Note 7 - Loss Per Share - Antidilutive Securities Excluded from the Diluted Calculations (Details) - shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share-based Payment Arrangement, Option [Member]
Antidilutive Securities (in shares)	713,564	344,889
Warrant [Member]
Antidilutive Securities (in shares)	2,108,277	331,927
Convertible Debt Securities [Member]
Antidilutive Securities (in shares)	103,734	504,770
Series B Convertible Preferred Stock [Member]
Antidilutive Securities (in shares)	7,925	7,925
Series D Convertible Preferred Stock [Member]
Antidilutive Securities (in shares)	350,000
Series E Convertible Preferred Stock [Member]
Antidilutive Securities (in shares)	461,503