General form of registration statement for all companies including face-amount certificate companies

Stock-Based Compensation - Stock option activity (Details)

v3.21.2
Stock-Based Compensation - Stock option activity (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Number of Options          
Outstanding beginning balance 14,713 19,656 18,542 15,180  
Options granted 1,707 4,293 1,563 3,995  
Options exercised (1,710) (254) (65) (2)  
Options forfeited (271) (8,982) (384) (631)  
Outstanding Ending balance 14,439 14,713 19,656 18,542 15,180
Options expected to vest 4,136 5,269      
Options exercisable 6,404 5,480      
Weighted Average Exercise Price          
Outstanding beginning balance (in dollars per share) $ 4.47 $ 2.35 $ 2.14 $ 2.11  
Options granted (in dollars per share) 30.95 9.19 5.04 2.33  
Options exercised (in dollars per share) 3.28 2.89 2.43 2.00  
Options forfeited (in dollars per share) 7.15 2.13 2.90 2.67  
Outstanding ending balance (in dollars per share) 7.70 4.47 $ 2.35 $ 2.14 $ 2.11
Options expected to vest (in dollars per share) 16.20 7.17      
Options exercisable (in dollars per share) $ 3.68 $ 2.52      
Additional disclosures          
Weighted Average Remaining Contractual Life (Years) 7 years 4 months 28 days 7 years 9 months 14 days 8 years 14 days 8 years 11 months 4 days 9 years 10 months 6 days
Options expected to vest (in years) 8 years 10 months 24 days        
Options exercisable (Years) 6 years 8 months 12 days        
Aggregate Intrinsic Value, outstanding (Beginning balance) $ 181,914 $ 86,024 $ 5,277    
Aggregate Intrinsic Value, outstanding (ending balance) 383,974 181,914 $ 86,024 $ 5,277  
Aggregate Intrinsic Value, expected to vest 75,637 50,983      
Aggregate Intrinsic Value, exercisable $ 195,205 $ 78,389