Note 11 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Notes Tables

Share-Based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Shares			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (Millions)
Outstanding at December 31, 2022		7,584,967		$	4.22		5.31
Granted		3,047,615		$	0.71
Exercised		(13,300	)	$	0.38
Cancelled		(21,116	)	$	25.79
Forfeited		(106	)	$	15.86
Outstanding at September 30, 2023		10,598,060		$	3.17		5.10	$	-
Vested or expected to vest at September 30, 2023		10,132,754		$	3.29		5.05	$	-
Exercisable at September 30, 2023		5,591,291		$	5.15		4.37	$	-

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Nine Months Ended September 30,
	2023		2022
Expected volatility		124% - 130%		128% - 133%
Risk-free interest rate		3.53% - 4.14%		1.25% - 2.98%
Expected life (in years)		3.8 - 4.5		3.8 - 4.5
Expected dividend yield		0%		0%
Weighted average grant date fair value		$0.59		$0.60

Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]

	Number of Shares			Weighted-Average Grant Date Fair Value
Outstanding at December 31, 2022		8,483,491		$	1.04
Granted		8,482,315		$	0.71
Vested		(3,623,411	)	$	1.14
Forfeited		(539,448	)	$	0.76
Outstanding at September 30, 2023		12,802,947		$	0.82

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended September 30,				Nine Months Ended September 30,
(In thousands)	2023		2022		2023		2022
Stock options	$	552	$	913	$	1,808	$	2,812
Restricted stock units		1,037		772		2,873		2,480
Performance restricted stock units		430		348		1,232		1,069
	$	2,019	$	2,033	$	5,913	$	6,361