Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Operating Loss Carryforwards [Line Items]
Income Tax Expense (Benefit)	$ 8	$ 29	$ 10	$ 9