Note 10 - Per Share Data (Details Textual) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	61,050,122	21,897,479
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	24,813,373	3,744,623
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	94,413,680	40,677,826