Note 5 - Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Balance at beginning of year	$ 10,075	$ 10,444	$ 10,841
Gross additions for tax positions of current year	200	125	215
Gross additions for tax positions of prior years	958	58	248
Reductions due to lapse of the statute of limitations	(1,148)	(446)	(243)
Foreign exchange rate impact	236
Foreign exchange rate impact		(106)	(617)
Balance at end of year	$ 10,321	$ 10,075	$ 10,444