Quarterly report pursuant to Section 13 or 15(d)

Organization and Accounting Policies (Narrative) (Details)

v3.20.2
Organization and Accounting Policies (Narrative) (Details)
 3 Months Ended 6 Months Ended
Jun. 30, 2020
USD ($)
/ $
Jun. 30, 2019
USD ($)
Jun. 30, 2020
USD ($)
/ $
Jun. 30, 2019
USD ($)
Jun. 20, 2026
Dec. 31, 2019
/ $
Dec. 31, 2018
Organization And Accounting Policies [Line Items]              
Impairment of proved crude oil and natural gas properties $ 0   $ 30,625,000        
Receivable balance, gross, noncurrent $ 3,800,000   $ 3,800,000        
Exchange rate | / $ 583.1   583.1     585.7  
Bad debt (recovery) expense and other $ 179,000 $ 5,000 $ 989,000 $ (24,000)      
Transfers between levels     0 0      
Consortium [Member]              
Organization And Accounting Policies [Line Items]              
Receivable balance, gross, noncurrent 11,300,000   11,300,000        
Government Of Gabon [Member]              
Organization And Accounting Policies [Line Items]              
Bad debt (recovery) expense and other $ 100,000 $ 3,000 $ 900,000 $ 29,000      
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Consortium [Member]              
Organization And Accounting Policies [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]              
Organization And Accounting Policies [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] | Government Of Gabon [Member]              
Organization And Accounting Policies [Line Items]              
Monthly royalty rate, based on production at the published price     13.00%        
Etame Marine Block [Member]              
Organization And Accounting Policies [Line Items]              
Impairment of proved crude oil and natural gas properties     $ 30,600,000        
Etame Marine Block [Member] | Prior Production Sharing Contract, Through September 17, 2018 [Member] | Consortium [Member]              
Organization And Accounting Policies [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]              
Organization And Accounting Policies [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]              
Organization And Accounting Policies [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]              
Organization And Accounting Policies [Line Items]              
Working interest ownership, percentage         10.00%