Financial Instruments Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Details) - Foreign currency contracts - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in accumulated other comprehensive income on derivatives (effective portion)	$ (2.1)	$ (6.4)
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	(0.7)	3.1
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)	2.0	4.9
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)	(2.7)	(1.8)
Designated as hedging instrument | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	(0.2)	(0.2)
Derivatives not designated as hedging instruments | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of loss recognized in income on derivatives	$ (1.8)	$ (7.0)