Note 2 - Net Income Per Share - Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Net income	$ 8,167	$ 7,408
Shares used in basic Net income per share (in shares)	134,253	130,992
Dilutive effect of stock options, RSUs, ESPP shares, and equity awards with a market condition or performance condition (in shares)	3,791	3,818
Shares used in diluted Net income per share (in shares)	138,044	134,810
Basic (in dollars per share)	$ 0.06	$ 0.06
Diluted (in dollars per share)	$ 0.06	$ 0.05
Stock options, RSUs, ESPP shares, and equity awards with a market condition or performance condition excluded as they are antidilutive (in shares)	1,056	812