Reportable Business Segments (Assets by Segment) (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Total assets	$ 4,081.8	$ 3,620.0	$ 2,941.0
Residential Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total assets	1,971.0	1,721.4	1,549.3
Commercial Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total assets	1,746.4	1,105.5	1,032.1
Corporate Segment and Other Operating Segment [Member]
Segment Reporting Information [Line Items]
Total assets	$ 364.4	$ 793.1	$ 359.6