Note 4 - Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

	As of December 31, 2021
	Adjusted		Unrealized		Unrealized			Market
	Cost		Gains		Losses			Value
Level 1:
Money Market Funds	$	1,670	$	-	$	-		$	1,670
U.S. Treasury securities considered cash equivalents		-		-		-			-
U.S. Treasury securities in short-term investments		29,989		-		(6	)		29,983
Total Financial Assets	$	31,659	$	-	$	(6	)	$	31,653

	As of December 31, 2020
	Adjusted		Unrealized		Unrealized		Market
	Cost		Gains		Losses		Value
Level 1:
Money Market Funds	$	6,035	$	-	$	-	$	6,035
U.S. Treasury securities considered cash equivalents		9,998		-		-		9,998
U.S. Treasury securities in short-term investments		24,979		15		-		24,994
Total Financial Assets	$	41,012	$	15	$	-	$	41,027