Reportable Business Segments (Key Financial Information by Segment) (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net Sales	$ 1,195,000,000	$ 1,426,800,000	$ 1,500,900,000	$ 1,072,600,000	$ 5,195,300,000	$ 5,341,300,000	$ 4,981,900,000
Cost of goods sold	805,700,000	939,600,000	983,400,000	731,700,000	3,460,500,000	3,563,800,000	3,432,700,000
Selling, general and administrative					681,400,000	730,600,000	705,500,000
Other (income) expense					(4,300,000)	5,000,000.0	(14,800,000)
Segment profit (loss)					1,057,700,000	$ 1,041,900,000	$ 858,500,000
Revenue from transactions with major customers					$ 0
Minimum percentage of consolidated net sales from single customer					10.00%	10.00%	10.00%
Impact of LIFO Change
Segment Reporting Information [Line Items]
Net Sales	0	0	0	0
Cost of goods sold	$ 3,700,000	$ (13,200,000)	$ 3,500,000	$ (7,300,000)
Segment Reporting, Reconciling Item, Corporate Nonsegment
Segment Reporting Information [Line Items]
Net Sales					$ 0	$ 0	$ 247,600,000
Cost of goods sold					0	700,000	178,900,000
Selling, general and administrative					91,400,000	107,000,000.0	157,800,000
Other (income) expense					13,600,000	12,700,000	4,800,000
Segment profit (loss)					(105,000,000.0)	(120,300,000)	(93,900,000)
Residential Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Net Sales					3,343,400,000	3,577,100,000	3,222,900,000
Residential Heating and Cooling [Member] | Operating Segments
Segment Reporting Information [Line Items]
Net Sales					3,343,400,000	3,577,100,000	3,222,900,000
Cost of goods sold					2,280,700,000	2,425,300,000	2,275,900,000
Selling, general and administrative					349,600,000	393,800,000	350,200,000
Other (income) expense					(15,400,000)	(2,500,000)	(14,800,000)
Segment profit (loss)					728,500,000	760,500,000	611,600,000
Residential Heating and Cooling [Member] | Operating Segments | Impact of LIFO Change
Segment Reporting Information [Line Items]
Cost of goods sold						800,000	1,400,000
Commercial Heating and Cooling [Member]
Segment Reporting Information [Line Items]
Net Sales					1,851,900,000	1,764,200,000	1,511,400,000
Commercial Heating and Cooling [Member] | Operating Segments
Segment Reporting Information [Line Items]
Net Sales					1,851,900,000	1,764,200,000	1,511,400,000
Cost of goods sold					1,179,800,000	1,137,800,000	977,900,000
Selling, general and administrative					240,400,000	229,900,000	197,500,000
Other (income) expense					(2,500,000)	(5,200,000)	(4,800,000)
Segment profit (loss)					$ 434,200,000	401,700,000	340,800,000
Commercial Heating and Cooling [Member] | Operating Segments | Impact of LIFO Change
Segment Reporting Information [Line Items]
Cost of goods sold						$ 4,800,000	$ 0