Business Segment Information - Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Segment Reporting Information [Line Items]
Net Revenues	$ 181,101	$ 159,842	$ 534,162	$ 465,124
Operating Income	14,603	6,787	41,055	17,639
Depreciation and Amortization Expenses	6,992	6,320	20,751	18,635
Capital Expenditures	4,515	4,999	14,928	12,031
Electronic Systems
Segment Reporting Information [Line Items]
Net Revenues	90,588	85,696	264,045	252,606
Structural Systems
Segment Reporting Information [Line Items]
Net Revenues	90,513	74,146	270,117	212,518
Operating Segments
Segment Reporting Information [Line Items]
Operating Income	22,534	13,013	63,949	36,843
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Net Revenues	90,588	85,696	264,045	252,606
Operating Income	9,657	9,050	28,750	23,463
Depreciation and Amortization Expenses	3,569	3,707	10,602	11,022
Capital Expenditures	1,768	879	4,820	5,091
Operating Segments | Structural Systems
Segment Reporting Information [Line Items]
Net Revenues	90,513	74,146	270,117	212,518
Operating Income	12,877	3,963	35,199	13,380
Depreciation and Amortization Expenses	3,350	2,576	9,750	7,510
Capital Expenditures	2,747	3,935	10,108	6,565
Segment Reconciling Items
Segment Reporting Information [Line Items]
Corporate General and Administrative Expenses	(7,931)	(6,226)	(22,894)	(19,204)
Corporate Administration
Segment Reporting Information [Line Items]
Depreciation and Amortization Expenses	73	37	399	103
Capital Expenditures	$ 0	$ 185	$ 0	$ 375