CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 150,277	$ 109,832	$ 308,466	$ 236,086
Other comprehensive income (loss):
Unrealized gains (losses) on investments	3,164	42	6,102	(4,085)
Unrealized gains (losses) on cash flow hedges	(24,013)	10,014	(38,130)	30,304
Total unrealized gains (losses)	(20,849)	10,056	(32,028)	26,219
Income tax benefit (expense)	5,093	(2,441)	7,826	(6,343)
Other comprehensive income (loss), net of tax benefit (expense)	(15,756)	7,615	(24,202)	19,876
Total comprehensive income	$ 134,521	$ 117,447	$ 284,264	$ 255,962