Income Taxes - Summary of components of provision (benefit) for income taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current (benefit) provision:
Federal	$ (24,727)	$ 119,074	$ 104,890
State	(3,638)	19,858	15,627
Foreign	7,898	2,907	1,918
Deferred (benefit) provision:
Federal	(31,178)	11,514	(12,025)
State	(1,835)	840	(1,035)
Total income tax (benefit) provision	$ (53,480)	$ 154,193	$ 109,375