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Demand notes payable, convertible debentures and credit agreement - related party (Details) (USD $)
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0 Months Ended | 1 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 0 Months Ended | 6 Months Ended | 12 Months Ended | 0 Months Ended | 3 Months Ended | 12 Months Ended | 0 Months Ended | 0 Months Ended | 0 Months Ended | ||||||||||||||||||||||||||
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Jun. 30, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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Dec. 31, 2010
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May 11, 2009
Ilios
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May 11, 2009
Director and Chief Executive Officer
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May 11, 2009
Director and Chief Executive Officer
Ilios
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Mar. 25, 2013
Chief Executive Officer (John N. Hatsopoulos)
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Dec. 31, 2012
Chief Executive Officer (John N. Hatsopoulos)
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Jun. 30, 2013
Chief Executive Officer (John N. Hatsopoulos)
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Dec. 31, 2011
Chief Executive Officer (John N. Hatsopoulos)
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Sep. 24, 2001
Chief Executive Officer (John N. Hatsopoulos)
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Jun. 30, 2013
Demand notes
Minimum
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Dec. 31, 2012
Demand notes
Minimum
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Jun. 30, 2013
Demand notes
Maximum
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Dec. 31, 2011
Demand notes
Maximum
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May 11, 2009
Demand notes
Director and Chief Executive Officer
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Nov. 30, 2012
Demand notes
Chief Executive Officer (John N. Hatsopoulos)
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Sep. 07, 2011
Demand notes
Chief Executive Officer (John N. Hatsopoulos)
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Sep. 10, 2008
Demand notes
Chief Executive Officer (John N. Hatsopoulos)
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Sep. 30, 2012
Convertible debentures
Common stock
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Jun. 30, 2013
Convertible debentures
Common stock
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Dec. 31, 2012
Convertible debentures
Common stock
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Dec. 31, 2011
Convertible debentures
Common stock
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Dec. 31, 2010
Convertible debentures
Common stock
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Sep. 30, 2012
Convertible debentures
Conversion of principal amount
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Sep. 30, 2012
Convertible debentures
Conversion of accrued interest
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May 11, 2009
Convertible debentures
Director and Chief Executive Officer
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Jun. 30, 2013
Convertible debentures
Director and Chief Executive Officer
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Dec. 31, 2012
Convertible debentures
Director and Chief Executive Officer
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Sep. 24, 2011
Convertible debentures
Director and Chief Executive Officer
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Sep. 24, 2001
Convertible debentures
Director and Chief Executive Officer
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Sep. 24, 2011
Convertible debentures
Director and Chief Executive Officer
Common stock
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Sep. 24, 2011
Convertible debentures
Director and Chief Executive Officer
Conversion of accrued interest
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Sep. 24, 2001
Convertible debentures
Member of board of directors
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May 11, 2009
Convertible debentures
Member of board of directors
Common stock
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May 11, 2009
Convertible debentures
Member of board of directors
Conversion of principal amount
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Sep. 24, 2011
Convertible debentures
Member of board of directors
Conversion of accrued interest
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May 11, 2009
Convertible debentures
Member of board of directors
Conversion of accrued interest
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Sep. 24, 2011
Convertible debentures
Chief Executive Officer (John N. Hatsopoulos)
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May 11, 2009
Convertible debentures
Chief Executive Officer (John N. Hatsopoulos)
Common stock
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May 11, 2009
Convertible debentures
Chief Executive Officer (John N. Hatsopoulos)
Conversion of accrued interest
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| Debt Instrument [Line Items] | ||||||||||||||||||||||||||||||||||||||||||
| Demand notes payable, related party, current | $ 1,337,500 | $ 1,337,500 | $ 1,037,500 | $ 1,300,000 | $ 1,300,000 | $ 1,000,000 | $ 50,000 | |||||||||||||||||||||||||||||||||||
| Principal amount | 300,000 | 750,000 | 250,000 | 330,000 | 200,000 | 100,000 | ||||||||||||||||||||||||||||||||||||
| Related party debt, stated interest rate | 1.50% | 5.00% | 5.00% | 6.00% | 6.00% | 6.00% | 6.00% | 5.00% | 6.00% | 6.00% | ||||||||||||||||||||||||||||||||
| Debentures accrued interest, first payment from issuance date | 6 years | |||||||||||||||||||||||||||||||||||||||||
| Conversion price in usd per share | $ 1.20 | $ 1.20 | $ 2.00 | $ 2.00 | $ 0.50 | |||||||||||||||||||||||||||||||||||||
| Number of shares of subsidiary common stock sold by the Company | 1,400,000 | 1,400,000 | ||||||||||||||||||||||||||||||||||||||||
| Subsidiary common stock sold by the Company, price in usd per share | $ 0.50 | $ 0.50 | ||||||||||||||||||||||||||||||||||||||||
| Extinguishment of debt, principal amount | 427,432 | 109,033 | ||||||||||||||||||||||||||||||||||||||||
| Extinguishment of debt, accrued interest | 163,535 | |||||||||||||||||||||||||||||||||||||||||
| Debt conversion, amount converted | 100,000 | 6,100 | 72,960 | 109,033 | 72,960 | 90,967 | 72,568 | |||||||||||||||||||||||||||||||||||
| Debt conversion, number of shares issued | 1,000,000 | 6,474 | 85,240 | 500,000 | 1,000,000 | |||||||||||||||||||||||||||||||||||||
| Common stock issuable upon conversion | 75,806 | 75,806 | 159,140 | 159,140 | ||||||||||||||||||||||||||||||||||||||
| Convertible debentures, related party, current | 90,967 | 90,967 | 0 | 190,967 | ||||||||||||||||||||||||||||||||||||||
| Line of Credit Facility, Maximum Borrowing Capacity | $ 1,000,000 | $ 1,500,000 | ||||||||||||||||||||||||||||||||||||||||