Financings (Contingently Convertible Securities) (Details) (USD $) | 9 Months Ended |
|---|---|
Sep. 30, 2011 | |
| Number of trading days, adjusted trigger price contingencies were met | 20 |
| Number of trading days | 30 |
2.875% Senior Notes [Member] | |
| Maturity Date | 2024 |
| Outstanding | $ 288,000,000 |
| Adjusted Conversion Price | $ 12.67 |
| Adjusted Trigger Price | $ 15.20 |
| Senior Notes Interest Rate | 2.875% |
5.50% Senior Notes [Member] | |
| Maturity Date | 2029 |
| Outstanding | 172,000,000 |
| Adjusted Conversion Price | $ 14.26 |
| Adjusted Trigger Price | $ 18.54 |
| Senior Notes Interest Rate | 5.50% |
3.375% Contingently Convertible Senior Notes due 2023 [Member] | |
| Senior Notes Interest Rate | 3.375% |
| Conversion Date | January 2011 |
| Principal Converted | 4,000,000 |
| Conversion Value per share of principal | 1,994.21 |
| Common Stock Issued on Settlement | 197,472 |
| Cash Paid on Settlement | $ 4,000,000 |