Financial Instruments - Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Detail) - Foreign Exchange Contracts - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in accumulated other comprehensive loss on derivatives (effective portion)	$ (21.3)	$ 6.3	$ 2.2
Amount and location of gain (loss) reclassified from accumulated other comprehensive loss into (loss) income (effective portion)	9.9	7.4	29.3
Designated as Hedging Instrument | Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) reclassified from accumulated other comprehensive loss into (loss) income (effective portion)	8.0	9.2	39.8
Designated as Hedging Instrument | Operating expenses
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) reclassified from accumulated other comprehensive loss into (loss) income (effective portion)	1.9	(1.8)	(10.5)
Designated as Hedging Instrument | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss recognized in (loss) income on derivatives (ineffective portion and amount excluded from effectiveness testing)	(0.2)	(0.3)	(0.7)
Not Designated as Hedging Instrument | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss recognized in loss (income) on derivatives	$ (19.1)	$ (11.1)	$ (1.7)