Leases - Lease Costs and Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	$ 24.6	$ 24.7	$ 49.5	$ 50.2
Variable lease cost	4.5	2.3	9.8	5.7
Cash paid for operating leases included in operating cash flows			48.3	47.6
Non-cash operating lease liabilities arising from obtaining operating lease right-of-use assets			9.7	18.4
Variable lease payments			9.8	5.7
Cost of subscription and maintenance revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	2.1	1.7	4.0	3.7
Variable lease cost	0.4	0.1	0.8	0.4
Cost of other revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	0.5	0.4	1.0	1.1
Variable lease cost	0.2	0.0	0.3	0.1
Marketing and sales
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	10.7	10.6	21.5	22.1
Variable lease cost	1.9	1.0	4.2	2.5
Research and development
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	7.7	7.8	15.7	15.7
Variable lease cost	1.4	0.7	3.1	1.8
General and administrative
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	3.6	4.2	7.3	7.6
Variable lease cost	$ 0.6	$ 0.5	$ 1.4	$ 0.9