Restructuring Activities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	$ 23,600		$ 23,600
Restructuring charges	0	$ 3,373	0	$ 10,784	$ 14,800	$ 8,800
Electronic Systems
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	900		900
Inventory write-down			100
Accrued severance and loss on early exit	100		100
Electronic Systems | Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	3,800		3,800
Electronic Systems | Lease termination
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	900		900
Electronic Systems | Professional service fees
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	200		200
Electronic Systems | Property and equipment impairment due to restructuring
Restructuring Cost and Reserve [Line Items]
Non-cash payments			100
Structural Systems
Restructuring Cost and Reserve [Line Items]
Inventory write-down			500
Accrued severance and loss on early exit	100		100
Structural Systems | Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	3,000		3,000
Structural Systems | Property and equipment impairment due to restructuring
Restructuring Cost and Reserve [Line Items]
Non-cash payments			9,800
Structural Systems | Other restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	400		400
Corporate Administration | Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	1,400		1,400
Corporate Administration | Professional service fees
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	1,000		1,000
Corporate Administration | Modification of stock-based compensation awards
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, cost incurred to date	$ 1,400		$ 1,400