Income Taxes - Schedule of Reconciliation of Income Tax Expense (Benefit) Computed by Applying Statutory Federal Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amount
Computed "expected" federal income tax	$ 50,636	$ 189,047	$ 146,609
State income tax, net of federal income tax benefit	4,486	14,773	11,850
Deferred tax adjustment related to change in overall state tax rate	1,213	(660)	(15,208)
Valuation allowance	(3,800)	17,676	8,975
Excess executive compensation	5,249	1,935	1,382
Reserve on uncertain tax positions	5,964	5	0
Uncertain tax positions	(23,216)	0	0
Tax Act	0	0	(11,367)
Other, net	62	(3,622)	(1,147)
Income tax expense	$ 40,594	$ 219,154	$ 141,094
Rate
Computed "expected" federal income tax	21.00%	21.00%	21.00%
State income tax, net of federal income tax benefit	1.86%	1.64%	1.70%
Deferred tax adjustment related to change in overall state tax rate	0.50%	(0.07%)	(2.18%)
Valuation allowance	(1.58%)	1.96%	1.29%
Excess executive compensation	2.18%	0.21%	0.20%
Reserve on uncertain tax positions	2.47%	0.00%	0.00%
Uncertain tax positions	(9.63%)	0.00%	0.00%
Tax Act	0	0	(0.0163)
Other, net	0.04%	(0.40%)	(0.16%)
Income tax expense	16.84%	24.34%	20.21%