Annual report pursuant to Section 13 and 15(d)

Segment Information (Segment Activity) (Details)

v3.6.0.2
Segment Information (Segment Activity) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Segment Reporting Information [Line Items]      
Revenues-oil and natural gas sales $ 59,784 $ 80,445 $ 127,691
Depreciation, depletion and amortization 6,926 32,998 20,074
Impairment of proved properties 88 81,322 98,341
Bad debt expense and other 1,222 2,968 2,400
Operating income (loss) (4,391) (103,106) (50,605)
Interest income (expense), net (2,613) (1,325) 75
Income tax expense 9,248 14,587 22,486
Additions to properties and equipment (4,061) 66,419 83,994
Total assets 81,032 123,958  
Continuing Operations [Member]      
Segment Reporting Information [Line Items]      
Long lived assets 28,019 33,357  
Total assets 78,893 115,573  
Operating Segments [Member] | Gabon [Member]      
Segment Reporting Information [Line Items]      
Revenues-oil and natural gas sales 59,460 79,947 126,322
Depreciation, depletion and amortization 6,531 32,125 19,079
Impairment of proved properties   78,080 98,341
Bad debt expense and other 1,222 2,968 2,400
Operating income (loss) 3,901 (87,243) (42,105)
Interest income (expense), net (2,614) (1,144) 42
Income tax expense 9,248 13,238 22,486
Additions to properties and equipment (4,242) 66,269 83,170
Operating Segments [Member] | Gabon [Member] | Continuing Operations [Member]      
Segment Reporting Information [Line Items]      
Long lived assets 17,291 21,329  
Total assets 64,478 98,858  
Operating Segments [Member] | Equatorial Guinea [Member]      
Segment Reporting Information [Line Items]      
Operating income (loss) (384) (1,342) (1,525)
Operating Segments [Member] | Equatorial Guinea [Member] | Continuing Operations [Member]      
Segment Reporting Information [Line Items]      
Long lived assets 10,000 10,000  
Total assets 10,122 10,200  
Operating Segments [Member] | United States [Member]      
Segment Reporting Information [Line Items]      
Revenues-oil and natural gas sales 324 498 1,369
Depreciation, depletion and amortization 151 633 901
Impairment of proved properties 88 3,242  
Operating income (loss) (72) (4,366) (119)
Additions to properties and equipment     8
Operating Segments [Member] | United States [Member] | Continuing Operations [Member]      
Segment Reporting Information [Line Items]      
Long lived assets   1,234  
Total assets 382 1,470  
Corporate And Other [Member]      
Segment Reporting Information [Line Items]      
Depreciation, depletion and amortization 244 240 94
Operating income (loss) (7,836) (10,155) (6,856)
Interest income (expense), net 1 (181) 33
Income tax expense   1,349  
Additions to properties and equipment 181 150 $ 816
Corporate And Other [Member] | Continuing Operations [Member]      
Segment Reporting Information [Line Items]      
Long lived assets 728 794  
Total assets $ 3,911 $ 5,045