Supplementary Financial Information - Allowance for Doubtful Accounts (Details) $ in Millions	9 Months Ended
	Jul. 31, 2019 USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 129
Provision for doubtful accounts	47
Deductions, net of recoveries	(61)
Balance at end of period	$ 115