Note 5 - Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2016

Notes Tables

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

			Fair Value Measurements at Reporting
			Date Using
			Quoted Prices in
			Active Markets		Significant Other		Significant
			for Identical Assets		Observable Inputs		Unobservable Inputs
	June 30, 2016		(Level 1)		(Level 2)		(Level 3)
Cash equivalents:
Money market funds	$	67,001	$	-	$	67,001	$	-
Investments:
Bank certificates of deposit	$	22,500	$	-	$	22,500	$	-

			Fair Value Measurements at Reporting
			Date Using
			Quoted Prices in
			Active Markets		Significant Other		Significant
			for Identical Assets		Observable Inputs		Unobservable Inputs
	December 31, 2015		(Level 1)		(Level 2)		(Level 3)
Cash equivalents:
Money market funds	$	61,385	$	-	$	61,385	$	-
Bank certificates of deposit		250		-		250		-
Total cash equivalents	$	61,635	$	-	$	61,635	$	-
Investments:
Corporate debt securities	$	2,001	$	-	$	2,001	$	-
Bank certificates of deposit		25,750		-		25,750		-
Total investments	$	27,751	$	-	$	27,751	$	-