Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Detail) (Foreign exchange contracts, USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2012	Jan. 31, 2011
Not Designated as Hedging Instrument | Interest and other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Recognized in Income on Derivative	$ (1.3)	$ 2.3
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated OCI on Derivatives (Effective Portion)	12.8	11.8
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	2.7	15.1
Designated as Hedging Instrument | Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(1.9)	13.0
Designated as Hedging Instrument | Operating expenses
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	4.6	2.1
Designated as Hedging Instrument | Interest and other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing)	$ 0.3	$ 0.1