CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Project revenue:
Energy sales	$ 36.5	$ 40.7	$ 113.6	$ 138.4
Energy capacity revenue	37.9	44.0	85.7	113.2
Other	34.2	16.5	131.7	54.2
Total project revenue	108.6	101.2	331.0	305.8
Project expenses:
Fuel	26.2	36.8	79.1	110.8
Operations and maintenance	19.8	28.2	63.4	79.4
Depreciation and amortization	31.4	25.3	90.5	75.6
Total project costs	77.4	90.3	233.0	265.8
Project other income:
Change in fair value of derivative instruments (Notes 6 and 7)	(1.9)	9.0	(5.8)	20.0
Equity in earnings (loss) of unconsolidated affiliates (Note 3)	9.2	9.6	(36.1)	27.9
Interest, net	(2.2)	(2.4)	(6.6)	(6.9)
Impairment (Note 4)	(57.3)	(84.7)	(57.3)	(84.7)
Other income, net	0.1	0.5	0.1	0.4
Total project other income (expense)	(52.1)	(68.0)	(105.7)	(43.3)
Project loss	(20.9)	(57.1)	(7.7)	(3.3)
Administrative and other expenses:
Administration	5.5	5.7	17.6	17.6
Interest expense, net	13.8	20.0	49.5	87.9
Foreign exchange loss (gain)	9.4	(3.4)	17.7	19.1
Other income, net		(1.7)		(3.9)
Total administrative and other expenses (income)	28.7	20.6	84.8	120.7
Loss from operations before income taxes	(49.6)	(77.7)	(92.5)	(124.0)
Income tax (benefit) expense (Note 8)	(15.9)	2.6	(38.5)	(14.2)
Net loss	(33.7)	(80.3)	(54.0)	(109.8)
Net (loss) income attributable to preferred shares of a subsidiary company	(0.8)	2.1	3.5	6.4
Net loss attributable to Atlantic Power Corporation	$ (32.9)	$ (82.4)	$ (57.5)	$ (116.2)
Net loss per share attributable to Atlantic Power Corporation shareholders: (Note 10)
Basic	$ (0.29)	$ (0.69)	$ (0.50)	$ (0.96)
Diluted	$ (0.29)	$ (0.69)	$ (0.50)	$ (0.96)
Weighted average number of common shares outstanding: (Note 9)
Basic (in shares)	115.3	119.3	115.1	120.9
Diluted (in shares)	115.3	119.3	115.1	120.9