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, 2014	Apr. 30, 2013
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in accumulated other comprehensive income on derivatives (effective portion)	$ (2.6)	$ 13.6
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	0.6	3.8
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)	1.4	4.3
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)	(0.5)
Designated as hedging instrument | Interest and other (expense) income, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	0	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	$ (5.7)	$ 1.5