v3.19.1
Document And Entity Information - USD ($)
12 Months Ended
Dec. 31, 2018
Mar. 25, 2019
Jun. 30, 2018
Document Information [Line Items]      
Entity Registrant Name JMP GROUP LLC    
Entity Central Index Key 0001302350    
Trading Symbol jmp    
Current Fiscal Year End Date --12-31    
Entity Filer Category Non-accelerated Filer    
Entity Current Reporting Status Yes    
Entity Voluntary Filers No    
Entity Well-known Seasoned Issuer No    
Entity Emerging Growth Company false    
Entity Small Business true    
Entity Common Stock, Shares Outstanding (in shares)   21,258,983  
Entity Public Float     $ 57,366,229
Entity Shell Company false    
Document Type 10-K    
Document Period End Date Dec. 31, 2018    
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY    
Amendment Flag false