Revenues, Accounts Receivable, Deferred Revenue and Remaining Performance Obligations, Deferred Revenue - Deferred Revenue (Details) - USD ($) $ in Millions	6 Months Ended
Jul. 31, 2020	Jul. 31, 2019
Revenue from Contract with Customer [Abstract]
Recognition of deferred revenue from opening deferred balance	$ 476.9	$ 395.1

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

Name:	us-gaap_ContractWithCustomerLiabilityRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration