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, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 5.4	$ 5.5
Net periodic benefit cost	(0.3)	(2.2)
Other employee benefit plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.4	0.3
Amortization of net prior service cost	(0.1)	(0.1)
Net periodic benefit cost	$ 0.3	$ 0.2