Restructuring Activities (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0	$ 2,173
Electronic Systems
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	900
Inventory Write-down	100
Accrued severance and loss on early exit	600
Electronic Systems | Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	3,800
Electronic Systems | Lease termination
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	900
Electronic Systems | Professional Service Fees
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	200
Structural Systems
Restructuring Cost and Reserve [Line Items]
Inventory Write-down	500
Accrued severance and loss on early exit	300
Structural Systems | Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	3,000
Structural Systems | Other restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	400
Restructuring Plan, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	23,600		$ 14,800	$ 8,800
Restructuring Plan, 2017 | Electronic Systems | Property and equipment impairment due to restructuring
Restructuring Cost and Reserve [Line Items]
Non-Cash Payments	100
Restructuring Plan, 2017 | Structural Systems | Property and equipment impairment due to restructuring
Restructuring Cost and Reserve [Line Items]
Non-Cash Payments	9,800
Corporate Administration
Restructuring Cost and Reserve [Line Items]
Accrued severance and loss on early exit	100
Corporate Administration | Severance and benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1,400
Corporate Administration | Professional Service Fees
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1,000
Corporate Administration | Modification of stock-based compensation awards
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 1,400