Note 3 - Goodwill and Purchased Intangible Assets - Purchased Intangible Assets, Subject to Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 26, 2015
Gross Carrying Amount	$ 57,329	$ 59,494
Accumulated Amortization	39,494	34,197
Rasco Technology [Member]
Gross Carrying Amount	25,785	26,904
Accumulated Amortization	$ 25,785	23,776
Remaining Useful Life (Year)
Ismeca Technology [Member]
Gross Carrying Amount	$ 26,191	27,043
Accumulated Amortization	$ 13,241	10,329
Remaining Useful Life (Year)	4 years
Trade Names [Member]
Gross Carrying Amount	$ 5,353	5,547
Accumulated Amortization	$ 468	$ 92
Remaining Useful Life (Year)	13 years 255 days