Fair Value Measurements - Level 3 Reconciliation (Details) - Guarantees [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Fair Value Assets And Liablities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability) Beginning Value	$ (19)	$ (19)	$ (23)	$ (10)
Transfers out of Level 3	0	0	0	0
Issuances	0	(5)	1	(16)
Settlements	0	1	3	3
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability) Ending Value	$ (19)	$ (23)	$ (19)	$ (23)