Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Jun. 21, 2016
Derivative [Line Items]
Reduction in earnings from excluded forward points and ineffectiveness	$ 18	$ 30	$ 29
Expected amount of accumulated other comprehensive income (loss) expected to be reclassified	49
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	1,136	(218)	$ 1
Visa Europe
Derivative [Line Items]
Net investment				$ 18,800
Visa Europe | Designated as Hedging Instrument
Derivative [Line Items]
Deferred cash consideration liability	1,200
Prepaid and other current assets
Derivative [Line Items]
Cash flow hedges in an asset position	8
Accrued Liabilities
Derivative [Line Items]
Cash flow hedges in a liability position	64
Collateral received with counterparties	2
Other Assets
Derivative [Line Items]
Posted collateral	51
Foreign exchange derivative instruments
Derivative [Line Items]
The aggregate notional amount of the Company's foreign currency forward contracts outstanding	1,800	1,600
Foreign exchange derivative instruments | Visa Europe
Derivative [Line Items]
The aggregate notional amount of the Company's foreign currency forward contracts outstanding	$ 1,000	$ 1,100