Loans Held for Investment - Nonaccrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	$ 22,314	$ 14,037
ACL	571	0
Non-Collateral Dependent Loans	12,776	15,172
ACL	0	126
Total Nonaccrual Loans	35,090	29,209
Nonaccrual Loans with No ACL	27,474	27,968
Investor loans secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	13,155	4,049
ACL	571	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	13,155	4,049
Nonaccrual Loans with No ACL	5,539	4,049
Investor loans secured by real estate \| CRE non-owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	12,179	2,792
ACL	571	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	12,179	2,792
Nonaccrual Loans with No ACL	4,563	2,792
Investor loans secured by real estate \| SBA secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	976	1,257
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	976	1,257
Nonaccrual Loans with No ACL	976	1,257
Business loans secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	5,582	7,226
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	5,582	7,226
Nonaccrual Loans with No ACL	5,582	7,226
Business loans secured by real estate \| SBA secured by real estate
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	604	1,143
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	604	1,143
Nonaccrual Loans with No ACL	604	1,143
Business loans secured by real estate \| CRE owner-occupied
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	4,978	6,083
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	4,978	6,083
Nonaccrual Loans with No ACL	4,978	6,083
Commercial loans
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	3,566	2,747
ACL	0	0
Non-Collateral Dependent Loans	12,776	15,172
ACL	0	126
Total Nonaccrual Loans	16,342	17,919
Nonaccrual Loans with No ACL	16,342	16,678
Commercial loans \| Commercial and industrial
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	1,816	2,040
ACL	0	0
Non-Collateral Dependent Loans	443	1,934
ACL	0	126
Total Nonaccrual Loans	2,259	3,974
Nonaccrual Loans with No ACL	2,259	2,733
Commercial loans \| Franchise non-real estate secured
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	1,086	0
ACL	0	0
Non-Collateral Dependent Loans	12,333	13,238
ACL	0	0
Total Nonaccrual Loans	13,419	13,238
Nonaccrual Loans with No ACL	13,419	13,238
Commercial loans \| SBA non-real estate secured
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	664	707
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	664	707
Nonaccrual Loans with No ACL	664	707
Retail loans
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	11	15
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	11	15
Nonaccrual Loans with No ACL	11	15
Retail loans \| Single family residential
Financing Receivable, Nonaccrual [Line Items]
Collateral Dependent Loans	11	15
ACL	0	0
Non-Collateral Dependent Loans	0	0
ACL	0	0
Total Nonaccrual Loans	11	15
Nonaccrual Loans with No ACL	$ 11	$ 15

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