Changes in the Escrow Account (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012
Escrow Account [Roll Forward]
Litigation Escrow Account Balance, Beginning of Period	$ 4,432		$ 2,857
Payments to Settlement Funds	4,400
Deposits into litigation escrow account			1,715
Litigation Escrow Account Balance, End of Period	49		4,432
Class Plaintiffs
Escrow Account [Roll Forward]
Payments to Settlement Funds	(4,033)	[1]
Individual Plaintiffs
Escrow Account [Roll Forward]
Payments to Settlement Funds	(350)	[1]
American Express [Member]
Escrow Account [Roll Forward]
Payments to Settlement Funds			$ (140)

[1] (1)These payments are associated with the interchange multidistrict litigation. The settlement with the class plaintiffs in these proceedings is subject to final court approval, which the Company cannot assure will be received, and to the adjudication of any appeals. See Note 20—Legal Matters.