Document and Entity Information - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2016
Mar. 10, 2017
Jun. 30, 2016
Document And Entity Information      
Entity Registrant Name B. Riley Financial, Inc.    
Entity Central Index Key 0001464790    
Document Type 10-K    
Trading Symbol RILY    
Document Period End Date Dec. 31, 2016    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity a Well-known Seasoned Issuer No    
Entity a Voluntary Filer No    
Entity's Reporting Status Current Yes    
Entity Filer Category Smaller Reporting Company    
Entity Public Float     $ 123,300
Entity Common Stock, Shares Outstanding   19,307,008  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2016