Derivative Financial Instruments (Narrative) (Details) (USD $) | 9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2011 | Dec. 31, 2010 | |
| Derivative Financial Instruments [Abstract] | ||
| Notional amounts on foreign currency exchange forward contracts outstanding | $ 3,940,000,000 | $ 3,550,000,000 |
| Net unrealized gains (losses) related to cash flow hedges | $ 7,600,000 | $ 21,600,000 |