XML 12 R1.htm IDEA: XBRL DOCUMENT v3.24.0.1
Document And Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2023
Feb. 28, 2024
Jun. 30, 2023
Document Information [Line Items]      
Entity Central Index Key 0001303942    
Entity Registrant Name BankFinancial CORP    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2023    
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2023    
Document Transition Report false    
Entity File Number 0-51331    
Entity Incorporation, State or Country Code MD    
Entity Tax Identification Number 75-3199276    
Entity Address, Address Line One 60 North Frontage Road    
Entity Address, City or Town Burr Ridge    
Entity Address, State or Province IL    
Entity Address, Postal Zip Code 60527    
City Area Code 800    
Local Phone Number 894-6900    
Title of 12(b) Security Common Stock, par value $0.01 per share    
Trading Symbol BFIN    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Document Financial Statement Error Correction [Flag] false    
Entity Shell Company false    
Entity Public Float     $ 94,800,000
Entity Common Stock, Shares Outstanding   12,460,678  
Auditor Name RSM US LLP    
Auditor Location Chicago, Illinois    
Auditor Firm ID 49