Note 5 - Financial Instruments Measured at Fair Value (Tables)

12 Months Ended

Dec. 30, 2023

Notes Tables

Unrealized Gain (Loss) on Investments [Table Text Block]

	At December 30, 2023
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses (1)		Value
Corporate debt securities (2)	$	45,105	$	147	$	15	$	45,237
U.S. treasury securities		20,439		26		116		20,349
Bank certificates of deposit		15,468		20		-		15,488
Asset-backed securities		8,017		17		10		8,024
Foreign government security		741		-		-		741
Municipal securities		330		5		-		335
	$	90,100	$	215	$	141	$	90,174

	At December 31, 2022
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses (1)		Value
Corporate debt securities (2)	$	59,283	$	30	$	240	$	59,073
Bank certificates of deposit		36,500		20		41		36,479
U.S. treasury securities		34,614		1		418		34,197
Asset-backed securities		12,727		10		79		12,658
Foreign government security		828		-		-		828
	$	143,952	$	61	$	778	$	143,235

Investments Classified by Contractual Maturity Date [Table Text Block]

	Amortized		Estimated
(in thousands)	Cost		Fair Value
Due in 1 year or less	$	57,981	$	57,887
Due after 1 year through 5 years		31,378		31,546
Due after 5 years through 10 years		741		741
	$	90,100	$	90,174

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

	Fair value measurements at December 30, 2023 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	157,697	$	-	$	-	$	157,697
Money market funds		-		81,115		-		81,115
Corporate debt securities		-		51,949		-		51,949
U.S. treasury securities		-		20,349		-		20,349
Bank certificates of deposit		-		15,488		-		15,488
Asset-backed securities		-		8,024		-		8,024
Foreign government security		-		741		-		741
Municipal securities		-		335		-		335
	$	157,697	$	178,001	$	-	$	335,698

	Fair value measurements at December 31, 2022 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	190,371	$	-	$	-	$	190,371
Corporate debt securities		-		69,753		-		69,753
Money market funds		-		40,290		-		40,290
Bank certificates of deposit		-		37,480		-		37,480
U.S. treasury securities		-		34,196		-		34,196
Asset-backed securities		-		12,658		-		12,658
Foreign government security		-		828		-		828
	$	190,371	$	195,205	$	-	$	385,576