Segment, Geographic and Product Family Information Information Regarding Operations by Geographic Area and Product Family (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Segment Reporting Information [Line Items]
Net revenue	$ 485.7	$ 511.9
Operating Segments
Segment Reporting Information [Line Items]
Net revenue	485.7	511.9
Architecture, Engineering and Construction | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	204.5	218.9
Manufacturing | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	142.1	158.0
AutoCAD and AutoCAD LT | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	91.5	85.9
Media and Entertainment | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	36.5	35.0
Other | Operating Segments
Segment Reporting Information [Line Items]
Net revenue	11.1	14.1
Americas
Segment Reporting Information [Line Items]
Net revenue	210.1	217.7
Americas | U.S.
Segment Reporting Information [Line Items]
Net revenue	179.8	184.7
Americas | Other Americas
Segment Reporting Information [Line Items]
Net revenue	30.3	33.0
Europe, Middle East and Africa
Segment Reporting Information [Line Items]
Net revenue	189.7	202.6
Asia Pacific
Segment Reporting Information [Line Items]
Net revenue	$ 85.9	$ 91.6