Stock-based Compensation Expense Schedule Of Share-based Compensation Options Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014	Jan. 31, 2015
Number of Shares
Options outstanding (in shares)				2.7
Granted (in shares)	[1]			0.0
Exercised (in shares)				(0.7)
Canceled/Forfeited (in shares)				0.0
Options outstanding (in shares)		2.0		2.0
Options vested and exercisable (in shares)		2.0		2.0
Options available (in shares)		20.8		20.8
Weighted average exercise price per share
Outstanding (in dollars per share)		$ 35.63		$ 35.63		$ 34.46
Granted (in dollars per share)	[1]			0.00
Exercised (in dollars per share)				31.43
Canceled/Forfeited (in dollars per share)				0.00
Vested and exercisable (in dollars per share)		$ 35.63		$ 35.63
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, Weighted average remaining contractual term				3 years 9 months
Options vested and exercisable, Weighted average remaining contractual term				3 years 9 months
Options outstanding, Aggregate Intrinsic Value	[2]	$ 38.4		$ 38.4
Options vested and exercisable, Aggregate Intrinsic Value	[2]	$ 38.4		$ 38.4
Sale of stock, price per share (in usd per share)		$ 55.19		$ 55.19
$12.31 - $29.49
Number of Shares
Options vested and exercisable (in shares)		0.7		0.7
Weighted average exercise price per share
Vested and exercisable (in dollars per share)		$ 24.62		$ 24.62
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise Price, Lower Limit (in dollars per share)		12.31		12.31
Exercise Price, Upper Limit (in dollars per share)		$ 29.49		$ 29.49
$29.50 - $41.62
Number of Shares
Options vested and exercisable (in shares)		0.8		0.8
Weighted average exercise price per share
Vested and exercisable (in dollars per share)		$ 39.68		$ 39.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise Price, Lower Limit (in dollars per share)		29.50		29.50
Exercise Price, Upper Limit (in dollars per share)		$ 41.62		$ 41.62
$42.39 - $43.81
Number of Shares
Options vested and exercisable (in shares)		0.5		0.5
Weighted average exercise price per share
Vested and exercisable (in dollars per share)		$ 43.80		$ 43.80
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Exercise Price, Lower Limit (in dollars per share)		42.39		42.39
Exercise Price, Upper Limit (in dollars per share)		43.81		43.81
Employee Qualified Stock Purchase Plan 1998 ESP Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards issued, share average price (in usd per share)		$ 35.59	$ 34.19	$ 36.29	$ 33.91
Shares issued under employee stock purchase plans		1.0	1.0	2.1	2.1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted average grant date fair value per share of stock options granted (in dollars per share)		$ 11.91	$ 15.44	$ 11.85	$ 15.14

[1] Autodesk did not grant stock options in the nine months ended October 31, 2015.

[2] Represents the total pre-tax intrinsic value, based on Autodesk’s closing stock price of $55.19 per share as of October 31, 2015, which would have been received by the option holders had all option holders exercised their options as of that date.