Business and Summary of Significant Accounting Policies Other Intangible Assets and Related Accumulated Amortization (Details) (USD $) In Millions, unless otherwise specified	Jan. 31, 2013		Jan. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Purchased technologies, at cost	$ 431.0	[1]	$ 400.5	[1]
Customer relationships, trade names, patents, and user lists, at cost	259.5	[2]	215.3	[2]
Finite-Lived Intangible Assets, Gross	690.5		615.8
Less: Accumulated amortization	(546.3)		(467.0)
Other intangible assets, net	$ 144.2		$ 148.8

[1] Beginning in fiscal 2013, the purchased technologies balances are presented gross. Previously, Autodesk reported the cost and amortization balance for purchased technologies net of fully amortized intangible assets. For comparability, the presentation of the purchased technologies cost and amortization balances at January 31, 2012 were adjusted to align to current year presentation.

[2] Included as a net balance in “Other assets” in the Consolidated Balance Sheet. Customer relationships and trade names include the effects of foreign currency translation.