Summary of Information about Contract Balance with Customers (Detail) - USD ($) $ in Millions	Sep. 30, 2018		Jun. 30, 2018	Dec. 31, 2017
Contract With Customer Asset And Liability [Abstract]
Receivables, net	$ 1,784.5			$ 1,696.7
Contract assets	19.3	[1]	$ 18.7	0.0
Contract liabilities	$ 31.6	[2]	$ 30.3	$ 33.0	[2]

[1] Included in other current assets.

[2] Included in other current and other non-current liabilities.