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Employee and Director Stock Plans - Intrinsic Value of Options Exercised and Weighted Average Grant Date Fair Value of Stock Options Granted (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
 12 Months Ended
Jan. 31, 2015
Jan. 31, 2014
Jan. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Intrinsic value of options exercised $ 67.6us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue [1] $ 149.0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue [1] $ 90.9us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue [1]
Weighted average grant date fair value per share of stock options granted $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue [2] $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue [2] $ 13.4us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue [2]
[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] The weighted average grant date fair value per share of stock options granted is calculated, as of the stock option grant date, using the Black-Scholes Merton ("BSM") option pricing model. For the twelve months ended January 31, 2015 and 2014, Autodesk did not grant stock options.