Accumulated Other Comprehensive Income (Loss) - Details of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 152.3
Other comprehensive income (loss) before reclassifications	18.0	$ 46.6
Less: amounts reclassified from accumulated other comprehensive income	1.1	3.5
Other comprehensive income, net of taxes	19.1	50.1
Ending balance	(364.8)
Unrecognized Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(103.4)	(276.7)
Other comprehensive income (loss) before reclassifications	0.0	2.8
Less: amounts reclassified from accumulated other comprehensive income	0.6	1.7
Other comprehensive income, net of taxes	0.6	4.5
Ending balance	(102.8)	(272.2)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(694.4)	(701.9)
Other comprehensive income (loss) before reclassifications	28.4	55.2
Less: amounts reclassified from accumulated other comprehensive income	0.0	0.0
Other comprehensive income, net of taxes	28.4	55.2
Ending balance	(666.0)	(646.7)
Cumulative Translation Adjustment | Intra-entity transactions
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Intra-entity currency translation adjustment in AOCI	(16.5)	11.3
Unrecognized Gains (Losses) on Derivative Instruments | Net Investment Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(46.8)	21.0
Other comprehensive income (loss) before reclassifications	(10.7)	(4.9)
Less: amounts reclassified from accumulated other comprehensive income	0.0	0.0
Other comprehensive income, net of taxes	(10.7)	(4.9)
Ending balance	(57.5)	16.1
Unrecognized Gains (Losses) on Derivative Instruments | Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(0.3)	8.5
Other comprehensive income (loss) before reclassifications	0.3	(6.5)
Less: amounts reclassified from accumulated other comprehensive income	0.5	1.8
Other comprehensive income, net of taxes	0.8	(4.7)
Ending balance	0.5	3.8
Accumulated Other Comprehensive Income (Loss), Net of Taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(844.9)	(949.1)
Ending balance	$ (825.8)	$ (899.0)