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           Summary of Significant Accounting Policies - Project Assets (Details) (USD $) 
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        3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
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           Sep. 30, 2012 
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           Sep. 30, 2011 
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           Sep. 30, 2012 
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           Sep. 30, 2011 
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           Dec. 31, 2011 
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| Accounting Policies [Abstract] | |||||
| Interest costs capitalized | $ 252,879 | $ 0 | $ 687,305 | $ 0 | |
| Minimum qualifying operating period for prorated repayments of grants | 5 years | ||||
| Amounts received from grants | 395,007 | 2,946,773 | 6,695,711 | ||
| Deferred grant income | 6,694,046 | 6,694,046 | 6,024,099 | ||
| Rebates received from utility company for cost and efficiency of installed units | $ 1,287,000 | $ 0 | |||
| X | ||||||||||
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- Definition 
          Government Grant, Qualification Requirement, Prorated Repayment Effective Period from Date Placed in Service No definition available. 
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| X | ||||||||||
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- Definition 
          Proceeds from Government Grants No definition available. 
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| X | ||||||||||
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- Definition 
          Rebates from Utility Company No definition available. 
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| X | ||||||||||
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- Details 
          
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| X | ||||||||||
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- Definition 
          Amount of interest capitalized during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Carrying amount as of the balance sheet date of unearned revenue or income not otherwise specified in the taxonomy which is expected to be taken into income after one year or beyond the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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