v2.4.0.8
Document and Entity Information
3 Months Ended
Mar. 31, 2014
May 01, 2014
Class A Common Stock [Member]
May 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 Yes    
Entity Filer Category Accelerated Filer    
Entity Common Stock, Shares Outstanding   2,174,912 9,333,677
Document Fiscal Year Focus 2014    
Document Fiscal Period Focus Q1    
Document Type 10-Q    
Amendment Flag false    
Document Period End Date Mar. 31, 2014