Summary of Accrual Activities by Components Related to Company's Restructuring Charges (Details) $ in Thousands	9 Months Ended
	Sep. 28, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance	$ 806
Restructuring charges	1,125
Cash payments	(512)
Non-cash write-offs and other adjustments	(11)
Accrued expense ending balance	1,408
Severance
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance	39
Restructuring charges	1,082
Cash payments	(187)
Non-cash write-offs and other adjustments	(11)
Accrued expense ending balance	923
Facility
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance	763
Cash payments	(282)
Accrued expense ending balance	481
Other Restructuring Charges
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance	4
Restructuring charges	43
Cash payments	(43)
Accrued expense ending balance	$ 4