For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13537-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13531-108611

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592

Name:	us-gaap_ConcentrationRiskPercentage
Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Concentration of Credit Risk - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2011 Accounts Receivable	Jan. 31, 2011 Accounts Receivable	Apr. 30, 2011 Domestic Line of Credit
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Line of credit facility, maximum borrowing capacity					$ 250.0
Total sales to the distributors Tech Data Corporation and its global affiliates ("Tech Data") relative to Autodesk's consolidated net revenue	17.00%	17.00%
Percentage of gross accounts receivable accounted for by Tech Data			17.00%	16.00%