Fair Value - Summary of Carrying Value and Fair Values of the Bank's Financial Instruments (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Financial assets:
Securities available for sale	$ 146,600,000	$ 182,355,000
Securities held to maturity, fair value	48,980,000	49,731,000
Loans held for sale	0	0
Carrying amount
Financial assets:
Restricted equity securities	8,799,000	6,032,000
Carrying amount | Level 1
Financial assets:
Cash and due from banks, interest-bearing deposits in financial institutions	69,789,000	63,456,000
Federal funds sold		16,654,000
Carrying amount | Level 2
Financial assets:
Securities available for sale	146,600,000	182,355,000
Securities held to maturity, fair value	45,635,000	46,864,000
Loans held for sale	53,225,000	42,111,000
Accrued interest receivable	3,849,000	3,942,000
Bank owned life insurance	22,335,000	21,900,000
Other assets	352,000	460,000
Financial liabilities:
Federal Home Loan Bank advances	95,000,000	55,000,000
Accrued interest payable	305,000	212,000
Carrying amount | Level 3 Fair Value Measurements
Financial assets:
Loans, net of unearned income	974,530,000	935,251,000
Financial liabilities:
Deposits	1,091,495,000	1,128,723,000
Other liabilities	3,800,000	5,349,000
Fair value | Level 1
Financial assets:
Cash and due from banks, interest-bearing deposits in financial institutions	69,789,000	63,456,000
Federal funds sold		16,654,000
Fair value | Level 2
Financial assets:
Securities available for sale	146,600,000	182,355,000
Securities held to maturity, fair value	48,980,000	49,731,000
Loans held for sale	54,407,000	42,302,000
Accrued interest receivable	3,849,000	3,942,000
Bank owned life insurance	22,335,000	21,900,000
Other assets	352,000	460,000
Financial liabilities:
Federal Home Loan Bank advances	94,980,000	54,989,000
Accrued interest payable	305,000	212,000
Fair value | Level 3 Fair Value Measurements
Financial assets:
Loans, net of unearned income	974,551,000	934,628,000
Financial liabilities:
Deposits	1,050,801,000	1,088,758,000
Other liabilities	$ 3,800,000	$ 5,349,000