Revenue from contracts (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from contracts

Schedule of disaggregation of revenue

	Year Ended December 31, 2020
										Consolidated
	Solid Fuel		Natural Gas		Hydroelectric			Corporate		Total
Project revenue:
Energy sales	$	58.8	$	24.2	$	54.9	$		—	$	137.9
Energy capacity revenue		34.6		79.2		—			—		113.8
Steam energy and capacity revenue		—		10.5		—			—		10.5
Waste heat revenue		1.0		—		—			—		1.0
Ancillary and transmission services		—		3.1		3.4			—		6.5
Asset management and operation		—		—		—			1.0		1.0
Miscellaneous revenue		0.1		1.2		—			—		1.3
		94.5		118.2		58.3			1.0		272.0

	Year Ended December 31, 2019
										Consolidated
		Solid Fuel		Natural Gas		Hydroelectric		Corporate		Total
Project revenue:
Energy sales	$	41.1	$	31.0	$	65.9	$	—	$	138.0
Energy capacity revenue		38.7		86.7		—		—		125.4
Steam energy and capacity revenue		—		11.7		—		—		11.7
Waste heat revenue		0.2		—		—		—		0.2
Ancillary and transmission services		—		4.7		2.9		—		7.6
Asset management and operation		—		—		—		1.0		1.0
Miscellaneous revenue		—		(2.3)		—		—		(2.3)
		80.0		131.8		68.8		1.0		281.6