Note 5 - Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

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

	Fair Value		Fair value measurement using
	March 31,
(in thousands)	2021		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	32,077	$	32,077	$	-	$	-
U.S. Treasury notes		3,029		3,029		-		-
Total Assets	$	35,106	$	35,106	$	-	$	-

	Fair Value		Fair value measurement using
	December 31,
(in thousands)	2020		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds	$	6,518		6,518	$	-	$	-
U.S. Treasury notes		9,101		9,101		-		-
Total Assets	$	15,619	$	15,619	$	-	$	-