Accumulated Other Comprehensive Loss, Net of Tax Changes in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Available-for-sale securities, before reclassifications	$ 0.0	$ 0.5	$ 0.5
Total other comprehensive income, before reclassifications	121.0	(125.0)
Total reclassification from AOCI	14.1	8.1	31.5
Accumulated Other Comprehensive Income (Loss), net of tax	(827.4)	(962.5)	(845.6)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Foreign currency translation adjustment, before reclassifications	130.7	(54.8)
Foreign currency translation adjustment, amount reclassified from AOCI, net of tax	1.1	3.7
Foreign currency translation adjustment, net of tax	(584.9)	(716.7)	(665.6)
Available-for-sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Available-for-sale securities, before reclassifications	0.0	0.5
Available-for-sale securities, amount reclassified from AOCI, net of tax	(0.6)	(1.2)
Available-for-sale securities adjustment, net of tax	0.0	0.6	1.3
Derivative Instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Derivative instruments, before reclassifications	0.0	0.0
Derivative instruments, amount reclassified from AOCI, net of tax	1.6	1.2
Derivative Instruments, net of tax	(6.8)	(8.4)	(9.6)
Defined Benefit and Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Defined Benefit and Postretirement Plans, before reclassifications	(9.7)	(70.7)
Defined benefit and Postretirement Plans, amount reclassified from AOCI, net of tax	12.0	4.4
Pension and Other Postretirement Benefit Plans, net of tax	$ (235.7)	$ (238.0)	$ (171.7)