Fresh Start Accounting (Gain on Settlement of Liabilities Subject to Compromise) (Details) - USD ($) $ in Thousands	2 Months Ended	4 Months Ended	8 Months Ended
	Aug. 31, 2020	Dec. 31, 2020	Aug. 31, 2020	Sep. 01, 2020	Dec. 31, 2019
Fresh-Start Adjustment [Line Items]
6.625% senior subordinated notes due 2021 (including accrued interest as of the petition date)				$ 672,369
Accounts payable				1,179
Employee separation benefit plan obligations				23,394
Litigation settlements		$ 2,070		45,000	$ 0
Royalty suspense accounts payable				20,273
Total liabilities subject to compromise				762,215
Separation settlement treatment				(6,905)
Common Stock, Value, Issued		(120)			$ (10,591)
Gain on settlement of liabilities subject to compromise	$ 567,853	0	$ 567,853
5% equity facility	$ 9,900	$ 0	$ 9,866
Allowed claim holders
Fresh-Start Adjustment [Line Items]
Common Stock, Value, Issued				(175,521)
Disputed Claims Reserve [Member]
Fresh-Start Adjustment [Line Items]
Common Stock, Value, Issued				$ (11,936)