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

Stockholders' Equity - Common Shares Reserved For Issuance (Details)

v3.21.2
Stockholders' Equity - Common Shares Reserved For Issuance (Details) - shares
Sep. 30, 2021
Dec. 31, 2020
Dec. 31, 2019
Common Stock      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 183,884,000 264,418,000  
Common Stock | Common Stock warrants      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 1,770,000 12,312,000  
Common Stock | Stock options      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 2,344,000 3,489,000  
Common Stock | Restricted stock units      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 9,158,000 0  
Common Stock | Public Warrants (as exercised for class A common stock) treated as liability      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 15,813,000 0  
Common Stock | Private Placement Warrants (as exercised for class A common stock) treated as liability      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 8,325,000 0  
Common Stock | Reserved Shares      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved 146,474,000 248,617,000  
Common Class A [Member]      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved   264,418 268,926
Common Class A [Member] | Class A Common Stock Warrants [Member]      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved   12,312 11,551
Common Class A [Member] | Stock Options Outstanding [Member]      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved   3,489 3,856
Common Class A [Member] | Shares Available For Future Grant [Member]      
Common Stock Capital Shares Reserved For Future Issuance [Line Items]      
Common Stock reserved   248,617 253,519