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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.