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		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in accumulated other comprehensive income on derivatives (effective portion)	$ 22.3	$ (4.6)	$ 22.5	$ 8.0
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	1.3	2.0	2.9	9.7
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)	2.1	2.3	4.6	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)	(0.8)	(0.3)	(1.7)	(1.3)
Designated as hedging instrument | Interest and other (expense) income, 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	(0.1)	0.3	(0.1)
Not 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	$ (4.5)	$ 2.9	$ (14.8)	$ 4.9