Fair Value Measurements - Estimated fair values and related carrying values of financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial assets:
Securities held to maturity	$ 10,095	$ 4,163
Level I [Member]
Financial assets:
Cash and cash equivalents	28,544	39,228
Securities held to maturity	0	0
Securities available for sale	0	0
Loans, net	0	0
Bank owned life insurance	0	0
Accrued interest receivable	0	0
Interest rate contracts		0
Financial liabilities:
Deposits	0	0
Securities sold under agreements to repurchase	0	0
FHLB borrowings	0	0
Subordinated notes	0	0
Accrued interest payable	0	0
Interest rate contracts		0
Level II [Member]
Financial assets:
Cash and cash equivalents	0	0
Securities held to maturity	10,095	4,163
Securities available for sale	301,567	374,571
Loans, net	0	0
Bank owned life insurance	23,925	23,273
Accrued interest receivable	5,093	5,204
Interest rate contracts		73
Financial liabilities:
Deposits	1,051,245	1,040,016
Securities sold under agreements to repurchase	34,864	26,869
FHLB borrowings	39,530	85,033
Subordinated notes	5,159	5,157
Accrued interest payable	387	410
Interest rate contracts		370
Level III [Member]
Financial assets:
Cash and cash equivalents	0	0
Securities held to maturity	0	0
Securities available for sale	0	0
Loans, net	852,280	802,535
Bank owned life insurance	0	0
Accrued interest receivable	0	0
Interest rate contracts		0
Financial liabilities:
Deposits	0	0
Securities sold under agreements to repurchase	0	0
FHLB borrowings	0	0
Subordinated notes	0	0
Accrued interest payable	0	0
Interest rate contracts		0
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	28,544	39,228
Securities held to maturity	10,683	4,207
Securities available for sale	301,567	374,571
Loans, net	848,693	794,635
Bank owned life insurance	23,925	23,273
Accrued interest receivable	5,093	5,204
Interest rate contracts		73
Financial liabilities:
Deposits	1,053,058	1,040,800
Securities sold under agreements to repurchase	34,864	26,869
FHLB borrowings	39,500	85,000
Subordinated notes	5,155	5,155
Accrued interest payable	387	410
Interest rate contracts		370
Fair Value [Member]
Financial assets:
Cash and cash equivalents	28,544	39,228
Securities held to maturity	10,095	4,163
Securities available for sale	301,567	374,571
Loans, net	852,280	802,535
Bank owned life insurance	23,925	23,273
Accrued interest receivable	5,093	5,204
Interest rate contracts		73
Financial liabilities:
Deposits	1,051,245	1,040,016
Securities sold under agreements to repurchase	34,864	26,869
FHLB borrowings	39,530	85,033
Subordinated notes	5,159	5,157
Accrued interest payable	387	410
Interest rate contracts		370
Interest Rate Swap [Member] | Level I [Member]
Financial assets:
Interest rate contracts	0
Financial liabilities:
Interest rate contracts	0
Interest Rate Swap [Member] | Level II [Member]
Financial assets:
Interest rate contracts	44
Financial liabilities:
Interest rate contracts	242
Interest Rate Swap [Member] | Level III [Member]
Financial assets:
Interest rate contracts	0
Financial liabilities:
Interest rate contracts	0
Interest Rate Swap [Member] | Carrying Amount [Member]
Financial assets:
Interest rate contracts	44
Financial liabilities:
Interest rate contracts	242
Interest Rate Swap [Member] | Fair Value [Member]
Financial assets:
Interest rate contracts	44
Financial liabilities:
Interest rate contracts	242
Interest Rate Cap [Member] | Level I [Member]
Financial assets:
Interest rate contracts	0	0
Interest Rate Cap [Member] | Level II [Member]
Financial assets:
Interest rate contracts	9	39
Interest Rate Cap [Member] | Level III [Member]
Financial assets:
Interest rate contracts	0	0
Interest Rate Cap [Member] | Carrying Amount [Member]
Financial assets:
Interest rate contracts	9	39
Interest Rate Cap [Member] | Fair Value [Member]
Financial assets:
Interest rate contracts	$ 9	$ 39