Annual report pursuant to Section 13 and 15(d)

Segments - Narrative (Details)

v3.10.0.1
Segments - Narrative (Details) - USD ($)
3 Months Ended 12 Months Ended
Dec. 31, 2018
Sep. 29, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2017
Sep. 30, 2017
Jul. 01, 2017
Apr. 01, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Segment Reporting Information                      
Impairment Loss $ 0 $ 0 $ 0 $ 0 $ 16,237,000 $ 0 $ 0 $ 0 $ 0 $ 16,237,000 $ 0
Goodwill 124,952,000       125,645,000       124,952,000 125,645,000 $ 115,207,000
Operating Segments | Aerospace                      
Segment Reporting Information                      
Impairment Loss                 0 16,200,000  
Purchased intangible impairment loss                 0    
Goodwill 125,000,000.0       125,600,000       125,000,000.0 125,600,000  
Operating Segments | Test Systems                      
Segment Reporting Information                      
Impairment Loss                 0    
Purchased intangible impairment loss                 0    
Goodwill $ 0       $ 0       $ 0 $ 0