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Name:	srt_DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesLineItems
Namespace Prefix:	srt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Oil and Gas Reserves Information (Unaudited) - Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Reserves (Parenthetical) (Detail)	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2018	Aug. 13, 2018	Dec. 31, 2017
Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves [Line Items]
Percentage of discount factor	10.00%
Predecessor
Discounted Future Net Cash Flows Relating To Proved Oil And Gas Reserves [Line Items]
Percentage of discount factor		10.00%	10.00%