CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income	$ 2,522	$ 2,070
Adjustments to reconcile net income to net cash provided by operating activities:
Client incentives	1,326	1,041
Share-based compensation (Note 9)	68	45
Depreciation and amortization of property, equipment, technology and intangible assets	145	146
Deferred income taxes	(919)	77
Right to recover for covered losses recorded in equity (Note 2)	(3)	(94)
Other	(23)	13
Change in operating assets and liabilities:
Settlement receivable	(180)	56
Accounts receivable	(146)	(89)
Client incentives	(986)	(1,129)
Other assets	92	66
Accounts payable	(51)	(102)
Settlement payable	275	79
Accrued and other liabilities	794	316
Accrued litigation (Note 11)	(152)	13
Net cash provided by operating activities	2,762	2,508
Investing Activities
Purchases of property, equipment, technology and intangible assets	(141)	(171)
Investment securities, available-for-sale:
Purchases	(1,636)	(1,032)
Proceeds from maturities and sales	1,076	788
Purchases of / contributions to other investments	(6)	(2)
Net cash used in investing activities	(707)	(417)
Financing Activities
Repayments of long-term debt (Note 4)	(1,750)	0
Dividends paid (Note 7)	(458)	(399)
Proceeds from issuance of commercial paper	0	566
Payments from litigation escrow account—U.S. retrospective responsibility plan (Note 2 and Note 11)	150	0
Cash proceeds from issuance of common stock under employee equity plans	53	56
Restricted stock and performance-based shares settled in cash for taxes	(88)	(60)
Net cash used in financing activities	(3,871)	(1,730)
Effect of exchange rate changes on cash and cash equivalents	80	(156)
(Decrease) increase in cash and cash equivalents	(1,736)	205
Cash and cash equivalents at beginning of period	9,874	5,619
Cash and cash equivalents at end of period	8,138	5,824
Supplemental Disclosure
Income taxes paid, net of refunds	183	96
Interest payments on debt (Note 4)	241	244
Accruals related to purchases of property, equipment, technology and intangible assets	26	69
Class A common stock
Financing Activities
Repurchase of class A common stock (Note 7)	$ (1,778)	$ (1,893)