Annual report pursuant to Section 13 and 15(d)

Financial instruments (Details)

v2.4.1.9
Financial instruments (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Credit Concentration Risk  
Financial Instruments  
Cash, insured amount 0.9us-gaap_CashFDICInsuredAmount
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CreditConcentrationRiskMember
Cash, uninsured amount 9.8us-gaap_CashUninsuredAmount
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CreditConcentrationRiskMember
Credit Availability Concentration Risk  
Financial Instruments  
Accounts Payable, Trade, Current 3.0us-gaap_AccountsPayableTradeCurrent
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CreditAvailabilityConcentrationRiskMember
Interest Rate Risk  
Financial Instruments  
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Discount Rate 0.6us-gaap_SensitivityAnalysisOfFairValueOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesImpactOf10PercentAdverseChangeInDiscountRate
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_InterestRateRiskMember
Minimum | Credit Concentration Risk  
Financial Instruments  
Investment Interest Rate 0.18%invest_InvestmentInterestRate
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CreditConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
Minimum | Credit Availability Concentration Risk  
Financial Instruments  
Debt Instrument, Term 0 years
Maximum | Credit Concentration Risk  
Financial Instruments  
Investment Interest Rate 0.40%invest_InvestmentInterestRate
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CreditConcentrationRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
Maximum | Credit Availability Concentration Risk  
Financial Instruments  
Debt Instrument, Term 7 years
Maximum | Currency Risk  
Financial Instruments  
Foreign Currency Cash And Cash Equivalents At Carrying Value 0.1urg_ForeignCurrencyCashAndCashEquivalentsAtCarryingValue
/ us-gaap_ConcentrationRiskByTypeAxis
= urg_CurrencyRiskMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember