Note 4 - Financial Instruments Measured at Fair Value (Tables)

9 Months Ended

Sep. 24, 2016

Notes Tables

Available-for-sale Securities [Table Text Block]

	September 24, 2016
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Corporate debt securities (1)	$	11,489	$	-	$	5	$	11,484
Foreign government security		639		-		-		639
Government-sponsoredenterprise securities		4,012		2		-		4,014
Bank certificates of deposit		3,313		1		-		3,314
	$	19,453	$	3	$	5	$	19,451

	December 26, 2015
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Foreign government security	$	650	$	-	$	-	$	650
Bank certificates of deposit		1,002		-		-		1,002
	$	1,652	$	-	$	-	$	1,652

Investments Classified by Contractual Maturity Date [Table Text Block]

	September 24, 2016				December 26, 2015
	Amortized		Estimated		Amortized		Estimated
	Cost		Fair Value		Cost		Fair Value
Due in one year or less	$	19,453	$	19,451	$	1,450	$	1,450
Due after one year through three years		-		-		202		202
	$	19,453	$	19,451	$	1,652	$	1,652

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

	Fair value measurements at September 24, 2016 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	58,299	$	-	$	-	$	58,299
Corporate debt securities		-		19,952		-		19,952
Government-sponsored enterprise securities		-		4,014		-		4,014
Money market funds		-		42,450		-		42,450
Bank certificates of deposit		-		3,314		-		3,314
Foreign government security		-		639		-		639
	$	58,299	$	70,369	$	-	$	128,668

	Fair value measurements at December 26, 2015 using:
							Total estimated
	Level 1		Level 2		Level 3		fair value
Cash	$	73,746	$	-	$	-	$	73,746
Foreign government security		-		650		-		650
Money market funds		-		41,624		-		41,624
Bank certificates of deposit		-		1,002		-		1,002
	$	73,746	$	43,276	$	-	$	117,022