Segments Information Concerning the Operations Of Reportable Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2010	Apr. 30, 2010	Jan. 31, 2012		Jan. 31, 2011		Jan. 31, 2010
Revenue, Net	$ 592.4	$ 548.6	$ 546.3	$ 528.3	$ 527.7	$ 476.7	$ 472.8	$ 474.6	$ 2,215.6		$ 1,951.8		$ 1,713.7
Gross Profit	534.9	489.0	488.9	473.7	479.3	428.2	424.4	423.3	1,986.5		1,755.2		1,521.9
Depreciation and Amortization									115.5		105.4		111.5
Platform Solutions and Emerging Business
Revenue, Net									833.1		716.2		624.0
Gross Profit									788.0		678.9		589.7
Depreciation and Amortization									1.8		3.0		3.1
Architecture, Engineering And Construction
Revenue, Net									626.4		568.0		513.3
Gross Profit									569.7		517.6		465.2
Depreciation and Amortization									0.7		1.6		1.8
Manufacturing
Revenue, Net									540.3		470.0		386.9
Gross Profit									496.1		439.5		358.4
Depreciation and Amortization									1.7		2.3		2.5
Media and Entertainment
Revenue, Net									215.8		197.6		189.1
Gross Profit									174.6		153.9		144.4
Depreciation and Amortization									0.5		1.1		1.8
All Other Segments
Revenue, Net									0	[1]	0	[1]	0.4	[1]
Unallocated Amount to Segment
Gross Profit									(41.9)	[2]	(34.7)	[2]	(35.8)	[2]
Depreciation and Amortization									$ 110.8		$ 97.4		$ 102.3

[1] Other primarily consisted of revenue from Autodesk’s Location Services division, which Autodesk disposed of in February 2009.

[2] Unallocated amounts primarily relate to corporate expenses and other costs and expenses that are managed outside the reportable segments, including stock-based compensation expense.