Business Segment Information - Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Segment Reporting Information [Line Items]
Net Revenues	$ 147,309	$ 180,495	$ 320,784	$ 353,061
Operating Income	10,025	13,604	23,651	26,452
Depreciation and Amortization Expenses	7,327	7,004	14,663	13,759
Capital Expenditures	2,584	5,888	5,536	10,413
Electronic Systems
Segment Reporting Information [Line Items]
Net Revenues	91,950	89,260	190,070	173,457
Structural Systems
Segment Reporting Information [Line Items]
Net Revenues	55,359	91,235	130,714	179,604
Operating Segments
Segment Reporting Information [Line Items]
Operating Income	16,652	21,685	37,164	41,415
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Net Revenues	91,950	89,260	190,070	173,457
Operating Income	10,438	9,912	25,560	19,093
Depreciation and Amortization Expenses	3,524	3,531	7,099	7,033
Capital Expenditures	2,117	2,216	2,932	3,052
Operating Segments | Structural Systems
Segment Reporting Information [Line Items]
Net Revenues	55,359	91,235	130,714	179,604
Operating Income	6,214	11,773	11,604	22,322
Depreciation and Amortization Expenses	3,739	3,400	7,428	6,400
Capital Expenditures	467	3,672	2,604	7,361
Segment Reconciling Items
Segment Reporting Information [Line Items]
Corporate General and Administrative Expenses	(6,627)	(8,081)	(13,513)	(14,963)
Corporate Administration
Segment Reporting Information [Line Items]
Depreciation and Amortization Expenses	64	73	136	326
Capital Expenditures	$ 0	$ 0	$ 0	$ 0