Restructuring Activities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Restructuring Charges	$ 5,238	$ 0	$ 7,411	$ 0
Electronic Systems
Restructuring Cost and Reserve [Line Items]
Inventory Write-down	200
Accrued severance and loss on early exit	1,000		1,000
Restructuring Reserve [Roll Forward]
Restructuring Charges	600
Electronic Systems | Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			2,200
Structural Systems
Restructuring Cost and Reserve [Line Items]
Inventory Write-down			500
Accrued severance and loss on early exit	600		600
Restructuring Reserve [Roll Forward]
Restructuring Charges	500
Structural Systems | Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			2,500
Structural Systems | Other restructuring
Restructuring Reserve [Roll Forward]
Restructuring Charges	3,300
Restructuring Plan, 2017
Restructuring Reserve [Roll Forward]
Beginning balance			2,725
Restructuring Charges	5,400		7,579		$ 8,800
Cash Payments			(3,902)
Non-Cash Payments			(4,480)
Change in Estimates			0
Ending balance	1,922		1,922		2,725
Restructuring Plan, 2017 | Severance and benefits
Restructuring Reserve [Roll Forward]
Beginning balance			2,659
Restructuring Charges			2,554
Cash Payments			(3,631)
Non-Cash Payments			0
Change in Estimates			0
Ending balance	1,582		1,582		2,659
Restructuring Plan, 2017 | Other restructuring
Restructuring Reserve [Roll Forward]
Ending balance	91		91
Restructuring Plan, 2017 | Modification of stock-based compensation awards
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			105
Cash Payments			0
Non-Cash Payments			(105)
Change in Estimates			0
Ending balance	0		0		0
Restructuring Plan, 2017 | Property and equipment impairment due to restructuring
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			4,375
Cash Payments			0
Non-Cash Payments			(4,375)
Change in Estimates			0
Ending balance	0		0		0
Restructuring Plan, 2017 | Professional Service Fees
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			356
Cash Payments			(265)
Non-Cash Payments			0
Change in Estimates			0
Ending balance					0
Restructuring Plan, 2017 | Lease termination
Restructuring Reserve [Roll Forward]
Beginning balance			66
Restructuring Charges			21
Cash Payments			(6)
Non-Cash Payments			0
Change in Estimates			0
Ending balance	81		81		66
Restructuring Plan, 2017 | Inventory Reserve
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			168
Cash Payments			0
Non-Cash Payments			0
Change in Estimates			0
Ending balance	168		168		0
Restructuring Plan, 2017 | Structural Systems | Property and equipment impairment due to restructuring
Restructuring Reserve [Roll Forward]
Non-Cash Payments			(7,900)
Minimum | Restructuring Plan, 2017
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	20,000		20,000
Maximum | Restructuring Plan, 2017
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	22,000		22,000
Corporate Administration
Restructuring Cost and Reserve [Line Items]
Accrued severance and loss on early exit	300		300
Restructuring Reserve [Roll Forward]
Restructuring Charges	700
Corporate Administration | Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			1,100
Corporate Administration | Other restructuring
Restructuring Reserve [Roll Forward]
Restructuring Charges	400
Corporate Administration | Modification of stock-based compensation awards
Restructuring Reserve [Roll Forward]
Restructuring Charges			1,500
Corporate Administration | Professional Service Fees
Restructuring Reserve [Roll Forward]
Restructuring Charges			400
Restructuring Charges | Restructuring Plan, 2017
Restructuring Reserve [Roll Forward]
Beginning balance			2,725
Restructuring Charges			7,411
Cash Payments			(3,902)
Non-Cash Payments			(4,480)
Change in Estimates			0
Ending balance	1,754		1,754		2,725
Cost of Sales | Restructuring Plan, 2017
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			168
Cash Payments			0
Non-Cash Payments			0
Change in Estimates			0
Ending balance	$ 168		$ 168		$ 0