v2.4.0.8
Commitments and contingencies (Details) (USD $)
In Millions, unless otherwise specified
 0 Months Ended 9 Months Ended
Sep. 09, 2013
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Aug. 19, 2013
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May 07, 2013
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Sep. 30, 2013
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Oct. 04, 2013
Commitments and contingencies          
Number of District Court actions alleged from July 23, 2010 to March 4, 2013       3  
Number of District Court actions alleged from August 8, 2012 to February 28, 2013       2  
Number of actions were succeeded by specific action with an amended claim       3  
Number of actions by which specific Ontario actions were succeeded       1  
Shareholder class action lawsuits
          
Commitments and contingencies          
Number of purported securities fraud class action complaints filed       5  
Number of action complaints filed ordered to consolidate   5      
Number of plaintiff applicants directed to file supplemental submissions 2        
Number of notices of actions relating to Canadian securities class action claims       3  
Estimate damages claimed for statutory misrepresentation         $ 197.4
Number of District Court actions in which discoveries are stayed       5  
Number of District Court actions alleged in specific period       5  
Number of investors filed motion     6