Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2015
Reserves deducted from asset accounts:
Balance at End of Year		$ 610,500
Successor | Accounts receivable and other receivables
Reserves deducted from asset accounts:
Balance at Beginning of Year	$ 0	0
Additions (Reductions) Charged to Costs and Expenses	0
Charged to Other Accounts	0
Deductions	0
Balance at End of Year	0	0
Successor | Current assets — supplies and inventory
Reserves deducted from asset accounts:
Balance at Beginning of Year	0	0
Additions (Reductions) Charged to Costs and Expenses	0	365
Charged to Other Accounts	0	(17)
Deductions	0	87
Balance at End of Year	0	261
Successor | Deferred income taxes
Reserves deducted from asset accounts:
Balance at Beginning of Year	1,033,982	1,021,553
Additions (Reductions) Charged to Costs and Expenses	(12,429)	(410,982)
Charged to Other Accounts	0
Deductions	0
Balance at End of Year	1,021,553	$ 610,571
Predecessor | Accounts receivable and other receivables
Reserves deducted from asset accounts:
Balance at Beginning of Year	0		$ 159
Additions (Reductions) Charged to Costs and Expenses	0		7,683
Charged to Other Accounts	0		0
Deductions	7,842		0
Balance at End of Year			7,842
Predecessor | Current assets — supplies and inventory
Reserves deducted from asset accounts:
Balance at Beginning of Year	0		6,625
Additions (Reductions) Charged to Costs and Expenses	844		431
Charged to Other Accounts	(5,060)		0
Deductions	1,775		1,065
Balance at End of Year			5,991
Predecessor | Deferred income taxes
Reserves deducted from asset accounts:
Balance at Beginning of Year	1,033,982		270,251
Additions (Reductions) Charged to Costs and Expenses	(101,417)		865,148
Charged to Other Accounts			0
Deductions	$ 0		0
Balance at End of Year			$ 1,135,399