Document and Entity Information
9 Months Ended
Sep. 30, 2014
Oct. 29, 2014
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2014  
Document Fiscal Year Focus 2014  
Document Fiscal Period Focus Q3  
Trading Symbol ISTR  
Entity Registrant Name INVESTAR HOLDING CORP  
Entity Central Index Key 0001602658  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Common Stock, Shares Outstanding   7,254,244