Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands			1 Months Ended	12 Months Ended
	Apr. 23, 2018	Sep. 11, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018
Goodwill And Intangible Assets [Line Items]
Goodwill				$ 136,057	$ 117,435
Purchase price, net of cash acquired				0	59,798	$ 0
Amortization expense of intangible asset				$ 10,700	9,300	$ 9,000
Minimum
Goodwill And Intangible Assets [Line Items]
Acquired intangible assets amortization period				10 years
Maximum
Goodwill And Intangible Assets [Line Items]
Acquired intangible assets amortization period				18 years
Certified Thermoplastics Co., LLC
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 18,622
Equity interest acquired	100.00%						100.00%
Purchase price, net of cash acquired	$ 30,700
Gross purchase price	$ 30,810
Lightning Diversion Systems, Inc.
Goodwill And Intangible Assets [Line Items]
Goodwill			$ 34,900
Equity interest acquired		100.00%	100.00%
Purchase price, net of cash acquired		$ 60,000	$ 60,000
Gross purchase price		$ 62,000	$ 62,000
Structural Systems
Goodwill And Intangible Assets [Line Items]
Goodwill				$ 18,622	0
Electronic Systems
Goodwill And Intangible Assets [Line Items]
Goodwill				$ 117,435	$ 117,435