Restructuring Activities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Restructuring Charges	$ 3,373	$ 64	$ 10,784	$ 64
Cost of Sales
Restructuring Reserve [Roll Forward]
Restructuring Charges			200
Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			19,800
Electronic Systems
Restructuring Cost and Reserve [Line Items]
Inventory Write-down	200
Accrued severance and loss on early exit	1,500		1,500
Restructuring Reserve [Roll Forward]
Restructuring Charges	700
Electronic Systems | Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			2,900
Electronic Systems | Professional Service Fees
Restructuring Reserve [Roll Forward]
Restructuring Charges	400
Structural Systems
Restructuring Cost and Reserve [Line Items]
Inventory Write-down			500
Accrued severance and loss on early exit	500		500
Restructuring Reserve [Roll Forward]
Restructuring Charges	300
Structural Systems | Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			2,800
Structural Systems | Other restructuring
Restructuring Reserve [Roll Forward]
Restructuring Charges	1,300
Restructuring Plan, 2017
Restructuring Reserve [Roll Forward]
Beginning balance			2,725
Restructuring Charges			10,952		$ 8,800
Cash Payments			(4,971)
Non-Cash Payments			(5,889)
Change in Estimates			(539)
Ending balance	2,278		2,278		2,725
Restructuring Plan, 2017 | Severance and benefits
Restructuring Reserve [Roll Forward]
Beginning balance			2,659
Restructuring Charges			3,849
Cash Payments			(3,994)
Non-Cash Payments			0
Change in Estimates			(539)
Ending balance	1,975		1,975		2,659
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 | Lease termination
Restructuring Reserve [Roll Forward]
Beginning balance			66
Restructuring Charges			3
Cash Payments			(69)
Non-Cash Payments			0
Change in Estimates			0
Ending balance	0		0		66
Restructuring Plan, 2017 | Property and equipment impairment due to restructuring
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			5,784
Cash Payments			0
Non-Cash Payments			(5,784)
Change in Estimates			0
Ending balance	0		0		0
Restructuring Plan, 2017 | Professional Service Fees
Restructuring Reserve [Roll Forward]
Beginning balance			0
Restructuring Charges			1,043
Cash Payments			(908)
Non-Cash Payments			0
Change in Estimates			0
Ending balance	135		135		0
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 | Electronic Systems | Property and equipment impairment due to restructuring
Restructuring Reserve [Roll Forward]
Non-Cash Payments	(100)
Restructuring Plan, 2017 | Structural Systems | Property and equipment impairment due to restructuring
Restructuring Reserve [Roll Forward]
Non-Cash Payments			(9,200)
Minimum | Restructuring Plan, 2017
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	21,000		21,000
Maximum | Restructuring Plan, 2017
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	23,000		23,000
Corporate Administration
Restructuring Cost and Reserve [Line Items]
Accrued severance and loss on early exit	300		300
Restructuring Reserve [Roll Forward]
Restructuring Charges	300
Corporate Administration | Severance and benefits
Restructuring Reserve [Roll Forward]
Restructuring Charges			1,400
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	300		700
Restructuring Charges | Restructuring Plan, 2017
Restructuring Reserve [Roll Forward]
Beginning balance			2,725
Restructuring Charges			10,784
Cash Payments			(4,971)
Non-Cash Payments			(5,889)
Change in Estimates			(539)
Ending balance	2,110		2,110		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