Annual report pursuant to Section 13 and 15(d)

Restricted Cash (Details)

v2.4.1.9
Restricted Cash (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Restricted Cash    
Non-current restricted cash $ 7,556us-gaap_RestrictedCashAndCashEquivalentsNoncurrent $ 5,055us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
Surety Bond [Member]    
Restricted Cash    
Reclamation bonding requirement 26,537urg_ReclamationBondingRequirement
/ us-gaap_LossContingenciesByNatureOfContingencyAxis
= us-gaap_SuretyBondMember
 
Certificate of deposit [Member]    
Restricted Cash    
Non-current restricted cash 100us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
100us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
Certificate of deposit [Member] | Collectibility of Receivables [Member]    
Restricted Cash    
Restricted cash pledged as collateral 100us-gaap_PledgedAssetsSeparatelyReportedSecuritiesPledgedAsCollateralAtFairValue
/ us-gaap_LossContingenciesByNatureOfContingencyAxis
= us-gaap_CollectibilityOfReceivablesMember
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_CertificatesOfDepositMember
 
Money Market Funds [Member]    
Restricted Cash    
Non-current restricted cash 7,456us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_MoneyMarketFundsMember
4,955us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_MoneyMarketFundsMember
Money Market Funds [Member] | Surety Bond [Member]    
Restricted Cash    
Restricted cash pledged as collateral $ 7,456us-gaap_PledgedAssetsSeparatelyReportedSecuritiesPledgedAsCollateralAtFairValue
/ us-gaap_LossContingenciesByNatureOfContingencyAxis
= us-gaap_SuretyBondMember
/ us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis
= us-gaap_MoneyMarketFundsMember