Quarterly report pursuant to Section 13 or 15(d)

Revenue (Narrative) (Details)

v3.20.2
Revenue (Narrative) (Details) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended 9 Months Ended
Aug. 31, 2020
Apr. 30, 2020
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Jun. 20, 2026
Dec. 31, 2019
Dec. 31, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Interval period, between lifting         30 days        
Income taxes paid in-kind with crude oil $ 6,900 $ 1,900 $ 6,883 $ 8,738 $ 7,347      
Foreign income taxes receivable     $ 1,124   $ 1,124        
Foreign taxes payable attributable to sharing obligation               $ 5,700  
Minimum [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Lifting period, time to complete         1 day        
Maximum [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Lifting period, time to complete         2 days        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Consortium [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Monthly royalty rate, based on production at the published price         13.00%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Government Of Gabon [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Monthly royalty rate, based on production at the published price         13.00%        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Purchase agreement payment period         30 days        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Government Of Gabon [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Monthly royalty rate, based on production at the published price         13.00%        
Etame Marine Block [Member] | Prior Production Sharing Contract, Through September 17, 2018 [Member] | Consortium [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Working interest ownership, percentage     7.50%   7.50%        
Etame Marine Block [Member] | Prior Production Sharing Contract, Through September 17, 2018 [Member] | Government Of Gabon [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Working interest ownership, percentage                 7.50%
Etame Marine Block [Member] | Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Government Of Gabon [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Working interest ownership, percentage     7.50%   7.50%        
Etame Marine Block [Member] | Scenario, Forecast [Member] | Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Government Of Gabon [Member]                  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]                  
Working interest ownership, percentage             10.00%