Note 2 - Net Income Per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Net income	$ 26,739	$ 12,607	$ 67,390	$ 31,403
Shares used in basic Net income per share (in shares)	136,638	135,598	136,476	134,903
Dilutive effect of stock options, RSUs, ESPP shares, and equity awards with a market condition or performance condition (in shares)	4,994	5,926	5,687	5,860
Shares used in diluted Net income per share (in shares)	141,632	141,524	142,163	140,763
Basic (in dollars per share)	$ 0.20	$ 0.09	$ 0.49	$ 0.23
Diluted (in dollars per share)	$ 0.19	$ 0.09	$ 0.47	$ 0.22
Stock options, RSUs, ESPP shares, and equity awards with a market condition or performance condition excluded as they are antidilutive (in shares)	358	370	182	514