Note 7 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

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

	Fair Value		Fair value measurement using
	December 31,
(in thousands)	2018		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	5,234	$	5,234	$	-	$	-
U.S. Treasury notes		19,912	$	19,912
Certificate of deposit		171		171		-		-
Total Assets	$	25,317	$	25,317	$	-	$	-

	Fair Value		Fair value measurement using
	December 31,
(in thousands)	2017		Level 1		Level 2		Level 3
Assets:
Cash and cash equivalents	$	1,815	$	1,815	$	-	$	-
Certificate of deposit		225		225		-		-
Total Assets	$	2,040	$	2,040	$	-	$	-