Summary of Significant Accounting Policies - Components of Accounts Receivables (Details) - USD ($) $ in Thousands	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Accounts, Notes, Loans and Financing Receivable, Net, Current [Abstract]
Accounts receivable	$ 495,763	$ 393,229
Unbilled accounts receivable	64,067	63,080
Total accounts receivable	559,830	456,309
Less allowance for doubtful accounts	(5,613)	(5,165)	$ (3,201)	$ (2,561)
Total accounts receivable, net	$ 554,217	$ 451,144