U.S. and Europe Retrospective Responsibility Plan U.S. and Europe Retrospective Responsibility Plan Additional Details (Details) € in Millions, $ in Millions						12 Months Ended
	Sep. 30, 2018 USD ($)		Sep. 30, 2017 USD ($)		Sep. 30, 2016	Sep. 30, 2018 EUR (€)	Sep. 30, 2018 USD ($)		Sep. 30, 2017 USD ($)		Jun. 21, 2016 EUR (€)
Class of Stock [Line Items]
Loss Contingency, Litigation Loss Sharing Agreement, Obligation Threshold | €											€ 1,000
Limit Of Protection From VE Territory Covered Losses											70.00%
VE covered loss, maximum amount of loss to allow adjustment of conversion rate during six-month period | €						€ 20
Recovery through conversion rate adjustment							$ 0		$ 0
Right to recover for covered losses (Note 2)	$ (7)	[1]	$ (52)	[2]			(7)	[1]	(52)	[2]
Series B Preferred Stock
Class of Stock [Line Items]
Recovery through conversion rate adjustment							35		190
Preferred stock, conversion rate	12.9550		13.077	[3]	13.952
Series C Preferred Stock
Class of Stock [Line Items]
Recovery through conversion rate adjustment							21		1
Preferred stock, conversion rate	13.8880		13.948
Right to Recover for Covered Losses
Class of Stock [Line Items]
Recovery through conversion rate adjustment							$ 56		191
MasterCard
Class of Stock [Line Items]
Omnibus loss sharing agreement percentage	33.3333%						33.3333%
Visa
Class of Stock [Line Items]
Omnibus loss sharing agreement percentage	66.6667%						66.6667%
U.S. Covered Litigation | Interchange Multidistrict Litigation
Class of Stock [Line Items]
Provision for unsettled legal matters							$ 600		$ 0

[1] (2) The as-converted value of preferred stock is calculated as the product of: (a) 2 million and 3 million shares of the UK&I and Europe preferred stock outstanding, respectively, as of September 30, 2018; (b) 12.955 and 13.888, the class A common stock conversion rate applicable to the UK&I and Europe preferred stock outstanding, respectively, as of September 30, 2018; and (c) $150.09, Visa’s class A common stock closing stock price as of September 30, 2018. Earnings per share is calculated based on unrounded numbers.

[2] (3) The as-converted value of preferred stock is calculated as the product of: (a) 2 million and 3 million shares of the UK&I and Europe preferred stock outstanding, respectively, as of September 30, 2017; (b) 13.077 and 13.948, the class A common stock conversion rate applicable to the UK&I and Europe preferred stock outstanding, respectively, as of September 30, 2017; and (c) $105.24, Visa’s class A common stock closing stock price as of September 30, 2017. Earnings per share is calculated based on unrounded numbers.

[3] The class B to class A common stock conversion rate is presented on a rounded basis. Conversion calculations for dividend payments are based on a conversion rate rounded to the tenth decimal.