Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	$ 17.4	[1]	$ 10.3	[1]
Liabilities	(21.1)	[1]	(18.8)	[1]
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	17.4		10.3
Liabilities	(21.1)		(18.8)
Available for sale securities	20.3		20.0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets	17.4		10.3
Liabilities	(21.1)		(18.8)
Available for sale securities	$ 20.3		$ 20.0

[1] Consolidated balance sheet location: Asset: Other current and non-current assets Liability: Other current and non-current liabilities