Debt (Schedule Of Long Term Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Feb. 02, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total debt, gross			$ 1,300,000
liabilities subject to compromise	$ 0	$ 1,572,772	1,335,794
Total debt, net
Revision of Prior Period, Reclassification, Adjustment [Member]
Debt Instrument [Line Items]
liabilities subject to compromise			(1,300,000)
Senior Unsecured Notes Due 2024 [Member]
Debt Instrument [Line Items]
Total debt, gross			500,000
New Senior Unsecured Notes Due 2021 [Member]
Debt Instrument [Line Items]
Total debt, gross			$ 800,000