Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 30,451	$ 29,335	$ 59,133	$ 57,005
Other Comprehensive Income (Loss), Net of Tax
Unrealized gains (losses) on available-for-sale securities	26,961	(25,750)	40,559	(20,569)
Reclassification adjustment for losses included in net income	118	49	57	45
Net unrealized gains (losses) on available-for-sale securities	27,079	(25,701)	40,616	(20,524)
Tax effect	(10,491)	9,957	(15,735)	7,978
Net of tax amount	16,588	(15,744)	24,881	(12,546)
Unrealized (losses) gains on derivatives used for cash flow hedges	(4,020)	3,896	(13,948)	(2,097)
Reclassification adjustment for losses included in net income	1,578	1,257	3,407	2,508
Net unrealized (losses) gains on derivatives used for cash flow hedges	(2,442)	5,153	(10,541)	411
Tax effect	946	(1,996)	4,084	(169)
Net of tax amount	(1,496)	3,157	(6,457)	242
Total other comprehensive income (loss), net of tax	15,092	(12,587)	18,424	(12,304)
Total Comprehensive Income	$ 45,543	$ 16,748	$ 77,557	$ 44,701