Loans Held for Investment - Collateral Dependent Loans by Collateral Type (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	$ 17,682
Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	304
Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,559
Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,636
Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,304
Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,466
Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,367
Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,046
Investor loans secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	4,997
Investor loans secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,636
Investor loans secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,466
Investor loans secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	895
Investor loans secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | CRE non-owner-occupied
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,838
Investor loans secured by real estate | CRE non-owner-occupied | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | CRE non-owner-occupied | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | CRE non-owner-occupied | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	2,636
Investor loans secured by real estate | CRE non-owner-occupied | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | CRE non-owner-occupied | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	202
Investor loans secured by real estate | CRE non-owner-occupied | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | CRE non-owner-occupied | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Construction and land
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	895
Investor loans secured by real estate | Construction and land | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Construction and land | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Construction and land | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Construction and land | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Construction and land | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | Construction and land | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	895
Investor loans secured by real estate | Construction and land | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,264
Investor loans secured by real estate | SBA secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | SBA secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | SBA secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | SBA secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | SBA secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,264
Investor loans secured by real estate | SBA secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Investor loans secured by real estate | SBA secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	7,189
Business loans secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	304
Business loans secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,559
Business loans secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,304
Business loans secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	22
Business loans secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | SBA secured by real estate
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	1,084
Business loans secured by real estate | SBA secured by real estate | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	304
Business loans secured by real estate | SBA secured by real estate | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	758
Business loans secured by real estate | SBA secured by real estate | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | SBA secured by real estate | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | SBA secured by real estate | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | SBA secured by real estate | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	22
Business loans secured by real estate | SBA secured by real estate | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | CRE owner-occupied
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	6,105
Business loans secured by real estate | CRE owner-occupied | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | CRE owner-occupied | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	801
Business loans secured by real estate | CRE owner-occupied | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | CRE owner-occupied | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,304
Business loans secured by real estate | CRE owner-occupied | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | CRE owner-occupied | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Business loans secured by real estate | CRE owner-occupied | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,046
Commercial loans | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	5,046
Commercial loans | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	4,309
Commercial loans | Commercial and industrial | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Commercial and industrial | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Commercial and industrial | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Commercial and industrial | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Commercial and industrial | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Commercial and industrial | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | Commercial and industrial | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	4,309
Commercial loans | SBA non-real estate secured
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	737
Commercial loans | SBA non-real estate secured | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | SBA non-real estate secured | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | SBA non-real estate secured | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | SBA non-real estate secured | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | SBA non-real estate secured | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | SBA non-real estate secured | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Commercial loans | SBA non-real estate secured | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	737
Retail loans
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	450
Retail loans | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	450
Retail loans | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Single family residential
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	450
Retail loans | Single family residential | Office Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Single family residential | Industrial Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Single family residential | Retail Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Single family residential | Land Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Single family residential | Hotel Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	0
Retail loans | Single family residential | Residential Properties
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	450
Retail loans | Single family residential | Business Assets
Financing Receivable, Past Due [Line Items]
Collateral dependent loans	$ 0