Income Taxes - Summary of Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amount
Computed expected federal income tax	$ (79,952)	$ (230,860)	$ (65,546)
State income tax, net of federal income tax benefit	(4,239)	(10,888)	(3,152)
Deferred tax adjustment related to change in overall state tax rate	(48)	(663)	2,822
Valuation allowance	(505)	221	187
Provision to return adjustments	(3,242)	(121)	(6,326)
Excess stock compensation	2,965	0	0
Tax Act	(242,875)	0	0
Other, net	(932)	(164)	(1,367)
Income tax (benefit) expense	$ (328,828)	$ (242,475)	$ (73,382)
Rate
Statutory federal income tax rate (as a percent)	35.00%	35.00%	35.00%
State income tax, net of federal income tax benefit (as a percent)	1.86%	1.65%	1.68%
Deferred tax adjustment related to change in overall state tax rate (as a percent)	0.02%	0.10%	(1.51%)
Valuation allowance (as a percent)	0.22%	(0.03%)	(0.10%)
Provision to return adjustments (as a percent)	1.42%	0.02%	3.38%
Excess stock compensation (as a percent)	(1.30%)	(0.00%)	(0.00%)
Tax reform (as a percent)	106.32%	0.00%	0.00%
Other, net (as a percent)	0.41%	0.02%	0.73%
Income tax benefit (as a percent)	143.95%	36.76%	39.18%