Securities, Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Available-for-sale, amortized cost [Abstract]
Due in one year or less	$ 30,015		$ 30,015
Due after one through five years	128,605		128,605
Due after five through ten years	124,654		124,654
Due after ten years	50,436		50,436
U.S. government sponsored agency mortgage-backed securities	212,829		212,829
Amortized cost	546,539		546,539		$ 613,395
CRA investment funds	25,000		25,000
Amortized cost	571,539		571,539		638,395
Available-for-sale, fair value [Abstract]
Due in one year or less	30,092		30,092
Due after one through five years	129,937		129,937
Due after five through ten years	126,142		126,142
Due after ten years	51,338		51,338
U.S. government sponsored agency mortgage-backed securities	214,176		214,176
Total debt securities	551,685		551,685		615,297
CRA investment funds	25,028		25,028
Total securities	576,713		576,713
Held-to-maturity, amortized cost [Abstract]
Due in one year or less	0		0
Due after one through five years	1,181		1,181
Due after five through ten years	480		480
Due after ten years	0		0
U.S. government sponsored agency mortgage-backed securities	0		0
Amortized cost	1,661		1,661		1,662
CRA investment funds	0		0
Total securities	1,661		1,661
Held-to-maturity, fair value [Abstract]
Due in one year or less	0		0
Due after one through five years	1,182		1,182
Due after five through ten years	469		469
Due after ten years	0		0
U.S. government sponsored agency mortgage-backed securities	0		0
Total debt securities	1,651		1,651		1,644
CRA investment funds	0		0
Total securities	1,651		1,651
Securities gains (loss), net	12	$ (34)	142	$ (145)
Realized pre-tax gain on sale of securities			840
Realized pre-tax loss on sale of securities			698
Amortized cost of securities pledged as collateral to secure public deposit and for other purposes	217,600		217,600		267,100
Amortized cost of securities sold under agreements to repurchase	$ 286,400		$ 286,400		$ 280,900