Loans and Allowance for Credit Losses on Loans - Amortized Cost Basis of Collateral-dependent Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans	$ 1,216	$ 1,974
Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans	25	29
Business Assets
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans	1,191	1,815
Unsecured
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans		130
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans	1,216	1,974
Commercial | Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans	25	29
Commercial | Business Assets
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans	$ 1,191	1,815
Commercial | Unsecured
Financing Receivable, Recorded Investment, Past Due [Line Items]
Collateral dependent loans		$ 130