CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Operating Activities
Net income including non-controlling interest	$ 2,563	$ 2,319
Adjustments to reconcile net income including non-controlling interest to net cash provided by (used in) operating activities:
Amortization of client incentives	1,120	978
Share-based compensation	98	76
Excess tax benefit for share-based compensation	(56)	(27)
Depreciation and amortization of property, equipment, technology and intangible assets	190	160
Deferred income taxes	1,580	(200)
Other	35	(36)
Change in operating assets and liabilities:
Income tax receivable	(984)	(30)
Settlement receivable	(34)	(96)
Accounts receivable	(79)	(95)
Client incentives	(1,108)	(724)
Other assets	(327)	(2)
Accounts payable	(15)	(94)
Settlement payable	3	253
Accrued and other liabilities	218	41
Accrued litigation	(4,384)	(140)
Net cash (used in) provided by operating activities	(1,180)	2,383
Investing Activities
Purchases of property, equipment, technology and intangible assets	(211)	(162)
Proceeds from disposal of property, equipment and technology		2
Investment securities, available-for-sale:
Purchases	(1,854)	(2,140)
Proceeds from sales and maturities	1,616	1,530
Net cash used in investing activities	(449)	(770)
Financing Activities
Repurchase of class A common stock (Note 7)	(3,073)	(75)
Dividends paid (Note 7)	(437)	(300)
Deposits into litigation escrow account—retrospective responsibility plan		1,565
Payments from litigation escrow account—retrospective responsibility plan	4,383	140
Cash proceeds from exercise of stock options	84	77
Restricted stock and performance shares settled in cash for taxes	(64)
Excess tax benefit for share-based compensation	56	27
Payment for earn-out related to PlaySpan acquisition	(12)
Principal payments on capital lease obligations	(5)	(6)
Net cash provided by (used in) financing activities	932	(1,702)
Effect of Exchange Rate on Cash and Cash Equivalents		4
Decrease in cash and cash equivalents	(697)	(85)
Cash and cash equivalents at beginning of year	2,074	2,127
Cash and cash equivalents at end of period	1,377	2,042
Supplemental Disclosure of Cash Flow Information
Income taxes paid, net of refunds	421	1,071
Amounts included in accounts payable and accrued and other liabilities related to purchases of property, equipment, technology and intangible assets	$ 41	$ 52