Fresh Start Accounting (Narrative) (Details) - USD ($)	1 Months Ended	2 Months Ended	3 Months Ended
	Feb. 02, 2021	Mar. 31, 2021	Mar. 31, 2021
Fresh-Start Adjustment [Line Items]
Preconfirmation, Assets	$ 1,497,411,000	$ 1,456,800,000	$ 1,456,800,000
Postconfirmation, Liabilities	554,118,000	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	8,400,000	1,300,000
Reorganization Expenses, Cash Used In Operating Activities	3,100,000	0
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
Maximum [Member]
Fresh-Start Adjustment [Line Items]
Bankruptcy Proceedings, Enterprise Value		$ 880,000,000.0	$ 880,000,000.0