Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 07, 2018
Document Information [Line Items]
Entity Registrant Name	BioCardia, Inc.
Entity Central Index Key	0000925741
Trading Symbol	bcda
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding (in shares)		38,241,244
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Amendment Flag	false