Employee Retirement Plans - Components of net retirement cost (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Defined Contribution Plan, Cost		$ 2.5	$ 2.5	$ 7.5	$ 6.8
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	[1]	$ 0.2	$ 0.2	$ 0.5	$ 0.5

[1] The non-service cost components of net periodic benefit cost are included in other, net (income) expense in our Consolidated Statements of Operations.