Pension and Other Retiree Benefits (Other Changes Recognized in Accumulated Other Comprehensive Income) (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]
Current year actuarial loss (gain)	$ 5.9	$ 0.9	$ 7.1
Amortization of actuarial (loss) gain	(2.0)	(1.8)	(2.1)
Current year prior service credit	0.0	0.0	0.0
Amortization of prior service (cost) credit	(0.4)	(0.4)	(0.4)
Foreign exchange rate changes	0.0	0.0	0.0
Total recognized in other comprehensive income (loss)	3.5	(1.3)	4.6
Total recognized in net periodic benefit cost (income) and other comprehensive income (loss)	2.1	(2.4)	5.2
Pension | International
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial loss (gain)	14.3	27.9	3.8
Amortization of actuarial (loss) gain	(3.0)	(2.3)	(2.4)
Current year prior service credit	0.0	0.0	0.0
Amortization of prior service (cost) credit	0.0	0.0	0.0
Foreign exchange rate changes	10.7	(15.5)	(5.6)
Total recognized in other comprehensive income (loss)	22.0	10.1	(4.2)
Total recognized in net periodic benefit cost (income) and other comprehensive income (loss)	18.5	5.9	(9.9)
Post-retirement
Defined Benefit Plan Disclosure [Line Items]
Current year actuarial loss (gain)	0.0	(1.0)	(3.4)
Amortization of actuarial (loss) gain	0.4	1.0	0.9
Current year prior service credit	0.0	0.0	(0.2)
Amortization of prior service (cost) credit	0.0	0.0	0.3
Foreign exchange rate changes	(0.2)	0.5	0.1
Total recognized in other comprehensive income (loss)	0.2	0.5	(2.3)
Total recognized in net periodic benefit cost (income) and other comprehensive income (loss)	$ 0.0	$ (0.2)	$ (3.0)