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Stock-Based Compensation - 2016 Employee Stock Purchase Plan (Details) - USD ($)
$ in Millions
12 Months Ended
Jan. 01, 2019
Jan. 01, 2018
Dec. 31, 2019
Jun. 21, 2016
Stock Based Compensation        
Increase in shares available for grant (in shares) 1,000,802 939,698    
Unrecognized compensation cost, other than options     $ 4.4  
Weighted-average period (in years)     4 months 24 days  
Class A common stock committed under 2016 ESPP        
Stock Based Compensation        
Maximum automatic annual increase (in shares)     1,800,000  
Maximum automatic annual increase as a percentage of outstanding common shares     1.00%  
Common Class A | Class A common stock committed under 2016 ESPP        
Stock Based Compensation        
Shares reserved for issuance (in shares)       2,400,000
Discount from market price, offering date (as a percent)     15.00%  
Discount from market price, purchase date (as a percent)     15.00%  
Purchase price, percentage of fair market value (as a percent)     85.00%