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

9 Months Ended

Sep. 26, 2020

Notes Tables

Available-for-sale Securities [Table Text Block]

	September 26, 2020
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses (1)		Value
Foreign government security	$	949	$	-	$	-	$	949

	December 28, 2019
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses (1)		Value
Foreign government security	$	904	$	-	$	-	$	904

Investments Classified by Contractual Maturity Date [Table Text Block]

	September 26, 2020				December 28, 2019
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
Due in one year or less	$	949	$	949	$	-	$	-
Due after one year through three years		-		-		904		904
	$	949	$	949	$	904	$	904

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

	Fair value measurements at September 26, 2020 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	144,727	$	-	$	-	$	144,727
Money market funds		-		25,199		-		25,199
Foreign government security		-		949		-		949
	$	144,727	$	26,148	$	-	$	170,875

	Fair value measurements at December 28, 2019 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	147,523	$	-	$	-	$	147,523
Money market funds		-		7,671		-		7,671
Foreign government security		-		904		-		904
	$	147,523	$	8,575	$	-	$	156,098