Equity Awards and Instruments - Stock Grants (Details) - Class B Common Stock - 2020 Incentive Award Plan - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fully vested shares granted (in shares)	7,824	17,411
Fully vested shares granted	$ 450	$ 219

Value, after forfeiture, of shares issued under share-based payment arrangement. Excludes employee stock ownership plan (ESOP).

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