Note 1 - Organization and Operations - Proportions of Patients (Details)	3 Months Ended
	Mar. 31, 2019
Vascular Stenosis [Member] | Vonapanitase [Member]
Patients experiencing common adverse events	35.10%
Vascular Stenosis [Member] | Placebo [Member]
Patients experiencing common adverse events	41.70%
Fistula Thrombosis [Member] | Vonapanitase [Member]
Patients experiencing common adverse events	16.80%
Fistula Thrombosis [Member] | Placebo [Member]
Patients experiencing common adverse events	18.60%
Local Swelling [Member] | Vonapanitase [Member]
Patients experiencing common adverse events	5.00%
Local Swelling [Member] | Placebo [Member]
Patients experiencing common adverse events	2.00%
Hemotoma [Member] | Vonapanitase [Member]
Patients experiencing common adverse events	5.00%
Hemotoma [Member] | Placebo [Member]
Patients experiencing common adverse events	3.90%