Income Taxes - Income Tax Reconciliation (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2023	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Income Tax [Line Items]
Income tax based on statutory rate			$ 43.2		$ 117.0		$ 119.3
Increase (decrease) resulting from:
Repatriation of non-United States earnings			4.6		10.7		5.7
State income taxes, net of federal benefit			2.0		5.5		5.0
Change in valuation allowance	[1]		53.5		13.7		22.0
Work Opportunity Tax Credit	[2]		(5.6)		(14.4)		(12.1)
Foreign-Derived Intangible Income deduction			(7.2)		(9.6)		(10.7)
Goodwill impairment	[3]		10.9		8.9		0.0
Change in unrecognized tax benefits		$ (48.8)	(14.4)	[4]	4.2	[4]	1.6	[4]
Other, net			6.7		7.5		6.0
Total provision			117.1		183.3		185.7
French Business Tax
Increase (decrease) resulting from:
Non-United States tax rate difference:	[5]		13.0		24.6		26.7
Other
Increase (decrease) resulting from:
Non-United States tax rate difference:	[6]		$ 10.4		$ 15.2		$ 22.2

[1] Losses incurred in 2023, 2022 and 2021 in Germany resulted in an increase in valuation allowance of $46.3, $13.5 and $20.1, respectively.

[2] The Work Opportunity Tax Credit is currently authorized until December 31, 2025.

[3] Non-deductible portion of the goodwill impairment charges recorded in the Netherlands in 2023 and 2022.

[4] Effective settlement of an audit during the third quarter of 2023 resulted in the recognition of a tax benefit of $10.8. For 2022 and 2021, the Work Opportunity Tax Credit and Other, net categories were updated to separately reflect the Change in unrecognized tax benefits.

[5] The French business tax is allowed as a deduction for French income tax purposes. The gross amount of the French business tax was $16.4, $31.2 and $33.7 for 2023, 2022, and 2021 respectively. The amounts in the table above of $13.0, $24.6 and $26.7 for 2023, 2022, and 2021, respectively, represent the French business tax expense net of the French tax benefit using the United States federal rate of 21%. In December 2023, the French Parliament approved the Finance Bill for 2024 which reversed the scheduled elimination of the business tax in 2024 and replaced it with a gradual reduction of the tax rate (i.e., 0.28% in 2024, 0.19% in 2025, 0.09% in 2026) before eliminating altogether in 2027.

[6] Included in Other Non-United States tax rate differences is the impact of all Non-United States pre-tax earnings and permanent tax differences at the local statutory tax rate versus the United States federal rate of 21%. This includes benefits of $0.8, $1.5 and $2.5 for 2023, 2022 and 2021, respectively, related to the difference between the United States federal rate and the French tax rate applied to the respective gross amounts of the French business tax deduction previously mentioned.