CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 94,943	$ 65,915
Other comprehensive income (loss):
Unrealized (losses) gains on investments	(1,567)	3,024
Unrealized gains (losses) on cash flow hedges	4,779	(24,374)
Total unrealized gains (losses)	3,212	(21,350)
Income tax (expense) benefit	(1,232)	8,140
Other comprehensive income (loss), net of tax (expense) benefit	1,980	(13,210)
Total comprehensive income	$ 96,923	$ 52,705