Retirement Benefits - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) benefit_plan	Dec. 31, 2022 USD ($) benefit_plan	Dec. 31, 2021 USD ($) benefit_plan
Defined Benefit Plan Disclosure [Line Items]
Pension charge	$ 0.0	$ 7.0	$ 0.0
Number of defined contribution pension plans | benefit_plan	4
Defined contribution pension plans, total costs	$ 32.3	$ 25.8	$ 23.3
Number of multiemployer defined benefit pension plans | benefit_plan		1	1
Multiemployer plan total employer contributions		$ 0.2	$ 0.2
Futures contract supported by cash or cash equivalents	100.00%
United States
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.20%	5.50%
United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.80%	5.00%
Canada
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.61%	5.01%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension charge	$ 18.5	$ 18.1	(0.7)
Benefit obligation	674.9	670.8	937.7
Settlement losses	0.0	8.8	$ 0.0
Employer contributions	$ 26.5	$ 19.8
Discount rate	5.16%	5.46%	2.79%
Pension Benefits | Continuing Operations
Defined Benefit Plan Disclosure [Line Items]
Settlement losses		$ 7.0
Pension Benefits | Discontinued Operations
Defined Benefit Plan Disclosure [Line Items]
Settlement losses		1.8
Pension Benefits | United States
Defined Benefit Plan Disclosure [Line Items]
Defined benefit obligation per plan, as a percent of total benefit obligation (as a percent)	89.00%
Employer contributions	$ 20.0	10.0	$ 0.0
Pension Benefits | United Kingdom
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		2.5
Company Stock
Defined Benefit Plan Disclosure [Line Items]
Employer stock included in plan assets	$ 0.0	$ 0.0