Bankruptcy Proceedings, Emergence and Fresh Start Accounting Schedule Of Liabilities Subject to Compromise (Details) - USD ($) $ in Thousands	8 Months Ended	12 Months Ended
	Sep. 12, 2016	Dec. 31, 2018
Reorganizations [Abstract]
Liabilities Subject to Compromise, Senior Notes	$ 1,075,000
Liabilities Subject to Compromise, Interest on Senior Notes	47,213
Liabilities Subject to Compromise, Firm Transportation Obligation	11,077
Liabilities Subject to Compromise, Compensation	9,733
Liabilities Subject to Compromise, Deferred Compensation	4,676
Liabilities Subject to Compromise, Accounts Payable	1,487
Liabilities Subject to Compromise, Litigation claims	1,092
Liabilities Subject to Compromise, Other accrued liabilities	3,885
Liabilities Subject to Compromise	1,154,163
Cash settlements paid or reserved at emergence	3,915
Liabilities subject to compromise, gain	$ 1,150,248	$ 0