Note 8 - Loss Per Share - Antidilutive Securities Excluded from the Diluted Calculations (Details) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities (in shares)	325,000	0
Share-based Payment Arrangement, Option [Member]
Antidilutive Securities (in shares)	1,013,780	818,117
Warrant [Member]
Antidilutive Securities (in shares)	31,747,118	7,257,883
Convertible Debt Securities [Member]
Antidilutive Securities (in shares)	0	574,367
Series B Convertible Preferred Stock [Member]
Antidilutive Securities (in shares)	79,246	79,246
Series D Convertible Preferred Stock [Member]
Antidilutive Securities (in shares)	0	0
Series E Convertible Preferred Stock [Member]
Antidilutive Securities (in shares)	0	0