Restructuring and Other Charges - Narrative (Details) employee in Thousands, $ in Millions		12 Months Ended
	Sep. 30, 2019 USD ($) employee	Oct. 31, 2020 USD ($)	Oct. 31, 2019 USD ($)	Oct. 31, 2018 USD ($)
Restructuring Cost and Reserve [Line Items]
Other charges		$ 105	$ 28	$ 33
Fiscal 2020 Plan
Restructuring Cost and Reserve [Line Items]
Estimated pre-tax charges	$ 1,000
Labor costs related to workforce reductions | Fiscal 2020 Plan
Restructuring Cost and Reserve [Line Items]
Estimated pre-tax charges	$ 900
Minimum | Fiscal 2020 Plan
Restructuring Cost and Reserve [Line Items]
Expected number of positions to be eliminated | employee	7
Maximum | Fiscal 2020 Plan
Restructuring Cost and Reserve [Line Items]
Expected number of positions to be eliminated | employee	9