Fair Value Measurements - Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Financial Assets:
Investment securities held to maturity	$ 34,023	$ 36,874
Level 1
Financial Assets:
Cash and cash equivalents	142,477	121,636
Other interest earning deposits	0	0
Investment securities available for sale	1,982	1,973
Investment securities held to maturity	0	0
Loans held for sale	0	0
Total loans receivable, net	0	0
Accrued interest receivable	9	3
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	2,616,659	2,380,934
Certificate of deposit accounts	0	0
Total deposits	2,616,659	2,380,934
Securities sold under agreement to repurchase	22,829	32,181
Junior subordinated debentures	0	0
Accrued interest payable	52	62
Level 2
Financial Assets:
Cash and cash equivalents	0	0
Other interest earning deposits	5,259	10,145
Investment securities available for sale	701,111	740,873
Investment securities held to maturity	34,023	36,874
Loans held for sale	8,177	5,710
Total loans receivable, net	0	0
Accrued interest receivable	3,421	3,009
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	0	0
Certificate of deposit accounts	436,977	525,768
Total deposits	436,977	525,768
Securities sold under agreement to repurchase	0	0
Junior subordinated debentures	0	0
Accrued interest payable	137	328
Level 3
Financial Assets:
Cash and cash equivalents	0	0
Other interest earning deposits	0	0
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans held for sale	0	0
Total loans receivable, net	2,393,455	2,279,081
Accrued interest receivable	7,401	6,824
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	0	0
Certificate of deposit accounts	0	0
Total deposits	0	0
Securities sold under agreement to repurchase	0	0
Junior subordinated debentures	19,351	19,082
Accrued interest payable	20	21
Carrying Value
Financial Assets:
Cash and cash equivalents	142,477	121,636
Other interest earning deposits	5,244	10,126
Investment securities available for sale	703,093	742,846
Investment securities held to maturity	32,832	35,814
Federal Home Loan Bank stock	4,148	12,188
Loans held for sale	7,981	5,582
Total loans receivable, net	2,375,040	2,223,348
Accrued interest receivable	10,831	9,836
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	2,616,659	2,380,934
Certificate of deposit accounts	437,539	525,397
Total deposits	3,054,198	2,906,331
Securities sold under agreement to repurchase	22,829	32,181
Junior subordinated debentures	19,351	19,082
Accrued interest payable	209	411
Fair Value
Financial Assets:
Cash and cash equivalents	142,477	121,636
Other interest earning deposits	5,259	10,145
Investment securities available for sale	703,093	742,846
Investment securities held to maturity	34,023	36,874
Loans held for sale	8,177	5,710
Total loans receivable, net	2,393,455	2,279,081
Accrued interest receivable	10,831	9,836
Financial Liabilities:
Noninterest deposits, NOW accounts, money market accounts and savings accounts	2,616,659	2,380,934
Certificate of deposit accounts	436,977	525,768
Total deposits	3,053,636	2,906,702
Securities sold under agreement to repurchase	22,829	32,181
Junior subordinated debentures	19,351	19,082
Accrued interest payable	$ 209	$ 411