Reportable Business Segments (Equity Method Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total income from equity method investments	$ 15.6	$ 13.4	$ 12.0
Commercial Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total income from equity method investments	(2.3)	(1.7)	(1.4)
Residential Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total income from equity method investments	(11.4)	(8.8)	(8.5)
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total income from equity method investments	$ (1.9)	$ (2.9)	$ (2.1)