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CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Class A Common Stock      
Common stock, par value (USD per share) $ 0.001 $ 0.001  
Class B Common Stock      
Common stock, par value (USD per share) 0.001 0.001  
Class C Common Stock      
Common stock, par value (USD per share) 0.001 0.001  
Common Stock | Class A Common Stock      
Common stock, par value (USD per share) 0.001 0.001 $ 0.001
Common Stock | Class B Common Stock      
Common stock, par value (USD per share) 0.001 0.001 0.001
Common Stock | Class C Common Stock      
Common stock, par value (USD per share) $ 0.001 $ 0.001 $ 0.001