v3.5.0.2
Basic and diluted (loss) earnings per share (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Numerator:        
Loss from continuing operations attributable to Atlantic Power Corporation $ (82.4) $ (5.5) $ (116.2) $ (5.5)
(Loss) income from discontinued operations, net of tax   (0.5)   31.6
Net (loss) income attributable to Atlantic Power Corporation $ (82.4) $ (6.0) $ (116.2) $ 26.1
Denominator:        
Weighted average basic shares outstanding 119.3 122.1 120.9 121.8
Dilutive potential shares:        
Convertible debentures (in shares) 8.1 22.4 14.9 22.8
LTIP notional units (in shares) 0.1 0.1 0.1 0.1
Potentially dilutive shares 127.5 144.6 135.9 144.7
Diluted loss per share from continuing operations attributable to Atlantic Power Corporation $ (0.69) $ (0.05) $ (0.96) $ (0.05)
Diluted earnings per share from discontinued operations       0.26
Diluted (loss) earnings per share attributable to Atlantic Power Corporation $ (0.69) $ (0.05) $ (0.96) $ 0.21
Potentially dilutive shares from convertible debentures excluded from fully diluted shares $ 8.1 $ 22.4 $ 14.9 $ 22.8