Quarterly report pursuant to Section 13 or 15(d)

Organization and Accounting Policies (Narrative) (Details)

v3.21.2
Organization and Accounting Policies (Narrative) (Details)
 3 Months Ended 6 Months Ended 24 Months Ended
Jun. 20, 2026
Feb. 25, 2021
Jun. 30, 2021
USD ($)
/ $
Jun. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Jun. 30, 2021
USD ($)
/ $
Jun. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
/ $
Feb. 24, 2021
Organization And Accounting Policies [Line Items]                  
Impairment of proved crude oil and natural gas properties     $ 0 $ 0   $ 0 $ 30,625,000    
Receivable balance, gross, noncurrent     $ 9,300,000     $ 9,300,000   $ 4,500,000  
Abandonment funding payments missed               $ 2,900,000  
Exchange rate | / $     552.2     552.2   534.8  
Transfers between levels           $ 0 $ 0    
Office and Miscellaneous Equipment [Member]                  
Organization And Accounting Policies [Line Items]                  
Estimated useful life of assets           5 years      
Leasehold Improvements [Member] | Minimum [Member]                  
Organization And Accounting Policies [Line Items]                  
Estimated useful life of assets           5 years      
Leasehold Improvements [Member] | Maximum [Member]                  
Organization And Accounting Policies [Line Items]                  
Estimated useful life of assets           7 years      
Consortium [Member]                  
Organization And Accounting Policies [Line Items]                  
Receivable balance, gross, noncurrent     $ 13,500,000     $ 13,500,000   $ 13,400,000  
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        
Working interest ownership, percentage   58.80%             31.10%
Etame Marine Block [Member] | Sasol Gabon S.A. [Member]                  
Organization And Accounting Policies [Line Items]                  
Increase (decrease) in working interest ownership percentage   27.80%              
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] | 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]                  
Organization And Accounting Policies [Line Items]                  
Increase (decrease) in working interest ownership percentage (1.60%)                
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]                  
Increase (decrease) in working interest ownership percentage 2.50%                
Working interest ownership, percentage 10.00%