CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Sep. 30, 2021
Investment securities, available-for sale, Amortized cost current $ 0 $ 21,139
Investment securities, held-to-maturity, Fair value current 266 308
Investment securities, available-for sale, Amortized cost noncurrent 53,953 146,796
Investment securities, held-to-maturity, Fair value noncurrent $ 471 $ 419
Preferred stock par value (in dollars per share) $ 0.0001 $ 0.0001
Preferred stock, shares authorized (in shares) 155,387,025 0
Preferred stock, shares issued (in shares) 139,444,346 0
Preferred stock, shares outstanding (in shares) 139,444,346 0
Liquidation preference $ 470,256 $ 0
Preferred stock par value, (in dollars per share) $ 0.0001  
Preferred stock, shares authorized (in shares) 155,387,025  
Preferred stock, shares issued (in shares) 139,444,346  
Preferred stock, shares outstanding (in shares) 139,444,346  
Liquidation preference $ 470,256  
Common stock, par value, (in dollars per share) $ 0.0001  
Common stock, shares authorized (in shares) 351,572,668  
Common stock, shares, issued (in shares) 89,972,184  
Common stock, shares, outstanding (in shares) 89,206,266  
Treasury stock, shares held (in shares) 0 14,730
Common stock exchange ratio 206.81%  
Common Class A    
Common stock, par value, (in dollars per share) $ 0.0001 $ 0.0001
Common stock, shares authorized (in shares) 0 2,500,000,000
Common stock, shares, issued (in shares) 0 278,308,964
Common stock, shares, outstanding (in shares) 0 278,308,964
Common Class B    
Common stock, par value, (in dollars per share) $ 0.0001 $ 0.0001
Common stock, shares authorized (in shares) 351,572,668 500,000,000
Common stock, shares, issued (in shares) 89,206,266 142,318,711
Common stock, shares, outstanding (in shares) 89,206,266 142,318,711