OTHER COMPREHENSIVE INCOME - RECLASSIFICATION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Significant amounts reclassified out of each component of AOCI
Noninterest Income	$ 11,301	$ 7,806	$ 47,024	$ 40,277
Interest expense on deposits	(1,620)	(1,068)	(4,359)	(3,233)
Interest expense on FHLB advances	(2,664)	(2,982)	(8,590)	(8,907)
Total interest expense	(4,536)	(4,683)	(13,680)	(14,086)
Income tax (expense) benefit	(4,848)	(3,119)	(18,100)	(14,234)
Net income	9,828	5,640	35,903	27,748
Net of tax, total all reclassification amounts	(54)	(65)	(166)	(141)
Unrealized gain on securities available for sale | Reclassification out of Accumulated Other Comprehensive Income
Significant amounts reclassified out of each component of AOCI
Noninterest Income				88
Income tax (expense) benefit				(31)
Net income				57
Unrealized loss on cash flow hedge | Interest rate swap | Reclassification out of Accumulated Other Comprehensive Income
Significant amounts reclassified out of each component of AOCI
Interest expense on deposits	(42)	(49)	(128)	(148)
Interest expense on FHLB advances	(41)	(51)	(128)	(156)
Total interest expense	(83)	(100)	(256)	(304)
Income tax (expense) benefit	29	35	90	106
Net income	$ (54)	$ (65)	$ (166)	$ (198)