XML 141 R118.htm IDEA: XBRL DOCUMENT v3.19.1

RELATED-PARTY TRANSACTIONS - Operations with related parties (Details) - BRL (R$) R$ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Controlling shareholders
RELATED PARTY TRANSACTIONS
Guarantee fee percentage	0.95%	0.95%	0.95%
Debenture guarantee fees	R$ 194	R$ 689	R$ 4,732
Revenue from rental agreement	445	801	1,001
Investments
RELATED PARTY TRANSACTIONS
Sales to Related parties	1,382,584	630,190	421,415
Purchases from related parties	129,513	121,618	141,275
Net amount, related party transactions	R$ 1,253,071	R$ 508,572	R$ 280,140

X

- Definition

Reflects the guarantee fee as a percentage on the amount of debentures guaranteed.

+ References

No definition available.

+ Details

Name:	ggb_DebentureGuaranteeFeePercentage
Namespace Prefix:	ggb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The expense related to the guarantee of debentures.

+ References

No definition available.

+ Details

Name:	ggb_DebentureGuaranteeFees
Namespace Prefix:	ggb_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The net revenue (purchases) from transactions with related parties.

+ References

No definition available.

+ Details

Name:	ggb_NetRevenuePurchasesFromTransactionsWithRelatedParties
Namespace Prefix:	ggb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Revenue from rental agreement entered with related party.

+ References

No definition available.

+ Details

Name:	ggb_RevenueFromRentalAgreementWithRelatedParty
Namespace Prefix:	ggb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

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

+ References

No definition available.

+ Details

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

X

- Definition

The amount of goods purchased by the entity in related party transactions. [Refer: Related parties [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 24
-IssueDate 2018-01-01
-Paragraph 21
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2018-03-01&anchor=para_21_a&doctype=Standard
-URIDate 2018-03-16

+ Details

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

X

- Definition

The amount of revenue arising from the sale of goods in related party transactions. [Refer: Revenue; Related parties [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 24
-IssueDate 2018-01-01
-Paragraph 21
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2018-03-01&anchor=para_21_a&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_RevenueFromSaleOfGoodsRelatedPartyTransactions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=ggb_ControllingShareholdersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_ClassesOfAssetsAxis=ifrs-full_InvestmentsAccountedForUsingEquityMethodMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: