XML 167 R145.htm IDEA: XBRL DOCUMENT
v3.8.0.1

EQUITY - Treasury stocks (Details) - BRL (R$) R$ / shares in Units, R$ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Capital |  |  |
Equity at beginning of period | R$ 24,274,653 | R$ 31,970,383 | R$ 33,254,534
Repurchases |  | 95,370 | 189,071
Exercise of stock options | 19,682 | 5,560 | 35,902
Transfer of shares |  | 205,800 |
Equity at end of period | R$ 23,893,941 | R$ 24,274,653 | R$ 31,970,383
Investments and working capital reserve |  |  |
Investments and working capital reserve, annual percentage | 5.00% |  |
Common shares |  |  |
Capital |  |  |
Number of shares outstanding at beginning of the year | 571,929,945 | 571,929,945 | 571,929,945
Repurchases | 0 | 0 | 0
Exercise of stock options | 0 | 0 | 0
Transfer of shares | 0 | 0 | 0
Number of shares outstanding at end of period | 571,929,945 | 571,929,945 | 571,929,945
Preferred shares |  |  |
Capital |  |  |
Number of shares outstanding at beginning of the year | 1,137,018,570 | 1,114,744,538 | 1,132,613,562
Repurchases |  | 10,000,000 | 19,923,200
Exercise of stock options | 308,614 | 2,274,032 | 2,054,176
Transfer of shares |  | 30,000,000 |
Number of shares outstanding at end of period | 1,137,327,184 | 1,137,018,570 | 1,114,744,538
Treasury Stocks |  |  |
Capital |  |  |
Equity at beginning of period | R$ (98,746) | R$ (383,363) | R$ (233,142)
Repurchases |  | 95,343 | 186,033
Exercise of stock options | 22,661 | 10,461 | 35,812
Transfer of shares |  | 369,499 |
Equity at end of period | R$ (76,085) | R$ (98,746) | R$ (383,363)
Average acquisition cost | R$ 8.68 | R$ 10.89 | R$ 12.24
Treasury Stocks | Common shares |  |  |
Capital |  |  |
Number of shares outstanding at beginning of the year | 1,697,538 | 1,697,538 | 1,697,538
Repurchases |  | 0 | 0
Exercise of stock options | 0 | 0 | 0
Transfer of shares |  | 0 |
Number of shares outstanding at end of period | 1,697,538 | 1,697,538 | 1,697,538
Equity at beginning of period | R$ 557 | R$ 557 | R$ 557
Repurchases |  | 0 | 0
Exercise of stock options | 0 | 0 | 0
Transfer of shares |  | 0 |
Equity at end of period | R$ 557 | R$ 557 | R$ 557
Treasury Stocks | Preferred shares |  |  |
Capital |  |  |
Number of shares outstanding at beginning of the year | 9,012,675 | 31,286,707 | 13,417,683
Repurchases |  | 10,000,000 | 19,923,200
Exercise of stock options | (308,614) | (2,274,032) | (2,054,176)
Transfer of shares |  | (30,000,000) |
Number of shares outstanding at end of period | 8,704,061 | 9,012,675 | 31,286,707
Equity at beginning of period | R$ 98,189 | R$ 382,806 | R$ 232,585
Repurchases |  | 95,343 | 186,033
Exercise of stock options | (22,661) | (10,461) | (35,812)
Transfer of shares |  | (369,499) |
Equity at end of period | R$ 75,528 | R$ 98,189 | R$ 382,806

X
- Definition The increase (decrease) in the number of shares outstanding resulting from exercise of stock options. + References No definition available. + Details
Name: | ggb_IncreaseDecreaseInNumberOfSharesOutstandingThroughExerciseOfStockOptions
Namespace Prefix: | ggb_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The increase (decrease) in the number of shares outstanding resulting from treasury share transactions. + References No definition available. + Details
Name: | ggb_IncreaseDecreaseInNumberOfSharesOutstandingThroughTreasuryShareTransactions
Namespace Prefix: | ggb_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition 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. + References No definition available. + Details
Name: | ggb_InvestmentsAndWorkingCapitalAnnualReservePercent
Namespace Prefix: | ggb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition The decrease in the number of shares outstanding resulting from purchase of treasury shares. + References No definition available. + Details
Name: | ggb_PurchaseOfTreasurySharesNumber
Namespace Prefix: | ggb_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The average purchase price per share of the treasury shares. + References No definition available. + Details
Name: | ggb_TreasurySharesAverageAcquisitionPricePerShare
Namespace Prefix: | ggb_
Data Type: | num:perShareItemType
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_DisclosureOfClassesOfShareCapitalLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of residual interest in the assets of the entity after deducting all its liabilities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 1 -IssueDate 2017-01-01 -Paragraph 24 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=1&date=2017-03-01&anchor=para_24_a&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 1 -IssueDate 2017-01-01 -Paragraph 32 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=1&date=2017-03-01&anchor=para_32_a_i&doctype=Standard -URIDate 2017-03-09 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 13 -IssueDate 2017-01-01 -Paragraph 93 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2017-03-01&anchor=para_93_a&doctype=Standard -URIDate 2017-03-09 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 13 -IssueDate 2017-01-01 -Paragraph 93 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2017-03-01&anchor=para_93_b&doctype=Standard -URIDate 2017-03-09 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 13 -IssueDate 2017-01-01 -Paragraph 93 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2017-03-01&anchor=para_93_e&doctype=Standard -URIDate 2017-03-09 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard -URIDate 2017-03-09 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 78 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_e&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_Equity
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The increase (decrease) in equity resulting from the exercise of options. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 106 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncreaseDecreaseThroughExerciseOfOptions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The increase (decrease) in equity resulting from treasury share transactions. [Refer: Equity; Treasury shares] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 106 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_IncreaseDecreaseThroughTreasuryShareTransactions
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The number of shares that have been authorised and issued, reduced by treasury shares held. [Refer: Treasury shares] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 79 -Subparagraph a -Clause iv -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_79_a_iv&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_NumberOfSharesOutstanding
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The decrease in equity resulting from the purchase of treasury shares. [Refer: Treasury shares] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 106 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_PurchaseOfTreasuryShares
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | ifrs-full_ClassesOfShareCapitalAxis=ifrs-full_OrdinarySharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ClassesOfShareCapitalAxis=ifrs-full_PreferenceSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_ComponentsOfEquityAxis=ifrs-full_TreasurySharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |