|
Stock-based compensation - Stock Option Activity (Details) (USD $)
|
3 Months Ended | 12 Months Ended | 3 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Mar. 31, 2014
|
Mar. 31, 2014
Tecogen
|
Dec. 31, 2012
Tecogen
|
Dec. 31, 2013
Tecogen
|
Mar. 31, 2014
Ilois
|
Mar. 31, 2013
Ilois
|
Dec. 31, 2013
Ilois
|
Mar. 31, 2014
Minimum
Tecogen
|
Dec. 31, 2012
Minimum
Tecogen
|
Mar. 31, 2014
Minimum
Ilois
|
Dec. 31, 2012
Minimum
Ilois
|
Mar. 31, 2014
Maximum
Tecogen
|
Dec. 31, 2012
Maximum
Tecogen
|
Mar. 31, 2014
Maximum
Ilois
|
Dec. 31, 2012
Maximum
Ilois
|
|
| Stock Options Outstanding [Roll Forward] | |||||||||||||||
| Beginning (shares) | 1,148,000 | 575,000 | |||||||||||||
| Granted (shares) | 43,325 | 0 | |||||||||||||
| Exercised (shares) | (5,000) | 0 | |||||||||||||
| Canceled and forfeited (shares) | 0 | 0 | |||||||||||||
| Expired (shares) | 0 | 0 | |||||||||||||
| Ending (shares) | 1,186,325 | 575,000 | |||||||||||||
| Exercisable (shares) | 919,250 | 125,000 | |||||||||||||
| Vested and expected to vest (shares) | 1,186,325 | 575,000 | |||||||||||||
| Exercise Price Per Share [Abstract] | |||||||||||||||
| Exercise Price Per Share, Beginning (per share) | $ 1.2 | $ 1.20 | $ 0.10 | $ 0.10 | $ 4.5 | $ 4.50 | $ 0.50 | $ 0.50 | |||||||
| Exercise Price Per Share, Granted (per share) | $ 4.5 | $ 0.00 | |||||||||||||
| Exercise Price Per Share, Exercised (per share) | $ 1 | $ 0 | |||||||||||||
| Exercise Price Per Share, Cancelled and forfeited (per share) | $ 0 | $ 0 | |||||||||||||
| Exercise Price Per Share, Expired (per share) | $ 0 | $ 0 | |||||||||||||
| Exercise Price Per Share, Ending (per share) | $ 1.2 | $ 1.20 | $ 0.10 | $ 0.10 | $ 4.5 | $ 4.50 | $ 0.50 | $ 0.50 | |||||||
| Weighted Average Exercise Price [Roll Forward] | |||||||||||||||
| Beginning (usd per share) | $ 2.13 | $ 0.29 | |||||||||||||
| Granted (usd per share) | $ 4.50 | $ 0.00 | |||||||||||||
| Exercised (usd per share) | $ 1 | $ 0 | |||||||||||||
| Canceled and forfeited (usd per share) | $ 0.00 | $ 0 | |||||||||||||
| Expried (usd per share) | $ 0.00 | $ 0 | |||||||||||||
| Ending (usd per share) | $ 2.22 | $ 0.29 | |||||||||||||
| Exercisable (usd per share) | $ 1.90 | $ 0.50 | |||||||||||||
| Vested and expected to vest (usd per share) | $ 2.22 | $ 0.29 | |||||||||||||
| Weighted Average Remaining Life | 5 years 8 months 23 days | 5 years 9 months 18 days | 6 years 2 months 9 days | 6 years 5 months 9 days | |||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] | |||||||||||||||
| Outstanding, Aggregate Intrinsic Value | $ 2,704,600 | $ 2,721,100 | $ 120,000 | $ 120,000 | |||||||||||
| Exercisable, Aggregate Intrinsic Value | 2,387,075 | 0 | |||||||||||||
| Vested and expected to vest, Aggregate Intrinsic Value | $ 2,704,600 | $ 120,000 | |||||||||||||