Loans - Aging of Past Due Loans by Class of Loans - Additional Information (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Aging of Past Due Loans by Class of Loans
Past due loans 30 day or greater	$ 15,315,000	$ 8,873,000
Nonaccrual loans - held-for-investment	8,675,000	13,699,000
30 days or greater past due nonaccrual loans	15,315,000	8,873,000
30 days or greater past due
Aging of Past Due Loans by Class of Loans
30 days or greater past due nonaccrual loans	7,413,000	430,000
Less than 30 days past due
Aging of Past Due Loans by Class of Loans
Less than 30 days past due nonaccrual loans held-for-investment	$ 1,262,000	$ 13,269,000