Number of shares of the company's common stock owned by the plan.

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- Definition

The pretax total of net gain (loss), prior service cost (credit), and transition assets (obligations), as well as minimum pension liability if still remaining, included in accumulated other comprehensive income associated with a defined benefit pension or other postretirement plan(s) because they have yet to be recognized as components of net periodic benefit cost.

+ References

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-Name Accounting Standards Codification
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- References

No definition available.

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- Definition

The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

+ References

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- Definition

Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Prior Service Cost
-URI http://asc.fasb.org/extlink&oid=49177896

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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- References

No definition available.

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- Definition

Amount of other defined benefit plan costs.

+ References

No definition available.

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Service Cost (Component of Net Periodic Pension Cost)
-URI http://asc.fasb.org/extlink&oid=6525008

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-Publisher FASB
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- Definition

The amount of the cost recognized during the period for defined contribution plans.

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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.

+ References

No definition available.

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RETIREMENT FUND AND PROFIT SHARING PLAN (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Bel Fuse Inc Employees Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Compensation expense	$ 300	$ 300
Bel Fuse Inc Employees Savings Plan [Member] \| Common Class A [Member]
Defined Contribution Plan Disclosure [Line Items]
Shares owned by plan (in shares)	13,928
Bel Fuse Inc Employees Savings Plan [Member] \| Common Class B [Member]
Defined Contribution Plan Disclosure [Line Items]
Shares owned by plan (in shares)	168,647
Non Defined Retirement Fund [Member]
Defined Contribution Plan Disclosure [Line Items]
Compensation expense	$ 100	100
Non Defined Retirement Fund [Member] \| Common Class A [Member]
Defined Contribution Plan Disclosure [Line Items]
Shares owned by plan (in shares)	3,323
Non Defined Retirement Fund [Member] \| Common Class B [Member]
Defined Contribution Plan Disclosure [Line Items]
Shares owned by plan (in shares)	17,342
SERP [Member]
Components of SERP expense [Abstract]
Service cost	$ 148	138
Interest cost	165	142
Net amortization	98	92
Net periodic benefit cost	411	$ 372
Amounts recognized in accumulated other comprehensive loss, pretax [Abstract]
Prior service cost	820		$ 866
Net loss	3,005		3,465
Total amounts recognized in accumulated other comprehensive loss	$ 3,825		$ 4,331