Business Combinations - 2017 Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 2,706,974	$ 2,518,245	$ 2,471,241
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired	259,700
Fair value of stock reserved for future use	4,400
Goodwill	178,500
Business acquisition, goodwill, expected tax deductible amount	11,900
Identifiable intangibles assets acquired	95,700
Acquisition-related costs	$ 6,500
Provisional information, initial accounting incomplete, measurement period	12 months
Minimum | Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Definite lived intangible asset amortization period	1 year
Maximum | Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Definite lived intangible asset amortization period	7 years