Restructuring Activities (Details) $ in Thousands	6 Months Ended
	Jul. 01, 2017 USD ($)
Restructuring Reserve [Roll Forward]
Beginning balance	$ 654
Charges	0
Cash Payments	(156)
Change in Estimates	0
Ending balance	498
Lease termination
Restructuring Reserve [Roll Forward]
Beginning balance	654
Charges	0
Cash Payments	(156)
Change in Estimates	0
Ending balance	498
Restructuring Plan, 2015 | Severance benefits and loss on early exit from leases
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2,200
Restructuring Plan, 2015 | Structural Systems | Severance and benefits
Restructuring Reserve [Roll Forward]
Ending balance	400
Restructuring Plan, 2016 | Severance benefits and loss on early exit from leases
Restructuring Cost and Reserve [Line Items]
Restructuring costs	200
Restructuring Plan, 2016 | Electronic Systems | Lease termination
Restructuring Reserve [Roll Forward]
Ending balance	$ 100