Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016		Jun. 30, 2017	Jun. 30, 2016
Business Acquisition [Line Items]
Income tax expense (benefit)	$ 855	$ 10	[1]	$ 4,036	$ 1,442	[1]
Loss on Contract Termination	0	$ 1,877	[1]	$ 0	$ 1,877	[1]
Income tax expense (benefit), charitable contributions	$ (71)
Effective income tax rate reconciliation, percent	29.00%	2.00%		47.00%	26.00%
Revaluation of the Visa Europe put option					$ 255
Increase in unrecognized tax benefits	$ 60			$ 116
Effective income tax rate reconciliation Unrecognized Tax Benefits that would Favorably Impact Effective Tax Rate	52			149
New Accounting Pronouncement, Early Adoption, Effect
Business Acquisition [Line Items]
Income tax expense (benefit)	(13)			(59)
Visa Europe
Business Acquisition [Line Items]
Income tax expense (benefit)	$ 1,500			$ 1,500

[1] The Company did not include Visa Europe's financial results in the Company's unaudited consolidated statements of operations from the acquisition date, June 21, 2016, through June 30, 2016 as the impact was immaterial. The dilutive impact of the outstanding shares of series B and C convertible participating preferred stock from June 21, 2016 through June 30, 2016 was also not included in the calculation of basic or diluted earnings per share as the effect was immaterial. See Note 2—Visa Europe and Note 10—Earnings Per Share to these unaudited consolidated financial statements.