Note 3 - Fair Value Measurements - Changes in Fair Value of Level 3 Fair Value Measurements (Details) - Accrued Warrant Liability [Member] - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Beginning Balance		$ 78,637	$ 1,041,455
Total (gains) or losses, realized and unrealized, included in earnings (1)	[1]	(72,223)	(962,818)
Ending Balance		$ 6,414	$ 78,637

[1] Unrealized gains or losses related to the accrued warrant liability were included as change in value of accrued warrant liability.