Quarterly report pursuant to Section 13 or 15(d)

Organization and Accounting Policies (Narrative) (Details)

v3.21.1
Organization and Accounting Policies (Narrative) (Details)
 3 Months Ended
Jun. 20, 2026
Feb. 25, 2021
USD ($)
Mar. 31, 2021
USD ($)
/ $
Mar. 31, 2020
USD ($)
Feb. 24, 2021
Dec. 31, 2020
/ $
Organization And Accounting Policies [Line Items]            
Impairment of proved crude oil and natural gas properties     $ 0 $ 30,625,000    
Receivable balance, gross, noncurrent     $ 8,800,000      
Exchange rate | / $     559.3     534.8
Transfers between levels     $ 0 0    
Bargain purchase gain     7,651,000      
Sasol Gabon S.A. [Member]            
Organization And Accounting Policies [Line Items]            
Bargain purchase gain   $ 7,700,000 7,700,000      
Bargain purchase gain, net of tax   5,500,000 $ 5,500,000      
Bargain purchase gain, income tax benefit   $ 2,200,000   2,200,000    
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     $ 12,900,000      
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%      
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%      
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%