Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Details)

v3.19.1
Stock-Based Compensation (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended
Dec. 31, 2018
May 17, 2018
Mar. 28, 2019
Dec. 27, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares issued under employee stock plan (in shares) 60,871      
Shares issued under employee stock plan $ 1,400   $ 1,419  
Stock purchase plan, expense     $ 143  
Class A Common Stock        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Common stock, par value     $ 0.001 $ 0.001
Employee Stock Purchase Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair market value measurement period   6 months    
Employee Stock Purchase Plan [Member] | Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Purchase price, as a percentage of fair market value   85.00%    
Employee Stock Purchase Plan [Member] | Class A Common Stock        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares of stock authorized under the plan     1,500,000  
Common stock, par value     $ 0.001