Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 31, 2019 USD ($)	Oct. 08, 2019 USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments | Segment	2
Goodwill	$ 170,830,000	$ 170,917,000
Restructuring charges	2,424,000	0	$ 14,671,000
Provision for loss on contracts	2,300,000	4,200,000
Production cost of contracts	6,971,000	9,402,000
Contract liability revenue	6,300,000
Miscellaneous expenses	1,400,000
Severance and Benefits
Significant Accounting Policies [Line Items]
Restructuring charges	$ 2,400,000
Minimum
Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets (in years)	10 years
Maximum
Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets (in years)	18 years
Nobles Worldwide, Inc.
Significant Accounting Policies [Line Items]
Goodwill				$ 34,900,000	$ 34,850,000
Electronic Systems
Significant Accounting Policies [Line Items]
Goodwill	$ 117,435,000	$ 117,435,000
Percentage of fair value in excess of carrying amount		44.00%
Structural Systems
Significant Accounting Policies [Line Items]
Goodwill	$ 53,395,000	$ 53,482,000
Percentage of fair value in excess of carrying amount	69.00%
Structural Systems | Nobles Worldwide, Inc.
Significant Accounting Policies [Line Items]
Goodwill				$ 34,900,000
Other Assets
Significant Accounting Policies [Line Items]
Interest rate cap hedge premium	$ 0