XML 27 R20.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Intangible Assets (Including Goodwill) | 6 Months Ended
--- | ---
Jun. 30, 2018
Text block1 [abstract] |
Intangible Assets (Including Goodwill) | NOTE 14 - INTANGIBLE ASSETS (INCLUDING GOODWILL)
(in millions of Euros) |  | Goodwill |  |  | Technology |  |  | Computer Software |  |  | Customer relationships |  |  | Work in Progress |  |  | Other |  |  | Total intangible assets (excluding goodwill) |
Net balance at January 1, 2018 |  |  | 403 |  |  |  | 24 |  |  |  | 18 |  |  |  | 15 |  |  |  | 9 |  |  |  | 2 |  |  |  | 68 |
Additions |  |  | — |  |  |  | — |  |  |  | 1 |  |  |  | — |  |  |  | 4 |  |  |  | — |  |  |  | 5 |
Amortization expense |  |  | — |  |  |  | (2 | ) |  |  | (4 | ) |  |  | — |  |  |  | — |  |  |  | — |  |  |  | (6 | )
Transfer during the period |  |  | — |  |  |  | — |  |  |  | 2 |  |  |  | — |  |  |  | (2 | ) |  |  | — |  |  |  | — |
Effects of changes in foreign exchange rates |  |  | 11 |  |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 1 |  |  |  | — |  |  |  | 1 |
Net balance at June 30, 2018 |  |  | 414 |  |  |  | 22 |  |  |  | 17 |  |  |  | 15 |  |  |  | 12 |  |  |  | 2 |  |  |  | 68 |
Cost |  |  | 414 |  |  |  | 83 |  |  |  | 58 |  |  |  | 39 |  |  |  | 13 |  |  |  | 2 |  |  |  | 195 |
Less accumulated amortization and impairment |  |  | — |  |  |  | (61 | ) |  |  | (41 | ) |  |  | (24 | ) |  |  | (1 | ) |  |  | — |  |  |  | (127 | )
Net balance at June 30, 2018 |  |  | 414 |  |  |  | 22 |  |  |  | 17 |  |  |  | 15 |  |  |  | 12 |  |  |  | 2 |  |  |  | 68 |

X
- Definition Text Block [Abstract] + References No definition available. + Details
Name: | cstm_TextBlock1Abstract
Namespace Prefix: | cstm_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for intangible assets. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 38 -IssueDate 2017-01-01 -Section Disclosure -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=38&date=2017-03-01&anchor=sect_Disclosure&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_DisclosureOfIntangibleAssetsExplanatory
Namespace Prefix: | ifrs-full_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration