Fair Value Measurements - Estimated fair values and related carrying values of financial instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financial assets:
Securities held to maturity	$ 10,957	$ 4,163
Level I [Member]
Financial assets:
Cash and cash equivalents	55,791	39,228
Securities held to maturity	0	0
Securities available for sale	0	0
Loans held for sale	0
Loans, net	0	0
Bank owned life insurance	0	0
Accrued interest receivable	0	0
Interest rate cap	0	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 swaps	0	0
Level I [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	0
Level II [Member]
Financial assets:
Cash and cash equivalents	0	0
Securities held to maturity	10,957	4,163
Securities available for sale	352,618	374,571
Loans held for sale	669
Loans, net	0	0
Bank owned life insurance	23,761	23,273
Accrued interest receivable	5,030	5,204
Interest rate cap	287	73
Financial liabilities:
Deposits	1,090,406	1,040,016
Securities sold under agreements to repurchase	31,540	26,869
FHLB borrowings	63,655	85,033
Subordinated notes	5,168	5,157
Accrued interest payable	407	410
Interest rate swaps	733	370
Level II [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	3	39
Level III [Member]
Financial assets:
Cash and cash equivalents	0	0
Securities held to maturity	0	0
Securities available for sale	0	0
Loans held for sale	0
Loans, net	843,307	802,535
Bank owned life insurance	0	0
Accrued interest receivable	0	0
Interest rate cap	0	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 swaps	0	0
Level III [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	0
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	55,791	39,228
Securities held to maturity	10,727	4,207
Securities available for sale	352,618	374,571
Loans held for sale	669
Loans, net	834,690	794,635
Bank owned life insurance	23,761	23,273
Accrued interest receivable	5,030	5,204
Interest rate cap	287	73
Financial liabilities:
Deposits	1,091,505	1,040,800
Securities sold under agreements to repurchase	31,540	26,869
FHLB borrowings	63,500	85,000
Subordinated notes	5,155	5,155
Accrued interest payable	407	410
Interest rate swaps	733	370
Carrying Amount [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	3	39
Fair Value [Member]
Financial assets:
Cash and cash equivalents	55,791	39,228
Securities held to maturity	10,957	4,163
Securities available for sale	352,618	374,571
Loans held for sale	669
Loans, net	843,307	802,535
Bank owned life insurance	23,761	23,273
Accrued interest receivable	5,030	5,204
Interest rate cap	287	73
Financial liabilities:
Deposits	1,090,406	1,040,016
Securities sold under agreements to repurchase	31,540	26,869
FHLB borrowings	63,655	85,033
Subordinated notes	5,168	5,157
Accrued interest payable	407	410
Interest rate swaps	733	370
Fair Value [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	$ 3	$ 39