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Stockholders' equity (Tables)
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12 Months Ended |
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Dec. 31, 2013
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Tecogen
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Schedule of Stock Option Activity |
Stock option activity for the years ended December 31, 2013 and 2012 was as follows: | Common Stock Options | | | Number of
Options | | | Exercise
Price Per
Share | | Weighted
Average
Exercise
Price | | Weighted
Average
Remaining
Life | | Aggregate
Intrinsic
Value | | | Outstanding, December 31, 2011 | | | 1,095,250 | | | $0.12-$2.80 | | $ | 1.92 | | 5.53 years | | $ | 1,387,150 | | | Granted | | | 17,500 | | | 3.20 | | | 3.20 | | | | | | | | Exercised | | | — | | | — | | | — | | | | | | | | Canceled and forfeited | | | (15,938) | | | 1.20 - 2.60 | | | 1.28 | | | | | | | | Expired | | | (313) | | | 2.60 | | | 2.60 | | | | | | | | Outstanding, December 31, 2012 | | | 1,096,500 | | | $0.12-$3.20 | | $ | 1.96 | | 4.66 years | | $ | 1,356,400 | | | Exercisable, December 31, 2012 | | | 662,563 | | | | | $ | 1.56 | | | | $ | 1,096,225 | | | Vested and expected to vest, December 31, 2012 | | | 1,096,500 | | | | | $ | 1.96 | | | | $ | 1,356,400 | | | | | | | | | | | | | | | | | | | | Outstanding, December 31, 2012 | | | 1,096,500 | | | $0.12-$3.20 | | $ | 1.96 | | 4.66 years | | $ | 1,356,400 | | | Granted | | | 76,500 | | | 3.20-4.50 | | | 3.86 | | | | | | | | Exercised | | | (25,000) | | | 0.12 | | | 0.12 | | | | | | | | Canceled and forfeited | | | — | | | — | | | — | | | | | | | | Expired | | | — | | | — | | | — | | | | | | | | Outstanding, December 31, 2013 | | | 1,148,000 | | | $1.20-$4.50 | | $ | 2.13 | | 5.80 years | | $ | 2,721,100 | | | Exercisable, December 31, 2013 | | | 799,500 | | | | | $ | 1.79 | | | | $ | 2,166,550 | | | Vested and expected to vest, December 31, 2013 | | | 1,148,000 | | | | | $ | 2.13 | | | | $ | 2,721,100 | |
| Summary of Weighted Average Assumptions Used in Black-Scholes Option Pricing |
The weighted average assumptions used in the Black-Scholes option pricing model for options granted in 2013 and 2012 are as follows: | | | 2013 | | 2012 | | | Stock option awards: | | | | | | | Expected life | | 5.63 years | | 6.25 years | | | Risk-free interest rate | | 1.34% | | 0.70% | | | Expected volatility | | 26.5%-36.1% | | 35.9%-36.0% | |
| Schedule of Restricted Stock Activity |
Restricted stock activity for the years ended December 31, 2013 and 2012 was as follows: | | | Number of
Restricted
Stock | | Weighted
Average
Grant Date
Fair Value | | | Unvested, December 31, 2011 | | 483,317 | | $ | 1.44 | | | Granted | | — | | | — | | | Vested | | — | | | — | | | Forfeited | | (84,247) | | | 1.36 | | | Unvested, December 31, 2012 | | 399,070 | | $ | 1.44 | | | | | | | | | | | Granted | | — | | | — | | | Vested | | — | | | — | | | Forfeited | | (37,500) | | | 2.60 | | | Unvested, December 31, 2013 | | 361,570 | | $ | 1.31 | |
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Ilois
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Schedule of Stock Option Activity |
Stock option activity relating to Ilios for the year ended December 31, 2013 and 2012 was as follows: | Common Stock Options | | Number of
Options | | | Exercise
Price
Per Share | | Weighted
Average
Exercise
Price | | Weighted
Average
Remaining
Life | | Aggregate
Intrinsic
Value | | | Outstanding, December 31, 2011 | | 525,000 | | | $0.10-$0.50 | | $ | 0.27 | | 8.23 years | | $ | 120,000 | | | Granted | | 50,000 | | | 0.50 | | | 0.50 | | | | | | | | Exercised | | — | | | — | | | — | | | | | | | | Canceled and forfeited | | — | | | — | | | — | | | | | | | | Expired | | — | | | — | | | — | | | | | | | | Outstanding, December 31, 2012 | | 575,000 | | | $0.10-$0.50 | | $ | 0.29 | | 7.44 years | | $ | 120,000 | | | Exercisable, December 31, 2012 | | — | | | | | $ | — | | | | $ | — | | | Vested and expected to vest, December 31, 2012 | | 575,000 | | | | | $ | 0.29 | | | | $ | 120,000 | | | | | | | | | | | | | | | | | | | Outstanding, December 31, 2012 | | 575,000 | | | $0.10-$0.50 | | $ | 0.29 | | 7.44 years | | $ | 120,000 | | | Granted | | — | | | — | | | — | | | | | | | | Exercised | | — | | | — | | | — | | | | | | | | Canceled and forfeited | | — | | | — | | | — | | | | | | | | Expired | | — | | | — | | | — | | | | | | | | Outstanding, December 31, 2013 | | 575,000 | | | $0.10-$0.50 | | $ | 0.29 | | 6.44 years | | $ | 120,000 | | | Exercisable, December 31, 2013 | | — | | | | | $ | 0.50 | | | | $ | — | | | Vested and expected to vest, December 31, 2013 | | 575,000 | | | | | $ | 0.29 | | | | $ | 120,000 | |
| Summary of Weighted Average Assumptions Used in Black-Scholes Option Pricing |
For the Ilios awards, the weighted average assumptions used in the Black-Scholes option pricing model for options granted in 2012 are as follows: | | | 2012 | | | Stock option awards: | | | | | Expected life | | 6.25 years | | | Risk-free interest rate | | 2.03 | % | | Expected volatility | | 36.1 | % | |
| Schedule of Restricted Stock Activity |
Restricted stock activity for the Ilios awards, for the years ended December 31, 2013 and 2012 was as follows: | | | Number of
Restricted
Stock | | Weighted
Average
Grant Date
Fair Value | | | Unvested, December 31, 2011 | | 560,000 | | $ | 0.24 | | | Granted | | — | | | — | | | Vested | | — | | | — | | | Forfeited | | (50,000) | | | 0.10 | | | Unvested, December 31, 2012 | | 510,000 | | $ | 0.24 | | | | | | | | | | | Granted | | — | | | — | | | Vested | | — | | | — | | | Forfeited | | (200,000) | | | 0.50 | | | Unvested, December 31, 2013 | | 310,000 | | $ | 0.10
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