Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			$ 14,181.3
Total other comprehensive income (loss), net of tax	$ (46.9)	$ 53.4	(211.4)	$ 273.2
Ending balance	6,026.2		6,026.2
Cumulative Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(318.8)
Other comprehensive (loss) income before reclassifications			(212.8)
Amounts reclassified to earnings			16.8
Total other comprehensive income (loss), net of tax			(196.0)
Ending balance	(514.8)		(514.8)
Pension and Postretirement Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(385.5)
Other comprehensive (loss) income before reclassifications			(43.6)
Amounts reclassified to earnings			7.8
Total other comprehensive income (loss), net of tax			(35.8)
Reclassification to retained earnings			(54.5)
Ending balance	(475.8)		(475.8)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(58.8)
Other comprehensive (loss) income before reclassifications			6.0
Amounts reclassified to earnings			14.4
Total other comprehensive income (loss), net of tax			20.4
Reclassification to retained earnings			(8.1)
Ending balance	(46.5)		(46.5)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(763.1)
Other comprehensive (loss) income before reclassifications			(250.4)
Amounts reclassified to earnings			39.0
Total other comprehensive income (loss), net of tax			(211.4)
Reclassification to retained earnings			(62.6)
Ending balance	$ (1,037.1)		$ (1,037.1)