CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - 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	$ 57,205	$ 91,016	$ 123,120	$ 138,715
Other comprehensive income (loss):
Unrealized gains (losses) on investments	1,293	(3,180)	4,317	(2,507)
Unrealized (losses) gains on cash flow hedges	(8,732)	18,156	(33,106)	2,467
Total unrealized (losses) gains	(7,439)	14,976	(28,789)	(40)
Income tax benefit (expense)	2,855	(5,840)	10,995	(15)
Other comprehensive (loss) income, net of tax benefit (expense)	(4,584)	9,136	(17,794)	(55)
Total comprehensive income	$ 52,621	$ 100,152	$ 105,326	$ 138,660