Acquisitions - Total Purchase Consideration for Business and Asset Acquisitions (Details) - USD ($) $ in Millions	Jul. 31, 2020	Oct. 31, 2019
Schedule Of Business Acquisitions And Asset Acquisition, By Acquisition [Line Items]
Goodwill	$ 2,445.0	$ 2,428.9
Series Of Individually Immaterial Business Acquisitions And Asset Acquisitions
Schedule Of Business Acquisitions And Asset Acquisition, By Acquisition [Line Items]
Total identifiable intangible assets	6.5	30.1
Goodwill	1.8	29.8
Net tangible assets	0.8	7.3
Total purchase price	9.1	67.2
Series Of Individually Immaterial Business Acquisitions And Asset Acquisitions | Customer relationships
Schedule Of Business Acquisitions And Asset Acquisition, By Acquisition [Line Items]
Total identifiable intangible assets	6.5	7.5
Series Of Individually Immaterial Business Acquisitions And Asset Acquisitions | Technology
Schedule Of Business Acquisitions And Asset Acquisition, By Acquisition [Line Items]
Total identifiable intangible assets	0.0	12.3
Series Of Individually Immaterial Business Acquisitions And Asset Acquisitions | Trademarks
Schedule Of Business Acquisitions And Asset Acquisition, By Acquisition [Line Items]
Total identifiable intangible assets	0.0	10.2
Series Of Individually Immaterial Business Acquisitions And Asset Acquisitions | Other
Schedule Of Business Acquisitions And Asset Acquisition, By Acquisition [Line Items]
Total identifiable intangible assets	$ 0.0	$ 0.1