Debt (Bank Loans) (Details)		12 Months Ended
Mar. 31, 2015 Novelis Korea Bank Loan [Member] USD ($)	Mar. 31, 2015 Novelis Korea Bank Loan [Member] KRW	Mar. 31, 2015 Novelis Korea Bank Loan [Member] Korea 91-day Certificate of Deposit Rate [Member] Minimum [Member]	Mar. 31, 2015 Novelis Korea Bank Loan [Member] Korea 91-day Certificate of Deposit Rate [Member] Maximum [Member]	Mar. 31, 2015 BNDES Loans due February 2015 through April 2021 [Member] USD ($)
Debt Instrument [Line Items]
Principal amount	$ 192,000,000	212,000,000,000
Outstanding long-term loan due within one year	$ 78,000,000				$ 2,000,000
Basis spread on variable rate			0.80%	1.38%

Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19,20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Article 5

Name:	us-gaap_LongTermDebtCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant