Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Sep. 30, 2013
Accrued liabilities
Visa Europe put option	$ 145	[1]	$ 145	[1]
Fair Value, Measurements, Recurring
Accrued liabilities
Visa Europe put option	145		145
Level 1 | Fair Value, Measurements, Recurring
Prepaid and other current assets:
Fair value, total assets	2,879		2,920
Accrued liabilities
Fair value, total liabilities	0		0
Level 2 | Fair Value, Measurements, Recurring
Prepaid and other current assets:
Fair value, total assets	3,199		3,047
Accrued liabilities
Fair value, total liabilities	13		15
Level 3 | Fair Value, Measurements, Recurring
Prepaid and other current assets:
Fair value, total assets	7		7
Accrued liabilities
Fair value, total liabilities	145		145
Visa Europe put option | Level 3 | Fair Value, Measurements, Recurring
Accrued liabilities
Visa Europe put option	145		145
Foreign exchange derivative instruments | Level 2 | Fair Value, Measurements, Recurring
Accrued liabilities
Foreign exchange derivative instruments	13		15
Money market funds | Level 1 | Fair Value, Measurements, Recurring
Cash equivalents and restricted cash:
Cash equivalents and restricted cash:	998		1,071
Commercial paper | Level 2 | Fair Value, Measurements, Recurring
Cash equivalents and restricted cash:
Cash equivalents and restricted cash:	44		51
Equity securities | Level 1 | Fair Value, Measurements, Recurring
Investment securities:
Trading securities	89		75
Available-for-sale securities	122		101
U.S. government-sponsored debt securities | Level 2 | Fair Value, Measurements, Recurring
Investment securities:
Available-for-sale securities	2,743		2,704
U.S. Treasury securities | Level 1 | Fair Value, Measurements, Recurring
Investment securities:
Available-for-sale securities	1,670		1,673
Corporate Debt Securities | Level 2 | Fair Value, Measurements, Recurring
Investment securities:
Available-for-sale securities	378		269
Auction rate securities | Level 3 | Fair Value, Measurements, Recurring
Investment securities:
Available-for-sale securities	7		7
Foreign exchange derivative instruments | Level 2 | Fair Value, Measurements, Recurring
Prepaid and other current assets:
Prepaid and other current assets:	$ 34		$ 23

[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.