Basis of Presentation and General Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017	Dec. 29, 2017	Dec. 30, 2016
Basis Of Presentation And General Information [Line Items]
Revenue recognized as a result of change in contract liability	$ 5,000,000	$ 4,900,000	$ 9,800,000	$ 11,300,000
Deferred commissions					$ 1,400,000	$ 1,800,000
Commissions expense	400,000	500,000	700,000	900,000
Impairment loss recognized to capitalization of deferred commission	$ 0	$ 0	$ 0	$ 0
Minimum [Member]
Basis Of Presentation And General Information [Line Items]
Business relationship agreement period			6 months
Maximum [Member]
Basis Of Presentation And General Information [Line Items]
Business relationship agreement period			12 months
Customer contract period			12 months