Pension and Other Post-Retirement Benefits Pension and Other Post-Retirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Oct. 01, 2020	Sep. 30, 2021	Oct. 01, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment		$ (0.0)		$ (33.7)
Defined Benefit Plan Estimated Future Employer Contributions Remainder Of Year			$ 10.2
Expected UK Pension Plan Contribution For Year			1.9
Expected UK-Belfast Pension Plan Contribution For Year			182.6
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax		0.0		2.3
Defined Benefit Plan, Service Cost	$ 0.3	0.1	0.7	0.5
Defined Benefit Plan, Interest Cost	0.1	0.2	0.3	0.7
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(0.2)	(0.2)	(0.6)	(0.6)
Defined Benefit Plan, Amortization of Gain (Loss)	(0.2)	(0.4)	(1.0)	(1.3)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0.0	0.0	0.0	(0.2)
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	0.0	0.0	0.0	12.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	0.0	(0.3)	(0.6)	11.1
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax		(31.9)		0.4
Defined Benefit Plan, Service Cost	11.2	0.2	32.9	0.7
Defined Benefit Plan, Interest Cost	15.8	5.4	43.3	20.1
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(40.0)	(16.6)	(119.0)	(49.5)
Defined Benefit Plan, Amortization of Gain (Loss)	0.0	0.0	0.0	0.2
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	(61.0)	0.0	(61.0)	33.9
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	0.0	4.2	(0.1)	9.3
Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits	0.0	(1.6)	0.0	31.4
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ (74.0)	$ (8.4)	$ (103.9)	$ 46.1