Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Detail) (Foreign exchange contracts, USD $) In Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011	Jul. 31, 2010
Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Accumulated OCI on Derivatives (Effective Portion)	$ 7.0	$ 2.0	$ (2.6)	$ 12.9
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(1.3)	6.1	(3.2)	10.0
Fair Value Hedging | Net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(3.8)	6.1	(7.6)	9.5
Fair Value Hedging | Operating expenses
Derivative Instruments, Gain (Loss) [Line Items]
Amount and Location of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	2.5		4.4	0.5
Fair Value Hedging | 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)	0.3	0.3		0.2
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 Derivative	$ 3.7	$ 1.1	$ 2.0	$ (0.6)