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Stockholders' Equity - Employee Stock Purchase Plan (Details) - USD ($)
$ in Thousands
3 Months Ended
Jan. 01, 2021
Jan. 01, 2020
Mar. 31, 2021
Mar. 31, 2020
Apr. 27, 2017
Stockholders' Equity          
Stock-based compensation expense     $ 2,457 $ 2,728  
Employee Stock Purchase Plan          
Stockholders' Equity          
Purchase price of common stock under plan (as a percent)     85.00%    
Offering period (in months)     6 months    
Shares reserved     1,782,422   1,600,000
Incremental share increase (in shares)     500,000    
Incremental share increase (as a percent)     1.00%    
Increase in number of shares reserved and available for issuance 194,518 190,539      
Stock-based compensation expense     $ 300 $ 200