Note 16 - Warrants - Warrant Activity (Details) - Stock Warrants [Member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Outstanding, number of warrant shares (in shares)	2,071,172	333,034
Outstanding, weighted average exercise price (in dollars per share)	$ 2.05	$ 13.39
Outstanding, weighted average remaining contractual life (Year)	2 years 4 months 24 days	2 years 4 months 24 days	3 years 8 months 12 days
Outstanding, weighted average fair value (in dollars per share)	$ 0.20	$ 1.34	$ 3.38
Exercised, number of warrant shares (in shares)	(4,911,764)	(15,385)
Exercised, weighted average exercise price (in dollars per share)	$ 0.68	$ 13.00
Reserved for future issuance, number of warrant shares (in shares)	644,966	1,753,523
Reserved for future issuance, weighted average exercise price (in dollars per share)	$ 0.35	$ 1.39
Reserved for future issuance, weighted average remaining contractual life (Year)	1 year 3 months 18 days	2 years 2 months 12 days
Reserved for future issuance, weighted average fair value (in dollars per share)	$ 0.45	$ 1.22
Granted, number of warrant shares (in shares)	50,735,292
Granted, weighted average exercise price (in dollars per share)	$ 0.68
Granted, weighted average remaining contractual life (Year)	2 years 4 months 24 days
Restricted stock units, Granted, weighted average grant date fair value (in dollars per share)	$ 0.19
Exchanged, number of warrant shares (in shares)	(2,040,757)
Exchanged, weighted average exercise price (in dollars per share)	$ 1.24
Outstanding, number of warrant shares (in shares)	46,498,909	2,071,172	333,034
Outstanding, weighted average exercise price (in dollars per share)	$ 0.71	$ 2.05	$ 13.39