Fair Value Measurements and Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended	12 Months Ended				12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009	Jan. 24, 2011 Other Investments Visa Vale issuer Companhia Brasileira de Solucoes e Servicos	Sep. 30, 2011 Other Investments Visa Vale issuer Companhia Brasileira de Solucoes e Servicos	Sep. 30, 2011 Companhia Brasileira de Solucoes e Servicos	Sep. 30, 2011 Auction Rate Securities	Sep. 30, 2011 Fair Value, Measurements, Recurring Level 3	Sep. 30, 2011 Non Marketable Equity Investments	Sep. 30, 2010 Non Marketable Equity Investments	Sep. 30, 2009 Non Marketable Equity Investments	Sep. 30, 2010 Reserve Primary Fund	Sep. 30, 2011 Visa Europe Fair Value, Measurements, Recurring	Sep. 30, 2010 Visa Europe Fair Value, Measurements, Recurring	Sep. 30, 2009 Visa Europe Fair Value, Measurements, Recurring	Sep. 30, 2011 Fair Value, Measurements, Recurring		Sep. 30, 2010 Fair Value, Measurements, Recurring
Fair Value, Measurement Inputs, Disclosure [Line Items]
Proceeds from call of auction rate securities							$ 10
Pre-tax gain from call of auction rate securities							4
Put option, fair value													145	267	346	145	[1]	267	[1]
Earn-out related to PlaySpan acquisition								24
Non-marketable equity securities, recognized losses due to impairment									0	3	7
Percentage of investment ownership sold				10.00%		10.00%
Non-marketable equity investments									100	114
Pre-tax gain related to pro-rata ownership in Reserve Primary Fund	108	49	575									20
Trading assets, mutual fund investments related to various employee compensation plans	57	60
Gain on other investments from the sale of equity interest in Visa Vale, pre-tax gain				$ 85	$ 85

[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.