Reportable Business Segments (Assets by Segment) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Segment Reporting Information [Line Items]
Total assets	$ 4,545.0	$ 4,081.8
Operating Segments
Segment Reporting Information [Line Items]
Total assets	4,132.8	3,717.4
Corporate and Other
Segment Reporting Information [Line Items]
Total assets	412.2	364.4
Residential Heating and Cooling [Member] | Operating Segments
Segment Reporting Information [Line Items]
Total assets	2,230.0	1,971.0
Commercial Heating and Cooling | Operating Segments
Segment Reporting Information [Line Items]
Total assets	$ 1,902.8	$ 1,746.4