Accumulated Other Comprehensive Income (Loss) - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities	$ (93)	$ 844	$ 932	$ 1,425
Interest expense - subordinated debentures and term loans	(1,670)	(1,648)	(3,330)	(3,289)
Income tax expense	(8,856)	(5,888)	(14,690)	(10,505)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	17,968	15,160	34,140	28,780
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	(293)	321	143	474
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on available for sale securities
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Other income - net realized gains on sales of available for sale securities	(93)	844	932	1,425
Income tax expense	33	(295)	(326)	(499)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	(60)	549	606	926
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) for the Period | Unrealized gains (losses) on cash flow hedges
Reclassification Adjustments out of Accumulated Other Comprehensive Income [Line Items]
Interest expense - subordinated debentures and term loans	(358)	(351)	(712)	(695)
Income tax expense	125	123	249	243
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ (233)	$ (228)	$ (463)	$ (452)