XML 91 R68.htm IDEA: XBRL DOCUMENT
v3.21.1

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Details) | 12 Months Ended
--- | ---
Dec. 31, 2019 shares
Dividends and Interest on equity |
Minimum annual mandatory dividend (as a percent) | 30.00%
Legal reserve, as a percent of net income | 5.00%
Earnings per Share |
Antidilutive shares excluded from calculation of diluted EPS | 0

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

X
- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References No definition available. + Details
Name: | ggb_IfrsAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix: | ggb_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Legal reserves, as a percent of net income. + References No definition available. + Details
Name: | ggb_LegalReserveAsPercentOfNetIncome
Namespace Prefix: | ggb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of mandatory minimum annual dividend payable by the company. + References No definition available. + Details
Name: | ggb_MandatoryMinimumAnnualDividendPercentage
Namespace Prefix: | ggb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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