Basic and Diluted Earnings Per Share (Detail) $ / shares in Units, shares in Millions, $ in Millions			12 Months Ended
		Mar. 19, 2015	Sep. 30, 2017 USD ($) $ / shares shares		Sep. 30, 2016 USD ($) $ / shares shares		Sep. 30, 2015 USD ($) $ / shares shares
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income allocation - Basic | $	[1]		$ 6,699		$ 5,991	[2]	$ 6,328
Dilutive shares of outstanding stock awards included in computation of weighted-average dilutive shares outstanding			5		5		6
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			2		2		2
Class A common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income allocation - Basic | $	[1]		$ 5,170		$ 4,738	[2]	$ 5,044
Weighted Average Shares Outstanding - Basic			1,845		1,906	[2]	1,954
Earnings per Share - Basic | $ / shares	[3]		$ 2.80		$ 2.49	[2]	$ 2.58
Income allocation - Diluted | $	[1]		$ 6,699		$ 5,991	[2]	$ 6,328
Weighted Average Shares Outstanding - Diluted	[1],[3],[4]		2,395		2,414	[2]	2,457
Earnings per Share - Diluted | $ / shares	[3]		$ 2.80		$ 2.48	[2]	$ 2.58
Common stock split, conversion ratio		4
Class B common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income allocation - Basic | $	[1]		$ 1,134		$ 1,006	[2]	$ 1,045
Weighted Average Shares Outstanding - Basic			245		245	[2]	245
Earnings per Share - Basic | $ / shares	[3]		$ 4.62		$ 4.10	[2]	$ 4.26
Income allocation - Diluted | $	[1]		$ 1,132		$ 1,004	[2]	$ 1,042
Weighted Average Shares Outstanding - Diluted	[1],[3]		245	[5]	245	[2],[4]	245	[4]
Earnings per Share - Diluted | $ / shares	[3]		$ 4.61		$ 4.09	[2]	$ 4.25
Weighted Average Number Shares Outstanding, As-Converted Basis			405		405
Class C common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income allocation - Basic | $	[1]		$ 163		$ 185	[2]	$ 224
Weighted Average Shares Outstanding - Basic			14		19	[2]	22
Earnings per Share - Basic | $ / shares	[3]		$ 11.21		$ 9.94	[2]	$ 10.33
Income allocation - Diluted | $	[1]		$ 162		$ 185	[2]	$ 223
Weighted Average Shares Outstanding - Diluted	[1],[3]		14	[5]	19	[2],[4]	22	[4]
Earnings per Share - Diluted | $ / shares	[3]		$ 11.19		$ 9.93	[2]	$ 10.30
Weighted Average Number Shares Outstanding, As-Converted Basis			58		75		87
Participating Securities
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income allocation - Basic | $	[1],[5]		$ 232		$ 62	[2]	$ 15
Income allocation - Diluted | $	[1],[5]		$ 232		$ 61	[2]	$ 15
Series B Preferred Stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number Shares Outstanding, As-Converted Basis			33
Series C Preferred Stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number Shares Outstanding, As-Converted Basis			44

[1] Net income is allocated based on proportional ownership on an as-converted basis. The weighted-average number of shares of as-converted class B common stock used in the income allocation was 405 million for fiscal 2017, 2016 and 2015. The weighted-average number of shares of as-converted class C common stock used in the income allocation was 58 million, 75 million and 87 million for fiscal 2017, 2016 and 2015, respectively. The weighted-average number of shares of preferred stock, included within participating securities, was 33 million of as-converted UK&I preferred stock, and 44 million of as-converted Europe preferred stock for fiscal 2017.

[2] See Note 2—Visa Europe.

[3] Figures in the table may not recalculate exactly due to rounding. Earnings per share is calculated based on unrounded numbers. The number of shares and per share amounts for the prior periods presented have been retroactively adjusted to reflect the four-for-one stock split effected in the second quarter of fiscal 2015. See Note 13—Stockholders' Equity.

[4] Weighted-average diluted shares outstanding are calculated on an as-converted basis, and include incremental common stock equivalents, as calculated under the treasury stock method. The computation includes 5 million common stock equivalents for fiscal 2017 and 2016 and 6 million common stock equivalents for fiscal 2015, because their effect would have been dilutive. The computation excludes 2 million of common stock equivalents for fiscal 2017, 2016 and 2015, because their effect would have been anti-dilutive.

[5] Participating securities include preferred stock outstanding and unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents, such as the Company's UK&I and Europe preferred stock, restricted stock awards, restricted stock units and earned performance-based shares. UK&I and Europe preferred stock were issued as part of the purchase price consideration in connection with the Visa Europe acquisition and are convertible into a number of shares of class A common stock or class A equivalent preferred stock upon certain conditions. Participating securities' income is allocated based on the weighted-average number of shares of as-converted stock. See Note 2—Visa Europe and Note 13—Stockholders' Equity.