Restructuring - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017	Oct. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 9	$ 69	$ 12	$ 152
Current restructuring liability reported in Accrued restructuring	286		286		$ 445
Non-current restructuring liability reported in Other liabilities	55		55		96
All Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges			12
Current restructuring liability reported in Accrued restructuring	$ 64		$ 64		$ 158