Investment Securities (Available-for-sale Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities
Amortized Cost	$ 730,632	$ 632,967
Gross Unrealized Gains	14,248	12,693
Gross Unrealized Losses	(8,660)	(8,780)
Available-for-sale securities	736,220	636,880
U.S. Treasury and government agencies
Schedule of Available-for-sale Securities
Amortized Cost	0	1
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale securities	0	1
U.S. government sponsored agencies
Schedule of Available-for-sale Securities
Amortized Cost	3,885	5,836
Gross Unrealized Gains	49	114
Gross Unrealized Losses	0	0
Available-for-sale securities	3,934	5,950
States and political subdivisions
Schedule of Available-for-sale Securities
Amortized Cost	112,186	62,292
Gross Unrealized Gains	2,430	2,510
Gross Unrealized Losses	(403)	(59)
Available-for-sale securities	114,213	64,743
Residential mortgage-backed securities
Schedule of Available-for-sale Securities
Amortized Cost	580,579	529,245
Gross Unrealized Gains	6,655	5,910
Gross Unrealized Losses	(7,533)	(7,864)
Available-for-sale securities	579,701	527,291
Commercial mortgage-backed securities
Schedule of Available-for-sale Securities
Amortized Cost	27,262	28,021
Gross Unrealized Gains	122	112
Gross Unrealized Losses	(184)	(286)
Available-for-sale securities	27,200	27,847
Bank-issued trust preferred securities
Schedule of Available-for-sale Securities
Amortized Cost	5,134	6,132
Gross Unrealized Gains	0	3
Gross Unrealized Losses	(466)	(490)
Available-for-sale securities	4,668	5,645
Equity securities
Schedule of Available-for-sale Securities
Amortized Cost	1,586	1,440
Gross Unrealized Gains	4,992	4,044
Gross Unrealized Losses	(74)	(81)
Available-for-sale securities	$ 6,504	$ 5,403