Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data | Sep. 30, 2011 | Dec. 31, 2010 |
|---|---|---|
| Condensed Consolidated Balance Sheets [Abstract] | ||
| Preference shares, par value | $ 0.01 | $ 0.01 |
| Preference shares, shares authorized | 100 | |
| Preferred stock, shares issued | 0 | 0 |
| Preferred stock, shares outstanding | 0 | 0 |
| Common stock, par value | $ 0.01 | $ 0.01 |
| Common stock, shares authorized | 900 | 900 |
| Common stock, shares issued | 246 | 196 |
| Common stock, shares outstanding | 246 | 196 |