v2.4.0.6
Guarantees and condensed consolidating financial information (Details 3) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Project revenue:    
Total project revenue $ 140.2 $ 118.7
Project expenses:    
Fuel 49.6 46.2
Operations and maintenance 28.3 24.7
Development 1.7  
Depreciation and amortization 41.3 26.5
Total project expenses 120.9 97.4
Project other income (expense):    
Change in fair value of derivative instruments 12.6 (57.2)
Equity in earnings of unconsolidated affiliates 7.2 2.9
Interest, net (8.0) (4.0)
Total project other income (expense) 11.8 (58.3)
Project income (loss) 31.1 (37.0)
Administrative and other expenses (income):    
Administration 8.3 7.7
Interest, net 25.9 22.0
Foreign exchange loss (gain) (7.5) 1.0
Total administrative and other expenses (income) 26.7 30.7
Income (loss) from continuing operations before income taxes 4.4 (67.7)
Income tax benefit (2.5) (16.9)
Net income (loss) from continuing operations 6.9 (50.8)
Net income from discontinued operations 0.9 11.6
Net income (loss) 7.8 (39.2)
Net income attributable to noncontrolling interest 1.3  
Net income (loss) attributable to noncontrolling interest (1.9) (0.1)
Net income (loss) attributable to Atlantic Power Corporation 6.5 (42.3)
Guarantor Subsidiaries
    
Project revenue:    
Total project revenue 131.6  
Project expenses:    
Fuel 49.6  
Operations and maintenance 26.5  
Development 1.7  
Depreciation and amortization 37.5  
Total project expenses 115.3  
Project other income (expense):    
Change in fair value of derivative instruments 12.6  
Equity in earnings of unconsolidated affiliates 7.2  
Interest, net (5.2)  
Total project other income (expense) 14.6  
Project income (loss) 30.9  
Administrative and other expenses (income):    
Administration 4.6  
Interest, net 19.3  
Foreign exchange loss (gain) (2.5)  
Total administrative and other expenses (income) 21.4  
Income (loss) from continuing operations before income taxes 9.5  
Income tax benefit (2.5)  
Net income (loss) from continuing operations 12.0  
Net income from discontinued operations 0.9  
Net income (loss) 12.9  
Net income (loss) attributable to noncontrolling interest (1.9)  
Net income (loss) attributable to Atlantic Power Corporation 14.8  
Curtis Palmer
    
Project revenue:    
Total project revenue 8.8  
Project expenses:    
Operations and maintenance 1.6  
Depreciation and amortization 3.8  
Total project expenses 5.4  
Project other income (expense):    
Interest, net (2.8)  
Total project other income (expense) (2.8)  
Project income (loss) 0.6  
Administrative and other expenses (income):    
Income (loss) from continuing operations before income taxes 0.6  
Net income (loss) from continuing operations 0.6  
Net income (loss) 0.6  
Net income (loss) attributable to Atlantic Power Corporation 0.6  
Atlantic Power
    
Project expenses:    
Operations and maintenance 0.3  
Total project expenses 0.3  
Project other income (expense):    
Project income (loss) (0.3)  
Administrative and other expenses (income):    
Administration 3.7  
Interest, net 6.6  
Foreign exchange loss (gain) (5.0)  
Total administrative and other expenses (income) 5.3  
Income (loss) from continuing operations before income taxes (5.6)  
Net income (loss) from continuing operations (5.6)  
Net income (loss) (5.6)  
Net income (loss) attributable to Atlantic Power Corporation (5.6)  
Eliminations
    
Project revenue:    
Total project revenue (0.2)  
Project expenses:    
Operations and maintenance (0.1)  
Total project expenses (0.1)  
Project other income (expense):    
Project income (loss) (0.1)  
Administrative and other expenses (income):    
Income (loss) from continuing operations before income taxes (0.1)  
Net income (loss) from continuing operations (0.1)  
Net income (loss) (0.1)  
Net income (loss) attributable to noncontrolling interest 3.2  
Net income (loss) attributable to Atlantic Power Corporation $ (3.3)