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Stock-Based and Other Long-Term Incentive Compensation - Restricted Stock Narrative (Details) - Restricted Stock $ in Millions |  |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Apr. 28, 2021 | Apr. 28, 2020 shares | Jun. 18, 2014 shares | Dec. 31, 2020 USD ($) independent_director shares | Dec. 31, 2019 USD ($) shares | Jun. 20, 2019 shares | Dec. 31, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Shares outstanding (in shares) |  |  |  | 258,101 | 279,766 |  | 214,630
Granted (in shares) |  |  |  | 123,185 | 199,810 |  |
Stock based compensation expense | $ |  |  |  | $ 2.2 | $ 2.5 |  |
Total unrecognized compensation expense | $ |  |  |  | $ 1.8 |  |  |
Recognition period |  |  |  | 3 years |  |  |
Chief Executive Officer |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Award vesting period |  | 3 years |  |  |  |  |
Granted (in shares) |  | 94,133 |  |  |  |  |
Chief Financial Officer |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Granted (in shares) |  | 10,000 |  |  |  |  |
Vice President of Technical Services |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Granted (in shares) |  | 10,000 |  |  |  |  |
Executive Officer | Forecast |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Award vesting period | 3 years |  |  |  |  |  |
Director |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Award vesting period |  |  |  | 1 year |  |  |
Granted (in shares) |  |  |  | 4,432 |  |  |
Number of independent directors | independent_director |  |  |  | 4 |  |  |
2009 Restricted Stock/Units Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Additional shares authorized (in shares) |  |  | 500,000 |  |  |  |
Number of shares authorized (in shares) |  |  | 800,000 |  |  |  |
Shares outstanding (in shares) |  |  |  | 34,899 |  |  |
Award vesting period |  |  |  | 1 year |  |  |
Issuance under the equity incentive plan (in shares) |  |  |  | 200,141 |  |  |
Equity Incentive Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Number of shares authorized (in shares) |  |  |  |  |  | 500,000 |
Shares outstanding (in shares) |  |  |  | 223,202 |  |  |
Award vesting period |  |  |  | 3 years |  |  |

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