Financial Instruments - Schedule of Pre-Tax Effect of Derivative Instruments and Related Hedged Items in a Fair Value Hedging Relationship (Details) - Interest rate contracts - Interest and other, net - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019
Derivative Instruments, Gain (Loss)
Total amounts of income/ (expense) line items presented in the statement of financial performance in which the effects of fair value hedges are recorded	$ 0	$ (45)	$ 13	$ (71)
Gain/(Loss) Recognized in Earnings on Derivative Instrument	10	4	10	16
Gain/(Loss) Recognized in Earnings on Derivative and Related Hedged Item	$ (10)	$ (4)	$ (10)	$ (16)