Note F - Common Stock and Warrants - Reserved Authorized Shares of Common Stock for Future Issuance (Details) - shares	Mar. 31, 2019	Dec. 31, 2018
Common shares reserved for future issuance (in shares)	14,699,518	13,641,913
Series A Convertible Preferred Stock [Member]
Common shares reserved for future issuance (in shares)	1,112,334	1,112,334
Warrant [Member]
Common shares reserved for future issuance (in shares)	2,527,763	2,527,763
Share-based Payment Arrangement [Member]
Common shares reserved for future issuance (in shares)	5,117,655	3,704,755
Possible Future Issuances Under Equity Incentive Plans [Member]
Common shares reserved for future issuance (in shares)	293,586	648,272
2021 Notes [Member]
Common shares reserved for future issuance (in shares)	4,481,182	4,481,182
Convertible Notes Payable [Member]
Common shares reserved for future issuance (in shares)	1,166,998	1,167,607