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

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- Definition Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill. + References No definition available. + Details
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- Definition The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 35 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=28370743&loc=d3e66150-109466 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230 + Details
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