Investment In and Advances To Non-Consolidated Affiliates and Related Party Transactions (Details Textual)			6 Months Ended						6 Months Ended		6 Months Ended
	Sep. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2014 Alunorf [Member] USD ($)	Sep. 30, 2013 Alunorf [Member] USD ($)	Sep. 30, 2014 Alunorf [Member] EUR (€)	Mar. 31, 2014 Alunorf [Member] USD ($)	Sep. 30, 2014 Alunorf [Member] Supplemental Employee Retirement Plan [Member] USD ($)	Sep. 30, 2014 Alunorf [Member] Supplemental Employee Retirement Plan [Member] EUR (€)	Sep. 30, 2014 Parent Company of Entity [Member] USD ($)	Mar. 31, 2014 Parent Company of Entity [Member] USD ($)	Sep. 30, 2014 AV Metals, Inc. [Member] USD ($)
Investment In and Advances To Non-Consolidated Affiliates and Related Party Transactions [Abstract]
Interest income on a loan due from a non-consolidated affiliate			$ 1,000,000
Interest income earned on loan due from Alunorf			less than $1 million	less than $1 million
Guarantee as percentage of outstanding debt			50.00%
Maximum exposure for gauranteed obligation					6,000,000		4,000,000	3,000,000
Revenue from related parties									1,000,000
Net Sales between Novelis and Parent company			1	1
Accounts receivable-related parties	60,000,000	54,000,000	60,000,000			54,000,000			1,000,000	1,000,000
Return of capital to parent company											$ 250,000,000