Note 10 - Net Loss Per Share - Schedule of Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Number of potential common shares excluded (in shares)	35,511	35,999	34,526	34,170
Share-Based Payment Arrangement, Option [Member]
Number of potential common shares excluded (in shares)	13,337	8,905	12,219	7,991
Series B Convertible Preferred Stock [Member]
Number of potential common shares excluded (in shares)	165	175	165	176
Warrant [Member]
Number of potential common shares excluded (in shares)	22,009	26,919	22,142	26,003