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
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 273,104	$ 289,535	$ 680,902	$ 784,375
Other comprehensive income, net of tax:
Change in value of derivatives	25	25	75	75
Other comprehensive income	25	25	75	75
Comprehensive income (loss)	$ 273,129	$ 289,560	$ 680,977	$ 784,450