Note I - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Jun. 30, 2020	Apr. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Common Stock, Shares Authorized (in shares)			100,000,000	85,000,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)			$ 2.18	$ 1.97
Deferred Compensation Arrangement with Individual, Shares Authorized for Issuance (in shares)			2,066,343	2,428,329	2,375,760
Chief Executive Officer, Chief Financial Officer and Employees [Member]
Deferred Compensation Arrangement with Individual, Shares Authorized for Issuance (in shares)			1,891,979	2,256,844
Non-Employees [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)			174,364	171,485
Warrants Associated With April 2020 Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)		2,710,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 1.20
Warrants and Rights Outstanding, Term (Year)		3 years
Warrants Associated With the June 2020 Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	3,749,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 2.60
Warrants and Rights Outstanding, Term (Year)	3 years
April 6, 2020 Public Offering [Member]
Proceeds from Issuance of Common Stock, Gross		$ 5.1
Stock Issued During Period, Shares, New Issues (in shares)		5,420,000
Share Price (in dollars per share)		$ 0.95
June 30, 2020 Public Offering [Member]
Proceeds from Issuance of Common Stock, Gross	$ 14.6
Stock Issued During Period, Shares, New Issues (in shares)	6,770,000
Share Price (in dollars per share)	$ 2.15