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Marketable Securities: (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2012
Marketable Securities: |
Reconciliation of marketable securities |
|  | March 31, 2012 |  | December 31, 2011 |
--- | --- | --- | --- | --- | ---
Government debt securities, at par value |  | $ | 25,048 |  | $ | 25,147 |
Less discount |  |  | (256 | ) |  | (314 | )
|  |  | 24,792 |  |  | 24,833 |
Unrealized gain |  |  | 1,499 |  |  | 1,803 |
Fair value (Level 1 measurement) |  | $ | 26,291 |  | $ | 26,636 |
Future contractual maturities of marketable securities |
1 year or less |  | $ | 1,378 |
2 to 5 years |  |  | 23,670 |
|  | $ | 25,048 |

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