XML 154 R131.htm IDEA: XBRL DOCUMENT
v3.21.1

EMPLOYEE BENEFITS - Defined benefit pension plan - Reconciliation of plan assets and liabilities (Details) - Defined benefit pension plan - BRL (R$) R$ in Thousands | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | --- | ---
Reconciliations of assets and liabilities of the plans |  |  |  |
Net | R$ (1,441,592) | R$ (1,138,591) |  |
Defined benefit obligation | (1,441,592) | (1,138,591) |  |
Present value of the defined benefit obligations |  |  |  |
Reconciliations of assets and liabilities of the plans |  |  |  |
Net | (5,921,285) | (4,601,965) | R$ (4,391,251) | R$ (4,314,592)
Plan assets |  |  |  |
Reconciliations of assets and liabilities of the plans |  |  |  |
Net | 4,652,000 | 3,656,891 | R$ 3,568,934 | R$ 3,456,613
Asset ceiling restrictions on recognition of net funded assets |  |  |  |
Reconciliations of assets and liabilities of the plans |  |  |  |
Net | R$ (172,307) | R$ (193,517) |  |

X
- References No definition available. + Details
Name: | ggb_ReconciliationsOfPlanAssetsAndLiabilitiesAbstract
Namespace Prefix: | ggb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 140 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_140_a&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_LiabilityAssetOfDefinedBenefitPlans
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of deficit in a defined benefit plan. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2020-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_55&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_RecognisedLiabilitiesDefinedBenefitPlan
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | ifrs-full_DefinedBenefitPlansAxis=ifrs-full_DefinedBenefitPlansOtherThanMultiemployerPlansStatePlansAndPlansThatShareRisksBetweenEntitiesUnderCommonControlMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_PresentValueOfDefinedBenefitObligationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_PlanAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_NetDefinedBenefitLiabilityAssetAxis=ifrs-full_EffectOfAssetCeilingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |