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

Net (Loss)/Income Per Share of Class A Common Stock - Potentially Dilutive Shares (Details)

v3.21.2
Net (Loss)/Income Per Share of Class A Common Stock - Potentially Dilutive Shares (Details) - shares
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Dec. 31, 2019
Restricted Common Stock [Member]            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share         891,000 0
Common Stock Warrants [Member]            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share         12,312,000 11,551,000
Restricted class A common stock            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 420,000 1,022,000 420,000 1,022,000    
Restricted stock units            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 9,158,000 0 9,158,000 0    
Common Stock warrants            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 1,770,000 12,312,000 1,770,000 12,312,000    
Public Warrants (as exercised for class A common stock) treated as liability            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 15,813,000 0 15,813,000 0    
Private Placement Warrants (as exercised for class A common stock) treated as liability            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 8,325,000 0 8,325,000 0    
Sponsor earn-out shares            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 2,372,000 0 2,372,000 0    
Stock options            
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]            
Antidilutive securities excluded from the computation of earnings per share 2,344,000 3,561,000 2,344,000 3,561,000 3,489,000 3,856,000