Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Stock Option Activity (Details)

v3.20.1
Stock-Based Compensation - Stock Option Activity (Details) - Tecogen - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Dec. 31, 2017
Stock Options Outstanding [Roll Forward]      
Beginning (shares) 1,352,874    
Granted (shares) 0    
Exercised (shares) (1,000)    
Canceled and forfeited (shares) (67,278)    
Ending (shares) 1,284,596 1,352,874  
Exercisable (shares) 905,054    
Vested and expected to vest (shares) 1,227,665    
Exercise Price Per Share [Abstract]      
Exercise Price Per Share, Outstanding, Minimum (per share) $ 0.79 $ 0.79  
Exercise Price Per Share, Outstanding, Maximum (dollars per share) 10.33 10.33  
Exercise Price Per Share, Exercised (dollars per share) 1.20    
Weighted Average Exercise Price [Roll Forward]      
Beginning (usd per share) 3.57    
Granted (usd per share)    
Exercised (usd per share) 1.20    
Canceled and forfeited (usd per share) 1.25    
Ending (usd per share) 3.69 $ 3.57  
Exercisable (usd per share) 3.71    
Vested and expected to vest (usd per share) $ 3.70    
Weighted Average Remaining Life 5 years 3 months 26 days   5 years 3 months 20 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]      
Outstanding, Aggregate Intrinsic Value $ 3,664 $ 95,381  
Exercisable, Aggregate Intrinsic Value 3,664    
Vested and expected to vest, Aggregate Intrinsic Value $ 3,664    
Minimum      
Exercise Price Per Share [Abstract]      
Exercise Price, Canceled and Forfeited (dollars per share) $ 1.20    
Maximum      
Exercise Price Per Share [Abstract]      
Exercise Price, Canceled and Forfeited (dollars per share) $ 4.50