Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2013		Jan. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments and Hedges, Carrying Amount	$ 10.2	[1]
Designated as Hedging Instrument | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated OCI on Derivatives (Effective Portion)	5.1		12.8
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	11.4		2.7
Designated as Hedging Instrument | Foreign exchange contracts | Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	16.0		(1.9)
Designated as Hedging Instrument | Foreign exchange contracts | Operating expenses
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(4.6)		4.6
Designated as Hedging Instrument | Foreign exchange contracts | 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)	(0.2)		0.3
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts | Interest and other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Recognized in Income on Derivative	$ 1.5		$ (1.3)

[1] Included in “Prepaid expenses and other current assets,” "Other assets," or “Other accrued liabilities” in the accompanying Consolidated Balance Sheets.