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Goodwill - Changes in the Net Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 28, 2025	Sep. 29, 2024	Sep. 28, 2025	Sep. 29, 2024	Dec. 29, 2024
Goodwill [Roll Forward]
Goodwill, beginning balance			$ 304.2	$ 151.1	$ 151.1
Additions					225.9
Adjustments			(0.1)
Reallocation			0.0
Impairment adjustments	$ (102.0)	$ 0.0	(102.0)	0.0	(72.8)
Goodwill, ending balance	202.1		202.1		304.2
Goodwill, impaired, accumulated impairment loss	174.8		174.8		72.8
Science, Engineering & Technology
Goodwill [Roll Forward]
Goodwill, beginning balance			261.4	111.3	111.3
Additions					222.9
Adjustments			0.0
Reallocation			(22.3)
Impairment adjustments			(102.0)		(72.8)
Goodwill, ending balance	137.1		137.1		261.4
Education
Goodwill [Roll Forward]
Goodwill, beginning balance			42.8	39.8	39.8
Additions					3.0
Adjustments			(0.1)
Reallocation			0.0
Impairment adjustments			0.0		0.0
Goodwill, ending balance	42.7		42.7		42.8
Enterprise Talent Management
Goodwill [Roll Forward]
Goodwill, beginning balance			0.0	$ 0.0	0.0
Additions					0.0
Adjustments			0.0
Reallocation			22.3
Impairment adjustments			0.0		0.0
Goodwill, ending balance	$ 22.3		$ 22.3		$ 0.0