Cash Paid for Interest (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Debt Instrument [Line Items]
Interest paid	$ 97.1	[1]	$ 63.6	[1]

[1] Interest paid includes payments of interest relating to the settlement of income tax audits in the first quarter of 2012 as well as net settlements on interest rate swaps more fully discussed in Note 7.