The fine for existence of cartel.

No definition available.

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- Definition

The fine levied on the company and other long steel producers as a percentage of gross revenues in the year before administrative proceedings was commenced.

+ References

No definition available.

+ Details

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- Definition

The fine for existence of cartel updated by judicial accounting.

+ References

No definition available.

+ Details

Name:	ggb_FineForExistenceOfCartelUpdatedByJudicialAccounting
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Data Type:	xbrli:monetaryItemType
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- Definition

It represents the number of civil construction unions.

+ References

No definition available.

+ Details

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- Definition

The number of lawsuits that challenged the investigation.

+ References

No definition available.

+ Details

Name:	ggb_NumberOfLawsuitsChallengedInvestigation
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- Definition

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

+ References

No definition available.

+ Details

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- Definition

The amount of the estimated financial effect of contingent liabilities. [Refer: Contingent liabilities [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2021-01-01
-Paragraph 86
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2021-en-r&anchor=para_86_a&doctype=Standard
-URIDate 2021-03-24

+ Details

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- Details

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Namespace Prefix:
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- Details

Name:	srt_LitigationCaseAxis=ggb_AntitrustLegislationMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=ggb_OtherDemandsOfCivilNatureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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TAX, CIVIL AND LABOR CLAIMS AND CONTINGENT ASSETS - Civil Contingencies, Labor Contingencies and Administrative proceedings (Details) R$ in Thousands			12 Months Ended
	Aug. 01, 2013 BRL (R$)	Sep. 23, 2005 BRL (R$) item	Dec. 31, 2021 BRL (R$) item
Contingencies
Number of lawsuits that challenged the investigation \| item			2
Civil contingencies \| Antitrust Legislation
Contingencies
Number of civil construction unions \| item		2
Fine for existence of cartel on gross revenues (in percentage)		7.00%
Fine for existence of cartel		R$ 245,070
Fine for existence of cartel updated by judicial accounting	R$ 417,820
Civil contingencies \| Other Demands Of a Civil Nature
Contingencies
Estimated financial effect of contingent liabilities			R$ 456,848
Labor Contingencies
Contingencies
Estimated financial effect of contingent liabilities			R$ 452,847