Annual report pursuant to Section 13 and 15(d)

Stock-based Compensation (Details Textual)

v3.8.0.1
Stock-based Compensation (Details Textual) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
1 Months Ended 12 Months Ended
Oct. 30, 2017
Aug. 31, 2017
Jun. 30, 2017
Jun. 20, 2017
Jun. 10, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant           4,838 948    
Proceeds from Stock Options Exercised           $ 46 $ 110 $ 225  
Defined Contribution Plan, Employer Matching Contribution, Percent of Match   100.00%              
Restricted Cash and Cash Equivalent Item, Agreement           Of the 760 RSUs granted and 132 RSUs vested during the year ended December 31, 2017, 120 were granted and 115 vested to employees terminated in connection with the restructuring in May 2017.      
Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options           $ 599      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition           2 years 29 days      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value           $ 1,239      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross           760      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value           $ 1.63      
Employee Stock Option [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options           $ 3,301      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition           2 years 3 months 18 days      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value           $ 86 103 1,089  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value           2,192 $ 2,456 $ 1,138  
Proceeds from Stock Options Exercised           $ 46      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value           $ 1.26 $ 3.52 $ 5.74  
Equity Incentive Plan 2014 [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized 4,400     4,714 3,714        
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized 2,955                
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant           4,838      
Share based Compensation Arrangement By Share Based Payment Award Shares Withheld To Cover Exercise Amount 25,205                
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross 356     1,000 1,656        
Common Stock, Capital Shares Reserved for Future Issuance                 2,058
Equity Incentive Plan 2014 [Member] | Minimum [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized 4,714                
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent           100.00%      
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period           4 years      
Equity Incentive Plan 2014 [Member] | Maximum [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized 9,114                
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent           110.00%      
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period           10 years      
Employee Stock Purchase Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Common Stock, Capital Shares Reserved for Future Issuance     500            
Defined Contribution Plan, Employer Matching Contribution, Percent of Match     25.00%            
Defined Contribution Plan, Maximum Annual Contributions Percentage,Thereafter     85.00%