Options Outstanding and Exercisable (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	Oct. 31, 2011 Year		Jan. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Exercisable - Number of Shares	18.2
Options Exercisable - Weighted average contractual life (in years)	2.3
Options Exercisable - Weighted average exercise price	$ 31.12
Options Exercisable - Aggregate intrinsic value	$ 122.1	[1]
Options Outstanding - Number of Shares	30.1		30.4
Options Outstanding - Weighted average contractual life (in years)	4.1
Options Outstanding - Weighted average exercise price	$ 31.42		$ 28.93
Options Outstanding - Aggregate intrinsic value	$ 189.1	[1]
Range 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	$ 0.61
Range of per-share exercise prices, Upper Limit	$ 17.37
Options Exercisable - Number of Shares	4.0
Options Exercisable - Weighted average exercise price	$ 12.89
Options Outstanding - Number of Shares	6.0
Options Outstanding - Weighted average exercise price	$ 13.57
Range 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	$ 17.39
Range of per-share exercise prices, Upper Limit	$ 29.49
Options Exercisable - Number of Shares	3.1
Options Exercisable - Weighted average exercise price	$ 26.46
Options Outstanding - Number of Shares	6.8
Options Outstanding - Weighted average exercise price	$ 27.68
Range 3
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	$ 29.50
Range of per-share exercise prices, Upper Limit	$ 37.16
Options Exercisable - Number of Shares	4.6
Options Exercisable - Weighted average exercise price	$ 32.95
Options Outstanding - Number of Shares	6.1
Options Outstanding - Weighted average exercise price	$ 32.66
Range 4
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	$ 37.26
Range of per-share exercise prices, Upper Limit	$ 41.62
Options Exercisable - Number of Shares	2.2
Options Exercisable - Weighted average exercise price	$ 38.65
Options Outstanding - Number of Shares	6.2
Options Outstanding - Weighted average exercise price	$ 40.49
Range 5
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of per-share exercise prices, Lower Limit	$ 41.70
Range of per-share exercise prices, Upper Limit	$ 49.80
Options Exercisable - Number of Shares	4.3
Options Exercisable - Weighted average exercise price	$ 45.75
Options Outstanding - Number of Shares	5.0
Options Outstanding - Weighted average exercise price	$ 45.48

[1] Represents the total pre-tax intrinsic value, based on Autodesk's closing stock price of $34.60 per share as of October 31, 2011, which would have been received by the option holders had all option holders exercised their options as of that date.