Borrowed Funds and Mandatorily Redeemable Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) note	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Borrowed funds and mandatorily redeemable securities
Total long-term debt and mandatorily redeemable securities	$ 81,864	$ 71,639
Annual maturities of long-term debt
2021	3,168
2022	4,830
2023	2,049
2024	11,187
2025	145
Thereafter	60,485
Mandatorily redeemable securities
Interest expense	2,140	2,220	$ 1,610
Securities subject to mandatory redemption
Borrowed funds and mandatorily redeemable securities
Mandatorily redeemable securities	20,358	17,972
Federal Home Loan Bank borrowings
Borrowed funds and mandatorily redeemable securities
Long-term debt	$ 55,183	45,819
Annual maturities of long-term debt
Number of Federal Home Loan Bank borrowings, fixed rate notes | note	18
Collateral security	$ 68,950
Other long-term debt
Borrowed funds and mandatorily redeemable securities
Long-term debt	$ 6,323	$ 7,848
Minimum | Federal Home Loan Bank borrowings
Borrowed funds and mandatorily redeemable securities
Interest rate on Federal Home Loan Bank borrowings (as a percent)	0.54%
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%