Acquisitions Purchase Price allocation (Details) - USD ($) $ in Thousands	12 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 2,354,800	$ 2,164,700	$ 2,197,100
Acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	121,900	94,000	24,200
Goodwill	123,100	164,700	16,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	(4,800)	(900)	6,600
Business Combination, Consideration Transferred	240,200	257,800	47,700
Acquisitions [Member] | Technology [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	71,700	32,900	0
Acquisitions [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	43,100	47,300	21,000
Acquisitions [Member] | Trademarks [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	7,100	13,700	3,200
Acquisitions [Member] | Non-compete agreement [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 0	$ 100	$ 0