Reportable Business Segments (Equity Method Investments) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Segment Reporting Information [Line Items]
Total income from equity method investments	$ 1.4	$ 2.5	$ 2.0	$ 5.8
Operating Segments
Segment Reporting Information [Line Items]
Total income from equity method investments	1.2	2.7	1.8	5.9
Corporate and Other
Segment Reporting Information [Line Items]
Total income from equity method investments	0.2	(0.2)	0.2	(0.1)
Residential Heating and Cooling [Member] \| Operating Segments
Segment Reporting Information [Line Items]
Total income from equity method investments	0.4	2.4	1.2	4.8
Commercial Heating and Cooling \| Operating Segments
Segment Reporting Information [Line Items]
Total income from equity method investments	$ 0.8	$ 0.3	$ 0.6	$ 1.1

Amount of income (loss) for proportionate share of equity method investee's income (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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