Quarterly report pursuant to Section 13 or 15(d)

Segment Information (Segment Activity) (Detail)

v3.3.0.814
Segment Information (Segment Activity) (Detail)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2015
USD ($)
Sep. 30, 2014
USD ($)
Sep. 30, 2015
USD ($)
segment
Sep. 30, 2014
USD ($)
Dec. 31, 2014
USD ($)
Segment Reporting Information [Line Items]          
Number of reportable operating segments | segment     4    
Revenues-oil and gas sales $ 17,546 $ 24,486 $ 62,922 $ 104,659  
Depreciation, depletion and amortization 8,259 4,289 23,493 15,444  
Impairment of proved properties 17,988   29,208    
Operating income (loss) (32,121) 6,687 (68,429) 39,870  
Interest income (expense), net (462) 19 (1,107) 65  
Income tax expense 2,707 3,761 10,345 18,897  
Total assets 195,079   195,079   $ 248,849
Operating Segments [Member] | Gabon [Member]          
Segment Reporting Information [Line Items]          
Revenues-oil and gas sales 17,405 24,132 62,496 103,507  
Depreciation, depletion and amortization 8,060 4,035 22,844 14,638  
Impairment of proved properties 17,988   29,208    
Operating income (loss) (29,007) 10,326 (31,286) 49,239  
Interest income (expense), net (294) 12 (944) 37  
Income tax expense 2,707 3,761 10,345 18,897  
Total assets 150,040   150,040   192,957
Operating Segments [Member] | Angola [Member]          
Segment Reporting Information [Line Items]          
Depreciation, depletion and amortization 3 5 9 11  
Operating income (loss) (1,170) (1,319) (30,014) (3,165)  
Total assets 22,268   22,268   22,305
Operating Segments [Member] | Equatorial Guinea [Member]          
Segment Reporting Information [Line Items]          
Operating income (loss) (287) (254) (944) (591)  
Total assets 10,295   10,295   10,197
Operating Segments [Member] | United States [Member]          
Segment Reporting Information [Line Items]          
Revenues-oil and gas sales 141 354 426 1,152  
Depreciation, depletion and amortization 140 239 467 749  
Operating income (loss) 42 (100) (372) (33)  
Total assets 5,904   5,904   6,611
Corporate, Non-Segment [Member]          
Segment Reporting Information [Line Items]          
Depreciation, depletion and amortization 56 10 173 46  
Operating income (loss) (1,699) (1,966) (5,813) (5,580)  
Interest income (expense), net (168) $ 7 (163) $ 28  
Total assets $ 6,572   $ 6,572   $ 16,779