Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation (Details)

v3.20.2
Basis of Presentation (Details)
3 Months Ended 9 Months Ended
Oct. 04, 2019
USD ($)
Jul. 12, 2019
USD ($)
Jul. 01, 2019
USD ($)
Feb. 13, 2019
USD ($)
Sep. 26, 2020
USD ($)
Sep. 28, 2019
USD ($)
Mar. 30, 2019
USD ($)
Sep. 26, 2020
USD ($)
reporting_unit
Sep. 28, 2019
USD ($)
Dec. 31, 2019
USD ($)
Business Acquisition [Line Items]                    
Acquisition of Business, Net of Cash Acquired               $ 0 $ 21,785,000  
Proceeds on Sale of Assets               1,600,000 0  
Allowance for doubtful accounts         $ 3,900,000     3,900,000   $ 3,600,000
Bad debt expense               1,700,000    
Writeoff charges against allowance         1,100,000     1,200,000    
Research and development, design and related engineering         16,400,000 $ 25,600,000   $ 65,000,000.0 80,000,000.0  
Number of reporting units impaired | reporting_unit               4    
Impairment loss               $ 86,312,000    
Right-of-use asset impairment         0 0   691,000 0  
Equity Investment Other Than Temporary Impairment         $ 3,500,000     3,493,000 $ 0  
Freedom Communication Technologies, Inc.                    
Business Acquisition [Line Items]                    
Acquisition of Business, Net of Cash Acquired     $ 21,800,000              
Cash acquired     $ 600,000              
Diagnosys                    
Business Acquisition [Line Items]                    
Cash paid to acquire stock $ 7,000,000.0                  
Fair value of contingent purchase consideration 2,500,000                  
Potential additional earn-out $ 13,000,000.0                  
Achievement period 3 years                  
Earn-out achievement benchmark $ 72,000,000.0                  
Aerospace Segment                    
Business Acquisition [Line Items]                    
Impairment loss               $ 86,300,000    
Divestiture by Sale | Test Systems Segment                    
Business Acquisition [Line Items]                    
Total cash proceeds of divesture       $ 103,800,000            
Gain on sale, net of tax             $ 80,100,000      
Income taxes from divesture             $ 19,700,000      
Disposed by Sale | Airfield Lighting Product Line Assets                    
Business Acquisition [Line Items]                    
Proceeds on Sale of Assets   $ 1,000,000.0                
Percentage of revenue (as a percentage)   1.00%                
Loss on sale           $ 1,300,000