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Subsequent Event - Additional Information (Detail) - EUR (€)	Jul. 09, 2019	Jun. 30, 2019
Statement [LineItems]
Debt instrument face amount		€ 2,373,000,000
Constellium SE senior unsecured notes (Issued May 2014, due 2021) [member]
Statement [LineItems]
Debt instrument face amount		€ 300,000,000
Interest rate on debt		5.16%
Partial Redemption [member] | Constellium SE senior unsecured notes (Issued May 2014, due 2021) [member]
Statement [LineItems]
Debt instrument face amount	€ 100,000,000
Interest rate on debt	4.625%
Debt redemption price	100.00%

X

- Definition

Debt instrument, redemption price, percentage.

+ References

No definition available.

+ Details

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- Definition

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+ References

No definition available.

+ Details

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X

- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-IssueDate 2018-01-01
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- Details

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- Details

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