v3.3.1.900
Income taxes (Details) - USD ($)
$ in Millions
12 Months Ended 36 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2015
Components of income tax expenses (benefit)        
Current income tax expense $ 5.3 $ 3.8 $ 8.6  
Deferred tax benefit (35.7) (35.2) (41.4)  
Total income tax benefit, net (30.4) (31.4) (32.8)  
Canadian enacted statutory rate (as a percent)       26.00%
Reconciliation of income taxes        
Computed income taxes at Canadian statutory rate (29.8) (47.5) (14.7)  
Countries with different tax rates (4.9) (19.2) (5.3)  
Income tax benefit after adjustments for countries with different income tax rates (34.7) (66.7) (20.0)  
Change in valuation allowance 6.6 40.5 12.1  
Income tax expense (benefit) after adjustments for countries with different income tax rates and valuation allowance (28.1) (26.2) (7.9)  
Dividend withholding tax and other cash taxes 1.1 0.8 3.7  
Foreign exchange (7.0) (7.4) (9.9)  
Changes in tax rates 2.1 (5.8) (2.8)  
Federal stimulus grant     (18.9)  
Production tax credits (3.6) (0.3) (4.4)  
Changes in estimates of tax basis of equity method investments (6.3) (4.1) 23.0  
Capital gain on intercompany notes 2.1      
Goodwill impairment 14.8 33.9 13.6  
Capital loss recognized on tax restructuring   (10.2)    
Intra-period allocation from the Wind projects (5.0) (15.8) (30.9)  
Other (0.5) 3.7 1.7  
Total other reconciliation items (2.3) (5.2) (24.9)  
Total income tax benefit, net (30.4) (31.4) $ (32.8)  
Deferred tax assets:        
Loss carryforwards 238.4 340.3   $ 238.4
Other accrued liabilities 0.1 0.4   0.1
Finance and share issuance costs 1.7 6.2   1.7
Tax credit 4.7     4.7
Disallowed interest carryforward   3.4    
Derivative instruments 15.1 22.3   15.1
Other long-term notes 5.2     5.2
Other 9.8 10.3   9.8
Total deferred tax assets 275.0 382.9   275.0
Valuations allowance (175.2) (168.6)   (175.2)
Net deferred tax assets 99.8 214.3   99.8
Deferred tax liabilities:        
Intangible assets (79.0) (75.0)   (79.0)
Property, plant and equipment (106.5) (208.9)   (106.5)
Other long-term investments   (22.8)    
Total deferred tax liabilities (185.5) (306.7)   (185.5)
Net deferred tax liability (85.7) (92.4)   (85.7)
Net deferred tax position        
Long-term deferred tax liabilities (85.7) $ (92.4)   $ (85.7)
IRS        
Net deferred tax position        
Settlement amount related to change in the taxable income $ 3.6