Business Segment Information - Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2017	Apr. 02, 2016
Segment Reporting Information [Line Items]
Net Revenues	$ 136,297	$ 142,148
Segment Operating Income	9,736	9,111
Operating Income	4,100	4,293
Depreciation and Amortization Expenses	5,782	5,855
Capital Expenditures	6,621	2,401
Operating Segments | Structural Systems
Segment Reporting Information [Line Items]
Net Revenues	57,575	64,017
Segment Operating Income	2,632	2,724
Depreciation and Amortization Expenses	2,352	2,057
Capital Expenditures	5,188	2,054
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Net Revenues	78,722	78,131
Segment Operating Income	7,104	6,387
Depreciation and Amortization Expenses	3,423	3,761
Capital Expenditures	1,433	347
Corporate Administration
Segment Reporting Information [Line Items]
Corporate General and Administrative Expenses	(5,636)	(4,818)
Depreciation and Amortization Expenses	$ 7	$ 37