Annual report pursuant to Section 13 and 15(d)

Impairment of Proved Properties - Additional Information (Detail)

v2.4.1.9
Impairment of Proved Properties - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Impairment Of Proved Properties [Line Items]      
Company recognized an impairment loss $ 98.3us-gaap_GoodwillAndIntangibleAssetImpairment   $ 7.6us-gaap_GoodwillAndIntangibleAssetImpairment
Impairment of Oil and Gas Properties   0us-gaap_ImpairmentOfOilAndGasProperties  
Etame field      
Impairment Of Proved Properties [Line Items]      
Company recognized an impairment loss 38.5us-gaap_GoodwillAndIntangibleAssetImpairment
/ dei_LegalEntityAxis
= egy_EtameMember 		   
Ebouri field      
Impairment Of Proved Properties [Line Items]      
Company recognized an impairment loss 5.9us-gaap_GoodwillAndIntangibleAssetImpairment
/ dei_LegalEntityAxis
= egy_EbouriMember 		   
Southeast Etame And North Tchibala field      
Impairment Of Proved Properties [Line Items]      
Company recognized an impairment loss $ 53.9us-gaap_GoodwillAndIntangibleAssetImpairment
/ dei_LegalEntityAxis
= egy_SoutheastEtameAndNorthTchibalaMember