Derivative Instruments - Summary of Outstanding Contracts with Respect to Natural Gas (Detail) - Natural Gas [Member]	9 Months Ended
Sep. 30, 2018 MMBTU $ / MMBTU
October 2018 to December 2018 Swaps
Derivative [Line Items]
Natural Gas Production Derivative Volume, MMBtus \| MMBTU	57,960,000
Swaps Weighted Average Price \| $ / MMBTU	2.88
April 2019 to December 2019 Swaps [Member]
Derivative [Line Items]
Natural Gas Production Derivative Volume, MMBtus \| MMBTU	14,850,000
Swaps Weighted Average Price \| $ / MMBTU	2.68

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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