Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income	$ 91,518	$ 83,300
Other comprehensive income, net of tax:
Change in value of derivatives	21	21
Other comprehensive income	21	21
Comprehensive income	$ 91,539	$ 83,321