Business Segment Information - Segment Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total Assets	$ 837,347	$ 790,429
Goodwill and Intangibles	295,574	309,279
Operating Segments | Electronic Systems
Segment Reporting Information [Line Items]
Total Assets	448,606	411,981
Goodwill and Intangibles	201,077	210,453
Operating Segments | Structural Systems
Segment Reporting Information [Line Items]
Total Assets	325,604	328,718
Goodwill and Intangibles	94,497	98,826
Corporate Administration
Segment Reporting Information [Line Items]
Total Assets	$ 63,137	$ 49,730