Emergence from Bankruptcy and Fresh Start Accounting (Unsecured or Under-Secured Liabilities Previously Reported) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Oct. 01, 2016	Jan. 11, 2016
Fresh-Start Adjustment [Line Items]
Accrued expenses and other current liabilities	$ 184,161	$ 205,240
Accounts payable	134,137	95,953
Other noncurrent liabilities	$ 59,457	$ 63,824
Liabilities Subject to Compromise			$ 5,278,612
Scenario, previously reported
Fresh-Start Adjustment [Line Items]
Debt				$ 5,026,806
Accrued expenses and other current liabilities				136,295
Accounts payable				106,297
Other noncurrent liabilities				9,214
Liabilities Subject to Compromise				$ 5,278,612