Note 4 - Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2022

Notes Tables

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

	March 31, 2022						December 31, 2021
	Quoted Prices in		Direct or				Quoted Prices in		Direct or
	Active Markets		Indirect				Active Markets		Indirect
	for Identical		Observable				for Identical		Observable
	Assets (Level 1)		Inputs (Level 2)		Total		Assets (Level 1)		Inputs (Level 2)		Total
Assets
Cash equivalents:
Money market funds	$	33,810	$	—	$	33,810	$	37,023	$	—	$	37,023
Total cash equivalents		33,810		—		33,810		37,023		—		37,023
Restricted cash:
Money market funds		220		—		220		557		—		557
Total assets measured at fair value	$	34,030	$	—	$	34,030	$	37,580	$	—	$	37,580