Defined Benefit Pension Plans and Other Post-Employment Benefit Plans - Components of Net Periodic Benefit Cost (Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Components of net periodic benefit cost (income):
Service cost	$ 1.2	$ 1.8	$ 2.2	$ 3.5
Interest cost	5.5	5.7	11.0	11.5
Expected return on plan assets	(9.7)	(10.0)	(19.3)	(20.1)
Amortization of net actuarial loss	0.8	1.6	1.7	3.2
Net periodic income	(2.2)	(0.9)	(4.4)	(1.9)
Cost of settlement/curtailment	0.1	0.8	0.1	1.3
Total benefit (income) cost	(2.1)	(0.1)	(4.3)	(0.6)
U.S.
Components of net periodic benefit cost (income):
Service cost	0.1	0.1	0.1	0.1
Interest cost	1.6	1.7	3.2	3.5
Expected return on plan assets	(2.2)	(2.4)	(4.4)	(4.9)
Amortization of net actuarial loss	0.2	0.2	0.5	0.4
Net periodic income	(0.3)	(0.4)	(0.6)	(0.9)
Cost of settlement/curtailment	0.0	0.8	0.0	0.8
Total benefit (income) cost	(0.3)	0.4	(0.6)	(0.1)
International
Components of net periodic benefit cost (income):
Service cost	1.1	1.7	2.1	3.4
Interest cost	3.9	4.0	7.8	8.0
Expected return on plan assets	(7.5)	(7.6)	(14.9)	(15.2)
Amortization of net actuarial loss	0.6	1.4	1.2	2.8
Net periodic income	(1.9)	(0.5)	(3.8)	(1.0)
Cost of settlement/curtailment	0.1	0.0	0.1	0.5
Total benefit (income) cost	(1.8)	(0.5)	(3.7)	(0.5)
Other employee benefit plans
Components of net periodic benefit cost (income):
Service cost	0.0	0.1	0.0	0.1
Interest cost	0.4	0.4	0.7	0.9
Amortization of net prior service cost	(0.1)	(0.3)	(0.2)	(0.8)
Amortization of net actuarial loss	(0.1)	(0.1)	(0.1)	(0.1)
Net periodic income	$ 0.2	$ 0.1	$ 0.4	$ 0.1