Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Stock Option Activity (Details)

v3.21.2
Stock-Based Compensation - Stock Option Activity (Details) - Tecogen - USD ($)
6 Months Ended 9 Months Ended
Jun. 30, 2021
Jun. 30, 2019
Sep. 30, 2021
Dec. 31, 2020
Stock Options Outstanding [Roll Forward]        
Beginning (shares) 2,496,242   2,496,242  
Granted (shares)     208,000  
Exercised (shares)     0  
Canceled and forfeited (shares)     (253,500)  
Ending (shares)     2,450,742  
Exercisable (shares)     794,533  
Vested and expected to vest (shares)     2,202,311  
Exercise Price Per Share [Abstract]        
Exercise Price Per Share, Outstanding, Minimum (per share) $ 0.71   $ 0.71  
Exercise Price Per Share, Outstanding, Maximum (dollars per share) 10.33   10.33  
Exercise price per share, Granted (dollars per share)     1.75  
Exercise Price, Canceled and Forfeited (dollars per share)     2.60  
Weighted Average Exercise Price [Roll Forward]        
Beginning (usd per share) $ 1.94   1.94  
Granted (usd per share)     1.75  
Canceled and forfeited (usd per share)     2.60  
Ending (usd per share)     1.86  
Exercisable (usd per share)     3.48  
Vested and expected to vest (usd per share)     $ 1.95  
Weighted Average Remaining Life   7 years 4 months 13 days 7 years 7 months 13 days  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]        
Outstanding, Aggregate Intrinsic Value     $ 1,608,837 $ 731,744
Exercisable, Aggregate Intrinsic Value     163,557  
Vested and expected to vest, Aggregate Intrinsic Value     $ 1,392,045