Fair Value and Financial Instruments (Details) (USD $) In Millions | Sep. 30, 2011 | Dec. 31, 2010 |
|---|---|---|
Fair Value | Money market funds and highly liquid debt securities | ||
| Assets: | ||
| Money market funds and highly liquid debt securities | $ 2,500 | $ 2,618 |
Fair Value | Money market funds | ||
| Assets: | ||
| Money market funds and highly liquid debt securities | 2,450 | 2,591 |
Fair Value | Highly liquid debt securities | ||
| Assets: | ||
| Money market funds and highly liquid debt securities | 50 | 27 |
Fair Value | Corporate bonds | ||
| Assets: | ||
| Other investments | 12 | 12 |
Fair Value | Government bonds. | ||
| Assets: | ||
| Other investments | 3 | 3 |
Fair Value | Interest rate contracts | ||
| Assets: | ||
| Derivatives | 15 | 15 |
Fair Value | Foreign exchange contracts | ||
| Assets: | ||
| Derivatives | 137 | 159 |
| Liabilities: | ||
| Derivatives | 180 | 158 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds and highly liquid debt securities | ||
| Assets: | ||
| Money market funds and highly liquid debt securities | 2,450 | 2,591 |
Significant Other Observable Inputs (Level 2) | Money market funds and highly liquid debt securities | ||
| Assets: | ||
| Money market funds and highly liquid debt securities | 50 | 27 |
Significant Other Observable Inputs (Level 2) | Government bonds. | ||
| Assets: | ||
| Other investments | 3 | 3 |
Significant Other Observable Inputs (Level 2) | Interest rate contracts | ||
| Assets: | ||
| Derivatives | 15 | 15 |
Significant Other Observable Inputs (Level 2) | Foreign exchange contracts | ||
| Assets: | ||
| Derivatives | 137 | 159 |
| Liabilities: | ||
| Derivatives | 180 | 158 |
Significant Unobservable (Level 3) Inputs | Corporate bonds | ||
| Assets: | ||
| Other investments | $ 12 | $ 12 |