Quarterly report pursuant to Section 13 or 15(d)

Segment Information (Detail)

v3.2.0.727
Segment Information (Detail)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2015
USD ($)
Jun. 30, 2014
USD ($)
Jun. 30, 2015
USD ($)
segment
Jun. 30, 2014
USD ($)
Dec. 31, 2014
USD ($)
Segment Reporting Information [Line Items]          
Number of reportable operating segments | segment     4    
Revenues-oil and gas sales $ 27,137 $ 52,098 $ 45,376 $ 80,172  
Depreciation, depletion and amortization 9,299 6,995 15,234 11,155  
Impairment of proved properties 5,821   11,220 0  
Operating income (loss) (1,030) 33,828 (36,308) 33,181  
Interest income (expense), net (339) 17 (645) 46  
Income tax expense 4,273 9,009 7,638 15,135  
Total assets 234,287   234,287   $ 248,849
Operating Segments | Gabon          
Segment Reporting Information [Line Items]          
Revenues-oil and gas sales 26,991 51,631 45,091 79,375  
Depreciation, depletion and amortization 9,078 6,706 14,784 10,602  
Impairment of proved properties 5,821   11,220    
Operating income (loss) 2,266 36,223 (2,279) 38,913  
Interest income (expense), net (343) 9 (650) 24  
Income tax expense 4,273 9,009 7,638 15,135  
Total assets 182,898   182,898   192,957
Operating Segments | Angola [Member]          
Segment Reporting Information [Line Items]          
Depreciation, depletion and amortization 3   6 6  
Operating income (loss) (978) (721) (28,844) (1,847)  
Total assets 21,588   21,588   22,305
Operating Segments | Equatorial Guinea          
Segment Reporting Information [Line Items]          
Operating income (loss) (418) (139) (657) (339)  
Total assets 10,326   10,326   10,197
Operating Segments | United States          
Segment Reporting Information [Line Items]          
Revenues-oil and gas sales 146 467 285 797  
Depreciation, depletion and amortization 157 270 327 510  
Operating income (loss) (663) 130 (414) 67  
Interest income (expense), net       22  
Total assets 5,934   5,934   6,611
Corporate, Non-Segment          
Segment Reporting Information [Line Items]          
Depreciation, depletion and amortization 61 19 117 37  
Operating income (loss) (1,237) (1,665) (4,114) $ (3,613)  
Interest income (expense), net 4 $ 8 5    
Total assets $ 13,541   $ 13,541   $ 16,779