Quarterly report pursuant to Section 13 or 15(d)

Related party transactions (Details)

v3.7.0.1
Related party transactions (Details)
 1 Months Ended 3 Months Ended
Aug. 02, 2016
USD ($)
$ / shares
shares
Jul. 31, 2016
USD ($)
$ / shares
shares
Mar. 31, 2017
USD ($)
company
May 19, 2016
Dec. 28, 2015
USD ($)
Schedule of Equity Method Investments [Line Items]          
Number of affiliated companies | company     3    
Equity interest in joint venture (percent)     43.00%    
Warrant exercise price (per share) | $ / shares   $ 4.00      
Proceeds from the exercise of warrants   $ 2,700,000      
Investments in joint venture     $ 13,500,000    
Ultra Emissions Technology Ltd.          
Schedule of Equity Method Investments [Line Items]          
Equity interest in joint venture (percent)         50.00%
Warrants exercised for investment in joint venture $ 2,000,000        
TTcogen, LLC          
Schedule of Equity Method Investments [Line Items]          
Equity interest in joint venture (percent)       50.00%  
Offshore Investors          
Schedule of Equity Method Investments [Line Items]          
Investment by other party to joint venture         $ 3,000,000
Tedom a.s.          
Schedule of Equity Method Investments [Line Items]          
Equity interest in joint venture (percent)       50.00%  
Warrant          
Schedule of Equity Method Investments [Line Items]          
Warrants exercised (shares) | shares   675,000      
Warrant | Ultra Emissions Technology Ltd.          
Schedule of Equity Method Investments [Line Items]          
Warrants exercised (shares) | shares 2,000,000        
Warrant exercise price (per share) | $ / shares $ 1.00        
Co-venturer          
Schedule of Equity Method Investments [Line Items]          
Investments in joint venture     $ 6,500,000