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Stock-based compensation - Stock Option Activity (Details) (USD $)
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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 | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2013
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Mar. 31, 2013
Tecogen
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Dec. 31, 2012
Tecogen
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Mar. 31, 2013
Ilois
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Mar. 31, 2012
Ilois
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Dec. 31, 2012
Ilois
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Mar. 31, 2013
Minimum
Tecogen
|
Dec. 31, 2012
Minimum
Tecogen
|
Mar. 31, 2013
Minimum
Ilois
|
Dec. 31, 2012
Minimum
Ilois
|
Mar. 31, 2013
Maximum
Tecogen
|
Dec. 31, 2012
Maximum
Tecogen
|
Mar. 31, 2013
Maximum
Ilois
|
Dec. 31, 2012
Maximum
Ilois
|
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| Stock Options Outstanding [Roll Forward] | ||||||||||||||
| Beginning (shares) | 4,386,000 | 575,000 | ||||||||||||
| Granted (shares) | 0 | 0 | ||||||||||||
| Exercised (shares) | 0 | 0 | ||||||||||||
| Canceled and forfeited (shares) | 0 | 0 | ||||||||||||
| Expired (shares) | 0 | 0 | ||||||||||||
| Ending (shares) | 4,386,000 | 4,386,000 | 575,000 | |||||||||||
| Exercisable (shares) | 3,249,250 | 56,250 | ||||||||||||
| Vested and expected to vest (shares) | 4,386,000 | 575,000 | ||||||||||||
| Exercise Price Per Share [Abstract] | ||||||||||||||
| Exercise Price Per Share, Beginning (per share) | $ 0.03 | $ 0.03 | $ 0.10 | $ 0.10 | $ 0.80 | $ 0.80 | $ 0.50 | $ 0.50 | ||||||
| Exercise Price Per Share, Granted (per share) | $ 0 | $ 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) | $ 0.03 | $ 0.03 | $ 0.10 | $ 0.10 | $ 0.80 | $ 0.80 | $ 0.50 | $ 0.50 | ||||||
| Weighted Average Exercise Price [Roll Forward] | ||||||||||||||
| Beginning (usd per share) | $ 0.49 | $ 0.29 | ||||||||||||
| Granted (usd per share) | $ 0.00 | $ 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) | $ 0.49 | $ 0.49 | $ 0.29 | |||||||||||
| Exercisable (usd per share) | $ 0.43 | $ 0.50 | ||||||||||||
| Vested and expected to vest (usd per share) | $ 0.49 | $ 0.29 | ||||||||||||
| Weighted Average Remaining Life | 4 years 4 months 27 days | 4 years 7 months 27 days | 7 years 2 months 9 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 | $ 120,000 | $ 120,000 | ||||||||||
| Exercisable, Aggregate Intrinsic Value | 1,201,075 | 0 | ||||||||||||
| Vested and expected to vest, Aggregate Intrinsic Value | $ 1,356,400 | $ 120,000 | ||||||||||||