Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 29,614	$ 29,294	$ 86,619	$ 84,701
Other Comprehensive Income (Loss), Net of Tax
Unrealized gains (losses) on available-for-sale securities	11,506	(2,764)	(9,063)	32,553
Reclassification adjustment for losses included in net income	50	61	95	182
Net unrealized gains (losses) on available-for-sale securities	11,556	(2,703)	(8,968)	32,735
Tax effect	(4,476)	1,049	3,502	(12,687)
Net of tax amount	7,080	(1,654)	(5,466)	20,048
Unrealized (losses) gains on derivatives used for cash flow hedges	(8,630)	201	(10,727)	(11,468)
Reclassification adjustment for losses included in net income	1,263	0	3,771	0
Net unrealized (losses) gains on derivatives used for cash flow hedges	(7,367)	201	(6,956)	(11,468)
Tax effect	2,854	(78)	2,685	4,450
Net of tax amount	(4,513)	123	(4,271)	(7,018)
Total other comprehensive income (loss), net of tax	2,567	(1,531)	(9,737)	13,030
Total Comprehensive Income	$ 32,181	$ 27,763	$ 76,882	$ 97,731