Deferred Revenue and Performance Obligations - Additional Information (Detail) - Subscription services - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Revenue From Contracts With Customers [Line Items]
Recognition of deferred revenue	$ 178.2	$ 142.7	$ 311.2	$ 240.4
Revenue expected to be recognized from remaining performance obligations	567.5		567.5
Revenue expected to recognize from remaining performance obligations over the next 12 months	$ 418.6		$ 418.6