Acquisitions (Summary of Fair Value of Assets Acquired and Liabilities Assumed by Major Class) (Details) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 2,450.8	$ 1,620.2
Fiscal 2019 Acquisitions
Business Acquisition [Line Items]
Goodwill	867.0
Deferred revenue (current and non-current)	(30.0)
Net tangible assets	26.0
Total	1,124.4
Fiscal 2019 Acquisitions | Developed technologies
Business Acquisition [Line Items]
Finite-lived intangibles	94.9
Fiscal 2019 Acquisitions | Customer relationships and other non-current intangible assets
Business Acquisition [Line Items]
Finite-lived intangibles	136.9
Fiscal 2019 Acquisitions | Trade name
Business Acquisition [Line Items]
Finite-lived intangibles	29.6
Assemble Systems Inc
Business Acquisition [Line Items]
Goodwill	72.0
Deferred revenue (current and non-current)	(1.7)
Net tangible assets	4.1
Total	93.6
Goodwill, measurement period adjustment	0.1
Net tangible assets, measurement period adjustment	0.1
Assemble Systems Inc | Developed technologies
Business Acquisition [Line Items]
Finite-lived intangibles	4.4
Assemble Systems Inc | Customer relationships and other non-current intangible assets
Business Acquisition [Line Items]
Finite-lived intangibles	12.0
Assemble Systems Inc | Trade name
Business Acquisition [Line Items]
Finite-lived intangibles	2.8
PlanGrid
Business Acquisition [Line Items]
Goodwill	588.7
Deferred revenue (current and non-current)	(25.5)
Net tangible assets	18.4
Total	777.6
PlanGrid | Developed technologies
Business Acquisition [Line Items]
Finite-lived intangibles	78.0
PlanGrid | Customer relationships and other non-current intangible assets
Business Acquisition [Line Items]
Finite-lived intangibles	98.0
PlanGrid | Trade name
Business Acquisition [Line Items]
Finite-lived intangibles	20.0
BuildingConnected, Inc.
Business Acquisition [Line Items]
Goodwill	206.3
Deferred revenue (current and non-current)	(2.8)
Net tangible assets	3.5
Total	253.2
BuildingConnected, Inc. | Developed technologies
Business Acquisition [Line Items]
Finite-lived intangibles	12.5
BuildingConnected, Inc. | Customer relationships and other non-current intangible assets
Business Acquisition [Line Items]
Finite-lived intangibles	26.9
BuildingConnected, Inc. | Trade name
Business Acquisition [Line Items]
Finite-lived intangibles	$ 6.8