Note 5 - Stockholders' Equity - Share-based Compensation Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Allocated Share-based Compensation Expense	$ 329,755	$ 578,820	$ 1,504,143	$ 2,866,773
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	185,492	397,825	993,927	1,371,378
General and Administrative Expense [Member]
Allocated Share-based Compensation Expense	$ 144,263	$ 180,995	$ 510,216	$ 1,495,395