Accumulated Other Comprehensive Loss - Amounts Reclassified Out of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	$ (21.9)	$ (227.8)	$ (42.9)	$ (410.4)
Total before tax	3.5	(195.4)	(49.4)	(344.5)
Income tax	(20.3)	53.1	(24.4)	44.7
Reclassification out of Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total before tax	40.7	187.0	80.5	386.0
Income tax	(1.5)	(36.9)	(3.2)	(38.6)
Total reclassifications for the period	39.2	150.1	77.3	347.4
Reclassification out of Accumulated Other Comprehensive Loss | Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	1.8	0.7	2.9	(1.6)
Reclassification out of Accumulated Other Comprehensive Loss | Amortization of prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	(1.2)	(1.6)	(2.9)	(3.1)
Reclassification out of Accumulated Other Comprehensive Loss | Amortization of actuarial losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	40.1	45.2	80.5	90.0
Reclassification out of Accumulated Other Comprehensive Loss | Settlement losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other (expense), net	$ 0.0	$ 142.7	$ 0.0	$ 300.7