Annual report pursuant to Section 13 and 15(d)

Stockholders' equity - Stock-Based Compensation (Details)

v3.6.0.2
Stockholders' equity - Stock-Based Compensation (Details) - USD ($)
1 Months Ended 6 Months Ended 12 Months Ended
Jul. 31, 2016
Jul. 31, 2016
Dec. 31, 2015
Jun. 30, 2016
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Warrants granted     900,000     250,000
Warrant exercise price per share (in dollars per share) $ 4.00 $ 4.00 $ 4.00     $ 4.00
Warrants exercised for investment in joint venture   $ 2,700,000.0        
Warrants expired (shares) 225,000          
Options granted, exercise price range, lower limit (usd per share)         $ 0.79  
Options granted, exercise price range, upper limit (usd per share)         $ 4.27  
Warrant            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Warrants exercised (shares)   675,000        
Tecogen            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted         207,701 165,000
Options granted, exercise price range, lower limit (usd per share)         $ 0.79 $ 3.39
Options granted, exercise price range, upper limit (usd per share)         $ 4.27 $ 4.05
Fair value of options issued         $ 236,315 $ 250,462
Weighted-average grant date fair value of options granted         $ 1.14 $ 1.52
Recognized stock-based compensation         $ 165,931 $ 189,511
Compensation cost related to unvested restricted stock awards and stock option awards not yet recognized     $ 592,494   $ 444,939 $ 592,494
Compensation cost not yet recognized, weighted average period of recognition         2 years 11 months 5 days  
Tecogen | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Award vesting period           4 years
Award expiration period           10 years
Tecogen | Restricted stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unvested restricted stock outstanding     163,350   77,508 163,350
Tecogen | Restricted stock | Minimum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Vesting percentage         25.00%  
Tecogen | Restricted stock | Maximum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Award vesting period         1 year  
Vesting percentage         33.00%  
Tecogen | Amended Plan | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares of common stock reserved for future issuance         3,838,750  
Number of shares remaining available for future issuance     1,614,533   1,607,357 1,614,533
Tecogen | 2009 Plan | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted       82,701    
Ilois | Restricted stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unvested restricted stock outstanding     160,000   0 160,000
Ilois | 2009 Plan            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Number of shares remaining available for future issuance       1,325,000    
Maximum number of shares allowable for issuance         2,000,000  
Options Issued in Conjunction with Ilios Merger | Tecogen            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted         82,701  
Remaining Options | Tecogen            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Options granted         125,000  
Remaining Options | Tecogen | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Award vesting period         4 years  
Award expiration period         10 years