Fresh Start Accounting (Narrative) (Details) - USD ($)		1 Months Ended	3 Months Ended	5 Months Ended	6 Months Ended
	Oct. 29, 2021	Feb. 02, 2021	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2021
Fresh-Start Adjustment [Line Items]
Preconfirmation, Assets		$ 1,497,411,000	$ 1,456,800,000	$ 1,456,800,000	$ 1,456,800,000
Postconfirmation, Liabilities		554,118,000	2,076,100,000	2,076,100,000	$ 2,076,100,000
Internal Rate Of Return					17.60%
Perpetuity Growth Rate					3.00%
Credit Adjusted Risk-Free Rate					5.60%
Reorganization Expenses, Discount Rate					5.30%
Reorganization Expenses			7,400,000	1,300,000	$ 15,800,000
Reorganization Expenses, Cash Used In Operating Activities		3,100,000		13,700,000
Reorganization Items		335,560,000		0
Reorganization Expenses, Professional Fees, Expense		2,700,000
Reorganization Expenses, Professional Fees, Lease Rejection Damages		$ 400,000
Minimum [Member]
Fresh-Start Adjustment [Line Items]
Bankruptcy Proceedings, Enterprise Value			710,000,000.0	710,000,000.0	710,000,000.0
Maximum [Member]
Fresh-Start Adjustment [Line Items]
Bankruptcy Proceedings, Enterprise Value			$ 880,000,000.0	$ 880,000,000.0	$ 880,000,000.0
Subsequent Event [Member]
Fresh-Start Adjustment [Line Items]
Net book value	$ 27,000,000.0
Proceeds from Sale of Other Assets	$ 43,800,000