Business Segments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2025	Sep. 29, 2024	Sep. 28, 2025	Sep. 29, 2024
Segment Reporting Information [Line Items]
Sales	$ 1,125.5	$ 1,051.2	$ 3,410.3	$ 3,189.4
Segment EBITDA	236.2	196.8	671.3	567.5
Corporate expenses	(15.6)	(13.4)	(48.4)	(49.9)
Closed operations and other income	4.5	2.3	4.5	1.7
Depreciation & amortization	(42.6)	(38.5)	(125.0)	(112.4)
Interest expense, net	(26.1)	(28.0)	(74.5)	(83.0)
Restructuring and other charges	(12.9)	(4.3)	(25.9)	(12.8)
Gain on sales of businesses	1.1	0.0	(2.6)	0.0
Income before taxes	144.6	114.9	399.4	311.1
Operating Segments
Segment Reporting Information [Line Items]
Sales	1,231.6	1,201.3	3,733.9	3,582.3
Depreciation & amortization	(42.6)	(38.5)	(125.0)	(112.4)
Operating Segments | HPMC
Segment Reporting Information [Line Items]
Sales	661.5	612.9	1,967.6	1,828.6
Allocated corporate overhead	14.3	17.9	48.6	50.4
Other segment items	501.4	471.8	1,498.2	1,443.6
Segment EBITDA	145.8	123.2	420.8	334.6
Depreciation & amortization	(21.2)	(18.6)	(61.8)	(52.8)
Operating Segments | AA&S
Segment Reporting Information [Line Items]
Sales	570.1	588.4	1,766.3	1,753.7
Allocated corporate overhead	14.2	18.4	50.2	50.8
Other segment items	465.5	496.4	1,465.6	1,470.0
Segment EBITDA	90.4	73.6	250.5	232.9
Depreciation & amortization	(19.7)	(18.2)	(58.3)	(54.5)
Sales to external customers | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,125.5	1,051.2	3,410.3	3,189.4
Sales to external customers | Operating Segments | HPMC
Segment Reporting Information [Line Items]
Sales	602.9	552.4	1,795.8	1,644.3
Sales to external customers | Operating Segments | AA&S
Segment Reporting Information [Line Items]
Sales	522.6	498.8	1,614.5	1,545.1
Intersegment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	106.1	150.1	323.6	392.9
Intersegment sales | Operating Segments | HPMC
Segment Reporting Information [Line Items]
Sales	58.6	60.5	171.8	184.3
Intersegment sales | Operating Segments | AA&S
Segment Reporting Information [Line Items]
Sales	$ 47.5	$ 89.6	$ 151.8	$ 208.6