Summary of Significant Accounting Policies - Components of Accounts Receivables (Details) - USD ($) $ in Thousands	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017
Accounts Receivable, Net
Accounts receivable	$ 758,341	$ 524,766
Unbilled accounts receivable	50,932	38,175
Total accounts receivable	809,273	562,941
Less allowance for doubtful accounts	(28,564)	(9,046)	$ (5,613)	$ (5,165)
Total accounts receivable, net	$ 780,709	$ 553,895