Stock-Based Compensation (Details) (USD $) In Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Sep. 30, 2011 | Sep. 30, 2010 | Sep. 30, 2011 | Sep. 30, 2010 | Dec. 31, 2010 | |
| Stock-Based Compensation | |||||
| Stock option expense | $ 6.0 | $ 5.8 | $ 17.6 | $ 16.0 | |
| Restricted stock and unit awards expense | 17.3 | 15.7 | 46.3 | 28.2 | |
| Total stock-based compensation expense | $ 23.3 | $ 21.5 | $ 63.9 | $ 44.2 | |
| Stock-Based Compensation (Textuals) [Abstract] | |||||
| Common shares issued from exercise of stock option outstanding | 3.6 | 1.8 | |||