Income Taxes - Income Tax Reconciliation (Parenthetical) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax [Line Items]
French business tax, gross			$ 16.4	$ 31.2	$ 33.7
Repatriation of non-United States earnings			4.6	10.7	5.7
Change in valuation allowance	[1]		53.5	13.7	22.0
Provision for income taxes			$ 117.1	183.3	185.7
Recognition of tax benefit		$ 10.8
2024			0.28%
2025			0.19%
2026			0.09%
Germany
Income Tax [Line Items]
Change in valuation allowance			$ 46.3	13.5	20.1
French Business Tax
Income Tax [Line Items]
Non-United States tax rate difference:	[2]		$ 13.0	$ 24.6	$ 26.7
United States
Income Tax [Line Items]
U.S. Federal statutory rate (as percent)			21.00%	21.00%	21.00%
French business tax difference
Income Tax [Line Items]
Repatriation of non-United States earnings			$ 0.8	$ 1.5	$ 2.5

[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 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.