Fair Value - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Oct. 31, 2019
Financial assets and liabilities measured at fair value on a recurring basis
Impairment of goodwill	$ 865	$ 0	$ 865	$ 0
HPC & MCS
Financial assets and liabilities measured at fair value on a recurring basis
Impairment of goodwill	865		865
HPC & MCS | Level 3
Financial assets and liabilities measured at fair value on a recurring basis
Impairment of goodwill	865
Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Fair value, short-term and long-term debt	17,300		17,300		$ 14,600
Reported Value Measurement [Member]
Financial assets and liabilities measured at fair value on a recurring basis
Fair value, short-term and long-term debt	$ 16,700		$ 16,700		$ 13,800