Supplementary Financial Information - Interest and Other, Net (Details) - USD ($) $ in Millions			3 Months Ended		9 Months Ended
	Jul. 31, 2020	Oct. 31, 2019	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Tax indemnifications	$ 30	$ 57	$ (1)	$ (784)	$ 0	$ (769)
Interest expense on borrowings			(55)	(57)	(176)	(182)
Loss on extinguishment of debt			(40)	0	(40)	0
Other, net			68	10	201	49
Interest and other, net			$ (28)	(831)	$ (15)	(902)
Change in tax indemnification				$ 764		$ 764