CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 128,458	$ 103,878	$ 436,924	$ 339,964
Other comprehensive income (loss):
Unrealized gains (losses) on investments	1,344	(1,811)	7,446	(5,896)
Unrealized gains (losses) on cash flow hedges	(10,083)	6,556	(48,213)	36,860
Total unrealized gains (losses)	(8,739)	4,745	(40,767)	30,964
Income tax benefit (expense)	2,135	(1,219)	9,961	(7,562)
Other comprehensive income (loss), net of tax benefit (expense)	(6,604)	3,526	(30,806)	23,402
Total comprehensive income	$ 121,854	$ 107,404	$ 406,118	$ 363,366