Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity and Share-Based Compensation - Share-Based Compensation Plan Information (Details)

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Stockholders' Equity and Share-Based Compensation - Share-Based Compensation Plan Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
May 31, 2016
Dec. 30, 2017
Dec. 31, 2016
Jan. 02, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Weighted average fair value of options granted (in dollars per share)   $ 1.85 $ 1.65 $ 1.19
Intrinsic value, options exercised   $ 1,911 $ 599 $ 346
Unrecognized share-based compensation expense   $ 3,276    
Weighted-average period of unrecognized compensation expense   2 years 7 months 20 days    
2016 Equity Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Maximum number of shares authorized to issued under condition one (in shares) 2,500,000      
Shares available for future grants (in shares) 3,894,000 7,065,000    
Share reserve increase period (in shares) 9 years      
Share reserve (in shares) 1,500,000      
Expiration period 10 years      
Option grant vesting period 4 years      
Exercise price of option grants 100.00%      
AutoMd 2014 Equity Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Weighted average fair value of options granted (in dollars per share)   $ 0.55 $ 0.55 $ 0.55
Employee Stock Option        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares withheld to satisfy employees' tax obligation (in shares)   260,000    
Employees' tax obligation   $ 900    
Employee Stock Option | AutoMd 2014 Equity Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares available for future grants (in shares)   0