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Equity Compensation Plans - Options (Details) - USD ($) |  | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2009 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | May 31, 2019
2019 Plan |  |  |  |  |
Equity Compensation Plans |  |  |  |  |
Number of shares authorized |  |  |  |  | 600,000
2009 Plan |  |  |  |  |
Equity Compensation Plans |  |  |  |  |
Granted (in shares) | 16,500 |  | 0 |  |
Exercised (in shares) |  | 0 | 4,500 |  |
Shares |  |  |  |  |
Exercised (in shares) |  | 0 | (4,500) |  |
Employee and Nonemployee Stock Options [Member] |  |  |  |  |
Equity Compensation Plans |  |  |  |  |
Total unrecognized compensation cost |  |  | $ 0 |  |
Aggregate Intrinsic Value |  |  |  |  |
Exercised (in dollars) |  |  | $ (27,000) | $ (27,000) |
Restricted Stock and Restricted Stock Units [Member] |  |  |  |  |
Equity Compensation Plans |  |  |  |  |
Vesting period |  | 3 years |  |  |

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