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Oil and Gas Reserves Information (Unaudited) - Additional Information (Detail)
12 Months Ended
Dec. 31, 2016
$ / bbl
$ / Mcf
Dec. 31, 2015
$ / bbl
$ / Mcf
Crude Oil and NGL Per Barrel    
Average Sales Price And Production Costs Per Unit Of Production [Line Items]    
Average sales prices | $ / bbl 37.62 46.88
Natural Gas Per Thousand Cubic Feet    
Average Sales Price And Production Costs Per Unit Of Production [Line Items]    
Average sales prices | $ / Mcf 2.29 2.34