CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ 73.5	$ (43.8)
Other comprehensive income, net of tax:
Unrealized loss on hedging activities	(0.5)	(0.3)
Net amount reclassified to earnings	0.5	0.3
Defined benefit plan, net of tax	(1.4)	(0.3)
Foreign currency translation adjustments	2.2	5.8
Other comprehensive income, net of tax	0.8	5.5
Comprehensive income (loss)	74.3	(38.3)
Less: Comprehensive loss attributable to preferred shares of a subsidiary company	(0.7)	(1.2)
Comprehensive income (loss) attributable to Atlantic Power Corporation	$ 75.0	$ (37.1)