v2.4.0.6
Income taxes (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Income taxes    
Income tax benefit from continuing operations $ 2.5  
Computed income taxes at Canadian statutory rate 1.1  
Change in tax rates in various tax jurisdictions 1.8  
Foreign exchange 2.3  
Permanent differences 2.4  
Valuation allowance 2.9  
Canadian enacted statutory rate (as a percent) 25.00%  
Components of income tax expenses (benefit)    
Current income tax expense 2.0 1.4
Deferred tax benefit (4.5) (18.3)
Total income tax benefit (2.5) (16.9)
Deferred tax assets:    
Valuations allowance $ 118.2