Segment, Geographic, Product and Significant Customer Information - Product Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015	Dec. 27, 2014
Segment Reporting Information [Line Items]
Products	$ 185,066	$ 146,945	$ 133,589
Automated Systems [Member]
Segment Reporting Information [Line Items]
Products	127,378	102,386	108,768
Integrated Systems [Member]
Segment Reporting Information [Line Items]
Products	43,846	31,579	15,334
Materials Characterization Systems [Member]
Segment Reporting Information [Line Items]
Products	$ 13,842	$ 12,980	$ 9,487