Reportable Business Segments (Assets by Segment) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total assets	$ 2,798.3	$ 2,567.6	$ 2,171.9
Residential Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total assets	1,449.4	1,456.4	1,149.7
Commercial Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Total assets	989.2	730.3	626.7
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Total assets	$ 359.7	$ 380.9	$ 395.5