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           Income taxes 
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           Dec. 31, 2013 
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| Income Tax Disclosure [Abstract] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Income taxes |               
     A  reconciliation of income taxes at the statutory Canadian income tax  rate to net income taxes included in the accompanying statements of  operations is as follows:
     
     Deferred tax assets and liabilities reflect the net tax effects of  net operating losses, credit carryforwards and temporary  differences between the carrying amounts of assets and liabilities  for financial reporting purposes and amounts used for income tax  purposes.   The components of the Company’s deferred tax assets  and liabilities are as follows:
          
   Based upon the level of historical  taxable loss, management believes it is more likely than not that  the Company will not realize the benefits of these deductible  differences and accordingly has established a full valuation  allowance as of December 31, 2013 and 2012.       As of December 31, 2013, the Company  had available total U.S. net operating loss carryforwards of  approximately $54.4 million,  which expire in the years 2017 through 2033. As of December 31,  2013, the Company had available total Canadian net operating loss  carryforwards of approximately $22.0 million,  which expire in the years   2014 through 2033.       The Company follows a comprehensive  model for recognizing, measuring, presenting and disclosing  uncertain tax positions taken or expected to be taken on a tax  return. Tax positions must initially be recognized in the financial  statements when it is more likely than not the position will be  sustained upon examination by the tax authorities. Such tax  positions must initially and subsequently be measured as the  largest amount of tax benefit that has a greater than   50% likelihood of being realized upon ultimate settlement  with the tax authority assuming full knowledge of the position and  relevant facts.       The Company currently has no  uncertain tax positions and is therefore not reflecting any  adjustments for such in its deferred tax  assets.       There are open statutes of limitations for  tax authorities in U.S., Canada and state jurisdictions to audit  the Company’s tax returns for the years ended December 31,  2010, 2011 and 2012.       The Company’s policy is to account  for income tax related interest and penalties in income tax expense  in the accompanying statements of operations. There have been no  income tax related interest or penalties assessed or recorded.          | 
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