Business Segment Information - Segment Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total Assets	$ 648,143	$ 566,753
Goodwill and Intangibles	248,149	232,128
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Total Assets	405,743	362,831
Goodwill and Intangibles	219,872	229,292
Operating Segments | Structural Systems
Segment Reporting Information [Line Items]
Total Assets	226,304	193,600
Goodwill and Intangibles	28,277	2,836
Corporate Administration
Segment Reporting Information [Line Items]
Total Assets	$ 16,096	$ 10,322