Pension and Other Retiree Benefits (Net Periodic Benefit Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension | U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.4	$ 1.3	$ 1.6
Interest cost	7.1	7.3	8.7
Expected return on plan assets	(12.3)	(11.9)	(12.2)
Amortization of net loss (gain)	2.0	1.8	2.1
Amortization of prior service cost (credit)	0.4	0.4	0.4
Curtailment gain	0.0	0.0	0.0
Settlement gain	0.0	0.0	0.0
Net periodic benefit (income) expense	(1.4)	(1.1)	0.6
Pension | International
Defined Benefit Plan Disclosure [Line Items]
Service cost	1.9	0.8	0.9
Interest cost	13.4	10.3	12.9
Expected return on plan assets	(21.8)	(17.6)	(21.9)
Amortization of net loss (gain)	3.0	2.3	2.4
Amortization of prior service cost (credit)	0.0	0.0	0.0
Curtailment gain	0.0	0.0	0.0
Settlement gain	0.0	0.0	0.0
Net periodic benefit (income) expense	(3.5)	(4.2)	(5.7)
Post-retirement
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.0	0.1	0.1
Interest cost	0.2	0.2	0.4
Expected return on plan assets	0.0	0.0	0.0
Amortization of net loss (gain)	(0.4)	(0.4)	(0.4)
Amortization of prior service cost (credit)	0.0	0.0	(0.3)
Curtailment gain	0.0	(0.6)	0.0
Settlement gain	0.0	0.0	(0.5)
Net periodic benefit (income) expense	$ (0.2)	$ (0.7)	$ (0.7)