Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 02, 2018
Document Information [Line Items]
Entity Registrant Name	PROTEON THERAPEUTICS INC
Entity Central Index Key	0001359931
Trading Symbol	prto
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Common Stock, Shares Outstanding (in shares)		19,221,292
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Ex Transition Period	false