Income Taxes - Summary of Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amount
Computed expected federal income tax	$ 146,609	$ (79,952)	$ (230,860)
State income tax, net of federal income tax benefit	11,850	(4,239)	(10,888)
Deferred tax adjustment related to change in overall state tax rate	(15,208)	(48)	(663)
Valuation allowance	8,975	(505)	221
Provision to return adjustments	(1,773)	(3,242)	(121)
Excess stock compensation	327	2,965	0
Tax Act	(11,367)	(242,875)	0
Other, net	1,681	(932)	(164)
Income tax (benefit) expense	$ 141,094	$ (328,828)	$ (242,475)
Rate
Statutory federal income tax rate (as a percent)	21.00%	35.00%	35.00%
State income tax, net of federal income tax benefit (as a percent)	1.70%	1.86%	1.65%
Deferred tax adjustment related to change in overall state tax rate (as a percent)	(2.18%)	0.02%	0.10%
Valuation allowance (as a percent)	1.29%	0.22%	(0.03%)
Provision to return adjustments (as a percent)	(0.25%)	1.42%	0.02%
Excess stock compensation (as a percent)	0.05%	(1.30%)	0.00%
Tax reform (as a percent)	(1.63%)	106.32%	(0.00%)
Other, net (as a percent)	0.24%	0.41%	0.02%
Income tax benefit (as a percent)	20.21%	143.95%	36.76%