Assets And Liabilities Measured At Fair Value (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Cash equivalents | $ 2,225 | $ 2,147 |
| Short term marketable securities | 910 | 889 |
| Available-for-sale securities | 1,294 | 1,220 |
| Debt | 2,480 | 2,574 |
| Fair Value, Inputs (Level 1) | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Cash equivalents | 2,225 | 2,147 |
| Short term marketable securities | 331 | 277 |
| Available-for-sale securities | 1,287 | 1,203 |
| Significant Other Observable Inputs (Level 2) | ||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Short term marketable securities | 579 | 612 |
| Available-for-sale securities | 7 | 17 |
| Debt | $ 2,480 | $ 2,574 |