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Stockholders' equity - Weighted Average Assumptions (Details) (USD $)
|
3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 12 Months Ended | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Mar. 31, 2014
|
Mar. 31, 2013
|
Mar. 31, 2014
Tecogen
|
Dec. 31, 2013
Tecogen
|
Dec. 31, 2012
Tecogen
|
Dec. 31, 2013
Tecogen
Stock options
|
Dec. 31, 2012
Tecogen
Stock options
|
Mar. 31, 2014
Tecogen
Restricted stock
|
Dec. 31, 2013
Tecogen
Restricted stock
|
Dec. 31, 2012
Tecogen
Restricted stock
|
Dec. 31, 2011
Tecogen
Restricted stock
|
Mar. 31, 2014
Ilois
|
Dec. 31, 2013
Ilois
|
Dec. 31, 2012
Ilois
|
Dec. 31, 2012
Ilois
Stock options
|
Dec. 31, 2013
Ilois
Restricted stock
|
Dec. 31, 2012
Ilois
Restricted stock
|
Dec. 31, 2013
Minimum
Tecogen
Restricted stock
|
Dec. 31, 2013
Minimum
Ilois
Restricted stock
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||||||||||||||||||
| Granted, Exercise Price (usd per share) | $ 4.50 | $ 3.20 | $ 0.00 | $ 0.00 | $ 0.50 | ||||||||||||||
| Award vesting period | 4 years | 4 years | 4 years | 90 days | 90 days | ||||||||||||||
| Fair value of options issued | $ 80,952 | $ 20,223 | $ 9,750 | ||||||||||||||||
| Weighted-average grant date fair value of options granted | $ 0.20 | ||||||||||||||||||
| Vesting percentage | 100.00% | 100.00% | |||||||||||||||||
| Expected life | 5 years 7 months 18 days | 6 years 3 months | 6 years 3 months | ||||||||||||||||
| Risk-free interest rate | 1.34% | 0.70% | 2.03% | ||||||||||||||||
| Expected volatility | 36.10% | ||||||||||||||||||
| Allocated Share-based Compensation Expense | 32,491 | 57,638 | 136,184 | (41,311) | 59,361 | ||||||||||||||
| Options granted | 43,325 | 76,500 | 17,500 | 0 | 0 | 50,000 | |||||||||||||
| Award expiration period | 10 years | 10 years | 10 years | ||||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number | 361,570 | 361,570 | 399,070 | 483,317 | 310,000 | 510,000 | |||||||||||||
| Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition | 0 years 6 months 22 days | 2 years 2 months 23 days | 1 year 7 months 1 day | ||||||||||||||||
| Compensation cost related to unvested restricted stock awards and stock option awards not yet recognized | $ 189,486 | $ 124,845 | $ 183,230 | $ 9,004 | $ 67,493 | ||||||||||||||