Fair Values of Financial Instruments - Estimated Fair Value and Related Carrying Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Carrying Amount
Financial assets:
Cash and due from banks	$ 29,882	$ 36,295
Interest bearing deposits	23,221	27,586
Federal funds sold	31,587	31,230
Securities: Available for sale	104,652	106,256
Loans, net of allowance for credit losses	1,012,560	990,239
Accrued interest receivable	3,302	3,138
Federal Home Loan Bank stock	4,959	5,180
Atlantic Central Bankers stock	131	131
Other investments	2,849	2,838
Financial liabilities:
Deposits	1,020,724	1,006,781
Accrued interest payable	584	572
FHLB advances, notes payable, and financing leases	98,950	105,021
Unrecognized financial instruments:
Commitments to extend credit	185,758	184,376
Standby letters of credit	5,362	4,045
Estimated Fair Value
Financial assets:
Cash and due from banks	29,882	36,295
Interest bearing deposits	23,221	27,586
Federal funds sold	31,587	31,230
Securities: Available for sale	104,652	106,256
Loans, net of allowance for credit losses	1,005,188	976,636
Accrued interest receivable	3,302	3,138
Federal Home Loan Bank stock	4,959	5,180
Atlantic Central Bankers stock	131	131
Other investments	2,849	2,838
Financial liabilities:
Deposits	1,028,956	1,008,842
Accrued interest payable	584	572
FHLB advances, notes payable, and financing leases	103,966	109,260
Unrecognized financial instruments:
Commitments to extend credit	185,758	184,376
Standby letters of credit	$ 5,362	$ 4,045