Note 3 - Financial Instruments Measured at Fair Value (Tables)

9 Months Ended

Sep. 29, 2018

Notes Tables

Available-for-sale Securities [Table Text Block]

	September 29, 2018
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses (1)		Value
Foreign government security	$	549	$	-	$	-	$	549

	December 30, 2017
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses (1)		Value
Corporate debt securities (2)	$	12,784	$	1	$	6	$	12,779
U.S. treasury securities		7,935		-		4		7,931
Foreign government security		619		-		-		619
	$	21,338	$	1	$	10	$	21,329

Investments Classified by Contractual Maturity Date [Table Text Block]

	September 29, 2018				December 30, 2017
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
Due in one year or less	$	-	$	-	$	21,338	$	21,329
Due after one year through three years		549		549		-		-
	$	549	$	549	$	21,338	$	21,329

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

	Fair value measurements at September 29, 2018 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	141,075	$	-	$	-	$	141,075
Money market funds		-		29,620		-		29,620
Foreign government security		-		549		-		549
	$	141,075	$	30,169	$	-	$	171,244

	Fair value measurements at December 30, 2017 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	100,850	$	-	$	-	$	100,850
Corporate debt securities		-		22,014		-		22,014
U.S. treasury securities		-		8,431		-		8,431
Government-sponsored enterprise securities		-		1,496		-		1,496
Money market funds		-		22,205		-		22,205
Foreign government security		-		619		-		619
	$	100,850	$	54,765	$	-	$	155,615