Stock-based Compensation Expense Summary of Restricted Stock Award and Restricted Stock Unit Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2013		Jul. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date			Jul. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 10.0	$ 5.6	$ 42.8	[1]	$ 65.9	[1]
PerformanceSharesUnitsPayoutPercentage	92.30%		92.30%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Awarded			500,000
Forfeited			(14,000)	[2]
Unreleased restricted stocck at April 30, 2012	800,000		800,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Forfeited (in usd per share)			$ 35.94	[2]
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Unreleased restricted stock at January 31, 2012			5,020,800
Awarded			1,216,500
Released			(1,409,800)
Forfeited			(282,800)
Unreleased restricted stocck at April 30, 2012	4,530,700		4,530,700
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Unreleased restricted stock at January 31, 2012 (in usd per share)			$ 33.89
Awarded (in usd per share)			$ 41.40
Released (in usd per share)			$ 34.19
Forfeited (in usd per share)			$ 37.85
Unreleased restricted stock at April 30, 2012 (in usd per share)	$ 36.98		$ 36.98

[1] The intrinsic value of options exercised is calculated as the difference between the exercise price of the option and the market value of the stock on the date of exercise.

[2] Based on Autodesk financial results for the performance period, the fiscal 2013 performance stock units were earned at 92.3% of the target award. The fiscal 2013 performance stock units will pay out at 92.3% percent of the target award; however, the vesting of the performance stock units is subject to the holders satisfying the remaining service condition of the awards.