Accumulated Other Comprehensive Income (Loss) - Details of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 609.7
Other comprehensive income (loss) before reclassifications			107.8	$ (19.0)
Less: amounts reclassified from accumulated other comprehensive income (loss)			5.4	(19.9)
Other comprehensive income (loss), net of taxes	$ 84.7	$ (15.4)	113.2	(38.9)
Ending balance	760.6		760.6
Unrecognized pension items			173.4
Cumulative translation adjustments in other comprehensive income (loss)			454.7
Unrecognized Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(276.7)	(266.0)
Other comprehensive income (loss) before reclassifications			175.0	(3.6)
Less: amounts reclassified from accumulated other comprehensive income (loss)			4.9	9.2
Other comprehensive income (loss), net of taxes			179.9	5.6
Ending balance	(96.8)	(260.4)	(96.8)	(260.4)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(701.9)	(564.0)
Other comprehensive income (loss) before reclassifications			5.5	19.4
Less: amounts reclassified from accumulated other comprehensive income (loss)			0.0	(46.0)
Other comprehensive income (loss), net of taxes			5.5	(26.6)
Ending balance	(696.4)	(590.6)	(696.4)	(590.6)
Cumulative Translation Adjustment | Intra-entity transactions
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Intra-entity currency translation adjustment in AOCI	(52.2)	(31.4)	(52.2)	(31.4)
Unrecognized Gains (Losses) on Derivative Instruments | Net Investment Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			21.0	1.7
Other comprehensive income (loss) before reclassifications			(64.0)	(15.4)
Less: amounts reclassified from accumulated other comprehensive income (loss)			0.0	0.0
Other comprehensive income (loss), net of taxes			(64.0)	(15.4)
Ending balance	(43.0)	(13.7)	(43.0)	(13.7)
Unrecognized Gains (Losses) on Derivative Instruments | Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			8.5	8.3
Other comprehensive income (loss) before reclassifications			(8.7)	(19.4)
Less: amounts reclassified from accumulated other comprehensive income (loss)			0.5	16.9
Other comprehensive income (loss), net of taxes			(8.2)	(2.5)
Ending balance	0.3	5.8	0.3	5.8
Accumulated Other Comprehensive Income (Loss), Net of Taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(949.1)	(820.0)
Ending balance	$ (835.9)	$ (858.9)	$ (835.9)	$ (858.9)