XML 143 R120.htm IDEA: XBRL DOCUMENT v3.19.1

RELATED-PARTY TRANSACTIONS - Debentures (Details) - Direct or indirect shareholders R$ in Thousands	Dec. 31, 2018 BRL (R$) instrument	Dec. 31, 2017 BRL (R$) instrument
RELATED PARTY TRANSACTIONS
Debentures held | R$	R$ 0	R$ 348
Number of debentures held | instrument	0	63

X

- Definition

Number of debt instruments held.

+ References

No definition available.

+ Details

Name:	ggb_NumberOfDebtInstrumentsHeld
Namespace Prefix:	ggb_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The amount of instruments representing indebtedness held by the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_55&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_DebtInstrumentsHeld
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Details

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