Stock-based Compensation Expense Stock-Based Compensation Expense - Additional Information (Details) $ / shares in Units, $ in Millions				3 Months Ended		6 Months Ended
		Jul. 31, 2015 USD ($) stock_plan shares	Jun. 10, 2015 shares	Jul. 31, 2015 USD ($) stock_plan shares	Jul. 31, 2014 USD ($)	Jul. 31, 2015 USD ($) stock_plan $ / shares shares	Jul. 31, 2014 USD ($) $ / shares shares	Jan. 31, 2015 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangements by share based payment awards, number of active plans (plan) | stock_plan		2		2		2
Share based compensation arrangement by share based payment award expired or terminated plans (plan) | stock_plan		2		2		2
Options granted in period	[1]					0
Restricted Stock Units (RSUs) and Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted in period, weighted average grant date fair value (in usd per share) | $ / shares						$ 59.47	$ 50.85
Awards vested in period, fair value | $						$ 93.4	$ 73.4
Awards granted in period						1,118,500
Awards, nonvested, number		7,145,600		7,145,600		7,145,600		7,801,300
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						3 years
Nonvested awards, total compensation cost not yet recognized | $		$ 198.1		$ 198.1		$ 198.1
Awards granted in period						700,000
Allocated share-based compensation expense | $				$ 28.0	$ 28.0	$ 65.8	50.9
Nonvested awards, total compensation cost not yet recognized, period for recognition						1 year 7 months 20 days
Awards, nonvested, number		6,300,000		6,300,000		6,300,000
Performance Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested awards, total compensation cost not yet recognized | $		$ 15.8		$ 15.8		$ 15.8
Awards granted in period						400,000
Allocated share-based compensation expense | $				$ 5.9	$ 4.8	$ 11.5	$ 7.8
Nonvested awards, total compensation cost not yet recognized, period for recognition						1 year 3 months 29 days
Awards, nonvested, number		800,000		800,000		800,000
Employee Qualified Stock Purchase Plan 1998 ESP Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee stock plan shares remaining available for issuance		39,600,000		39,600,000		39,600,000
Employee stock purchase plan maximum percentage of compensation to purchase shares by eligible participants						15.00%
Employee stock purchase plan minimum percentage of common stock fair value defined to purchase shares by eligible participants						85.00%
Options, other increases (decreases) in period						10,000,000
Options, other increases (decreases) in period percentage calculation						2.00%
Shares issued under employee stock purchase plans						1,100,000	1,100,000
Awards issued, share average price (in usd per share) | $ / shares						$ 36.91	$ 33.66
Weighted average grant date fair value per share of stock options granted (in dollars per share) | $ / shares						$ 15.99	$ 14.26
Directors stock plan 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards, number of additional shares authorized						900,000
Awards, number of shares authorized		1,700,000		1,700,000		1,700,000
Share-based compensation shares granted to share issued		2.11
Options granted in period		700,000
Employee stock plan shares remaining available for issuance		1,100,000		1,100,000		1,100,000
Directors stock plan 2012 | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		1 year
Directors stock plan 2012 | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Employee Stock Plan 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards, number of additional shares authorized			12,500,000.0
Awards, number of shares authorized		45,100,000.0		45,100,000.0		45,100,000.0
Stock issued during period, shares, restricted stock award, net of forfeitures		39,100,000
Stock issued during period, shares, share-based compensation, forfeited		6,000,000
Share-based compensation shares granted to share issued		1.79
Options granted in period		23,900,000
Award vesting period		3 years
Share based compensation arrangement by share based payment award options expiration term (in years)		10 years
Employee stock plan shares remaining available for issuance		23,300,000		23,300,000		23,300,000
Share-based Compensation Award, Tranche One | Performance Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU Annual Vesting Percentage						33.33%
Share-based Compensation Award, Tranche Two | Performance Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU Annual Vesting Percentage						33.33%
Share-based Compensation Award, Tranche Three | Performance Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU Annual Vesting Percentage						33.33%

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