v2.4.0.8
Income taxes (Details) (USD $)
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Income taxes        
Expected income tax benefit     $ 7,000,000  
Permanent differences benefits generated from U.S. treasury grant proceeds, production tax credits and foreign exchange differences     1,900,000  
Canadian enacted statutory rate (as a percent)     25.00%  
Goodwill impairment     13,700,000  
Increase in the valuation allowance     4,500,000  
Dividend withholding and preferred share taxes     6,200,000  
Changes in estimates at joint venture projects     5,200,000  
Offset related to treasury grant proceeds     19,400,000  
Treasury grant proceeds     1,603  
Foreign exchange     3,900,000  
Other permanent differences     1,000,000  
Components of income tax expenses (benefit)        
Current income tax expense 5,400,000 1,900,000 10,800,000 6,100,000
Deferred tax (benefit) expense (5,400,000) 1,200,000 (12,700,000) (25,200,000)
Total income tax (benefit) expense   3,100,000 (1,900,000) (19,100,000)
Deferred tax assets:        
Valuations allowance $ 122,000,000   $ 122,000,000