Reportable Business Segments (Assets by Segment) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Segment Reporting Information [Line Items]
Total assets	$ 3,524.6	$ 3,471.8
Residential Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total assets	1,869.5	1,626.0
Commercial Heating and Cooling
Segment Reporting Information [Line Items]
Total assets	1,281.8	1,052.6
Corporate & Other
Segment Reporting Information [Line Items]
Total assets	$ 373.3	$ 793.2