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Equity Awards and Instruments - Stock Grants Narrative (Details) - Class B Common Stock - 2020 Incentive Award Plan - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Fully vested shares granted (in shares) | 21,956 | 0 | 0
Fully vested shares granted | $ 319 |  |

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