Bankruptcy Proceedings, Emergence and Fresh Start Accounting Schedule of Cumulative Reorganization Adjustments (Details) - USD ($) $ in Thousands	8 Months Ended	12 Months Ended
	Sep. 12, 2016	Dec. 31, 2018	May 10, 2016
Reorganizations [Abstract]
Liabilities subject to compromise, gain	$ 1,150,248	$ 0
Fair Value of Equity Allocated to Unsecured Creditors	174,477
Fair Value of Unsecured Creditors Pending Resolution	10,396
Backstop Commitment Agreement, Backstop Commitment	6,022		$ 50,000
Postconfirmation, Additional Paid-in Capital	190,895
Cancellation of Equity Upon Emergence from Bankruptcy	882,992
Fresh-Start Adjustment, Increase (Decrease), Retained Earnings (Deficit)	$ 2,224,135