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
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 3.1	$ 4.3
Amortization of net prior service credit and net actuarial gain	0.1	0.0
Net periodic (income) cost	(0.5)	(0.2)
Other employee benefit plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.1	0.3
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) and Actuarial Gain (Loss), Net	(0.1)	(0.1)
Net periodic (income) cost	$ 0.0	$ 0.2