Summary Adoption of New Accounting Standard Impact on Balance Sheet (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets
Inventories, net	$ 865.0		$ 859.1
Other current assets	277.0		228.9
Equity
Retained earnings	4,165.2		4,079.2
ASU 2014-09
Assets
Inventories, net	865.0	$ 841.7	859.1
Other current assets	277.0	250.9	228.9
Equity
Retained earnings	4,165.2	4,082.4	$ 4,079.2
ASU 2014-09 | Balances without adoption of ASC 606
Assets
Inventories, net	885.4
Other current assets	251.3
Equity
Retained earnings	4,161.5
ASU 2014-09 | Effect of Changes
Assets
Inventories, net	(20.4)
Other current assets	25.7
Equity
Retained earnings	$ 3.7
ASU 2014-09 | Adjustments due to ASU 2014-09
Assets
Inventories, net		(17.4)
Other current assets		22.0
Equity
Retained earnings		$ 3.2