Financial Instruments - 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, 2015	Jan. 31, 2014	Jan. 31, 2013
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in accumulated other comprehensive income on derivatives (effective portion)	$ 46.4	$ 12.2	$ 5.1
Amount and location of gain reclassified from accumulated other comprehensive income into income (effective portion)	7.0	11.5	11.4
Designated as Hedging Instrument | Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain reclassified from accumulated other comprehensive income into income (effective portion)	10.5	13.1	16.0
Designated as Hedging Instrument | Operating expenses
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain reclassified from accumulated other comprehensive income into income (effective portion)	(3.5)	(1.6)	(4.6)
Designated as Hedging Instrument | Interest and other (expense) income, 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)	0.9	(0.1)	(0.2)
Not Designated as Hedging Instrument | Interest and other (expense) income, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of (loss) gain recognized in income on derivative	$ (25.5)	$ 12.8	$ 1.5