real estate | Current | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	48,426	50,604
Business loans secured by real estate | Current | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,144,734	2,186,679
Business loans secured by real estate | Current | Franchise real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	294,646	304,222
Business loans secured by real estate | 30-59
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	429
Business loans secured by real estate | 30-59 | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	137
Business loans secured by real estate | 30-59 | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Business loans secured by real estate | 30-59 | Franchise real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	292
Business loans secured by real estate | 60-89
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Business loans secured by real estate | 60-89 | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Business loans secured by real estate | 60-89 | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Business loans secured by real estate | 60-89 | Franchise real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Business loans secured by real estate | 90+
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	4,920	4,655
Business loans secured by real estate | 90+ | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Business loans secured by real estate | 90+ | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	4,628	4,655
Business loans secured by real estate | 90+ | Franchise real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	292	0
Commercial loans
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,087,328	2,121,255
Commercial loans | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,774,487	1,790,608
Commercial loans | Franchise non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	301,895	319,721
Commercial loans | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	10,946	10,926
Commercial loans | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	2,081,285	2,117,136
Commercial loans | Current | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,770,803	1,788,855
Commercial loans | Current | Franchise non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	300,336	318,162
Commercial loans | Current | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	10,146	10,119
Commercial loans | 30-59
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,983	2,036
Commercial loans | 30-59 | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,729	228
Commercial loans | 30-59 | Franchise non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	1,559
Commercial loans | 30-59 | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	254	249
Commercial loans | 60-89
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	575	1,294
Commercial loans | 60-89 | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	575	1,294
Commercial loans | 60-89 | Franchise non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Commercial loans | 60-89 | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Commercial loans | 90+
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	3,485	789
Commercial loans | 90+ | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,380	231
Commercial loans | 90+ | Franchise non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,559	0
Commercial loans | 90+ | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	546	558
Retail loans
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	74,183	74,701
Retail loans | Single family residential
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	72,353	72,752
Retail loans | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,830	1,949
Retail loans | Current
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	74,165	74,682
Retail loans | Current | Single family residential
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	72,335	72,733
Retail loans | Current | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	1,830	1,949
Retail loans | 30-59
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	19
Retail loans | 30-59 | Single family residential
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	19
Retail loans | 30-59 | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Retail loans | 60-89
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	18	0
Retail loans | 60-89 | Single family residential
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	18	0
Retail loans | 60-89 | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Retail loans | 90+
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Retail loans | 90+ | Single family residential
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	0	0
Retail loans | 90+ | Consumer
Financing Receivable, Past Due [Line Items]
Loans held for investment before basis adjustment	$ 0	$ 0