|
Collateral (Detail) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2015
|
Sep. 30, 2014
|
|---|---|---|
| Settlement Guarantee Management [Abstract] | ||
| Cash equivalents | $ 1,079 | $ 961 |
| Pledged securities at market value | 153 | 148 |
| Letters of credit | 1,196 | 1,242 |
| Guarantees | 1,211 | 1,554 |
| Total | $ 3,639 | $ 3,905 |