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Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Restricted Stock Awards      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Nonvested restricted stock awards or restricted stock units, Beginning Balance 1,879,000    
Granted 0   0
Vested (470,000)    
Forfeited 0    
Nonvested restricted stock awards or restricted stock units, Ending Balance 1,409,000 1,879,000  
Granted, Weighted Average Grant Date Fair Value   $ 3.88  
Restricted Stock Units for Class A Common Stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Nonvested restricted stock awards or restricted stock units, Beginning Balance 0    
Granted 2,800,000    
Vested (8,000)    
Forfeited (2,000)    
Nonvested restricted stock awards or restricted stock units, Ending Balance 2,790,000 0  
Restricted Stock Units for Class B Common Stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Nonvested restricted stock awards or restricted stock units, Beginning Balance 0    
Granted 24,633,000    
Vested (16,935,000)    
Forfeited 0    
Nonvested restricted stock awards or restricted stock units, Ending Balance 7,698,000 0  
Restricted Stock      
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Nonvested restricted stock awards or restricted stock units, Weighted Average Grant Date Fair Value, Beginning Balance $ 3.88    
Granted, Weighted Average Grant Date Fair Value 23.56    
Vested, Weighted Average Grant Date Fair Value 19.26    
Forfeited, Weighted Average Grant Date Fair Value 49.05    
Nonvested restricted stock awards or restricted stock units, Weighted Average Grant Date Fair Value, Ending Balance $ 26.74 $ 3.88