Fair Value Measurements and Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2013		Sep. 30, 2013
Fair Value, Measurement Inputs, Disclosure [Line Items]
Visa Europe put option	$ 145	[1]	$ 145	[1]
Probability of exercise by Visa Europe	40.00%
P/E differential at the time of exercise	1.9x
P/E differential at the time of exercise, ratio	190.00%
Spot price to earnings	21.5x
Spot price to earnings, ratio	2150.00%
Incremental price to earnings differential compared to estimate	(1.3x)
Incremental price to earnings differential compared to estimate, ratio	(130.00%)
Incremental probability of exercise by Visa Europe	5.00%
Increase in put option value due to increase in probability of exercise	18
Incremental assumed price to earnings differential at time of exercise	1.0x
Incremental P/E differential at time of exercise, ratio	100.00%
Increase in put option value due to increase in price to earnings differential	84
Available-for-sale securities, gross unrealized gains	110		93
Available-for-sale securities, gross unrealized losses	1		1
Fair Value, Measurements, Recurring
Fair Value, Measurement Inputs, Disclosure [Line Items]
Visa Europe put option	145		145
Non Marketable Equity Investments
Fair Value, Measurement Inputs, Disclosure [Line Items]
Non-marketable equity investments	$ 32		$ 30

[1] The put option is exercisable at any time at the sole discretion of Visa Europe with payment required 285 days thereafter. Classification in current liabilities is not an indication of management’s expectation of exercise and simply reflects the fact that the obligation resulting from the exercise of the instrument could become payable within 12 months.