| Energy Assets - Financing Lease Assets (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019 | 
|---|---|---|
| Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] | ||
| Financing lease assets | $ 42,402 | $ 42,402 | 
| Less - accumulated depreciation and amortization | (7,865) | (6,268) | 
| Financing lease assets, net | $ 34,537 | $ 36,134 | 
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- Definition Finance Lease, Right-Of-Use Asset, Accumulated Depreciation No definition available. 
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- Definition Finance Lease, Right-Of-Use Asset, Gross No definition available. 
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- References No definition available. 
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- Definition Amount, after accumulated amortization, of right-of-use asset from finance lease. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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