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Business Segment Information - Additional Information (Detail)
$ in Thousands
12 Months Ended
Dec. 31, 2015
USD ($)
Segment
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Segment Reporting [Abstract]      
Current operating units | Segment 3    
Segment Reporting Information [Line Items]      
Assets held for sale $ 26,728 $ 0  
Operating segments | Exploration and Production      
Segment Reporting Information [Line Items]      
Assets held for sale $ 26,700   $ 137,100