Note 2 - Business Acquisitions, Goodwill and Other Purchased Intangible Assets - Purchased Intangible Assets, Subject to Amortization (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 24, 2017	Dec. 31, 2016
Accumulated Amortization	$ 16,531	$ 13,709
Gross Carrying Amount	35,273	31,544
Developed Technology Rights [Member]
Accumulated Amortization	$ 11,396	9,597
Remaining Useful Life (Year)	3 years 328 days
Gross Carrying Amount	$ 21,009	19,195
Customer Relationships [Member]
Accumulated Amortization	$ 4,348	3,644
Remaining Useful Life (Year)	3 years 219 days
Gross Carrying Amount	$ 7,983	6,996
Trade Names [Member]
Accumulated Amortization	$ 734	468
Remaining Useful Life (Year)	12 years 182 days
Gross Carrying Amount	$ 6,176	5,353
Order or Production Backlog [Member]
Accumulated Amortization	$ 53
Remaining Useful Life (Year)	182 days
Gross Carrying Amount	$ 105