Derivative and Non-derivative Financial Instruments (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Reduction in earnings from excluded forward points and ineffectiveness	$ 12	$ 9	$ 18
Expected amount of accumulated other comprehensive income (loss) expected to be reclassified	22
Fair value hedge assets	89
Fair value hedge liabilities	2
Earnings related to forward points and interest differentials from forward contracts and swap agreements	95
Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	10,900	2,500
Visa Europe
Derivative [Line Items]
Investment in Subsidiary, Net	18,800
Visa Europe | Designated as Hedging Instrument
Derivative [Line Items]
Deferred cash consideration liability		1,100
Accrued Liabilities
Derivative [Line Items]
Collateral received with counterparties	34
Other Assets
Derivative [Line Items]
Posted collateral	33
Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	$ 800	1,200
3.15% Senior Notes due December 2025 | Senior Notes
Derivative [Line Items]
Stated interest rate (percent)	3.15%
Cash Flow Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Derivative asset	$ 47	78
Derivative liability	31	$ 20
Net Investment Hedging
Derivative [Line Items]
Derivative asset (liability)	$ 298