Fresh Start Accounting (Reorganization) (Details) - USD ($) $ in Thousands			1 Months Ended	8 Months Ended	9 Months Ended
		Feb. 02, 2021	Feb. 02, 2021	Sep. 30, 2021	Sep. 30, 2020
Fresh Start Accounting [Abstract]
Gain on settlement of liabilities subject to compromise		$ 667,258	$ 667,258
Allowed claim adjustment for Class 6 claims			(232,022)
Loss on fresh start adjustment	[1]		(77,376)
Professional fees			(16,005)
Rejected leases			13,347
Debtor in possession credit facility costs			(12,000)
Lease rejection damages			(4,956)
Extinguishment of RSUs for the Predecessor's incentive plan			(988)
Other items			(1,698)
Total reorganization income (expense), net			335,560	$ 0	$ 0
Adjustment for discontinued operations			$ 16,400

[1] Includes approximately $16.4 million in adjustments to assets and liabilities classified as held for sale. See Note 20-Discontinued Operations.