Summary Adoption of New Accounting Standard Impact on Income Statement (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	$ 2,812.8	$ 2,608.1
Cost of sales	(2,233.6)	(2,065.6)
Operating income	225.4	$ 217.6
ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	2,812.8
Cost of sales	(2,233.6)
Operating income	225.4
ASU 2014-09 | Balances without adoption of ASC 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	2,809.1
Cost of sales	(2,230.5)
Operating income	224.8
ASU 2014-09 | Effect of Changes
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net sales	3.7
Cost of sales	(3.1)
Operating income	$ 0.6