Note 3 - Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

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

	Level 1		Level 2		Level 3		Total
June 30, 2022
Recurring financial assets:
Money market funds	$	69,635	$	—	$	—	$	69,635
U.S. Treasury securities		—		19,773		—		19,773
Commercial paper		—		12,581		—		12,581
Corporate debt securities		—		7,664		—		7,664
Total	$	69,635	$	40,018	$	—	$	109,653

	Level 1		Level 2		Level 3		Total
December 31, 2021
Recurring financial assets:
Money market funds	$	70,978	$	—	$	—	$	70,978
U.S. Treasury securities		—		24,997		—		24,997
Commercial paper		—		7,491		—		7,491
Corporate debt securities		—		6,464		—		6,464
Total	$	70,978	$	38,952	$	—	$	109,930