Investment in and Advances to Non-Consolidated Affiliates and Related Party Transactions (Details Textual) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended		12 Months Ended			1 Months Ended	12 Months Ended
	Aug. 31, 2013 USD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Mar. 31, 2014 Alunorf [Member] USD ($)	Mar. 31, 2014 Alunorf [Member] EUR (€)	Mar. 31, 2013 Alunorf [Member] USD ($)	Aug. 31, 2013 Hindalco [Member] USD ($)	Mar. 31, 2014 Hindalco [Member] USD ($)	Mar. 31, 2013 Hindalco [Member] USD ($)	Mar. 31, 2012 Hindalco [Member] USD ($)	Mar. 31, 2014 AV Metals, Inc. [Member] USD ($)	Mar. 31, 2014 MiniMRF LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage												50.00%	[1]
Difference between carrying amount and underlying equity		$ 517
Investment In and Advances To Non-Consolidated Affiliates and Related Party Transactions [Abstract]
Interest income earned on loan due				less than $1 million	less than $1 million
Guarantee as percentage of outstanding debt				50.00%	50.00%
Maximum exposure for gauranteed obligation					6
Revenue from related party								1	5	5
Proceeds from sale of bauxite mining rights and certain alumina assets and liabilities	8						8
Accounts receivable - related parties		54	38	54		38		1	1
Sales of equipment to related party									2
Return of capital to shareholder		$ (250)									$ 250

[1] In March 2014, we made a decision to withdraw from our investment in MiniMRF LLC, in which we had a 50% ownership. The write-off of our investment as a result of this withdraw was less than $1 million. The operating results of MiniMRF LLC were not material to the Company.