Goodwill and Other Intangible Assets - Carrying Amount of Goodwill (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Gross goodwill	$ 239,291,000	$ 239,291,000
Accumulated goodwill impairment	(138,965,000)	(138,965,000)
Transfer to assets held for sale	(17,772,000)	(17,772,000)
Goodwill, net	82,554,000	82,554,000
Structural Systems
Goodwill [Line Items]
Gross goodwill	57,243,000	57,243,000
Accumulated goodwill impairment	(57,243,000)	(57,243,000)
Transfer to assets held for sale	0	0
Goodwill, net	0	0
Electronic Systems
Goodwill [Line Items]
Gross goodwill	182,048,000	182,048,000
Accumulated goodwill impairment	(81,722,000)	(81,722,000)
Transfer to assets held for sale	(17,772,000)	(17,772,000)
Goodwill, net	$ 82,554,000	$ 82,554,000