Borrowed Funds and Mandatorily Redeemable Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) note	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Borrowed funds and mandatorily redeemable securities
Total long-term debt and mandatorily redeemable securities	$ 71,639	$ 71,123
Annual maturities of long-term debt
2020	2,759
2021	3,047
2022	4,709
2023	1,928
2024	11,065
Thereafter	48,131
Mandatorily redeemable securities
Interest expense	2,220	1,610	$ 1,680
Securities subject to mandatory redemption
Borrowed funds and mandatorily redeemable securities
Mandatorily redeemable securities	17,972	16,542
Federal Home Loan Bank borrowings
Borrowed funds and mandatorily redeemable securities
Long-term debt	$ 45,819	46,444
Annual maturities of long-term debt
Number of Federal Home Loan Bank borrowings, fixed rate notes | note	17
Collateral security	$ 57,250
Other long-term debt
Borrowed funds and mandatorily redeemable securities
Long-term debt	$ 7,848	$ 8,137
Minimum | Federal Home Loan Bank borrowings
Borrowed funds and mandatorily redeemable securities
Interest rate on Federal Home Loan Bank borrowings (as a percent)	1.04%
Maximum | Federal Home Loan Bank borrowings
Borrowed funds and mandatorily redeemable securities
Interest rate on Federal Home Loan Bank borrowings (as a percent)	5.04%