Fair Value Measurements - Level 3 Reconciliation (Details) (Guarantees [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2015	Apr. 30, 2014
Guarantees [Member]
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	$ (8)	$ (6)	$ (8)	$ (6)
Transfers out of Level 3	0	0	0	0
Issuances	0	0	0	0
Settlements	1	0	1	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset (Liability) Ending Value	(7)	(6)	(7)	(6)
Change in unrealized gains on assets and liabilities still held	$ 0	$ 0	$ 0	$ 0