XML 11 R1.htm IDEA: XBRL DOCUMENT v3.19.2
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name ARCA Biopharma, Inc.  
Entity Central Index Key 0000907654  
Entity Current Reporting Status Yes  
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Period Focus Q2  
Trading Symbol ABIO  
Document Fiscal Year Focus 2019  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   1,455,556
Entity Shell Company false  
Entity File Number 000-22873  
Entity Tax Identification Number 363855489  
Entity Address, Address Line One 11080 CirclePoint Road  
Entity Address, Address Line Two Suite 140  
Entity Address, City or Town Westminster  
Entity Address, State or Province CO  
Entity Address, Postal Zip Code 80020  
City Area Code 720  
Local Phone Number 940-2200