Consolidated Balance Sheets Parenthetical (USD $) | Sep. 30, 2011 | Dec. 31, 2010 | Sep. 30, 2010 |
|---|---|---|---|
| Consolidated Balance Sheets Parenthetical [Abstract] | |||
| Common stock, par value (in dollars per share) | $ 0.001 | $ 0.001 | $ 0.001 |
| Common stock, authorized (in shares) | 100,000,000 | 100,000,000 | 100,000,000 |
| Common stock, shares issued (in shares) | 47,594,628 | 49,381,678 | 49,687,475 |
| Common stock, outstanding (in shares) | 47,594,628 | 49,278,578 | 49,687,475 |