Fair Value Measurements - Estimated fair values and related carrying values of financial instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financial assets:
Securities held to maturity	$ 1,375	$ 1,397
Level I [Member]
Financial assets:
Cash and cash equivalents	39,779	55,022
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 debt	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	1,375	1,397
Securities available for sale	372,779	348,263
Loans, net	4,351	1,289
Bank owned life insurance	23,107	22,617
Accrued interest receivable	5,007	4,285
Interest rate cap	136	50
Financial liabilities:
Deposits	1,032,511	989,563
Securities sold under agreements to repurchase	24,468	38,551
FHLB borrowings	60,022	55,042
Subordinated debt	5,157	5,159
Accrued interest payable	396	403
Interest rate swaps	619	337
Level II [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	35
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	777,115	750,283
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 debt	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	39,779	55,022
Securities held to maturity	1,500	1,500
Securities available for sale	372,779	348,263
Loans, net	769,467	743,060
Bank owned life insurance	23,107	22,617
Accrued interest receivable	5,007	4,285
Interest rate cap	136	50
Financial liabilities:
Deposits	1,032,353	989,080
Securities sold under agreements to repurchase	24,468	38,551
FHLB borrowings	60,000	55,000
Subordinated debt	5,155	5,155
Accrued interest payable	396	403
Interest rate swaps	619	337
Carrying Amount [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	35
Fair Value [Member]
Financial assets:
Cash and cash equivalents	39,779	55,022
Securities held to maturity	1,375	1,397
Securities available for sale	372,779	348,263
Loans, net	781,466	751,572
Bank owned life insurance	23,107	22,617
Accrued interest receivable	5,007	4,285
Interest rate cap	136	50
Financial liabilities:
Deposits	1,032,511	989,563
Securities sold under agreements to repurchase	24,468	38,551
FHLB borrowings	60,022	55,042
Subordinated debt	5,157	5,159
Accrued interest payable	396	403
Interest rate swaps	619	$ 337
Fair Value [Member] | Interest rate cap [Member]
Financial assets:
Interest rate cap	$ 35