Fair Value Measurements - Estimated Fair Values of Company's Financial Instruments (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Financial assets
Cash and cash equivalents	$ 91,407,000	$ 51,592,000
Loans, net of allowance	457,996,000	438,378,000
Federal Home Loan Bank stock	3,704,000	4,177,000
Accrued interest receivable	2,206,000	2,901,000
Financial liabilities
Deposits	608,508,000	579,535,000
Short term borrowings	18,280,000	12,705,000
Subordinated debentures	23,650,000	23,604,000
Interest payable	524,000	224,000
Fair Value, Inputs, Level 1
Financial assets
Cash and cash equivalents	91,407,000	51,592,000
Fair Value, Inputs, Level 2
Financial assets
Federal Home Loan Bank stock	3,707,000	4,177,000
Accrued interest receivable	2,206,000	2,901,000
Financial liabilities
Deposits	608,460,000	580,130,000
Short term borrowings	18,280,000	12,705,000
Subordinated debentures	24,211,000	21,989,000
Interest payable	524,000	224,000
Fair Value, Inputs, Level 3
Financial assets
Loans, net of allowance	$ 463,636,000	$ 436,893,000