Business Combinations - 2018 Acquisitions (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 11, 2017	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016
Business Acquisition [Line Items]
Payments to acquire business net of cash and short-term investments		$ 637,000
Goodwill		3,143,249	$ 2,706,974	$ 2,518,245
Black Duck Software
Business Acquisition [Line Items]
Payments to acquire business net of cash and short-term investments		544,000
Percent of company acquired	100.00%
Total purchase consideration	$ 565,100	565,088
Goodwill		395,395
Identifiable intangibles assets acquired		178,000
Acquisition-related costs		15,500
Equity awards and options acquired, amount		15,600
Fair value of assumed equity awards allocated to purchase consideration		1,588
Fair value of stock reserved for future use		14,000
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Goodwill		47,600
Identifiable intangibles assets acquired		51,900
Acquisition-related costs		3,800
Payments to acquire businesses, net of cash acquired		$ 93,000
Minimum | Black Duck Software
Business Acquisition [Line Items]
Definite lived intangible asset amortization period		1 year
Minimum | Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Definite lived intangible asset amortization period		1 year
Maximum | Black Duck Software
Business Acquisition [Line Items]
Definite lived intangible asset amortization period		10 years
Maximum | Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Definite lived intangible asset amortization period		7 years