Crude Oil and Natural Gas Properties and Equipment (Narrative) (Details) $ in Thousands				1 Months Ended			6 Months Ended	12 Months Ended
	Jun. 20, 2026	Sep. 16, 2019 item	Sep. 26, 2018 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Feb. 29, 2020 USD ($)	Dec. 31, 2019 USD ($) item	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 17, 2018 USD ($)	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Contractual obligation								$ 17,627
Reduction in VAT receivable								(1,268)	$ 275	$ (777)
Deferred tax assets, basis difference in fixed assets							$ 26,590	27,995	26,590
Impairment of proved crude oil and natural gas properties								30,625
Property, net							$ 68,258	37,036	68,258
Inventory adjustments								900
Consortium [Member]
Property, Plant and Equipment [Line Items]
Contractual obligation								56,757
Etame Marine Block [Member]
Property, Plant and Equipment [Line Items]
Allocated to proved leasehold cost								2,300
Impairment of proved crude oil and natural gas properties					$ 30,600
Property, net					$ 15,600
Undeveloped leasehold value								$ 11,500
Etame Marine Block [Member] | Government Of Gabon [Member]
Property, Plant and Equipment [Line Items]
Working interest ownership, percentage								7.50%
Monthly royalty rate, based on production at the published price								13.00%
Etame Marine Block [Member] | VAALCO Gabon S.A. [Member]
Property, Plant and Equipment [Line Items]
Working interest ownership, percentage								33.575%
Block P Offshore Equatorial Guinea [Member]
Property, Plant and Equipment [Line Items]
Working interest ownership, percentage								43.00%				31.00%
Increase (decrease) in working interest ownership percentage								12.00%
Undeveloped acreage								$ 10,000
Potential payment								$ 3,100
Period of development								25 years
Scenario, Forecast [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]
Property, Plant and Equipment [Line Items]
Working interest ownership, percentage	10.00%
Prior Production Sharing Contract, Through September 17, 2018 [Member]
Property, Plant and Equipment [Line Items]
Entitled percent for consortium after initial royalty percentage								70.00%
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%
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]
Property, Plant and Equipment [Line Items]
Number of exploitation areas | item								3
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%
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
Deferred tax liabilities, basis difference in fixed assets								18,600
Allocated to proved leasehold cost								22,500
Allocated to unproved leasehold cost								$ 13,700
Estimated costs of technical studies				$ 500
Entitled percent for consortium after initial royalty percentage								80.00%
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Consortium [Member]
Property, Plant and Equipment [Line Items]
Period of agreement for exploitation areas								10 years
Number of drilled wells required by agreement | item								2
Number of appraisal wellbores required by agreement | item								2
Number of wells drilled | item							1
Number of wellbores drilled | item							1
Number of technical studies required | item		2
Estimated costs of technical studies				$ 1,500
Entitled percent for consortium after initial royalty percentage								80.00%
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
Payment of signing bonus, allocated to proved and unproved property			$ 11,800
Reduction in VAT receivable			8,400			$ 4,200
Other accrued liabilities			1,700				$ 1,700		$ 1,700
Allocated to unproved leasehold cost								$ 6,700
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
Payment of signing bonus, allocated to proved and unproved property			35,000
Reduction in VAT receivable			25,000
Other accrued liabilities			$ 5,000
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
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
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]
Property, Plant and Equipment [Line Items]
Entitled percent for consortium after initial royalty percentage								70.00%
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%
Production Sharing Contract, After September 16, 2028 [Member] | Etame Marine Block [Member]
Property, Plant and Equipment [Line Items]
Number of contract extension periods | item								2
Production license agreement term extended by government								5 years