Financial Instruments Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions		Jul. 31, 2015	Jan. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Assets		$ 6.2	$ 21.3
Derivative Liabilities		3.5	5.4
Designated as hedging instrument
Derivatives, Fair Value [Line Items]
Derivative, notional amount		373.6	336.6
Net gain expected to be recognized in next 12 months		32.7
Foreign currency contracts | Designated as hedging instrument | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	[1]	5.0	20.4
Derivative assets, gross		8.8	23.8
Foreign currency contracts | Designated as hedging instrument | Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	[2]	2.9	5.4
Derivative liabilities, gross		6.8	8.7
Foreign currency contracts | Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative, notional amount		1.6	44.6
Foreign currency contracts | Derivatives not designated as hedging instruments | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets		1.2	0.9
Foreign currency contracts | Derivatives not designated as hedging instruments | Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities		$ 0.6	$ 0.0

[1] Considering Autodesk's master netting arrangements, these contracts are presented net settled. The gross balance is $8.8 million and $23.8 million at July 31, 2015 and January 31, 2015, respectively.

[2] Considering Autodesk's master netting arrangements, these contracts are presented net settled. The gross balance is $6.8 million and $8.7 million at July 31, 2015 and January 31, 2015, respectively.