Note 12 - Stock Based Compensation - Stock-based Compensation Expense (Details) - USD ($)		3 Months Ended
	Jan. 13, 2019	Mar. 31, 2019	Mar. 31, 2018
Liability Options [Member]
Total stock compensation expense	$ 1,741,919
Share-based Payment Arrangement, Option [Member]
Total stock compensation expense		$ 275,833	$ 215,139
General and Administrative Expense [Member] | Liability Options [Member]
Total stock compensation expense	1,074,183
General and Administrative Expense [Member] | Share-based Payment Arrangement, Option [Member]
Total stock compensation expense		224,676	166,701
Research and Development Expense [Member] | Liability Options [Member]
Total stock compensation expense	$ 667,736
Research and Development Expense [Member] | Share-based Payment Arrangement, Option [Member]
Total stock compensation expense		$ 51,157	$ 48,438