Note 3 - Summary of Accounting Policies - New Accounting Standards Adoption (Details) - USD ($)	Sep. 30, 2021	Jan. 01, 2021	Dec. 31, 2020
Warrant liability	$ 0	$ 0	$ 13,003,075
Additional paid-in capital		139,618,860	129,887,146
Accumulated deficit	$ (124,402,093)	(108,627,631)	$ (111,898,992)
Accounting Standards Update 2020-06 [Member]
Warrant liability		(13,003,075)
Additional paid-in capital		9,731,714
Accumulated deficit		$ 3,271,361