Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 1,022,023	$ 447,221	$ 602,703
Other comprehensive income, net of tax:
Change in value of derivatives	100	81	83
Other comprehensive income	100	81	83
Comprehensive income	$ 1,022,123	$ 447,302	$ 602,786