Income Taxes - Provision for income taxes (Details) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	Jan. 31, 2016	[1]	Oct. 31, 2015	Jul. 31, 2015	[2]	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Federal:
Current											$ (4.7)	$ (43.8)	$ 29.1
Deferred											220.9	(11.9)	(41.4)
State:
Current											0.5	(13.2)	0.6
Deferred											20.9	9.0	0.0
Foreign:
Current											68.4	69.5	63.9
Deferred											4.2	(8.4)	(1.1)
Income tax expense	$ 16.7		$ 21.3	$ 269.5		$ 2.7	$ (18.6)	$ 0.9	$ 11.6	$ 7.3	$ 310.2	$ 1.2	$ 51.1

[1] Subsequent to furnishing preliminary financial statements on Form 8-K on February 25, 2016 for the three and twelve months ended January 31, 2016, Autodesk identified a $4.5 million tax adjustment associated with deemed foreign withholding taxes related to non-permanently reinvested earnings in foreign jurisdictions which have not yet repatriated resulting in changes to the Consolidated Financial Statements as reflected in this Annual Report on Form 10-K. This non-cash adjustment resulted in an increase to GAAP diluted loss per share from $(0.15) to $(0.17) for the three months ended January 31, 2016.

[2] Certain second quarter fiscal 2016 balances have been revised to include the correction of an error identified in the third quarter of fiscal 2016, resulting in an additional $33.1 million of income tax expense from the previously reported results, primarily related to the establishment of a valuation allowance. See Note 1, "Business and Summary of Significant Accounting Policies" for further discussion.