Note 2 - Business Acquisitions, Goodwill and Other Purchased Intangible Assets - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jan. 04, 2017	Dec. 31, 2016	[1]	Dec. 26, 2015
Goodwill	$ 65,483		$ 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		2,291
Intangible assets subject to amortization		2,100
Goodwill		3,142
Total assets acquired		30,775
Liabilities assumed		(14,952)
Net assets acquired		$ 15,823

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