Retirement Benefits - Schedule of Amounts Included In Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Dec. 28, 2025	Dec. 29, 2024	Dec. 31, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost) credit	$ (6.7)	$ (7.1)
Net actuarial loss	0.0	0.0
Accumulated other comprehensive loss	(6.7)	(7.1)	$ (7.4)
Deferred tax effect	1.8	1.9
Accumulated other comprehensive loss, net of tax	(4.9)	(5.2)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service (cost) credit	0.0	0.8
Net actuarial loss	(54.8)	(53.1)
Accumulated other comprehensive loss	(54.8)	(52.3)	$ (54.5)
Deferred tax effect	27.5	27.0
Accumulated other comprehensive loss, net of tax	$ (27.3)	$ (25.3)