v3.8.0.1
Summary of Accounting Policies - Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands
Dec. 30, 2017
Dec. 31, 2016
Assets:    
Total assets $ 35,092 $ 35,014
Level 1    
Assets:    
Total assets 35,092 35,014
Level 2    
Assets:    
Total assets 0 0
Level 3    
Assets:    
Total assets 0 0
Money market funds    
Assets:    
Assets, fair value disclosure 17,810 17,637
Money market funds | Level 1    
Assets:    
Assets, fair value disclosure 17,810 17,637
Money market funds | Level 2    
Assets:    
Assets, fair value disclosure 0 0
Money market funds | Level 3    
Assets:    
Assets, fair value disclosure 0 0
Certificates of Deposit    
Assets:    
Assets, fair value disclosure 17,282 17,377
Certificates of Deposit | Level 1    
Assets:    
Assets, fair value disclosure 17,282 17,377
Certificates of Deposit | Level 2    
Assets:    
Assets, fair value disclosure 0 0
Certificates of Deposit | Level 3    
Assets:    
Assets, fair value disclosure $ 0 $ 0