Note 13 - Stock Based Compensation - Stock-based Compensation Expense (Details) - USD ($)		3 Months Ended			9 Months Ended
	Jan. 13, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock compensation expense		$ 663,593	$ 751,652		$ 2,387,829	$ 6,346,281
General and Administrative Expense [Member]
Stock compensation expense		489,853	510,398		1,675,414	4,136,727
Research and Development Expense [Member]
Stock compensation expense		$ 173,740	$ 241,254		$ 712,415	2,209,554
Liability Options [Member]
Stock compensation expense	$ 1,741,919			$ 1,741,919		1,741,919
Liability Options [Member] | General and Administrative Expense [Member]
Stock compensation expense						1,074,183
Liability Options [Member] | Research and Development Expense [Member]
Stock compensation expense						$ 667,736