XML 100 R92.htm IDEA: XBRL DOCUMENT
v3.20.2

FINANCIAL INSTRUMENTS - Derivatives Measured at Fair Value (Details) - EUR (€) € in Millions | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Disclosure of financial instruments measured at fair value [line items] |  |
Other financial assets - derivatives | € 31 | € 29
Other financial liabilities - derivatives | 75 | 58
Level 1 |  |
Disclosure of financial instruments measured at fair value [line items] |  |
Other financial assets - derivatives | 12 | 8
Other financial liabilities - derivatives | 30 | 19
Level 2 |  |
Disclosure of financial instruments measured at fair value [line items] |  |
Other financial assets - derivatives | 19 | 21
Other financial liabilities - derivatives | 45 | 39
Level 3 |  |
Disclosure of financial instruments measured at fair value [line items] |  |
Other financial assets - derivatives | 0 | 0
Other financial liabilities - derivatives | € 0 | € 0

X
- Definition Disclosure of financial instruments measured at fair value. + References No definition available. + Details
Name: | cstm_DisclosureOfFinancialInstrumentsMeasuredAtFairValueLineItems
Namespace Prefix: | cstm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of financial assets classified as derivative instruments. [Refer: Financial assets; Derivatives [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard -URIDate 2019-03-27 + Details
Name: | ifrs-full_DerivativeFinancialAssets
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of financial liabilities classified as derivative instruments. [Refer: Financial assets; Derivatives [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2019-01-01 -Paragraph 55 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard -URIDate 2019-03-27 + Details
Name: | ifrs-full_DerivativeFinancialLiabilities
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | ifrs-full_LevelsOfFairValueHierarchyAxis=ifrs-full_Level1OfFairValueHierarchyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_LevelsOfFairValueHierarchyAxis=ifrs-full_Level2OfFairValueHierarchyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_LevelsOfFairValueHierarchyAxis=ifrs-full_Level3OfFairValueHierarchyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |