Loans and Allowance for Credit Losses on Loans - Aging of Past Due Loans by Class of Loans - Additional Information (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Aging of Past Due Loans by Class of Loans
Past due loans 30 day or greater	$ 9,516,000	$ 6,229,000
30 days or greater past due
Aging of Past Due Loans by Class of Loans
Nonaccrual loans	1,658,000	1,918,000
Less than 30 days past due
Aging of Past Due Loans by Class of Loans
Nonaccrual loans	$ 3,633,000
Less than 30 days past due nonaccrual loans held-for-investment		$ 5,870,000