Loans Held for Investment - Collateral Dependent Loans by Collateral Type (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	$ 22,314	$ 14,037
Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	163	288
Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	441	1,536
Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,437	2,594
Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,224	5,304
Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	10,718	1,455
Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	251	113
Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	3,080	2,747
Investor loans secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	13,155	4,049
Investor loans secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,437	2,594
Investor loans secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	10,718	1,455
Investor loans secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	12,179	2,792
Investor loans secured by real estate | CRE non-owner-occupied | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | CRE non-owner-occupied | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | CRE non-owner-occupied | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,437	2,594
Investor loans secured by real estate | CRE non-owner-occupied | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | CRE non-owner-occupied | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	9,742	198
Investor loans secured by real estate | CRE non-owner-occupied | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | CRE non-owner-occupied | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	976	1,257
Investor loans secured by real estate | SBA secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | SBA secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | SBA secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | SBA secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | SBA secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	976	1,257
Investor loans secured by real estate | SBA secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Investor loans secured by real estate | SBA secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,582	7,226
Business loans secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	163	288
Business loans secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	441	1,536
Business loans secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	4,978	5,304
Business loans secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	98
Business loans secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	604	1,143
Business loans secured by real estate | SBA secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	163	288
Business loans secured by real estate | SBA secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	441	757
Business loans secured by real estate | SBA secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | SBA secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | SBA secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | SBA secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	98
Business loans secured by real estate | SBA secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	4,978	6,083
Business loans secured by real estate | CRE owner-occupied | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | CRE owner-occupied | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	779
Business loans secured by real estate | CRE owner-occupied | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | CRE owner-occupied | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	4,978	5,304
Business loans secured by real estate | CRE owner-occupied | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | CRE owner-occupied | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Business loans secured by real estate | CRE owner-occupied | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	3,566	2,747
Commercial loans | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	246	0
Commercial loans | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	240	0
Commercial loans | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	3,080	2,747
Commercial loans | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,816	2,040
Commercial loans | Commercial and industrial | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Commercial and industrial | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Commercial and industrial | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Commercial and industrial | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	246	0
Commercial loans | Commercial and industrial | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | Commercial and industrial | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	240	0
Commercial loans | Commercial and industrial | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,330	2,040
Commercial loans | Franchise non-real estate secured
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,086
Commercial loans | Franchise non-real estate secured | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Franchise non-real estate secured | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Franchise non-real estate secured | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Franchise non-real estate secured | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Franchise non-real estate secured | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Franchise non-real estate secured | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Franchise non-real estate secured | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,086
Commercial loans | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	664	707
Commercial loans | SBA non-real estate secured | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | SBA non-real estate secured | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | SBA non-real estate secured | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | SBA non-real estate secured | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | SBA non-real estate secured | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | SBA non-real estate secured | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Commercial loans | SBA non-real estate secured | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	664	707
Retail loans
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	11	15
Retail loans | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	11	15
Retail loans | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Single family residential
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	11	15
Retail loans | Single family residential | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Single family residential | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Single family residential | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Single family residential | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Single family residential | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0	0
Retail loans | Single family residential | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	11	15
Retail loans | Single family residential | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	$ 0	$ 0