v3.20.2
Equity (Details)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2020
USD ($)
Sep. 30, 2020
$ / shares
Sep. 30, 2019
USD ($)
Sep. 30, 2019
$ / shares
Sep. 30, 2020
USD ($)
Sep. 30, 2020
$ / shares
Sep. 30, 2019
USD ($)
Sep. 30, 2019
$ / shares
Increase (decrease) in shareholders' equity                
Balance at the beginning of the period $ 105.7   $ 190.8   $ 137.7   $ 192.4  
Net income (loss) 17.8   14.3   37.5   19.6  
Share-based compensation 0.3   0.4   1.1   1.2  
Common share repurchases (5.5)       (41.6)   (0.8)  
Preferred share repurchases     (0.1)   (6.4)   (8.0)  
Realized and unrealized loss on hedging activities, net of tax 0.1       (0.2)   (0.2)  
Foreign currency translation adjustments 2.5   (1.6)   (3.8)   3.3  
Balance at the end of the period 119.3   202.0   119.3   202.0  
Series 1                
Increase (decrease) in shareholders' equity                
Dividends on preferred shares of a subsidiary company (0.8)   (0.8)   (2.4)   (2.6)  
Dividends on preferred shares of a subsidiary company (in CAD per share) | $ / shares   $ 0.303125   $ 0.303125   $ 0.909375   $ 0.909375
Series 2                
Increase (decrease) in shareholders' equity                
Dividends on preferred shares of a subsidiary company (0.6)   (0.6)   (1.9)   (1.8)  
Dividends on preferred shares of a subsidiary company (in CAD per share) | $ / shares   0.358688   0.348125   1.076064   1.044375
Series 3                
Increase (decrease) in shareholders' equity                
Dividends on preferred shares of a subsidiary company (0.2)   (0.4)   (0.7)   (1.1)  
Dividends on preferred shares of a subsidiary company (in CAD per share) | $ / shares   $ 0.286976   $ 0.364858   $ 1.013464   $ 1.091448
Common Shares                
Increase (decrease) in shareholders' equity                
Balance at the beginning of the period 1,224.6   1,260.9   1,259.9   1,260.9  
Share-based compensation 0.3   0.4   1.1   1.2  
Common share repurchases (5.5)       (41.6)   (0.8)  
Balance at the end of the period 1,219.4   1,261.3   1,219.4   1,261.3  
Retained Deficit                
Increase (decrease) in shareholders' equity                
Balance at the beginning of the period (1,140.4)   (1,111.5)   (1,164.2)   (1,121.6)  
Net income (loss) 16.2   12.6   40.0   22.7  
Balance at the end of the period (1,124.2)   (1,098.9)   (1,124.2)   (1,098.9)  
Accumulated Other Comprehensive (loss) income                
Increase (decrease) in shareholders' equity                
Balance at the beginning of the period (147.3)   (141.5)   (140.7)   (146.2)  
Realized and unrealized loss on hedging activities, net of tax 0.1       (0.2)   (0.2)  
Foreign currency translation adjustments 2.5   (1.6)   (3.8)   3.3  
Balance at the end of the period (144.7)   (143.1)   (144.7)   (143.1)  
Total Atlantic Power Corporation Shareholder's Deficit                
Increase (decrease) in shareholders' equity                
Balance at the beginning of the period (63.1)   7.9   (45.0)   (6.9)  
Net income (loss) 16.2   12.6   40.0   22.7  
Share-based compensation 0.3   0.4   1.1   1.2  
Common share repurchases (5.5)       (41.6)   (0.8)  
Realized and unrealized loss on hedging activities, net of tax 0.1       (0.2)   (0.2)  
Foreign currency translation adjustments 2.5   (1.6)   (3.8)   3.3  
Balance at the end of the period (49.5)   19.3   (49.5)   19.3  
Preferred Shares of a Subsidiary Company                
Increase (decrease) in shareholders' equity                
Balance at the beginning of the period 168.8   182.9   182.7   199.3  
Net income (loss) 1.6   1.7   (2.5)   (3.1)  
Preferred share repurchases     (0.1)   (6.4)   (8.0)  
Balance at the end of the period 168.8   182.7   168.8   182.7  
Preferred Shares of a Subsidiary Company | Series 1                
Increase (decrease) in shareholders' equity                
Dividends on preferred shares of a subsidiary company (0.8)   (0.8)   (2.4)   (2.6)  
Preferred Shares of a Subsidiary Company | Series 2                
Increase (decrease) in shareholders' equity                
Dividends on preferred shares of a subsidiary company (0.6)   (0.6)   (1.9)   (1.8)  
Preferred Shares of a Subsidiary Company | Series 3                
Increase (decrease) in shareholders' equity                
Dividends on preferred shares of a subsidiary company $ (0.2)   $ (0.4)   $ (0.7)   $ (1.1)