Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Employee Stock Purchase Plan (Details)

v3.20.4
Stockholders' Equity - Employee Stock Purchase Plan (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
May 17, 2018
Dec. 31, 2020
Dec. 26, 2019
Dec. 27, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares issued under employee stock plan (in shares)   56,389 104,363  
Common Class A        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Common stock, par value (in dollars per share)   $ 0.001 $ 0.001  
Employee stock purchase plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fair market value measurement period (in months) 6 months      
Stock purchase plan, expense   $ 700 $ 500 $ 300
Employee stock purchase plan | Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Purchase price, as a percentage of fair market value 90.00%      
Employee stock purchase plan | Common Class A        
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 (in dollars per share) $ 0.001