Current report filing

Note 8 - Stock-based Compensation (Details Textual)

v3.19.1
Note 8 - Stock-based Compensation (Details Textual) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 28, 2017
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Subscription Rate   17.50%      
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares   5,300,000      
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period   4 years      
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period   10 years      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options   $ 2,360      
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition   1 year 306 days      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance   4,403,000     2,344,000
Employee Stock Option Vesting Schedule II [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance   91,000 85,000    
Employee Stock Option Vesting Schedule III [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance   850,000      
Employee Stock Option Vesting Schedule I [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance     480,000    
Restricted Stock Units (RSUs) [Member]          
Stock Redemption, Shares Per Share     1    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 150,000 150,000    
Share-based Compensation Award, Tranche One [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   50.00%      
Share-based Compensation Award, Tranche One [Member] | Employee Stock Option Vesting Schedule II [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   50.00% 50.00%    
Share-based Compensation Award, Tranche One [Member] | Employee Stock Option Vesting Schedule I [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage     50.00%    
Share-based Compensation Award, Tranche Four [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   16.67%      
Share-based Compensation Award, Tranche Four [Member] | Employee Stock Option Vesting Schedule I [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage     16.67%    
Share-based Compensation Award, Tranche Two [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   16.67%      
Share-based Compensation Award, Tranche Two [Member] | Employee Stock Option Vesting Schedule II [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   25.00% 25.00%    
Share-based Compensation Award, Tranche Two [Member] | Employee Stock Option Vesting Schedule I [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage     16.67%    
Share-based Compensation Award, Tranche Three [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage   16.67%      
Share-based Compensation Award, Tranche Three [Member] | Employee Stock Option Vesting Schedule II [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage       25.00% 25.00%
Share-based Compensation Award, Tranche Three [Member] | Employee Stock Option Vesting Schedule I [Member]          
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage     16.67%