v2.4.0.8
Document and Entity Information
9 Months Ended
Sep. 30, 2014
Nov. 01, 2014
Class A Common Stock [Member]
Nov. 01, 2014
Class B Common Stock [Member]
Entity Information [Line Items]      
Entity Registrant Name BEL FUSE INC /NJ    
Entity Central Index Key 0000729580    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status No    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   2,174,912 9,704,877
Document Fiscal Year Focus 2014    
Document Fiscal Period Focus Q3    
Document Type 10-Q    
Amendment Flag false    
Document Period End Date Sep. 30, 2014