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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 5.5	$ 5.5	$ 10.9	$ 11.0
Amortization of net prior service credit	0.1	0.0	0.1	0.0
Amortization of net actuarial gain	1.3	0.8	2.5	1.7
Net periodic cost (income)	0.0	(2.2)	(0.3)	(4.4)
Other employee benefit plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0.4	0.4	0.8	0.7
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 cost (income)	$ 0.2	$ 0.2	$ 0.5	$ 0.4