Nature of Ops and Sign. Acctg Policies (Antidilutive Securities) (Details 4) - $ / shares	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2020		Sep. 18, 2020	Dec. 31, 2019	Dec. 31, 2018
Series A Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share
Shares issuable upon exercise of warrants			2,631,579
Exercise price of warrants	$ 32.59		$ 32.59
Series B Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share
Shares issuable upon exercise of warrants			2,894,740
Exercise price of warrants	$ 35.41		$ 35.41
Stock appreciation rights
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0		1,007,000	2,027,000	2,743,000
Restricted stock and performance-based equity awards
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0		7,280,000	5,505,000	1,234,000
Convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0		87,888,000	0	0
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	328,000	[1]	0	0	0
Number of shares issuable upon full vesting of awards	1,200,000
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	5,526,000	[2]	0	0	0
Shares issuable upon exercise of warrants	5,500,000

[1] Shares represent the impact over the Successor period of the approximately 1.2 million shares of the Successor’s common stock issuable upon full vesting of the restricted stock unit awards issued on December 4, 2020 pursuant to the 2020 Omnibus Stock and Incentive Plan (see Note 11, Stock Compensation).

[2] Shares represent the impact over the Successor period of the approximately 5.5 million shares of the Successor’s common stock issuable upon full exercise of the series A warrants, at an exercise price of $32.59 per share, and series B warrants, at an exercise price of $35.41 per share, which were issued pursuant to the Plan to the Predecessor’s convertible senior notes, senior subordinated notes, and equity holders. The dilution from exercise of the series A or series B warrants could be reduced to the extent warrants are exercised on a cashless basis.