CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Activities
Net income	$ 2,500	$ 3,648
Adjustments to reconcile net income to net cash provided by operating activities:
Client incentives	2,072	1,577
Fair value adjustment for the Visa Europe put option	0	(255)
Share-based compensation (Note 11)	116	97
Excess tax benefit for share-based compensation	0	(43)
Depreciation and amortization of property, equipment, technology and intangible assets	277	241
Deferred income taxes	1,700	(29)
Right to recover for covered losses recorded in equity	(163)	0
Noncash Contribution Expense	192	0
Other	23	17
Change in operating assets and liabilities:
Settlement receivable	(1,946)	(6)
Accounts receivable	(40)	(97)
Client incentives	(2,306)	(1,912)
Other assets	(301)	(397)
Accounts payable	(83)	(34)
Settlement payable	883	(57)
Accrued and other liabilities	(35)	81
Accrued litigation (Note 14)	15	(12)
Net cash provided by operating activities	2,904	2,819
Investing Activities
Purchases of property, equipment, technology and intangible assets	(317)	(250)
Investment securities, available-for-sale:
Purchases	(1,083)	(17,437)
Proceeds from maturities and sales	3,972	15,860
Payments to Acquire Businesses, Net of Cash Acquired	302	14
Purchases of / contributions to other investments	(2)	(9)
Proceeds / distributions from other investments	0	4
Net cash provided by (used in) investing activities	2,268	(1,846)
Financing Activities
Dividends paid (Note 9)	(795)	(676)
Proceeds from issuance of senior notes (Note 6)	0	15,971
Debt issuance costs (Note 6)	0	(96)
Payments from litigation escrow account—U.S. retrospective responsibility plan (Note 3 and Note 14)	0	11
Cash proceeds from issuance of common stock under employee equity plans	87	49
Restricted stock and performance-based shares settled in cash for taxes	(66)	(85)
Excess tax benefit for share-based compensation	0	43
Net cash (used in) provided by financing activities	(4,243)	11,452
Effect of exchange rate changes on cash and cash equivalents	(121)	0
Increase in cash and cash equivalents	808	12,425
Cash and cash equivalents at beginning of year	5,619	3,518
Cash and cash equivalents at end of period	6,427	15,943
Supplemental Disclosure
Income taxes paid, net of refunds	1,611	1,501
Interest payments on debt (Note 6)	244	0
Net unrealized gain on currency forward contracts	0	116
Accruals related to purchases of property, equipment, technology and intangible assets	37	38
Class A common stock
Financing Activities
Repurchase of class A common stock (Note 9)	$ (3,469)	$ (3,765)