Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation (Details)

v3.19.2
Basis of Presentation (Details)
$ in Thousands
3 Months Ended 6 Months Ended
Feb. 13, 2019
USD ($)
Oct. 12, 2018
Jun. 29, 2019
USD ($)
Mar. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Jun. 29, 2019
USD ($)
Jun. 30, 2018
USD ($)
Jan. 01, 2019
USD ($)
Dec. 31, 2018
USD ($)
Business Acquisition [Line Items]                    
Research and development, design and related engineering     $ 27,700   $ 28,900   $ 54,400 $ 57,800    
Adoption of ASU 2018-02           $ 1,400        
Right-of-use assets     22,100       22,100      
Lease liability     22,340       22,340      
Property, plant and equipment, net     $ 117,389       $ 117,389     $ 120,862
Accounting Standards Update 2016-02                    
Business Acquisition [Line Items]                    
Right-of-use assets                 $ 18,400  
Lease liability                 18,500  
Accounting Standards Update 2016-02 | Reclassification                    
Business Acquisition [Line Items]                    
Property, plant and equipment, net                 $ (3,500)  
Convertible Class B Stock                    
Business Acquisition [Line Items]                    
Stock split ratio, common stock   0.15                
Divestiture by Sale | Test Systems Segment                    
Business Acquisition [Line Items]                    
Total cash proceeds of divesture $ 103,800                  
Gain on sale, net of tax       $ 80,100            
Income taxes from divesture       $ 21,300