Note 10 - Net Loss Per Share - Schedule of Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Number of potential common shares excluded (in shares)	33,531	32,322
Share-Based Payment Arrangement, Option [Member]
Number of potential common shares excluded (in shares)	11,089	7,067
Series B Convertible Preferred Stock [Member]
Number of potential common shares excluded (in shares)	165	177
Warrant [Member]
Number of potential common shares excluded (in shares)	22,277	25,078