Quarterly report pursuant to Section 13 or 15(d)

Shareholders' Equity and Capital Stock - addl information (Details)

v3.8.0.1
Shareholders' Equity and Capital Stock - addl information (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
shares
Mar. 30, 2018
shares
Mar. 31, 2017
USD ($)
shares
Mar. 31, 2016
shares
Mar. 31, 2018
$ / shares
Mar. 31, 2018
USD ($)
$ / shares
shares
Dec. 31, 2017
shares
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Outstanding, Intrinsic Value | $           $ 99  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period 67,719            
Stock Issued During Period, Shares, New Issues 1,536,169            
Share Price | (per share)         $ 0.77 $ 0.76  
Payments Of Stock Issuance Costs | $     $ 43        
Number of RSUs Vested 80,514            
Percent or RSUs that vest 80,514            
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Outstanding, Number           9,471,947 9,459,401
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number           6,302,049  
Stock based compensation | $ $ 330   287        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value | $ 200            
Proceeds from Stock Options Exercised | $ $ 42   $ 349        
Granted, Options 200,000            
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares           $ 0.94  
Capital Stock              
Stockholder's Equity Note [Line Items]              
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period 67,719,000            
In Money Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Outstanding, Number           2,874,875  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number           2,059,127  
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Stock Options | $           $ 900  
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition 2 years 3 months 18 days            
Restricted Stock Units (RSUs) [Member]              
Stockholder's Equity Note [Line Items]              
Number of RSUs Vested   62,000          
Percent or RSUs that vest   62,000          
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options | $           $ 600  
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition 1 year 4 months 24 days            
Granted, Options     0 0      
Restricted Stock Units (RSUs) [Member] | Capital Stock              
Stockholder's Equity Note [Line Items]              
Number of securities called by each unit           1  
Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Granted, Options     0 0      
Grant Date [Member] | Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 10.00%            
Four and One Half Months After Grant [Member] | Restricted Stock Units (RSUs) [Member]              
Stockholder's Equity Note [Line Items]              
Stock Option Vesting Period 4 months 15 days            
Four and One Half Months After Grant [Member] | Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 22.00%            
Nine Months After Grant [Member] | Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 22.00%            
Thirteen and One Half Months After Grant [Member] | Restricted Stock Units (RSUs) [Member]              
Stockholder's Equity Note [Line Items]              
Stock Option Vesting Period 13 months 15 days            
Thirteen and One Half Months After Grant [Member] | Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 22.00%            
Eighteen Months After Date Of Grant [Member] | Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 24.00%            
First Anniversary [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 33.30%            
First Anniversary [Member] | Employee Stock Option [Member]              
Stockholder's Equity Note [Line Items]              
Stock Option Vesting Period 3 years            
Second Anniversary [Member]              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 33.30%            
Third Anniversary (Member)              
Stockholder's Equity Note [Line Items]              
Share-Based Compensation Arrangement By Share-Based Payment Award, Award Vesting Percentage 33.40%