Note 3 - Cash and Investments (Tables)

9 Months Ended

Sep. 30, 2023

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	September 30, 2023		December 31, 2022
Cash	$	1,541	$	2,243
Cash equivalents (see detail in Note 4)		7,275		33,171
Restricted cash (see detail in Note 4)		222		221
Total cash, cash equivalents and restricted cash		9,038		35,635
Short-term investments		22,796		7
Total cash, cash equivalents, restricted cash and short-term investments	$	31,834	$	35,642

Debt Securities, Held-to-Maturity [Table Text Block]

							Gross		Gross
	Amortized		Allowance for		Net carrying		unrealized		unrealized		Fair
	cost		credit losses		amount		gains		losses		value
U.S. treasury securities	$	22,796	$	—	$	22,796	$	—	$	—	$	22,796
Total	$	22,796	$	—	$	22,796	$	—	$	—	$	22,796