Fair Value of Financial Instruments - Carrying values and estimated fair values of financial instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Carrying values and estimated fair values of financial instruments:
Prepayments of principal amount of loans assumed	$ 0
Financial assets:
Cash and cash equivalents	14,014	$ 30,077	$ 28,119	$ 39,843
Certificates of deposit with other banks	11,659	11,907
Securities available-for-sale	65,855	68,213
Securities held-to-maturity	53,441	55,871
Financial liabilities:
FHLB and other borrowings	178,245	101,287
Level I
Financial assets:
Cash and cash equivalents	14,014	30,077
Securities available-for-sale	73	77
Level II
Financial assets:
Certificates of deposit with other banks	11,891	12,035
Securities available-for-sale	65,782	68,136
Securities held-to-maturity	53,441	55,871
Loans held for sale	116,307	69,527
Accrued interest receivable	668	728
Financial liabilities:
Deposits	894,979	824,078
Repurchase agreements	26,263	32,673
FHLB and other borrowings	178,264	101,338
Accrued interest payable	437	376
Subordinated debt	31,172	31,172
Level III
Financial assets:
Loans, net	912,331	803,036
Mortgage servicing rights	1,262	1,423
Accrued interest receivable	2,255	1,659
Carrying Value
Financial assets:
Cash and cash equivalents	14,014	30,077
Certificates of deposit with other banks	11,659	11,907
Securities available-for-sale	65,855	68,213
Securities held-to-maturity	53,141	54,538
Loans held for sale	116,307	69,527
Loans, net	904,038	792,074
Mortgage servicing rights	1,262	1,423
Accrued interest receivable	2,923	2,387
Financial liabilities:
Deposits	890,969	823,227
Repurchase agreements	26,263	32,673
FHLB and other borrowings	178,245	101,287
Accrued interest payable	437	376
Subordinated debt	33,524	33,524
Total
Financial assets:
Cash and cash equivalents	14,014	30,077
Certificates of deposit with other banks	11,891	12,035
Securities available-for-sale	65,855	68,213
Securities held-to-maturity	53,441	55,871
Loans held for sale	116,307	69,527
Loans, net	912,331	803,036
Mortgage servicing rights	1,262	1,423
Accrued interest receivable	2,923	2,387
Financial liabilities:
Deposits	894,979	824,078
Repurchase agreements	26,263	32,673
FHLB and other borrowings	178,264	101,338
Accrued interest payable	437	376
Subordinated debt	31,172	31,172
Interest rate lock commitment | Level III
Financial assets:
Derivative asset	1,653	1,020
Interest rate lock commitment | Carrying Value
Financial assets:
Derivative asset	1,653	1,020
Interest rate lock commitment | Total
Financial assets:
Derivative asset	1,653	1,020
Interest rate cap | Level II
Financial assets:
Derivative asset	936	1,423
Interest rate cap | Carrying Value
Financial assets:
Derivative asset	936	1,423
Interest rate cap | Total
Financial assets:
Derivative asset	936	1,423
Forward sales commitments | Level II
Financial assets:
Derivative asset	783
Financial liabilities:
Derivative Liability		431
Forward sales commitments | Carrying Value
Financial assets:
Derivative asset	783
Financial liabilities:
Derivative Liability		431
Forward sales commitments | Total
Financial assets:
Derivative asset	$ 783
Financial liabilities:
Derivative Liability		$ 431