Financial Instruments Fair Value of Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2013		Jan. 31, 2013
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 18.2		$ 17.4
Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	9.5		10.7
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Prepaid expenses and other current assets [member]
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Net	8.7	[1]	6.7	[1]
Derivative Asset, Fair Value, Gross Asset	10.8		8.2
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Net	0.7	[2]	3.9	[2]
Derivative Liability, Fair Value, Gross Liability	$ 2.8		$ 5.4

[1] Considering Autodesk's master netting arrangements, these contracts are presented net settled. The gross balance is $10.8 million and $8.2 million at April 30, 2013 and January 31, 2013, respectively.

[2] Considering Autodesk's master netting arrangements, these contracts are presented net settled. The gross balance is $2.8 million and $5.4 million at April 30, 2013 and January 31, 2013, respectively.