Business Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total Assets	$ 515,429	$ 557,081
Goodwill and Intangibles	184,127	212,461
Operating Segments | Structural Systems
Segment Reporting Information [Line Items]
Total Assets	175,580	179,134
Goodwill and Intangibles	3,745	4,866
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Total Assets	325,780	363,227
Goodwill and Intangibles	180,382	207,595
Corporate Administration
Segment Reporting Information [Line Items]
Total Assets	$ 14,069	$ 14,720