Income Taxes - Summary of Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of actual provision for income taxes and provision for income taxes resulting from the use of federal statutory income tax
Statutory federal income tax rate (as a percent)	35.00%	35.00%	35.00%
Computed expected federal income tax	$ (65,546)	$ 11,341	$ 169,938
State income tax, net of federal income tax benefit	(3,152)	903	17,513
Deferred tax adjustment related to change in overall state tax rate	2,822	(86,956)	15,220
Valuation allowance	187	3,977	0
Uncertain tax positions	0	(1,974)	2,400
Provision to return adjustments	(6,326)	(791)	700
Other, net	(1,367)	1,433	(6)
Income tax (benefit) expense	$ (73,382)	$ (72,067)	$ 205,765