EQUITY - Reserves (Details)	12 Months Ended
Dec. 31, 2025
EQUITY.
Minimum legal reserve transfer as a percentage of net income	5.00%
Maximum legal reserve balance as a percentage of total paid-in capital	20.00%
Investments and working capital reserve, annual percentage	5.00%

The percentage of annual profits which may be transferred to the Investments and Working Capital Reserve if proposed by the Board of Directors and approved by shareholders.

No definition available.

Name:	ggb_InvestmentsAndWorkingCapitalAnnualReservePercent
Namespace Prefix:	ggb_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration