Debt (Short-Term Borrowings) (Details) In Millions, unless otherwise specified	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2014 Novelis Brazil Loan [Member] USD ($)	Sep. 30, 2014 Novelis Korea Bank Loan [Member] USD ($)	Sep. 30, 2014 Novelis Korea Bank Loan [Member] KRW	Sep. 30, 2014 Novelis Vietnam Loan [Member] USD ($)	Sep. 30, 2014 Novelis Vietnam Loan [Member] VND	Sep. 30, 2014 Bank Overdrafts [Member] USD ($)	Sep. 30, 2014 ABL Facility [Member] USD ($)	Sep. 30, 2014 ABL Facility [Member] Short-term Loan [Member] USD ($)	Sep. 30, 2014 KOREA, REPUBLIC OF Revolving Credit Facility [Member] USD ($)	Sep. 30, 2014 KOREA, REPUBLIC OF Revolving Credit Facility [Member] KRW
Short-term Debt [Line Items]
Short–term borrowings	$ 1,044	$ 723	$ 205	$ 55	58,000	$ 10	221,000	$ 3		$ 771	$ 189	199,000
Short-term debt, weighted average interest rate	3.67%	3.58%
Letters of credit outstanding amount									10
Remaining borrowing capacity									$ 219