Quarterly report pursuant to Section 13 or 15(d)

Restricted Cash (Details)

v2.4.1.9
Restricted Cash (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Restricted Cash and Cash Equivalents Items [Line Items]    
Non-current restricted cash $ 7,556,000us-gaap_RestrictedCashAndCashEquivalentsNoncurrent $ 7,556,000us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
Surety Bond [Member]    
Restricted Cash and Cash Equivalents Items [Line Items]    
Reclamation bonding requirement 26,700,000urg_ReclamationBondingRequirement
/ us-gaap_LossContingenciesByNatureOfContingencyAxis
= us-gaap_SuretyBondMember
 
Money Market Funds [Member]    
Restricted Cash and Cash Equivalents Items [Line Items]    
Non-current restricted cash 7,456,000us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_MoneyMarketFundsMember
7,456,000us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_MoneyMarketFundsMember
Money Market Funds [Member] | Surety Bond [Member]    
Restricted Cash and Cash Equivalents Items [Line Items]    
Restricted cash pledged as collateral 7,456,000us-gaap_PledgedAssetsSeparatelyReportedSecuritiesPledgedAsCollateralAtFairValue
/ us-gaap_LossContingenciesByNatureOfContingencyAxis
= us-gaap_SuretyBondMember
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_MoneyMarketFundsMember
 
Certificate of deposit [Member]    
Restricted Cash and Cash Equivalents Items [Line Items]    
Non-current restricted cash 100,000us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
100,000us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
Certificate of deposit [Member] | Collectibility of Receivables [Member]    
Restricted Cash and Cash Equivalents Items [Line Items]    
Restricted cash pledged as collateral $ 100,000us-gaap_PledgedAssetsSeparatelyReportedSecuritiesPledgedAsCollateralAtFairValue
/ us-gaap_LossContingenciesByNatureOfContingencyAxis
= us-gaap_CollectibilityOfReceivablesMember
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember