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SUBSIDIARIES AND OPERATING SEGMENTS (Details) | 12 Months Ended
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Dec. 31, 2020
Cross Operating Segment | Constellium Singen GmbH (AS&I and P&ARP) |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
Cross Operating Segment | Constellium Valais S.A. (AS&I and A&T) |
Disclosure of subsidiaries [line items] |
Country | Switzerland
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Automotive USA, LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Engley (Changchun) Automotive Structures Co Ltd. |
Disclosure of subsidiaries [line items] |
Country | China
% Group Interest | 54.00%
Consolidation Method | Consolidated
AS&I | Constellium Extrusions Decin S.r.o. |
Disclosure of subsidiaries [line items] |
Country | Czech Republic
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Extrusions Deutschland GmbH |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Extrusions Landau GmbH |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Extrusions Burg GmbH |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Extrusions France S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Extrusions Levice S.r.o. |
Disclosure of subsidiaries [line items] |
Country | Slovakia
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Automotive Mexico, S. DE R.L. DE C.V. |
Disclosure of subsidiaries [line items] |
Country | Mexico
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Automotive Mexico Trading, S. DE R.L. DE C.V. |
Disclosure of subsidiaries [line items] |
Country | Mexico
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Astrex Inc |
Disclosure of subsidiaries [line items] |
Country | Canada
% Group Interest | 50.00%
Consolidation Method | Consolidated
AS&I | Constellium Automotive Zilina S.r.o. |
Disclosure of subsidiaries [line items] |
Country | Slovakia
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Automotive Nanjing Co Ltd |
Disclosure of subsidiaries [line items] |
Country | China
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium Automotive Spain SL |
Disclosure of subsidiaries [line items] |
Country | Spain
% Group Interest | 100.00%
Consolidation Method | Consolidated
AS&I | Constellium UK Limited |
Disclosure of subsidiaries [line items] |
Country | United Kingdom
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | Constellium Issoire S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | Constellium Montreuil Juigné S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | Constellium China Limited |
Disclosure of subsidiaries [line items] |
Country | China
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | Constellium Japan KK |
Disclosure of subsidiaries [line items] |
Country | Japan
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | Constellium Rolled Products Ravenswood, LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | Constellium Ussel S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
A&T | AluInfra Services SA |
Disclosure of subsidiaries [line items] |
Country | Switzerland
% Group Interest | 50.00%
Consolidation Method | Consolidated
P&ARP | Constellium Deutschland GmbH |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Rolled Products Singen GmbH KG |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Property and Equipment Company, LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Neuf Brisach S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Muscle Shoals LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Holding Muscle Shoals LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Muscle Shoals Funding II LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Listerhill Total Maintenance Center LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Metal Procurement LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Constellium Bowling Green LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
P&ARP | Rhenaroll |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 50.00%
Consolidation Method | Equity
Holdings & Corporate | C-TEC Constellium Technology Center S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium Finance S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium France III |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium France Holdco S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium International |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium Paris S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium Germany Holdco GmbH & Co. KG |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium Germany Verwaltungs GmbH |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium U.S. Holdings I, LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium US Intermediate Holdings LLC |
Disclosure of subsidiaries [line items] |
Country | U.S.
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium Switzerland AG |
Disclosure of subsidiaries [line items] |
Country | Switzerland
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Constellium Treuhand UG |
Disclosure of subsidiaries [line items] |
Country | Germany
% Group Interest | 100.00%
Consolidation Method | Consolidated
Holdings & Corporate | Engineered Products International S.A.S. |
Disclosure of subsidiaries [line items] |
Country | France
% Group Interest | 100.00%
Consolidation Method | Consolidated

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