Investment in and Advances to Non-Consolidated Affiliates and Related Party Transactions (Ownership Structure and Percentage of Non-consolidated Affiliates) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	Dec. 31, 2014	Mar. 31, 2015
Aluminium Norf GmbH (Alunorf) [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%
Consorcio Candonga [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage		50.00%
Proceeds from sale of share in the joint venture	$ 63