Income taxes - Narrative (Details) - USD ($) |
12 Months Ended | |
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Dec. 31, 2018 |
Dec. 31, 2017 |
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| Internal Revenue Service (IRS) | ||
| Operating Loss Carryforwards [Line Items] | ||
| Operating loss carryforwards | $ 29,793,000 | |
| Income Tax Provision | ||
| Operating Loss Carryforwards [Line Items] | ||
| Change in valuation allowance | (153,000) | $ 277,000 |
| American DG Energy | ||
| Operating Loss Carryforwards [Line Items] | ||
| Ownership interest (percent) | 100.00% | |
| Annual limitation of acquired NOL | $ 391,394 | |
| Period of limitation on acquired NOL | 20 years | |
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- Definition Acquisition, Annual NOL Limitation, Amount No definition available.
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- Definition Acquisition, Net Operating Loss, Limitation Period No definition available.
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- Definition Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in the valuation allowance for deferred tax assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions. No definition available.
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