Note 4 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

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

	December 31, 2022
	Quoted Prices in
	Active Markets for		Direct or Indirect
	Identical Assets		Observable
	(Level 1)		Inputs (Level 2)		Total
Assets
Cash equivalents:
Money market funds	$	13,461	$	—	$	13,461
U.S. treasury securities		19,710		—		19,710
Total cash equivalents		33,171		—		33,171
Restricted cash:
Money market funds		221		—		221
Total assets measured at fair value	$	33,392	$	—	$	33,392

	December 31, 2021
	Quoted Prices in
	Active Markets for		Direct or Indirect
	Identical Assets		Observable
	(Level 1)		Inputs (Level 2)		Total
Assets
Cash equivalents:
Money market funds	$	37,023	$	—	$	37,023
Total cash equivalents		37,023		—		37,023
Restricted cash:
Money market funds		557		—		557
Total assets measured at fair value	$	37,580	$	—	$	37,580