Note 11 - Net Loss Per Share - Anti-dilutive Securities (Details) - shares shares in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Potentially dilutive common shares (in shares)		60,501	57,262	59,686	55,370
Unvested Stock [Member]
Potentially dilutive common shares (in shares)		2,014	1,981	2,033	1,666
Convertible Preferred Stocks [Member]
Potentially dilutive common shares (in shares)		57,039	41,725	56,239	40,159
Common Stock Warrants [Member]
Potentially dilutive common shares (in shares)		1,448	1,474	1,414	1,463
IPO Warrants [Member]
Potentially dilutive common shares (in shares)	[1]	0	12,082	0	12,082

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