Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Details Textual)

v3.19.3.a.u2
Summary of Significant Accounting Policies (Details Textual) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 28, 2019
Dec. 28, 2019
Dec. 29, 2018
Dec. 30, 2017
Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]          
Right-of-use assets $ 12,310 $ 12,310      
Lease liabilities 12,467 12,467      
Long-lived asset impairment   0      
Contract asset, current 2,796 2,796 $ 2,851    
Contract Liabilities, current 353 353 138    
Research and development costs charged to expense   15,163 $ 14,122 $ 10,624  
Restructuring charges $ 1,724 $ 1,724   $ 1,031  
Minimum [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Finite-lived intangible assets, estimated useful life   5 years      
Minimum [Member] | Custom Products [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Contract period for sale of product   3 months      
Minimum [Member] | Various Services [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Service contracts period   3 months      
Maximum [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Finite-lived intangible assets, estimated useful life   26 years      
Maximum [Member] | Custom Products [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Contract period for sale of product   1 year      
Maximum [Member] | Various Services [Member]          
Summary Of Significant Accounting Policies [Line Items]          
Percentage of revenue   5.00%      
Service contracts period   1 year      
ASU 2016-02          
Summary Of Significant Accounting Policies [Line Items]          
Right-of-use assets         $ 13,900
Lease liabilities         13,900
Cumulative-effect adjustment recognized in retained earnings         $ 134