Business Segments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2024	Dec. 31, 2023	Jan. 01, 2023
Segment Reporting Information [Line Items]
Sales	$ 4,362.1	$ 4,173.7	$ 3,836.0
Operating Segments
Segment Reporting Information [Line Items]
Sales	4,884.9	4,638.9	4,249.4
Operating Segments | Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Sales	522.8	465.2	413.4
Operating Segments | External Sales [Member]
Segment Reporting Information [Line Items]
Sales	4,362.1	4,173.7	3,836.0
Operating Segments | HPMC
Segment Reporting Information [Line Items]
Sales	2,526.2	2,302.0	1,815.7
Operating Segments | HPMC | Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Sales	247.7	181.8	174.5
Operating Segments | HPMC | External Sales [Member]
Segment Reporting Information [Line Items]
Sales	2,278.5	2,120.2	1,641.2
Operating Segments | AA&S
Segment Reporting Information [Line Items]
Sales	2,358.7	2,336.9	2,433.7
Operating Segments | AA&S | Intersegment Sales [Member]
Segment Reporting Information [Line Items]
Sales	275.1	283.4	238.9
Operating Segments | AA&S | External Sales [Member]
Segment Reporting Information [Line Items]
Sales	$ 2,083.6	$ 2,053.5	$ 2,194.8