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Property and Equipment - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
Jun. 30, 2017
Sep. 30, 2017
Property Plant And Equipment [Line Items]      
Impairment expense related to oil and natural gas properties $ 1.3   $ 3.5
Drilling Rigs That Would No Longer Be Marketed As Rigs      
Property Plant And Equipment [Line Items]      
Impairment charge for the write-down of drilling equipment   $ 29.0