Changes in Self Insurance Reserves (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Self Insurance Reserves [Line Items]
Self-insurance reserves, beginning balance	$ 27.1	[1]	$ 30.0	[1]	$ 19.9
Charged to costs and expenses	38.1		10.9		29.1
Payments	(9.4)		(13.8)		(19.0)
Self-insurance reserves, Ending balance	$ 55.8	[1]	$ 27.1	[1]	$ 30.0	[1]

[1] Refer to Note 2, "Contingencies" for further information on the Company's self-insurance reserves. These reserves primarily relate to legal defense costs for claims from 2008 and 2009.