Financial Instruments Effects of Derivative Instruments on Condensed Consolidated Statements of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in accumulated other comprehensive income on derivatives (effective portion)	$ 13.6	$ 1.5
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	3.8	4.8
Sales [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	4.3	6.3
Operating Expense [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(0.5)	(1.5)
Interest and other income (expense), net [member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest and other income (expense), net	(0.1)	0.1
Interest and other income (expense), net [member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest and other income, net	1.5
Interest and other income (expense), net [member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest and other income, net		$ 2.1