Fair Values of Financial Instruments - Estimated Fair Value and Related Carrying Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Carrying Amount
Financial assets:
Cash and due from banks	$ 31,483	$ 24,347
Interest bearing deposits	29,143	4,093
Federal funds sold	15,458	1,254
Securities: Available for sale	55,854	51,300
Loans, net of allowance for credit losses	626,607	625,513
Accrued interest receivable	2,098	2,103
Federal Home Loan Bank stock	2,761	2,652
Atlantic Central Bankers stock	131	131
Other investments	1,571	1,537
Financial liabilities:
Deposits	660,401	614,926
Accrued interest payable	567	392
FHLB advances and notes payable	55,495	56,989
Unrecognized financial instruments:
Commitments to extend credit	104,101	114,395
Standby letters of credit	1,853	3,276
Estimated Fair Value
Financial assets:
Cash and due from banks	31,483	24,347
Interest bearing deposits	29,143	4,093
Federal funds sold	15,458	1,254
Securities: Available for sale	55,854	51,300
Loans, net of allowance for credit losses	612,003	604,290
Accrued interest receivable	2,098	2,103
Federal Home Loan Bank stock	2,761	2,652
Atlantic Central Bankers stock	131	131
Other investments	1,571	1,537
Financial liabilities:
Deposits	629,813	570,509
Accrued interest payable	567	392
FHLB advances and notes payable	56,065	56,979
Unrecognized financial instruments:
Commitments to extend credit	104,101	114,395
Standby letters of credit	$ 1,853	$ 3,276