Defined Benefit Pension Plans and Other Post-Employment Benefit Plans - Net Period Benefit Costs (income) for Post-retirement Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 3.0	$ 4.3	$ 6.1	$ 8.6
Amortization of net prior service credit	0.0	0.1	0.1	0.1
Net periodic (income) cost	(0.5)	(0.2)	(1.0)	(0.4)
Other employee benefit plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.2	0.2	0.3	0.5
Amortization of net prior service credit	(0.1)	(0.1)	(0.2)	(0.2)
Amortization of net actuarial gain	(0.1)	(0.1)	(0.1)	(0.1)
Net periodic (income) cost	$ 0.0	$ 0.0	$ 0.0	$ 0.2