Schedule of main assumptions for intangible asstes impairment (Details)	12 Months Ended
Dec. 31, 2021
Packaging [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	Until 2031 + perpetuity
Gross Margin	Gross margin updated based on historical data, impacts of business restructuring and market trends
Cost atualization	Cost based on historical data of each product and impacts of business restructuring
Perpetual growth rate	1% growth.
Packaging [Member] \| Bottom of range [member]
IfrsStatementLineItems [Line Items]
Discount rate applied to cash flow projections	7.00%
Description of discount rates applied to cash flow projections	5.87%
Packaging [Member] \| Top of range [member]
IfrsStatementLineItems [Line Items]
Discount rate applied to cash flow projections	9.50%
Description of discount rates applied to cash flow projections	6.40%
Mining [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	Until 2064
Gross Margin	It reflects projection of costs due to the progress of the mining plan as well as startup and project ramp up. Prices and exchange rates projected according to sectoral reports.
Cost atualization	Update of costs based on historical data, progress of the mining plan as well as startup and project ramp up
Perpetual growth rate	Without perpetuity
Other Steel [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	Until 2031 + perpetuity
Gross Margin	Gross margin updated based on historical data and market trends
Cost atualization	Updated costs based on historical data and market trends
Perpetual growth rate	Without growth
Flat Steel [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	Until 2031 + perpetuity
Gross Margin	Gross margin updated based on historical data and market trends
Cost atualization	Updated costs based on historical data and market trends
Perpetual growth rate	Without growth
Flat Steel 1 [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	Until 2034 + perpetuity
Gross Margin	Gross margin updated based on historical data and market trends
Cost atualization	Updated costs based on historical data and market trends
Perpetual growth rate	Without growth
Logistic [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	Until 2027
Gross Margin	Estimated based on market study to capture cargo and operating costs according to market trend studies
Cost atualization	Study-based costs and market trends
Perpetual growth rate	Without perpetuity
Cement [Member]
IfrsStatementLineItems [Line Items]
Measurement of recoverable value	Discounted Cash Flow
Cash flow projection	by 2050
Gross Margin	Gross margin updated based on historical data and market trends
Cost atualization	Study-based costs and market trends
Perpetual growth rate	Without perpetuity
Packaging 1 [Member]
IfrsStatementLineItems [Line Items]
Discount rate applied to cash flow projections	922.00%

The description of the basis on which the cash-generating unit's (group of units') recoverable amount has been determined (ie value in use or fair value less costs of disposal). [Refer: Cash-generating units [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 134
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_134_c&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_DescriptionOfBasisOnWhichUnitsRecoverableAmountHasBeenDetermined
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The discount rate applied to cash flow projections for a cash-generating unit (group of units). [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 134
-Subparagraph d
-Clause v
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_134_d_v&doctype=Standard
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 134
-Subparagraph e
-Clause v
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_134_e_v&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_DescriptionOfDiscountRatesAppliedToCashFlowProjections
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The description of the justification for using any growth rate to extrapolate cash flow projections that exceeds the long-term average growth rate for the products, industries or country (countries) in which the entity operates, or for the market to which a cash-generating unit (group of units) is dedicated. [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 134
-Subparagraph d
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_134_d_iv&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_DescriptionOfJustificationForUsingGrowthRateThatExceedsLongtermAverageGrowthRate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The description of key assumptions on which management has based its cash flow projections for the period covered by the most recent budgets/forecasts for a cash-generating unit (group of units). Key assumptions are those to which the unit's (group of units') recoverable amount is most sensitive. [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 134
-Subparagraph d
-Clause i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_134_d_i&doctype=Standard
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 135
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_135_c&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_DescriptionOfKeyAssumptionsOnWhichManagementHasBasedCashFlowProjections
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The description of key assumptions on which management has based its determination of fair value less costs of disposal for a cash-generating unit (group of units). Key assumptions are those to which the unit's (group of units') recoverable amount is most sensitive. [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 134
-Subparagraph e
-Clause i
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_134_e_i&doctype=Standard
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 36
-IssueDate 2021-01-01
-Paragraph 130
-Subparagraph f
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2021-en-r&anchor=para_130_f_iii&doctype=Standard
-URIDate 2021-03-24

+ Details

Name:	ifrs-full_DescriptionOfKeyAssumptionsOnWhichManagementHasBasedDeterminationOfFairValueLessCostsOfDisposal
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	sid_DescriptionOfDiscountRatesAppliedToCashFlowProjections1
Namespace Prefix:	sid_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	sid_DescriptionOfKeyAssumptionsOnWhichManagementHasBasedOnCostAtualization
Namespace Prefix:	sid_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	sid_IfrsStatementLineItems
Namespace Prefix:	sid_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_PackagingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_MiningMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_OtherSteelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_FlatSteelMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_FlatSteel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_LogisticMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_CementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_IndividualAssetsOrCashgeneratingUnitsWithSignificantAmountOfGoodwillOrIntangibleAssetsWithIndefiniteUsefulLivesAxis=sid_Packaging1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: