XML 193 R156.htm IDEA: XBRL DOCUMENT v3.8.0.1

Provisions - Additional Information (Detail) € in Millions	12 Months Ended
	Dec. 31, 2017 EUR (€)
Disclosure of other provisions [line items]
Change in discount rate	0.50%
Close down and environmental remediation costs [member]
Disclosure of other provisions [line items]
Average discount rate	1.04%
Change in discount rate	0.50%
Change in provision	€ 2
Expected provisions settlement period	40 years

X

- Definition

Average discount rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	cstm_
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Balance Type:	na
Period Type:	duration

X

- Definition

Increase decrease of discount rate.

+ References

No definition available.

+ Details

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Namespace Prefix:	cstm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The description of the expected timing of outflows of economic benefits related to other provisions. [Refer: Other provisions]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2017-01-01
-Paragraph 85
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_85_a&doctype=Standard
-URIDate 2017-03-09

+ Details

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X

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
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X

- Definition

The increase in existing other provisions. [Refer: Other provisions]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2017-01-01
-Paragraph 84
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_b&doctype=Standard
-URIDate 2017-03-09

+ Details

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

X

- Details

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Namespace Prefix:
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Balance Type:
Period Type: