Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Net income	$ 484,730	[1]	$ 213,509	[1]	$ 215,865
Other comprehensive income, net of tax:
Unrealized gain (loss) on marketable securites, available for sale	(177)		5
Total comprehensive income	$ 484,553		$ 213,514		$ 215,865

[1] Per share amounts do not add across due to rounding differences in quarterly amounts and due to the impact of differences between the quarterly and annual weighted average share calculations.