v2.4.0.8
Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Mar. 01, 2014
Jun. 30, 2013
Document and Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2013    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2013    
Entity Registrant Name BankFinancial CORP    
Entity Central Index Key 0001303942    
Current Fiscal Year End Date --12-31    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   21,101,966  
Entity Well-known Seasoned Issuer No    
Entity Public Float     $ 168.2
Entity Current Reporting Status Yes    
Entity Voluntary Filers No