Name:	cmc_CurrentFederalTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of income tax expense for the period representing amounts paid or payable (or refundable) as determined by applying the provisions of foreign enacted tax law to the foreign taxable Income or Loss from continuing and discontinued operations.

No definition available.

Name:	cmc_CurrentForeignTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	cmc_CurrentIncomeTaxExpenseBenefitAbstractAbstract
Namespace Prefix:	cmc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The component of income tax expense for the period representing amounts of income taxes paid or payable (or refundable) for the period for all income tax obligations as determined by applying the provisions of relevant enacted tax laws to relevant amounts of taxable Income or Loss from continuing and discontinued operations.

No definition available.

Name:	cmc_CurrentIncomeTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of income tax expense for the period representing amounts paid or payable (or refundable) as determined by applying the provisions of enacted state and local tax law to relevant amounts of taxable Income or Loss from continuing and discontinued operations.

No definition available.

Name:	cmc_CurrentStateAndLocalTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of total income tax expense for the period comprised of the increase (decrease) during the period in the entity's domestic deferred tax assets and liabilities attributable to continuing and discontinued operations as determined by applying the provisions of the federally enacted tax law .

No definition available.

Name:	cmc_DeferredFederalIncomeTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The component of total income tax expense for the period comprised of the increase (decrease) in the entity's net foreign deferred tax assets and liabilities attributable to continuing and discontinued operations as determined by applying the provisions of applicable enacted tax laws of countries other than the country of domicile.

No definition available.

Name:	cmc_DeferredForeignIncomeTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	cmc_DeferredIncomeTaxExpenseBenefitAbstractAbstract
Namespace Prefix:	cmc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The component of income tax expense for the period representing the increase (decrease) in the entity's deferred tax assets and liabilities pertaining to continuing and discontinued operations.

No definition available.

Name:	cmc_DeferredIncomeTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

TThe component of total income tax expense for the period comprised of the increase (decrease) in the entity's state and local deferred tax assets and liabilities attributable to continuing and discontinued operations as determined by applying the provisions of the applicable enacted tax laws.

No definition available.

Name:	cmc_DeferredStateAndLocalIncomeTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing and discontinued operations.

No definition available.

Name:	cmc_IncomeTaxExpenseBenefitFromContinuingAndDiscontinuedOperations
Namespace Prefix:	cmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Tax effect allocated to a disposal group that is classified as a component of the entity reported as a separate component of income before extraordinary items. Includes the tax effects of the following: income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b),(c)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32672-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=18498875&loc=d3e38679-109324

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e957-107759

Name:	us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(h))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Article 4

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

-URI http://asc.fasb.org/extlink&oid=6515339

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a),(b)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319