Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Reduction in earnings from excluded forward points and ineffectiveness		$ 9	$ 18	$ 30
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax		(352)	1,136	$ (218)
Visa Europe
Derivative [Line Items]
Net investment		18,800
Visa Europe | Designated as Hedging Instrument
Derivative [Line Items]
Deferred cash consideration liability		1,100
Prepaid and other current assets
Derivative [Line Items]
Cash flow hedges in an asset position		78
Accrued Liabilities
Derivative [Line Items]
Cash flow hedges in a liability position		20
Collateral received with counterparties		56
Other Assets
Derivative [Line Items]
Posted collateral		2
Foreign exchange derivative instruments
Derivative [Line Items]
The aggregate notional amount of the Company's foreign currency forward contracts outstanding		2,500	1,800
Foreign exchange derivative instruments | Visa Europe
Derivative [Line Items]
The aggregate notional amount of the Company's foreign currency forward contracts outstanding		$ 1,200	$ 1,000
Subsequent Event
Derivative [Line Items]
Expected amount of accumulated other comprehensive income (loss) expected to be reclassified	$ 71