Note 9 - Net Loss Per Share Attributable to Common Stockholders - Basic and Diluted Common Shares (Details) - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Weighted average shares outstanding - basic and diluted (in shares)	121,328	118,262
Dilutive unvested stock, convertible preferred stock, Common Stock Warrants and IPO Warrants (in shares)	0	0
Diluted (in shares)	121,328	118,262
Net loss per common share - basic and diluted (in dollars per share)	$ (0.14)	$ (0.06)