Note 4 - Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2023

Notes Tables

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

	March 31, 2023				December 31, 2022
	Quoted Prices in				Quoted Prices in
	Active Markets				Active Markets
	for Identical				for Identical
	Assets (Level 1)		Total		Assets (Level 1)		Total
Assets
Cash equivalents:
Money market funds	$	5,428	$	5,428	$	13,461	$	13,461
U.S. treasury securities		—		—		19,710		19,710
Total cash equivalents		5,428		5,428		33,171		33,171
Restricted cash:
Money market funds		221		221		221		221
Total assets measured at fair value	$	5,649	$	5,649	$	33,392	$	33,392