Note 2 - Business Acquisitions - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Jan. 04, 2017	Dec. 31, 2016	Dec. 26, 2015
Goodwill	$ 65,613		$ 58,849	$ 60,264
Kita Manufacturing Co. LTD. and Kita USA, Inc. [Member]
Current assets, including cash received		$ 10,491
Property, plant and equipment		12,751
Other assets		2,397
Intangible assets subject to amortization		2,100
Goodwill		2,654
Total assets acquired		30,393
Liabilities assumed		(14,570)
Net assets acquired		$ 15,823