v3.8.0.1
Capital transactions (Additional Information) (Details) - USD ($)
 1 Months Ended 12 Months Ended
Nov. 13, 2017
Aug. 05, 2017
Apr. 05, 2017
Jan. 05, 2017
Dec. 08, 2016
Aug. 11, 2016
Mar. 15, 2016
Nov. 15, 2017
Apr. 17, 2017
Mar. 20, 2017
May 31, 2016
Mar. 29, 2016
Feb. 29, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Sep. 19, 2016
Jul. 31, 2016
Class of Stock [Line Items]                                    
Preferred stock, shares authorized                           1,000,000 1,000,000      
Shares issued for secondary offering, shares 2,314,500             434,783 434,783 117,361                
Ordinary shares issued to employees, directors and consultants       190,000                            
Proceeds from issuance of ordinary shares           $ 6,650,000         $ 350,000     $ 3,091,000 $ 7,001,000    
Share Price $ 1.20   $ 2.75             $ 2.85       $ 1.06        
Fair value of shares issued $ 0.80                               $ 3.30  
Stock Issued During Period, Value, New Issues $ 1,852,000                 $ 239,000                
Common stock, par value $ 0.004                         $ 0.004 $ 0.004      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value       $ 3.90                            
Securities Purchase Agreement [Member]                                    
Class of Stock [Line Items]                                    
Share Price   $ 2.70                                
Fair value of shares issued   $ 2.30               $ 2.04                
Stock Issued During Period, Value, New Issues   $ 1,000,000                                
Warrant Purchase on Issue of Ordinary Shares   326,087 326,087                              
Class of Warrant or Right, Exercise Price of Warrants or Rights   $ 2.75 $ 2.75                              
Securities Purchase Agreement, Warrants Issued percentage   75.00% 75.00%                              
Investor [Member]                                    
Class of Stock [Line Items]                                    
Number of ordinary shares agreed to be sold through share purchase agreement                                   1,900,000
Value of ordinary shares agreed to be sold through share purchase agreement                                 $ 1,900,000 $ 7,000,000
Ordinary Shares [Member]                                    
Class of Stock [Line Items]                                    
Ordinary shares issued to employees, directors and consultants         320,000   48,000         31,250 60,000          
Share Price         $ 3.43   $ 3.35         $ 3.38 $ 3.37