|
Marketable Securities (Contractual maturity) (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2015
|
Dec. 31, 2014
|
|---|---|---|
| Marketable securities by contractual maturity | ||
| Due in one year or less | $ 357 | |
| Due after one year through five years | 654 | |
| Due after five years through ten years | 5 | |
| Due after ten years | 15 | |
| Total marketable securities | $ 1,031 | $ 1,454 |