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, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 4.3	$ 5.4
Net periodic benefit cost	(0.2)	(0.3)
Other employee benefit plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.3	0.4
Amortization of net prior service credit	(0.1)	(0.1)
Net periodic benefit cost	$ 0.2	$ 0.3