Note 18 - Net Loss Per Share Attributable to Common Stockholders - Summary of Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	19,183,231	19,163,520	1,261,124
Share-based Payment Arrangement, Option [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	4,409,806	1,583,575	839,396
Warrant [Member] | Common Stock [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)	14,773,425	17,579,945	9,658
Warrant [Member] | Preferred Stock [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)			891
Series B and C Convertible Preferred Stock, Including Cumulative Dividends [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)			213,760
Series A Convertible Preferred Stock [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)			12,260
Convertible Debt Securities [Member]
Potentially dilutive securities excluded from denominator of the diluted earnings per share computation (in shares)			185,159