Note 8 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Balance as of		Fair value measurements
Description	December 31, 201 7		Level 1		Level 2		Level 3
Assets
Cash equivalents
Money market mutual funds	$	2,998	$	2,998		-		-
Short-term marketable securities and time deposits
U.S. GSE securities	$	786		-	$	786		-
Corporate debt securities	$	18,430		-	$	18,430		-
Long-term marketable securities
U.S. GSE securities	$	21,258		-	$	21,258		-
Corporate debt securities	$	56,398		-	$	56,398		-
Derivative liabilities	$	-		-	$	-		-

	Balance as of		Fair value measurements
Description	December 31, 2016		Level 1		Level 2		Level 3
Assets
Cash equivalents
Money market mutual funds	$	1,370	$	1,370		-		-
Short-term marketable securities and time deposits
U.S. GSE securities	$	376		-	$	376		-
Corporate debt securities	$	21,045		-	$	21,045		-
Long-term marketable securities
U.S. GSE securities	$	23,686		-	$	23,686		-
Corporate debt securities	$	54,406		-	$	54,406		-
Derivative assets	$	9		-	$	9		-