Segment, Geographic and Product Family Information - Operations by Geographic Area and Product Family (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Segment Reporting Information [Line Items]
Net revenue	$ 553.8	$ 515.3	$ 501.8	$ 485.7	$ 478.8	$ 489.6	$ 550.7	$ 511.9	$ 2,056.6	$ 2,031.0	$ 2,504.1
Total long-lived assets	145.0				158.6				145.0	158.6
Architecture, Engineering and Construction
Segment Reporting Information [Line Items]
Net revenue									866.5	880.9	949.1
Manufacturing
Segment Reporting Information [Line Items]
Net revenue									589.2	625.8	724.6
AutoCAD and AutoCAD LT
Segment Reporting Information [Line Items]
Net revenue									401.4	326.7	594.8
Media and Entertainment
Segment Reporting Information [Line Items]
Net revenue									152.0	138.9	160.0
Other
Segment Reporting Information [Line Items]
Net revenue									47.5	58.7	75.6
U.S.
Segment Reporting Information [Line Items]
Net revenue									740.4	742.1	803.9
Total long-lived assets	99.3				118.8				99.3	118.8
Other Americas
Segment Reporting Information [Line Items]
Net revenue									130.7	129.8	168.9
Total long-lived assets	14.6				5.9				14.6	5.9
Total Americas
Segment Reporting Information [Line Items]
Net revenue									871.1	871.9	972.8
Total long-lived assets	113.9				124.7				113.9	124.7
Europe, Middle East, and Africa
Segment Reporting Information [Line Items]
Net revenue									815.4	800.4	934.6
Total long-lived assets	16.7				18.7				16.7	18.7
Asia Pacific
Segment Reporting Information [Line Items]
Net revenue									370.1	358.7	$ 596.7
Total long-lived assets	$ 14.4				$ 15.2				$ 14.4	$ 15.2