|
Fair Value Measurements and Investments - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
|
6 Months Ended |
|
|
Mar. 31, 2015
|
Sep. 30, 2014
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| 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 |
21.8x |
|
| Spot price to earnings, ratio |
2180.00% |
|
| Incremental price to earnings differential compared to estimate |
2.3x |
|
| Incremental price to earnings differential compared to estimate, ratio |
230.00% |
|
| 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 |
|
| Non-marketable equity investments |
28 |
35 |
| Available-for-sale securities, gross unrealized gains |
11 |
48 |
| Available-for-sale securities, gross unrealized losses |
2 |
0 |
| Fair Value, Measurements, Recurring |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Visa Europe put option |
$ 145 |
$ 145 |