Note 2 - Summary of Significant Accounting Policies (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2020

Dec. 31, 2019

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	For Three Months Ended June 30, 2020			For Three Months Ended June 30, 2019			For Six Months  Ended June 30, 2020			For Six Months Ended June 30, 2019
Weighted average grant date fair value	$	2.80		$	3.61		$	2.80		$	3.61
Weighted average assumptions used:
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%
Risk-free interest rate		0.43	%		2.19	%		0.43	%		2.19	%
Expected volatility		76.00	%		127.52	%		76.00	%		127.52	%
Expected life (in years)		6.2			5.0			6.2			5.0

	201 9			2018
Weighted average grant date fair value	$	3.69		$	0.49
Weighted average assumptions used:
Expected dividend yield		0.00	%		0.00	%
Risk-free interest rate		2.00	%		0.83	%
Expected volatility		124.58	%		225.21	%
Expected life (in years)		5.00			4.91