Fair Value Measurements - Level 3 Reconciliation (Details) - Guarantees [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015
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	$ (10)	$ (8)	$ (10)	$ (8)
Transfers out of Level 3	0	0	0	0
Issuances	(10)	0	(11)	0
Settlements	1	1	2	1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability) Ending Value	(19)	(7)	(19)	(7)
Change in unrealized gains on assets and liabilities still held	$ 0	$ 0	$ 0	$ 0