CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 578,276	$ 487,476	$ 288,934
Other comprehensive income (loss):
Unrealized gains (losses) on investments	7,993	(2,561)	(716)
Unrealized gains (losses) on cash flow hedges	(38,414)	11,907	19,195
Total unrealized gains (losses)	(30,421)	9,346	18,479
Income tax (expense) benefit	7,431	(2,333)	(7,060)
Other comprehensive income (loss), net of tax (expense) benefit	(22,990)	7,013	11,419
Total comprehensive income	$ 555,286	$ 494,489	$ 300,353