Financial Instruments Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Details) (Foreign currency contracts, USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2015		Apr. 30, 2014
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in accumulated other comprehensive income on derivatives (effective portion)	$ 2.3		$ (2.6)
Amount and location of gain reclassified from accumulated other comprehensive income into income (effective portion)	7.7		0.6
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)	11.0		1.4
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)	(3.3)		(0.8)
Designated as hedging instrument | Interest and other income (expense), 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)	(0.1)		0
Derivatives not designated as hedging instruments | Interest and other income (expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivatives (1)	$ (1.4)	[1]	$ (5.8)	[1]

[1] Prior period balance has been adjusted to conform to current period presentation.