Note 3 - Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Fair Value, by Balance Sheet Grouping [Table Text Block]

	As of March 31, 2020
	Level 1		Level 2		Level 3		Total
Assets:
Cash and cash equivalents	$	—	$	—	$	—	$	—
Short-term investments		—		360,210		—		360,210
Total assets	$	—	$	360,210	$	—	$	360,210
Liabilities:
Accrued warrant liability	$	—	$	—	$	44,412	$	44,412

	As of December 31, 2019
	Level 1		Level 2		Level 3		Total
Assets:
Cash and cash equivalents	$	—	$	—	$	—	$	—
Short-term investments		—		452,301		—		452,301
Total assets	$	—	$	452,301	$	—	$	452,301
Liabilities:
Accrued warrant liability	$	—	$	—	$	6,414	$	6,414

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Three Months Ended			Three Months Ended
	March 31, 2020			March 31, 2019
	Accrued Warrant Liability			Accrued Warrant Liability
Beginning Balance	$	6,414		$	78,637
Total (gains) or losses, realized and unrealized, included in earnings (1)		160,689			94,821
Issuances		—			—
Settlements		(122,691	)		—
Ending Balance	$	44,412		$	173,458

Warrant [Member]

Notes Tables

Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]

	March 31, 2020	December 31, 2019
Stock Price	$1.66	$0.60
Exercise Price	3.64 4 - 20.40 40	3.64 4 - 20.40 40
Term in years	0.79 - 1.35	1.04 - 1.60
Volatility	68.40 - 97.72%	84.59 - 98.24%
Annual rate of quarterly dividends	0%	0%
Discount rate- bond equivalent yield	0.14 - 0.19%	1.58 - 1.59%