CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 158,189	$ 126,254
Other comprehensive income (loss):
Unrealized gains (losses) on investments	2,938	(4,127)
Unrealized gains (losses) on cash flow hedges	(14,117)	20,290
Total unrealized gains (losses)	(11,179)	16,163
Income tax benefit (expense)	2,733	(3,902)
Other comprehensive income (loss), net of tax benefit (expense)	(8,446)	12,261
Total comprehensive income	$ 149,743	$ 138,515