Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 29,335	$ 28,677	$ 57,005	$ 55,407
Other Comprehensive (Loss) Income, Net of Tax
Unrealized (losses) gains on available-for-sale securities	(25,750)	20,714	(20,569)	35,317
Reclassification adjustment for losses included in net income	49	48	45	121
Net unrealized (losses) gains on available-for-sale securities	(25,701)	20,762	(20,524)	35,438
Tax effect	9,957	(8,056)	7,978	(13,736)
Net of tax amount	(15,744)	12,706	(12,546)	21,702
Unrealized gains (losses) on derivatives used for cash flow hedges	3,896	(6,190)	(2,097)	(11,669)
Reclassification adjustment for losses included in net income	1,257	0	2,508	0
Net unrealized gains (losses) on derivatives used for cash flow hedges	5,153	(6,190)	411	(11,669)
Tax effect	(1,996)	2,402	(169)	4,528
Net of tax amount	3,157	(3,788)	242	(7,141)
Total other comprehensive (loss) income, net of tax	(12,587)	8,918	(12,304)	14,561
Total Comprehensive Income	$ 16,748	$ 37,595	$ 44,701	$ 69,968