Note 8 - Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Balance at beginning of year	$ 34,701	$ 10,321	$ 10,075
Additions for tax positions of current year	1,231	524	200
Additions (reductions) for tax positions of prior years	(484)
Additions (reductions) for tax positions of prior years		191	58
Reductions due to lapse of the statute of limitations	(957)	(645)	(1,148)
Additions related to Xcerra and Kita acquisitions		24,352	900
Reductions due to settlements	(30)
Foreign exchange rate impact	104		236
Foreign exchange rate impact		(42)
Balance at end of year	$ 34,565	$ 34,701	$ 10,321