v3.25.1

Document And Entity Information	May 27, 2025
Document Information [Line Items]
Entity, Registrant Name	BEL FUSE INC /NJ
Document, Type	8-K
Document, Period End Date	May 27, 2025
Entity, Incorporation, State or Country Code	NJ
Entity, File Number	000-11676
Entity, Tax Identification Number	22-1463699
Entity, Address, Address Line One	300 Executive Drive, Suite 300
Entity, Address, City or Town	West Orange
Entity, Address, State or Province	NJ
Entity, Address, Postal Zip Code	07052
City Area Code	201
Local Phone Number	432-0463
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Entity, Emerging Growth Company	false
Amendment Flag	false
Entity, Central Index Key	0000729580
ClassACommonStock Custom [Member]
Document Information [Line Items]
Title of 12(b) Security	Class A Common Stock
Trading Symbol	BELFA
Security Exchange Name	NASDAQ
ClassBCommonStock Custom [Member]
Document Information [Line Items]
Title of 12(b) Security	Class B Common Stock
Trading Symbol	BELFB
Security Exchange Name	NASDAQ

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

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- Definition

Area code of city

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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No definition available.

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- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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No definition available.

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Address Line 1 such as Attn, Building Name, Street Name

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Name of the City or Town

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Code for the postal or zip code

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Name of the state or province.

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- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
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- Definition

Indicate if registrant meets the emerging growth company criteria.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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No definition available.

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Two-character EDGAR code representing the state or country of incorporation.

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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Exchange Act
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- Definition

Local phone number for entity.

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No definition available.

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- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Exchange Act
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Title of a 12(b) registered security.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Name of the Exchange on which a security is registered.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
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-Subsection 12

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Trading symbol of an instrument as listed on an exchange.

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No definition available.

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- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Securities Act
-Number 230
-Section 425

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BEL FUSE INC /NJ 8-K