Fair Value Measurements - Estimated fair values and related carrying values of financial instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financial assets:
Securities held to maturity	$ 9,209	$ 4,163
Level I [Member]
Financial assets:
Cash and cash equivalents	65,721	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 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	9,209	4,163
Securities available for sale	377,025	374,571
Loans, net	0	0
Bank owned life insurance	23,434	23,273
Accrued interest receivable	5,172	5,204
Interest rate cap	242	73
Financial liabilities:
Deposits	1,083,820	1,040,016
Securities sold under agreements to repurchase	25,294	26,869
FHLB borrowings	95,155	85,033
Subordinated notes	5,163	5,157
Accrued interest payable	393	410
Interest rate swaps	766	370
Level II [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	12	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, net	823,904	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	65,721	39,228
Securities held to maturity	9,227	4,207
Securities available for sale	377,025	374,571
Loans, net	813,221	794,635
Bank owned life insurance	23,434	23,273
Accrued interest receivable	5,172	5,204
Interest rate cap	242	73
Financial liabilities:
Deposits	1,083,898	1,040,800
Securities sold under agreements to repurchase	25,294	26,869
FHLB borrowings	95,000	85,000
Subordinated notes	5,155	5,155
Accrued interest payable	393	410
Interest rate swaps	766	370
Carrying Amount [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	12	39
Fair Value [Member]
Financial assets:
Cash and cash equivalents	65,721	39,228
Securities held to maturity	9,209	4,163
Securities available for sale	377,025	374,571
Loans, net	823,904	802,535
Bank owned life insurance	23,434	23,273
Accrued interest receivable	5,172	5,204
Interest rate cap	242	73
Financial liabilities:
Deposits	1,083,820	1,040,016
Securities sold under agreements to repurchase	25,294	26,869
FHLB borrowings	95,155	85,033
Subordinated notes	5,163	5,157
Accrued interest payable	393	410
Interest rate swaps	766	370
Fair Value [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	$ 12	$ 39