Note 13 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 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)
Balance at December 31, 2022		7,584,967		$	4.22		5.31
Granted		3,047,615			0.71
Forfeited		(149,430	)		0.78
Cancelled		(25,173	)		27.32
Exercised		(13,300	)		0.38
Balance at December 31, 2023		10,444,679		$	3.20		4.80

Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable [Table Text Block]

	Number of Shares		Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value (Millions)
Exercisable at December 31, 2023		5,726,280	$	5.02		4.12	$	-
Vested or expected to vest at December 31, 2023		10,105,084	$	3.28		4.77	$	-

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

	Years Ended December 31,
	2023			2022
Expected dividend yield		0%			0%
Expected volatility	124%	-	130%	126%	-	133%
Risk-free interest rate	3.53%	-	4.14%	1.25%	-	4.40%
Expected life (in years)	3.8	-	4.5	3.8	-	4.5

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

	Number of Restricted Stock Units Outstanding			Weighted-Average Grant Date Fair Value
Unvested December 31, 2022		8,483,491		$	1.04
Granted		8,616,931			0.70
Vested		(3,937,130	)		1.10
Forfeited		(837,115	)		0.76
Unvested December 31, 2023		12,326,177		$	0.81

Share-Based Payment Arrangement, Cost by Plan [Table Text Block]

	Years Ended December 31,
	2023		2022
	(in thousands)
Stock options	$	2,338	$	3,654
Restricted stock units		3,954		3,319
Performance restricted stock units		1,626		1,443
	$	7,918	$	8,416