XML 155 R118.htm IDEA: XBRL DOCUMENT v3.8.0.1
Investments Accounted for Under Equity Method - Summary of Guarantees and Commitments (Detail) - Constellium-UACJ ABS LLC [member] - EUR (€)
€ in Millions
Dec. 31, 2017
Dec. 31, 2016
Disclosure of investments accounted for using equity method [line items]    
Total Guarantees and commitments given € 14 € 34
Financial guarantees [member]    
Disclosure of investments accounted for using equity method [line items]    
Total Guarantees and commitments given 11  
Loan Facility Commitment [Member]    
Disclosure of investments accounted for using equity method [line items]    
Total Guarantees and commitments given   15
Supplier guarantees [member]    
Disclosure of investments accounted for using equity method [line items]    
Total Guarantees and commitments given € 3 € 19