Goodwill and Other Intangible Assets - Carrying Amount of Finite-lived and Other Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 183,845	$ 161,445
Accumulated Amortization	69,152	59,872
Net Carrying Amount	114,693	101,573
Structural Systems
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	19,300	19,300
Accumulated Amortization	16,464	15,555
Net Carrying Amount	2,836	3,745
Electronic Systems
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	164,545	142,145
Accumulated Amortization	52,688	44,317
Net Carrying Amount	$ 111,857	97,828
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible assets (in years)	17 years
Gross Carrying Amount	$ 180,300	159,200
Accumulated Amortization	67,449	58,352
Net Carrying Amount	$ 112,851	100,848
Trade Names
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible assets (in years)	15 years
Gross Carrying Amount	$ 1,300	0
Accumulated Amortization	26	0
Net Carrying Amount	$ 1,274	0
Contract renewal
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible assets (in years)	14 years
Gross Carrying Amount	$ 1,845	1,845
Accumulated Amortization	1,493	1,362
Net Carrying Amount	$ 352	483
Technology
Finite-Lived Intangible Assets [Line Items]
Estimated useful life of intangible assets (in years)	15 years
Gross Carrying Amount	$ 400	400
Accumulated Amortization	184	158
Net Carrying Amount	$ 216	$ 242