Stockholders' equity - Common Stock and Receivable from Shareholder (Details)  | 
1 Months Ended | ||||||
|---|---|---|---|---|---|---|---|
| 
 May 18, 2017  
shares 
 | 
Apr. 13, 2016  | 
 May 03, 2016  
shares 
 | 
 Dec. 31, 2017  
shares 
 | 
 Dec. 31, 2016  
shares 
 | 
Apr. 30, 2016  | 
 Feb. 13, 2013  
shares 
 | 
|
| Class of Stock [Line Items] | |||||||
| Conversion ratio of restricted Ilios shares to Company common shares | 7.86 | ||||||
| Shares issued in acquisition (shares) | 4,662,937 | ||||||
| Common stock, shares outstanding | 24,766,892 | 19,981,912 | |||||
| Preferred stock, shares authorized | 10,000,000 | ||||||
| Private Placement | Common stock | |||||||
| Class of Stock [Line Items] | |||||||
| Shares issued in exchange for Ilios shares (shares) | 670,464 | ||||||
| Percentage of voting interests acquired (percent) | 100.00% | ||||||
| American DG Energy | |||||||
| Class of Stock [Line Items] | |||||||
| Outstanding common shares acquired (percent) | 100.00% | 
| X | ||||||||||
- Definition Conversion Ratio of Restricted Shares to Common Shares No definition available. 
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- Definition Number of shares of equity interests issued or issuable to acquire entity. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Percentage of voting equity interests acquired at the acquisition date in the business combination. 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 Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Number of shares of stock issued during the period pursuant to acquisitions. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
- 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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- Details 
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- Details 
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