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Fair Value Accounting (Narrative) (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Mill equipment $ 6,500,000us-gaap_AssetsHeldForSaleAtCarryingValue $ 6,500,000us-gaap_AssetsHeldForSaleAtCarryingValue
Level 3 percentage of fair value assets 39.00%vgz_Level3PercentageOfFairValueAssets  
Fair Value, Inputs, Level 3 [Member]    
Fair Value Inputs, Assets, Quantitative Information [Line Items]    
Mill equipment $ 6,500,000us-gaap_AssetsHeldForSaleAtCarryingValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
$ 6,500us-gaap_AssetsHeldForSaleAtCarryingValue
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member