Accumulated Other Comprehensive Loss - Amounts Reclassified Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	$ 3.6	$ 23.3	$ 217.2	$ 66.2
Total before tax	28.5	39.2	207.2	88.6
Income tax	20.4	0.7	55.7	25.1
Reclassification out of Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before tax	19.6	40.3	237.6	120.8
Income tax	(0.4)	(1.4)	(1.2)	(4.6)
Total reclassifications for the period	19.2	38.9	236.4	116.2
Reclassification out of Accumulated Other Comprehensive Loss | Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	0.5	1.9	(2.9)	4.8
Reclassification out of Accumulated Other Comprehensive Loss | Amortization of prior service benefit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	(1.4)	(1.6)	(4.0)	(4.5)
Reclassification out of Accumulated Other Comprehensive Loss | Amortization of actuarial losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	20.5	40.0	61.3	120.5
Reclassification out of Accumulated Other Comprehensive Loss | Settlement losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	$ 0.0	$ 0.0	$ 183.2	$ 0.0