Commitments - Loans (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Commitments to originate loans
Loan Commitments
Commitment amount	$ 8.7	$ 7.9
Commitments to originate loans | Minimum
Loan Commitments
Interest rate (as a percent)	3.375%	4.125%
Commitments to originate loans | Maximum
Loan Commitments
Interest rate (as a percent)	4.00%	5.00%
Unused lines of credit to borrowers
Loan Commitments
Commitment amount	$ 24.5	$ 26.9