Note 10 - Net Loss Per Share - Anti-dilutive Securities (Details) - shares shares in Thousands		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Potentially dilutive common shares (in shares)		56,055	52,552
Unvested Stock [Member]
Potentially dilutive common shares (in shares)		2,053	1,347
Convertible Preferred Stocks [Member]
Potentially dilutive common shares (in shares)		52,622	37,671
Common Stock Warrants [Member]
Potentially dilutive common shares (in shares)		1,380	1,452
IPO Warrants [Member]
Potentially dilutive common shares (in shares)	[1]	0	12,082

[1] The IPO Warrants were issued in connection with our initial public offering in 2015 and expired July 24, 2022.