XML 99 R91.htm IDEA: XBRL DOCUMENT v3.19.2

Property Plant and Equipment - Additional Information (Detail) € in Millions	6 Months Ended
	Jun. 30, 2019 EUR (€)
Disclosure of detailed information about property, plant and equipment [abstract]
Operating lease expenses	€ 7

X

- Definition

Operating lease expenses.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfPropertyPlantAndEquipmentAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration