Disclosure Of Fair Value Of Financial Instruments (Details) (USD $) In Billions | Sep. 30, 2011 | Dec. 31, 2010 |
|---|---|---|
| Disclosure Of Fair Value Of Financial Instruments [Abstract] | ||
| Fair value of company's long-term debt | $ 2.0 | $ 2.2 |
| Book value of company's long-term debt | $ 1.9 | $ 2.1 |