Analysis of income and expense.

No definition available.

Name:	cstm_AnalysisOfIncomeAndExpenseLineItems
Namespace Prefix:	cstm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Borrowing costs capitalised credit.

+ References

No definition available.

+ Details

Name:	cstm_BorrowingCostsCapitalizedCredit
Namespace Prefix:	cstm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Borrowing Redemption Fees

+ References

No definition available.

+ Details

Name:	cstm_BorrowingRedemptionFees
Namespace Prefix:	cstm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Borrowings nominal interest rate.

+ References

No definition available.

+ Details

Name:	cstm_BorrowingsNominalInterestRate
Namespace Prefix:	cstm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Expenses on factoring arrangements paid or payable.

+ References

No definition available.

+ Details

Name:	cstm_ExpensesOnFactoringArrangementsPaidOrPayable
Namespace Prefix:	cstm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest cost on pension and employee benefits.

+ References

No definition available.

+ Details

Name:	cstm_InterestCostOnPensionAndEmployeeBenefits
Namespace Prefix:	cstm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Realized and Unrealized Exchange Gains (Losses) on Financing Activities - Net

+ References

No definition available.

+ Details

Name:	cstm_RealizedAndUnrealizedExchangeGainsLossesOnFinancingActivitiesNet
Namespace Prefix:	cstm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Write Off Borrowing Costs

+ References

No definition available.

+ Details

Name:	cstm_WriteOffBorrowingCosts
Namespace Prefix:	cstm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of interest and other costs that an entity incurs in connection with the borrowing of funds that are recognised as an expense.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2022-03-24
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_BorrowingCostsRecognisedAsExpense
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The weighted average of interest and other costs that an entity incurs in connection with the borrowing of funds applicable to the borrowings of the entity that are outstanding during the period, other than borrowings made specifically for the purpose of obtaining a qualifying asset. [Refer: Weighted average [member]; Borrowings]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 23
-IssueDate 2022-03-24
-Paragraph 26
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=23&code=ifrs-tx-2022-en-r&anchor=para_26_b&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_CapitalisationRateOfBorrowingCostsEligibleForCapitalisation
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of costs associated with financing activities of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2022-03-24
-Paragraph 82
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_82_b&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_FinanceCosts
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of income or cost associated with interest and other financing activities of the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2022-03-24
-Paragraph 85
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2022-en-r&anchor=para_85&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_FinanceIncomeCost
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gain (loss) arising from the difference between the carrying amount of the financial liability extinguished and the measurement of the consideration paid (equity instruments issued) to the creditor. [Refer: Carrying amount [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRIC
-Number 19
-IssueDate 2022-03-24
-Paragraph 11
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRIC&num=19&code=ifrs-tx-2022-en-r&anchor=para_11&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

+ Details

Name:	ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of interest expense on borrowings. [Refer: Interest expense; Borrowings]

+ References

+ Details

Name:	ifrs-full_InterestExpenseOnBorrowings
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of interest expense on debt instruments issued. [Refer: Interest expense; Debt instruments issued]

+ References

+ Details

Name:	ifrs-full_InterestExpenseOnDebtInstrumentsIssued
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of interest expense on lease liabilities. [Refer: Lease liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2022-03-24
-Paragraph 53
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2022-en-r&anchor=para_53_b&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_InterestExpenseOnLeaseLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The nominal or face amount of a financial instrument, used to calculate payments made on that instrument.

+ References

+ Details

Name:	ifrs-full_NotionalAmount
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of finance income or cost that the entity does not separately disclose in the same statement or note. [Refer: Finance income (cost)]

+ References

+ Details

Name:	ifrs-full_OtherFinanceIncomeCost
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash outflow for repayments of bonds, notes and debentures.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2022-03-24
-Paragraph 17
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2022-en-r&anchor=para_17&doctype=Standard
-URIDate 2022-03-24

+ Details

Name:	ifrs-full_RepaymentsOfBondsNotesAndDebentures
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	ifrs-full_BorrowingsByNameAxis=cstm_ConstelliumSESeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=cstm_ConstelliumSESeniorUnsecuredNotesIssuedFebruaryTwoThousandSeventeenDueTwoThousandTwentyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=cstm_ConstelliumSESeniorUnsecuredNotesIssuedMayTwoThousandFourteenDueTwoThousandTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=cstm_ConstelliumSESeniorUnsecuredNotesIssuedNovemberTwoThousandSeventeenDueTwoThousandTwentySixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

FINANCE COSTS—NET (Details)	1 Months Ended						12 Months Ended
FINANCE COSTS—NET (Details)	Nov. 30, 2021 EUR (€)	Nov. 30, 2021 USD ($)	Jun. 30, 2021 EUR (€)	Jun. 30, 2021 USD ($)	Feb. 28, 2021 EUR (€)	Feb. 28, 2021 USD ($)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 EUR (€)	Dec. 31, 2020 EUR (€)	Dec. 31, 2022 USD ($)
Analysis of income and expense [line items]
Interest expense on borrowings							€ (91,000,000)	€ (103,000,000)	€ (122,000,000)
Interest expense on leases							(10,000,000)	(14,000,000)	(10,000,000)
Interest cost on pension and other benefits							(11,000,000)	(9,000,000)	(11,000,000)
Expenses on factoring arrangements							(15,000,000)	(9,000,000)	(10,000,000)
Net loss on settlement of debt							0	(27,000,000)	0
Realized and unrealized (losses) / gains on debt derivatives at fair value							1,000,000	10,000,000	(32,000,000)
Realized and unrealized exchange (losses) / gains on financing activities - net							(1,000,000)	(10,000,000)	37,000,000
Other finance expenses							(5,000,000)	(6,000,000)	(12,000,000)
Capitalized borrowing costs							1,000,000	1,000,000	1,000,000
Finance expenses							(131,000,000)	(167,000,000)	(159,000,000)
Finance costs - net							(131,000,000)	(167,000,000)	(159,000,000)
Redemption of senior notes							192,000,000	€ 1,052,000,000	€ 209,000,000
Nominal value							€ 2,053,000,000
Capitalization rate							5.00%	5.00%	6.00%
Constellium SE Senior Notes
Analysis of income and expense [line items]
Interest expense on debt instruments issued							€ 79,000,000	€ 92,000,000
Borrowing costs recognised as expense							€ 4,000,000	€ 4,000,000
Senior Unsecured Notes Issued February 2017 and due 2025
Analysis of income and expense [line items]
Redemption of senior notes					€ 536,000,000	$ 650,000,000
Nominal rate					6.625%	6.625%
Borrowing redemption fees					€ 9,000,000
Write off borrowing costs					€ 8,000,000
Senior Unsecured Notes Issued May 2014 and due 2024
Analysis of income and expense [line items]
Redemption of senior notes			€ 328,000,000	$ 400,000,000
Nominal rate			5.75%	5.75%
Borrowing redemption fees			€ 3,000,000
Write off borrowing costs			€ 3,000,000
Senior Unsecured Notes Issued November 2017 and due 2026
Analysis of income and expense [line items]
Redemption of senior notes	€ 177,000,000	$ 200,000,000
Nominal rate	5.875%	5.875%					5.875%
Borrowing redemption fees	€ 3,000,000
Write off borrowing costs	€ 1,000,000
Nominal value		$ 500,000,000					€ 281,000,000			$ 300,000,000