Retirement Benefits (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Jan. 01, 2023	Jan. 02, 2022
Defined Benefit Plan Disclosure [Line Items]
Pension remeasurement gain (loss)	$ (26.8)	$ 100.3	$ 147.2
Settlement loss (gain)	41.7	0.0	(64.9)
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	6.0	11.9	15.1
Interest cost on benefits earned in prior years	79.7	69.7	68.4
Expected return on plan assets	(84.8)	(128.2)	(136.4)
Amortization of prior service cost (credit)	0.3	0.4	0.6
Amortization of net actuarial loss	0.0	0.0	0.0
Pension remeasurement gain (loss)	(26.8)	100.3	147.2
Settlement loss (gain)	41.7	0.7	0.0
Total retirement benefit expense (income)	69.7	(145.8)	(199.5)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	0.6	1.1	1.5
Interest cost on benefits earned in prior years	10.9	7.7	8.0
Expected return on plan assets	0.0	0.0	0.0
Amortization of prior service cost (credit)	(0.9)	(0.9)	(2.4)
Amortization of net actuarial loss	6.0	13.2	13.9
Pension remeasurement gain (loss)	0.0	0.0	0.0
Settlement loss (gain)	0.0	0.0	(64.9)
Total retirement benefit expense (income)	$ 16.6	$ 21.1	$ (43.9)