Quarterly report pursuant to Section 13 or 15(d)

Stock-based compensation - Stock Option Activity (Details)

v3.2.0.727
Stock-based compensation - Stock Option Activity (Details) - USD ($)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2014
Jun. 30, 2015
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2014
Exercise Price Per Share [Abstract]          
Exercise Price Per Share, Expired (per share)   $ 0.00      
Tecogen          
Stock Options Outstanding [Roll Forward]          
Beginning (shares)   1,356,325      
Granted (shares)   0      
Exercised (shares)   (222,375)      
Canceled and forfeited (shares)   (26,200)      
Expired (shares)   0      
Ending (shares)   1,107,750      
Exercisable (shares)   768,384      
Vested and expected to vest (shares)   1,007,750      
Weighted Average Exercise Price [Roll Forward]          
Beginning (usd per share)   $ 2.77      
Granted (usd per share)   0.00      
Exercised (usd per share)   1.62      
Canceled and forfeited (usd per share)   2.25      
Expried (usd per share)   0.00      
Ending (usd per share)   3.01      
Exercisable (usd per share)   2.27      
Vested and expected to vest (usd per share)   $ 2.82      
Weighted Average Remaining Life   5 years 11 months 23 days 5 years 1 month 12 days    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]          
Outstanding, Aggregate Intrinsic Value   $ 1,498,750     $ 3,618,935
Exercisable, Aggregate Intrinsic Value   1,414,576      
Vested and expected to vest, Aggregate Intrinsic Value   $ 1,498,750      
Minimum | Tecogen          
Exercise Price Per Share [Abstract]          
ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit $ 1.2     $ 1.20  
Exercise Price Per Share, Granted (per share)   $ 1.20      
Exercise Price Per Share, Cancelled and forfeited (per share)       1.2  
ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit 1.2     1.20  
Maximum | Tecogen          
Exercise Price Per Share [Abstract]          
ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit 5.39     5.39  
Exercise Price Per Share, Granted (per share)   $ 2.60      
Exercise Price Per Share, Cancelled and forfeited (per share)       4.50  
ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit $ 5.39     $ 5.39