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		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 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)	$ 2.8	$ (1.0)	$ 0.2	$ 12.6
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	1.0	3.9	1.6	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)	1.1	4.4	2.5	8.7
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)	(0.1)	(0.5)	(0.9)	(1.0)
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)	0.2	(0.1)	0.2	0
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	$ (4.6)	$ 0.5	$ (10.3)	$ 2.0