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Warrants and Purchase Options For Purchase of Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified | 0 Months Ended | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
Oct. 02, 2011 | Jun. 29, 2011 | Oct. 02, 2010 | Sep. 28, 2010 | Oct. 31, 2006 | Jun. 30, 2011 | Sep. 30, 2010 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009 | Oct. 10, 2006
Warrants |  |  |  |  |  |  |  |  |  |  |
Number of shares of common stock that can be purchased with each warrant |  |  |  |  |  |  |  |  |  |  | 1
Exercise price of warrants (in dollars per share) |  |  |  |  |  |  |  |  |  |  | $ 5.00
Warrants outstanding (in shares) |  |  |  |  |  |  |  |  |  | 4,617,499 |
Warrants exercised (in shares) |  |  |  |  |  |  | 4,337,909 |  |  |  |
Cash proceeds from exercise of warrants |  |  |  |  |  |  | $ 21,690 |  | $ 21,690 |  |
Warrants repurchased by the broker (in shares) |  |  |  | 245,846 |  |  |  |  |  |  |
Repurchase of warrants |  |  |  | 277 |  |  |  |  | 277 |  |
Warrants expired (in shares) |  |  | 33,744 |  |  |  |  |  |  |  |
Unit Purchase Options |  |  |  |  |  |  |  |  |  |  |
Purchase of Unit Purchase Options by the underwriter, Early Bird Capital |  |  |  |  | 450,000 |  |  |  |  |  |
Number of shares of common stock that can be purchased with each UPO |  |  |  |  | 1 |  |  |  |  |  |
Number of warrants that can be purchased with each UPO |  |  |  |  | 1 |  |  |  |  |  |
Exercise price for cashless conversion of one share of common stock (in dollars per share) | $ 8.80 |  |  |  |  |  |  |  |  |  |
UPO exercised (in shares) |  | 450,000 |  |  |  |  |  |  |  |  |
Previous day's closing price used to calculate the number of shares of common stock issuable on exercise of UPO (in dollars per share) |  | $ 13.31 |  |  |  |  |  |  |  |  |
Number of shares of common stock issuable on exercise of UPO at the previous day's closing price |  | 152,480 |  |  |  |  |  |  |  |  |
Cash payment made in lieu of issuance of shares |  |  |  |  |  | $ 2,000 |  | $ 2,030 |  |  |

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