Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details 3) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 18, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount
Income tax provision calculated using the federal statutory income tax rate	$ (11,169)	$ (388,228)	$ 67,475	$ 86,086
State income taxes, net of federal income tax benefit	(2,532)	(86,937)	7,435	11,968
Tax shortfall (windfall) on stock-based compensation deduction	0	(1,502)	1,912	(1,565)
Valuation allowance	9,653	19,344	26,122	(42)
Tax attributes reduction - net of CODI exclusion	0	31,667	0	0
Enhanced oil recovery credits generated	0	0	0	(10,818)
Other	1,522	9,527	1,408	1,604
Total income tax expense (benefit)	$ (2,526)	$ (416,129)	$ 104,352	$ 87,233