Accumulated Other Comprehensive Income - Changes in Components of Accumulated Other Comprehensive Income, Net of Tax (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Other Comprehensive Income Loss [Line Items]
Stockholders Equity, Beginning Balance	$ 11,735.8
AOCI before reclassifications	(96.9)
Reclassifications to retained earnings (Note 2)	(42.9)
Reclassifications	35.6
Stockholders Equity, Ending Balance	11,271.3
Foreign Currency Translation [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders Equity, Beginning Balance	121.5
AOCI before reclassifications	(135.4)
Reclassifications to retained earnings (Note 2)	(17.4)
Stockholders Equity, Ending Balance	(31.3)
Defined Benefit Plan Items [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders Equity, Beginning Balance	(138.2)
AOCI before reclassifications	(29.7)
Reclassifications to retained earnings (Note 2)	(21.1)
Reclassifications	12.0
Stockholders Equity, Ending Balance	(177.0)
Total AOCI [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders Equity, Beginning Balance	(83.2)
Stockholders Equity, Ending Balance	(187.4)
Cash Flow Hedges [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders Equity, Beginning Balance	(66.5)
AOCI before reclassifications	68.2
Reclassifications to retained earnings (Note 2)	(4.4)
Reclassifications	23.6
Stockholders Equity, Ending Balance	$ 20.9