Revenue Recognition - Contract Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Disaggregation of Revenue [Line Items]
Net revenue	$ 989.3	$ 885.7
Design
Disaggregation of Revenue [Line Items]
Net revenue	885.1	797.7
Make
Disaggregation of Revenue [Line Items]
Net revenue	81.5	67.4
Other
Disaggregation of Revenue [Line Items]
Net revenue	22.7	20.6
Indirect
Disaggregation of Revenue [Line Items]
Net revenue	661.3	623.4
Direct
Disaggregation of Revenue [Line Items]
Net revenue	328.0	262.3
Americas
Disaggregation of Revenue [Line Items]
Net revenue	391.7	362.2
U.S.
Disaggregation of Revenue [Line Items]
Net revenue	324.0	300.6
Other Americas
Disaggregation of Revenue [Line Items]
Net revenue	67.7	61.6
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Net revenue	382.5	344.8
Asia Pacific
Disaggregation of Revenue [Line Items]
Net revenue	215.1	178.7
Architecture, Engineering and Construction
Disaggregation of Revenue [Line Items]
Net revenue	442.6	382.7
AutoCAD and AutoCAD LT
Disaggregation of Revenue [Line Items]
Net revenue	285.1	262.2
Manufacturing
Disaggregation of Revenue [Line Items]
Net revenue	197.3	182.9
Media and Entertainment
Disaggregation of Revenue [Line Items]
Net revenue	55.0	52.6
Other
Disaggregation of Revenue [Line Items]
Net revenue	$ 9.3	$ 5.3