XML 150 R127.htm IDEA: XBRL DOCUMENT v3.21.1

RELATED-PARTY TRANSACTIONS - Key Management compensation and other information from related parties (Details) R$ in Thousands	12 Months Ended
	Dec. 31, 2020 BRL (R$) EquityInstruments	Dec. 31, 2019 BRL (R$) EquityInstruments	Dec. 31, 2018 EquityInstruments
Key Management
RELATED PARTY TRANSACTIONS
Salaries, variable compensation and benefits | R$	R$ 41,165	R$ 32,359
Contributions to defined contribution pension plans | R$	1,416	1,687
Cost of long-term incentive plan | R$	39,766	26,631
Fundacao Gerdau, Instituto Gerdau and Fundacao Ouro Branco
RELATED PARTY TRANSACTIONS
Contributions to defined contribution pension plans | R$	R$ 104,322	R$ 96,191
Restricted and Performance Shares | Key Management
Restricted shares granted to Management
Balance, beginning of year	6,717,872	6,717,872	6,375,547
Granted	733,218	1,083,116
Exercised	(937,325)	(627,076)
Cancelled	(64,112)	(38,553)
Others	(6,595)	75,163
Balance, end of year	6,456,248	6,717,872	6,717,872

X

- Definition

The number of other equity instruments (i.e, other than share options) other adjustments in a share-based payment arrangement.

+ References

No definition available.

+ Details

Name:	ggb_NumberOfOtherEquityInstrumentsOtherAdjustmentsInShareBasedPaymentArrangement
Namespace Prefix:	ggb_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	ggb_RestrictedSharesGrantedToKeyManagementPersonnelAbstract
Namespace Prefix:	ggb_
Data Type:	xbrli:stringItemType
Balance Type:	na
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 compensation to key management personnel. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2020-01-01
-Paragraph 17
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2020-en-r&anchor=para_17&doctype=Standard
-URIDate 2020-01-01

+ Details

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

X

- Definition

The amount of compensation to key management personnel in the form of post-employment benefits. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2020-01-01
-Paragraph 17
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2020-en-r&anchor=para_17_b&doctype=Standard
-URIDate 2020-01-01

+ Details

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

X

- Definition

The amount of compensation to key management personnel in the form of share-based payments. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2020-01-01
-Paragraph 17
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=24&code=ifrs-tx-2020-en-r&anchor=para_17_e&doctype=Standard
-URIDate 2020-01-01

+ Details

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

X

- Definition

The number of other equity instruments (ie other than share options) granted in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2020-01-01
-Paragraph 47
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_47_b&doctype=Standard
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2020-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_NumberOfInstrumentsOtherEquityInstrumentsGranted
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of other equity instruments (ie other than share options) exercised or vested in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2020-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_NumberOfOtherEquityInstrumentsExercisedOrVestedInSharebasedPaymentArrangement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of other equity instruments (ie other than share options) expired in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2020-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_NumberOfOtherEquityInstrumentsExpiredInSharebasedPaymentArrangement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The number of other equity instruments (ie other than share options) outstanding in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2020-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_NumberOfOtherEquityInstrumentsOutstandingInSharebasedPaymentArrangement
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

X

- Details

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

X

- Details

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

X

- Details

Name:	ifrs-full_TypesOfSharebasedPaymentArrangementsAxis=ggb_RestrictedAndPerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: