Note 9 - Stockholders' Equity - Summary of Warrants (Details)	Mar. 31, 2020 $ / shares shares
Series G Warrants [Member]
Exercise price (in dollars per share) | $ / shares	$ 25,440
Number of warrants (in shares) | shares	48
Series H Warrants [Member]
Exercise price (in dollars per share) | $ / shares	$ 1.15
Number of warrants (in shares) | shares	217,392
Series I Warrants [Member]
Exercise price (in dollars per share) | $ / shares	$ 15,000
Number of warrants (in shares) | shares	48