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Fair Value of Derivative Instruments on Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 12, 2016	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative assets, current			$ 34,932	$ 0
Derivative assets, noncurrent			10,100	0
Derivative liabilities, noncurrent			0	13,900
Derivative Asset			45,032	0
Derivative liabilities, current			991	27,777
Derivative liabilities			991	41,677
Commodity contracts
Derivatives, Fair Value [Line Items]
Derivative Asset			44,000
Commodity contracts \| Derivative assets/liabilities - current
Derivatives, Fair Value [Line Items]
Derivative assets, current			34,932	0
Derivative liabilities, current			991	27,777
Commodity contracts \| Derivative assets/liabilities - noncurrent
Derivatives, Fair Value [Line Items]
Derivative assets, noncurrent			10,100	0
Derivative liabilities, noncurrent			0	13,900
Successor [Member]
Derivatives, Fair Value [Line Items]
Derivatives	$ (16,622)		37,427	(17,819)
Predecessor [Member]
Derivatives, Fair Value [Line Items]
Derivatives		$ (8,333)
Fair Value, Measurements, Recurring \| Commodity contracts
Derivatives, Fair Value [Line Items]
Derivative assets, current			34,932
Derivative assets, noncurrent			10,100
Derivative liabilities, noncurrent			0	13,900
Derivative liabilities, current			$ (991)	$ (27,777)