Quarterly report pursuant to Section 13 or 15(d)

Crude Oil and Natural Gas Properties and Equipment (Narrative) (Details)

v3.20.2
Crude Oil and Natural Gas Properties and Equipment (Narrative) (Details)
 1 Months Ended 3 Months Ended 9 Months Ended
Jun. 20, 2026
Sep. 26, 2018
USD ($)
Sep. 17, 2018
USD ($)
item
Feb. 29, 2020
USD ($)
Sep. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Sep. 30, 2020
USD ($)
item
Sep. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
Dec. 31, 2012
Property, Plant and Equipment [Line Items]                      
Reduction in VAT receivable             $ (919,000) $ 664,000      
Impairment of proved crude oil and natural gas properties         $ 0   30,625,000        
Property, net         38,845,000   38,845,000   $ 68,258,000    
Etame Marine Block [Member]                      
Property, Plant and Equipment [Line Items]                      
Allocated to proved leasehold cost         2,300,000   2,300,000        
Impairment of proved crude oil and natural gas properties           $ 30,600,000          
Property, net           $ 15,600,000          
Undeveloped leasehold value         $ 11,500,000   $ 11,500,000        
Etame Marine Block [Member] | VAALCO Gabon S.A. [Member]                      
Property, Plant and Equipment [Line Items]                      
Working interest ownership, percentage         33.575%   33.575%        
Block P Offshore Equatorial Guinea [Member]                      
Property, Plant and Equipment [Line Items]                      
Working interest ownership, percentage         43.00%   43.00%       31.00%
Increase (decrease) in working interest ownership percentage             12.00%        
Undeveloped acreage         $ 10,000,000.0   $ 10,000,000.0        
Potential payment         $ 3,100,000   $ 3,100,000        
Period of development             25 years        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Consortium [Member]                      
Property, Plant and Equipment [Line Items]                      
Entitled percent for consortium after initial royalty percentage             70.00%        
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]                      
Property, Plant and Equipment [Line Items]                      
Monthly royalty rate, based on production at the published price             13.00%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Etame Marine Block [Member] | Consortium [Member]                      
Property, Plant and Equipment [Line Items]                      
Working interest ownership, percentage         7.50%   7.50%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]                      
Property, Plant and Equipment [Line Items]                      
Working interest ownership, percentage                   7.50%  
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member]                      
Property, Plant and Equipment [Line Items]                      
Deferred tax assets, basis difference in fixed assets         $ 18,600,000   $ 18,600,000        
Deferred tax liabilities, basis difference in fixed assets         18,600,000   18,600,000        
Allocated to proved leasehold cost         22,500,000   22,500,000        
Allocated to unproved leasehold cost         13,700,000   13,700,000        
Estimated costs of technical studies             $ 500,000        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Consortium [Member]                      
Property, Plant and Equipment [Line Items]                      
Number of drilled wells required by agreement | item             2        
Number of appraisal wellbores required by agreement | item             2        
Number of wells drilled | item             2        
Number of wellbores drilled | item             2        
Number of technical studies required | item             2        
Estimated costs of technical studies             $ 1,500,000        
Entitled percent for consortium after initial royalty percentage             80.00%        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Government Of Gabon [Member]                      
Property, Plant and Equipment [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] | Signing Bonus [Member]                      
Property, Plant and Equipment [Line Items]                      
Contractual obligation     $ 21,800,000                
Payment of signing bonus, allocated to proved and unproved property   $ 11,800,000                  
Reduction in VAT receivable   8,400,000   $ 4,200,000              
Other accrued liabilities   1,700,000             $ 1,700,000    
Allocated to unproved leasehold cost         6,700,000   $ 6,700,000        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Signing Bonus [Member] | Consortium [Member]                      
Property, Plant and Equipment [Line Items]                      
Contractual obligation     $ 65,000,000.0                
Payment of signing bonus, allocated to proved and unproved property   35,000,000.0                  
Reduction in VAT receivable   25,000,000.0                  
Other accrued liabilities   $ 5,000,000.0                  
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Tax Impact [Member]                      
Property, Plant and Equipment [Line Items]                      
Allocated to unproved leasehold cost         $ 7,100,000   $ 7,100,000        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Etame Marine Block [Member]                      
Property, Plant and Equipment [Line Items]                      
Number of exploitation areas | item     3                
Period of agreement for exploitation areas     10 years       10 years        
Number of contract extension periods | item     2                
Production license agreement term extended by government     5 years                
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]                      
Property, Plant and Equipment [Line Items]                      
Working interest ownership, percentage         7.50%   7.50%        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Scenario, Forecast [Member] | Etame Marine Block [Member]                      
Property, Plant and Equipment [Line Items]                      
Increase (decrease) in working interest ownership percentage (0.80%)                    
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Scenario, Forecast [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]                      
Property, Plant and Equipment [Line Items]                      
Working interest ownership, percentage 10.00%                    
Increase (decrease) in working interest ownership percentage 2.50%                    
Production Sharing Contract, After September 16, 2028 [Member] | Consortium [Member]                      
Property, Plant and Equipment [Line Items]                      
Entitled percent for consortium after initial royalty percentage             70.00%