Fair Value of Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	Jan. 31, 2012	Jan. 31, 2011
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 18.1	$ 5.1
Derivative Liabilities	2.2	1.2
Designated as Hedging Instrument | Foreign exchange contracts | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	11.9	5.1
Designated as Hedging Instrument | Foreign exchange contracts | Other Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2.2	1.2
Not Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 6.2	$ 0