Note 13 - Net Loss Per Share Attributable to Common Stockholders - Calculation of Basic and Diluted Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net loss	$ (8,085)	$ (5,260)	$ (18,359)	$ (12,236)
Shares used to compute net loss per share - basic and diluted (in shares)	107,718,578	16,249,032	81,121,045	12,748,665
Net loss per share - basic and diluted (in dollars per share)	$ (0.08)	$ (0.32)	$ (0.23)	$ (0.96)