Financial Instruments - Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Detail) - Foreign Exchange Contracts - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in accumulated other comprehensive income on derivatives (effective portion)	$ 2.2	$ 46.4	$ 12.2
Amount and location of gain reclassified from accumulated other comprehensive income into income (effective portion)	29.3	7.0	11.5
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)	39.8	10.5	13.1
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)	(10.5)	(3.5)	(1.6)
Designated as Hedging Instrument | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of (loss) gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	(0.7)	0.9	(0.1)
Not Designated as Hedging Instrument | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of (loss) gain recognized in income on derivatives not designated as hedging instruments	$ (1.7)	$ (25.5)	$ 12.8