Business Segment Information - Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020
Segment Reporting Information [Line Items]
Revenue	$ 160,192	$ 147,309	$ 317,343	$ 320,784
Operating Income	13,092	10,025	23,702	23,651
Depreciation and Amortization Expenses	6,986	7,327	13,908	14,663
Capital Expenditures	3,844	2,584	6,457	5,536
Operating Segments
Segment Reporting Information [Line Items]
Operating Income	19,967	16,652	37,586	37,164
Segment Reconciling Items
Segment Reporting Information [Line Items]
Corporate General and Administrative Expenses	(6,875)	(6,627)	(13,884)	(13,513)
Corporate Administration
Segment Reporting Information [Line Items]
Depreciation and Amortization Expenses	59	64	118	136
Capital Expenditures	0	0	0	0
Electronic Systems
Segment Reporting Information [Line Items]
Revenue	102,797	91,950	201,901	190,070
Electronic Systems | Operating Segments
Segment Reporting Information [Line Items]
Operating Income	14,375	10,438	26,866	25,560
Depreciation and Amortization Expenses	3,426	3,524	6,849	7,099
Capital Expenditures	1,277	2,117	1,901	2,932
Structural Systems
Segment Reporting Information [Line Items]
Revenue	57,395	55,359	115,442	130,714
Structural Systems | Operating Segments
Segment Reporting Information [Line Items]
Operating Income	5,592	6,214	10,720	11,604
Depreciation and Amortization Expenses	3,501	3,739	6,941	7,428
Capital Expenditures	$ 2,567	$ 467	$ 4,556	$ 2,604