Financial Instruments Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Details) - Foreign currency contracts - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in accumulated other comprehensive income on derivatives (effective portion)	$ (6.4)	$ 2.3
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	3.1	7.7
Designated as hedging instrument | Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	4.9	11.0
Designated as hedging instrument | Operating expenses
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	(1.8)	(3.3)
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 derivatives (ineffective portion and amount excluded from effectiveness testing)	(0.2)	(0.1)
Derivatives not designated as hedging instruments | Interest and other (expense) income, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss recognized in income on derivatives	$ (7.0)	$ (1.4)