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EMPLOYEE BENEFITS (Details 3) - BRL (R$) R$ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
IfrsStatementLineItems [Line Items]
Fair value of plan assets at the beginning of the year	R$ 3,713,099	R$ 3,572,869
Return on plan assets (less interest income)	33,322	(62,338)	R$ 138,489
Fair value of plan assets at the end of the year	3,683,575	3,713,099	3,572,869
Defined benefit plans other than multi-employer plans, state plans and plans that share risks between entities under common control [member]
IfrsStatementLineItems [Line Items]
Fair value of plan assets at the beginning of the year	(3,713,099)	(3,572,869)	(3,584,244)
Consolidation of CSN Cimentos Brazil			(63,292)
Interest income	(335,322)	(401,054)	(369,488)
Benefits Paid	333,037	324,750	310,471
Participant contributions made in the year	(1,348)	(1,404)	(1,382)
Employer contributions made in the year	(165)	(184)	(144)
Return on plan assets (less interest income)	33,322	(62,338)	135,210
Fair value of plan assets at the end of the year	R$ (3,683,575)	R$ (3,713,099)	R$ (3,572,869)

X

- Definition

The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 57
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_57_a&doctype=Standard
-URIDate 2024-03-27

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X

- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from the return on plan assets, excluding amounts included in interest income or expense. The return on plan assets is interest, dividends and other revenue derived from the plan assets, together with realised and unrealised gains or losses on the plan assets, less any costs of managing plan assets and less any tax payable by the plan itself, other than tax included in the actuarial assumptions used to measure the present value of the defined benefit obligation. [Refer: Plan assets [member]; Net defined benefit liability (asset); Actuarial assumptions [domain]; Increase (decrease) in net defined benefit liability (asset) resulting from interest expense (income)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2024-01-01
-Paragraph 141
-Subparagraph c
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_c_i&doctype=Standard
-URIDate 2024-03-27

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- References

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