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Stock-based compensation - Stock Option Activity (Details) (USD $)
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3 Months Ended | 9 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 | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Sep. 30, 2013
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Sep. 30, 2013
Tecogen
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Sep. 30, 2013
Tecogen
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Dec. 31, 2012
Tecogen
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Sep. 30, 2013
Ilois
|
Sep. 30, 2012
Ilois
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Dec. 31, 2012
Ilois
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Sep. 30, 2013
Minimum
Tecogen
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Dec. 31, 2012
Minimum
Tecogen
|
Sep. 30, 2013
Minimum
Ilois
|
Dec. 31, 2012
Minimum
Ilois
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Sep. 30, 2013
Maximum
Tecogen
|
Dec. 31, 2012
Maximum
Tecogen
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Sep. 30, 2013
Maximum
Ilois
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Dec. 31, 2012
Maximum
Ilois
|
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| Stock Options Outstanding [Roll Forward] | |||||||||||||||
| Beginning (shares) | 1,096,500 | 575,000 | |||||||||||||
| Granted (shares) | 37,500 | 0 | |||||||||||||
| Exercised (shares) | 0 | 0 | |||||||||||||
| Canceled and forfeited (shares) | 0 | 0 | |||||||||||||
| Expired (shares) | 0 | 0 | |||||||||||||
| Ending (shares) | 1,134,000 | 1,134,000 | 1,096,500 | 575,000 | 575,000 | ||||||||||
| Exercisable (shares) | 815,438 | 815,438 | 62,500 | ||||||||||||
| Vested and expected to vest (shares) | 1,134,000 | 1,134,000 | 575,000 | ||||||||||||
| Exercise Price Per Share [Abstract] | |||||||||||||||
| Exercise Price Per Share, Beginning (per share) | $ 0.12 | $ 0.12 | $ 0.10 | $ 0.10 | $ 3.2 | $ 3.2 | $ 0.50 | $ 0.50 | |||||||
| Exercise Price Per Share, Granted (per share) | $ 3.2 | $ 0.00 | |||||||||||||
| Exercise Price Per Share, Exercised (per share) | $ 0 | $ 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) | $ 0.12 | $ 0.12 | $ 0.10 | $ 0.10 | $ 3.2 | $ 3.2 | $ 0.50 | $ 0.50 | |||||||
| Weighted Average Exercise Price [Roll Forward] | |||||||||||||||
| Beginning (usd per share) | $ 1.96 | $ 0.29 | |||||||||||||
| Granted (usd per share) | $ 3.20 | $ 0.00 | |||||||||||||
| Exercised (usd per share) | $ 0 | $ 0 | |||||||||||||
| Canceled and forfeited (usd per share) | $ 0.00 | $ 0 | |||||||||||||
| Expried (usd per share) | $ 0.00 | $ 0 | |||||||||||||
| Ending (usd per share) | $ 2.00 | $ 2.00 | $ 1.96 | $ 0.29 | $ 0.29 | ||||||||||
| Exercisable (usd per share) | $ 1.73 | $ 1.73 | $ 0.50 | ||||||||||||
| Vested and expected to vest (usd per share) | $ 2.00 | $ 2.00 | $ 0.29 | ||||||||||||
| Weighted Average Remaining Life | 3 years 11 months 10 days | 4 years 7 months 27 days | 6 years 8 months 7 days | 7 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 | $ 1,356,400 | $ 1,356,400 | $ 1,356,400 | $ 120,000 | $ 120,000 | ||||||||||
| Exercisable, Aggregate Intrinsic Value | 1,201,075 | 1,201,075 | 0 | ||||||||||||
| Vested and expected to vest, Aggregate Intrinsic Value | $ 1,356,400 | $ 1,356,400 | $ 120,000 | ||||||||||||