CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)
In Millions, unless otherwise specified
6 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Operating Activities    
Net income $ 3,119 $ 3,005
Adjustments to reconcile net income to net cash provided by operating activities:    
Amortization of client incentives 1,389 1,186
Share-based compensation 93 89
Excess tax benefit for share-based compensation (70) (68)
Depreciation and amortization of property, equipment, technology and intangible assets 245 214
Deferred income taxes 173 (375)
Other 15 12
Change in operating assets and liabilities:    
Settlement receivable 107 47
Accounts receivable (74) (71)
Client incentives (1,479) (1,251)
Other assets (467) (350)
Accounts payable (44) (68)
Settlement payable (206) (126)
Accrued and other liabilities 262 171
Accrued litigation (Note 12) (324) 1,055
Net cash provided by operating activities 2,739 3,470
Investing Activities    
Purchases of property, equipment, technology and intangible assets (202) (217)
Proceeds from Sale of Property, Plant, and Equipment 10  
Investment securities, available-for-sale:    
Purchases (1,267) (1,292)
Proceeds from sales and maturities 895 1,406
Purchases of / contributions to other investments (2) (3)
Proceeds from Sale of Other Investments 9  
Net cash used in investing activities (557) (106)
Financing Activities    
Repurchase of class A common stock (Note 8) (1,855) (2,210)
Dividends paid (Note 8) (591) (507)
Payments from (return to) litigation escrow account—retrospective responsibility plan (Note 2 and Note 12) 321 (1,056)
Cash proceeds from exercise of stock options 46 58
Restricted stock and performance-based shares settled in cash for taxes (106) (83)
Excess tax benefit for share-based compensation 70 68
Net cash used in financing activities (2,115) (3,730)
Effect of exchange rate changes on cash and cash equivalents 1 0
Increase (decrease) in cash and cash equivalents 68 (366)
Cash and cash equivalents at beginning of year 1,971 2,186
Cash and cash equivalents at end of period 2,039 1,820
Supplemental Disclosure    
Income taxes paid, net of refunds 1,376 1,392
Accruals related to purchases of property, equipment, technology and intangible assets $ 26 $ 27