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Commitments and Contingencies - Additional Information (Detail)
$ in Millions
9 Months Ended
Sep. 30, 2018
USD ($)
Commitments And Contingencies Disclosure [Abstract]  
Natural gas transportation and treating agreements through July 2019
Maximum commitments under natural gas transportation and treating agreements $ 1.0
Contract term related to drilling services through September 2019
Commitments for contracted drilling services $ 16.5