Note 2 - Business Acquisitions, Goodwill and Other Purchased Intangible Assets - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Mar. 25, 2017	Jan. 04, 2017	Dec. 31, 2016	[1]	Dec. 26, 2015
Goodwill	$ 63,048		$ 58,849		$ 60,264
Kita Manufacturing Co. LTD. and Kita USA, Inc. [Member]
Current assets, including cash received		$ 10,148
Fixed assets		12,751
Other assets		2,290
Intangible assets subject to amortization		4,650
Goodwill		3,083
Total assets acquired		32,922
Liabilities assumed		(15,671)
Net assets acquired		$ 17,251

[1] Derived from December 31, 2016 audited financial statements