Fresh Start Accounting (Gain on Settlement of Liabilities Subject to Compromise) (Details) - USD ($) $ in Thousands	1 Months Ended	2 Months Ended	8 Months Ended
	Sep. 30, 2020	Aug. 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	$ 2,655			45,000	$ 0
Royalty suspense accounts payable				20,273
Total liabilities subject to compromise				762,215
Separation settlement treatment				(6,905)
Successor common stock, $0.01 par value, 25,000,000 shares authorized, 12,000,000 shares issued as of September 30, 2020	120				$ 10,591
Gains on settlement of liabilities subject to compromise	0	$ 567,853	$ 567,853
5% equity facility	$ 0	$ 9,866	$ 9,866
Allowed claim holders [Member]
Fresh-Start Adjustment [Line Items]
Successor common stock, $0.01 par value, 25,000,000 shares authorized, 12,000,000 shares issued as of September 30, 2020				175,521
Disputed Claims Reserve [Member]
Fresh-Start Adjustment [Line Items]
Successor common stock, $0.01 par value, 25,000,000 shares authorized, 12,000,000 shares issued as of September 30, 2020				$ 11,936