Total cost of shares repurchased divided by the total number of shares repurchased.

No definition available.

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Namespace Prefix:	ggb_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

Name:	ggb_IfrsStockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	ggb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	ggb_IfrsStockRepurchaseProgramPeriodInForce
Namespace Prefix:	ggb_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of treasury shares cancelled.

+ References

No definition available.

+ Details

Name:	ggb_NumberOfTreasurySharesCancelled
Namespace Prefix:	ggb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of shares acquired as per the program.

+ References

No definition available.

+ Details

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Namespace Prefix:	ggb_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

The decrease in the number of shares outstanding resulting from purchase of treasury shares.

+ References

No definition available.

+ Details

Name:	ggb_PurchaseOfTreasurySharesNumber
Namespace Prefix:	ggb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The maximum percentage of total outstanding preferred shares authorized for repurchase.

+ References

No definition available.

+ Details

Name:	ggb_ShareBuyBackProgramPercentageOfTotalOutstandingPreferredShares
Namespace Prefix:	ggb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The average purchase price per share of the treasury shares.

+ References

No definition available.

+ Details

Name:	ggb_TreasurySharesAverageAcquisitionPricePerShare
Namespace Prefix:	ggb_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- 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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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares that have been authorised and issued, reduced by treasury shares held. [Refer: Treasury shares]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 79
-Subparagraph a
-Clause iv
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_79_a_iv&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_NumberOfSharesOutstanding
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The decrease in equity resulting from the purchase of treasury shares. [Refer: Treasury shares]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 106
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_106_d&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_PurchaseOfTreasuryShares
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ggb_IfrsShareRepurchaseProgramAxis=ggb_ShareBuybackProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=ifrs-full_OrdinarySharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=ifrs-full_PreferenceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ComponentsOfEquityAxis=ifrs-full_TreasurySharesMember
Namespace Prefix:
Data Type:	na
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EQUITY - Treasury stocks (Details) R$ / shares in Units, R$ in Thousands		12 Months Ended
	May 04, 2022 shares	Dec. 31, 2023 R$ / shares shares	Dec. 31, 2022 BRL (R$) R$ / shares shares	Dec. 31, 2021 R$ / shares shares	Nov. 08, 2022 shares	Dec. 31, 2020 shares
Share Buyback Program
EQUITY
Quantity of shares authorized to be acquired	55,000,000
Percentage of outstanding preferred shares	5.00%
Maximum duration period of share buyback program	18 months
Common shares
EQUITY
Outstanding shares		600,526,442	571,929,945	571,929,945	571,929,945	571,929,945
Preferred shares
EQUITY
Number of shares repurchased			44,564,000
Outstanding shares		1,148,995,967	1,091,630,395	1,133,816,901	1,101,467,245	1,129,231,487
Treasury Stocks
EQUITY
Average acquisition cost \| R$ / shares		R$ 19.91	R$ 18.30	R$ 12.43
Treasury Stocks \| Common shares
EQUITY
Number of shares repurchased			1,697,538		1,697,538
Outstanding shares				1,697,538		1,697,538
Treasury Stocks \| Preferred shares
EQUITY
Number of shares repurchased			44,564,000
Value of shares repurchased \| R$			R$ 1,073,124
Number of shares repurchased			44,564,000		44,564,000
Outstanding shares		7,544,641	9,836,850	12,214,344		16,799,758
Treasury Stocks \| Preferred shares \| Share Buyback Program
EQUITY
Number of shares repurchased			44,564,000
Value of shares repurchased \| R$			R$ 1,073,124
Average price per share \| R$ / shares		R$ 24.08
Percentage of shares acquired		81.0