Business Segment Information - Financial Information by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Segment Reporting Information [Line Items]
Revenue	$ 163,227	$ 150,371	$ 480,570	$ 471,155
Operating Income	13,363	10,265	37,065	33,916
Depreciation and Amortization Expenses	7,204	7,078	21,112	21,741
Capital Expenditures	3,562	2,382	10,019	7,918
Operating Segments
Segment Reporting Information [Line Items]
Operating Income	19,776	16,636	57,362	53,800
Segment Reconciling Items
Segment Reporting Information [Line Items]
Corporate General and Administrative Expenses	(6,413)	(6,371)	(20,297)	(19,884)
Corporate Administration
Segment Reporting Information [Line Items]
Depreciation and Amortization Expenses	58	58	176	194
Capital Expenditures	0	0	0	0
Electronic Systems
Segment Reporting Information [Line Items]
Revenue	104,721	103,470	306,622	293,540
Electronic Systems | Operating Segments
Segment Reporting Information [Line Items]
Operating Income	15,319	14,867	42,185	40,427
Depreciation and Amortization Expenses	3,547	3,492	10,396	10,591
Capital Expenditures	1,964	586	3,865	3,518
Structural Systems
Segment Reporting Information [Line Items]
Revenue	58,506	46,901	173,948	177,615
Structural Systems | Operating Segments
Segment Reporting Information [Line Items]
Operating Income	4,457	1,769	15,177	13,373
Depreciation and Amortization Expenses	3,599	3,528	10,540	10,956
Capital Expenditures	$ 1,598	$ 1,796	$ 6,154	$ 4,400