Supplementary Financial Information - Allowance for Doubtful Accounts (Details) $ in Millions	6 Months Ended
	Apr. 30, 2020 USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 111
Provision for doubtful accounts	32
Deductions, net of recoveries	(23)
Balance at end of period	$ 120