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Stock-Based Compensation - Option Activity (Details) - Common Stock - Class B
9 Months Ended
Sep. 30, 2021
shares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]  
Outstanding (in shares) 75,044
Granted stock (in shares) 17,690
Vested (in shares) (92,734)
Outstanding (in shares) 0