Fair Value Measurements - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Level 1
Financial Assets:
Cash and cash equivalents	$ 124,234	$ 103,745
Investment securities available for sale	112	123
Loans held for sale	0	0
Total loans receivable, net	0	0
Accrued interest receivable	11	3
Derivative assets - interest rate swaps	0	0
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	2,900,997	2,872,247
Certificate of deposit accounts	0	0
Federal Home Loan Bank advances	0	0
Securities sold under agreement to repurchase	21,255	22,104
Junior subordinated debentures	0	0
Accrued interest payable	41	44
Derivative liabilities - interest rate swaps	0	0
Level 2
Financial Assets:
Cash and cash equivalents	0	0
Investment securities available for sale	790,482	794,522
Loans held for sale	5,961	11,988
Total loans receivable, net	0	0
Accrued interest receivable	3,515	3,472
Derivative assets - interest rate swaps	3,055	2,804
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	0	0
Certificate of deposit accounts	389,373	357,536
Federal Home Loan Bank advances	110,900	79,600
Securities sold under agreement to repurchase	0	0
Junior subordinated debentures	0	0
Accrued interest payable	80	142
Derivative liabilities - interest rate swaps	3,055	2,804
Level 3
Financial Assets:
Cash and cash equivalents	0	0
Investment securities available for sale	0	0
Loans held for sale	0	0
Total loans receivable, net	2,725,031	2,675,811
Accrued interest receivable	7,555	7,450
Derivative assets - interest rate swaps	0	0
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	0	0
Certificate of deposit accounts	0	0
Federal Home Loan Bank advances	0	0
Securities sold under agreement to repurchase	0	0
Junior subordinated debentures	15,000	15,000
Accrued interest payable	30	29
Derivative liabilities - interest rate swaps	0	0
Carrying Value
Financial Assets:
Cash and cash equivalents	124,234	103,745
Investment securities available for sale	790,594	794,645
Federal Home Loan Bank stock	9,083	7,564
Loans held for sale	5,787	11,662
Total loans receivable, net	2,716,756	2,609,666
Accrued interest receivable	11,081	10,925
Derivative assets - interest rate swaps	3,055	2,804
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	2,900,997	2,872,247
Certificate of deposit accounts	390,253	357,401
Federal Home Loan Bank advances	110,900	79,600
Securities sold under agreement to repurchase	21,255	22,104
Junior subordinated debentures	19,863	19,717
Accrued interest payable	151	215
Derivative liabilities - interest rate swaps	3,055	2,804
Fair Value
Financial Assets:
Cash and cash equivalents	124,234	103,745
Investment securities available for sale	790,594	794,645
Loans held for sale	5,961	11,988
Total loans receivable, net	2,725,031	2,675,811
Accrued interest receivable	11,081	10,925
Derivative assets - interest rate swaps	3,055	2,804
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	2,900,997	2,872,247
Certificate of deposit accounts	389,373	357,536
Federal Home Loan Bank advances	110,900	79,600
Securities sold under agreement to repurchase	21,255	22,104
Junior subordinated debentures	15,000	15,000
Accrued interest payable	151	215
Derivative liabilities - interest rate swaps	$ 3,055	$ 2,804