Financial Instruments Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Details) - Foreign currency contracts - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jul. 31, 2015	Jul. 31, 2014		Jul. 31, 2015	Jul. 31, 2014
Designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in accumulated other comprehensive income on derivatives (effective portion)	$ 4.4	$ 2.8		$ 6.7	$ 0.2
Amount and location of gain (loss) reclassified from accumulated other comprehensive income into income (effective portion)	9.1	1.0		16.8	1.6
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)	11.3	1.1		22.3	2.5
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)	(2.2)	(0.1)		(5.5)	(0.9)
Designated as hedging instrument | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of (loss) gain recognized in income on derivatives (ineffective portion and amount excluded from effectiveness testing)	(0.2)	0.2		(0.3)	0.2
Derivatives not designated as hedging instruments | Interest and other expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount and location of gain (loss) recognized in income on derivatives (1)	$ 2.1	$ (4.8)	[1]	$ 0.7	$ (10.6)	[1]

[1] (1)Prior period balances have been adjusted to conform to current period presentation.