Assumptions Used to Estimate the Fair Value of Each Stock Option on the Date of Grant Using a Black-Scholes Option Pricing Model (Parenthetical) (Detail)	12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	29.30%	[1]	34.90%	[1]	33.40%	[1]
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	27.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	29.00%

[1] Based on the average of the Company’s implied and historical volatility. As the Company’s publicly-traded stock history is relatively short, historical volatility relies in part on the historical volatility of a group of peer companies that management believes is generally comparable to Visa. The relative weighting between Visa historical volatility and the historical volatility of the peer companies is based on the percentage of years Visa stock price information has been available since its initial public offering compared to the expected term. The expected volatilities ranged from 27% to 29% in fiscal 2013.