Supplementary Financial Information - Costs of Obtaining Contracts (Details) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Capitalized Contract Cost [Line Items]
Contract cost amortization	$ 98	$ 108
Contract liability	2,200	2,100	$ 1,900
Revenue recognized	1,100	900
Deferred contract fulfillment
Capitalized Contract Cost [Line Items]
Capitalized contract costs	65	47
Acquisition costs
Capitalized Contract Cost [Line Items]
Capitalized contract costs	$ 34	$ 30