Annual report pursuant to Section 13 and 15(d)

Nature of business and operations (Details)

v3.8.0.1
Nature of business and operations (Details)
12 Months Ended
May 18, 2017
USD ($)
$ / shares
shares
Dec. 31, 2017
USD ($)
segment
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
Class of Stock [Line Items]      
Number of operating segments | segment   2  
Common stock, par value (usd per share) | $ / shares $ 0.001 $ 0.001 $ 0.001
Shares issued in acquisition (shares) | shares 4,662,937    
Shares issued in acquisition, price per share (in USD per share) | $ / shares $ 4.02    
Issuance of stock to acquire American DG Energy, net | $   $ 18,482,656 $ 0
American DG Energy      
Class of Stock [Line Items]      
Outstanding common shares acquired (percent) 100.00%    
Common stock, par value (usd per share) | $ / shares $ 0.001    
Issuance of stock to acquire American DG Energy, net | $ $ 18,745,007    
Common stock      
Class of Stock [Line Items]      
Conversion exchange ratio 0.092    
Issuance of stock to acquire American DG Energy, net | $   $ 4,663