| Mineral Properties | 12 Months Ended | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Dec. 31, 2013 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mineral Industries Disclosures [Abstract] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mineral properties |   9.       Mineral Properties
   The  Company’s mineral properties consist of the  following:
 
 
 
   United  States
 Lost Creek  Property The  Company acquired certain Wyoming properties when Ur-Energy USA Inc.  entered into the Membership Interest Purchase Agreement  (“MIPA”) with New Frontiers Uranium, LLC in 2005.   Under the terms of the MIPA, the Company purchased   100% of NFU Wyoming, LLC.  Assets acquired in this  transaction include the Lost Creek Project, other Wyoming  properties and development databases.  NFU Wyoming,  LLC was acquired for aggregate consideration of $20  million plus interest. Since 2005, the Company has increased its  holdings adjacent to the initial Lost Creek acquisition through  staking additional claims and additional property purchases and  leases. 
In April  2013, the Company executed a royalty purchase agreement with the  royalty holder who owned the only private royalty reserved on the  Lost Creek Project. The   1.67% royalty had existed with respect to future production  of uranium on 20  mining claims at the Lost Creek Project. The Company issued one  million common shares of the Company with a fair value of $763  in full consideration of the conveyance and termination of the  royalty interest. There is a  royalty on each of the State of Wyoming sections under lease at the  Lost Creek, LC West and EN Projects, as required by law.   Other royalties exist on certain mining claims at the LC South and  EN Projects.  There are no royalties on the mining claims in  the LC North, LC East or LC West Projects.
   In September 2013, after the Company commenced mineral  extraction and production at the Lost Creek Project, it began  amortizing the related mineral properties on a straight-line  basis. Pathfinder  Mines Corporation 
The  Company acquired additional Wyoming properties when Ur-Energy USA,  Inc. closed a Share Purchase Agreement (“SPA”)  with an AREVA  Mining affiliate in  December 2013.  Under the terms of the SPA, the Company  purchased Pathfinder Mines Corporation  (“Pathfinder”)   to acquire additional proven mineral properties.   Assets acquired in this transaction include the Shirley Basin Mine,  portions of the Lucky Mc mine, machinery and equipment, vehicles,  office equipment and development databases.  Pathfinder was  acquired for aggregate consideration of $6.7  million, a 5% production  royalty under certain circumstances and the assumption of  $5.7  million in estimated asset reclamation obligations.   The purchase price allocation attributed $5.7 million to asset  retirement obligations, $3.3 million to deferred tax liabilities,  $15.3 million to mineral properties and the balance to the  remaining assets and liabilities.   We have performed a preliminary allocation of the purchase price to  the underlying assets and liabilities acquired. These amounts are  preliminary and adjustments may be necessary when the allocation is  finalized.
 Other U.S.  properties In June  2013, the Company decided to abandon the South Granite Mountain  project by not paying the claim fees due later in 2013. The cost of  that project of $261  was written off. At the January  2014 meeting, the Board of Directors determined that the Company  will be terminating the Mustang project in Nebraska.   The Company is in the process of notifying the leaseholders of the  terminations when the lease renewals become due.   The cost of that project of $1,168 was written off in 2013 as there  was no value to the Company as of December 31, 2013.   Canada   The  Company's Canadian properties include Screech Lake and Gravel Hill,  which are located in the Thelon Basin, Northwest Territories and  Bugs, which is located in the Baker Lake Basin,  Nunavut.  | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||