Note 8 - Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Balance at beginning of year	$ 10,321	$ 10,075	$ 10,444
Gross additions for tax positions of current year	524	200	125
Gross additions for tax positions of prior years	191	58	58
Reductions due to lapse of the statute of limitations	(645)	(1,148)	(446)
Foreign exchange rate impact	(42)		(106)
Foreign exchange rate impact		236
Balance at end of year	34,701	10,321	10,075
Xcerra and Kita [Member]
Gross additions related to Xcerra and Kita acquisitions	$ 24,352	$ 900