Debt (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended				3 Months Ended			3 Months Ended			3 Months Ended
	Jan. 31, 2012	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012 Aluminio [Member] D	Jan. 31, 2012 Aluminio [Member]	Mar. 31, 2012 Revolving Credit Agreement [Member] Y	Feb. 29, 2012 Revolving Credit Agreement [Member]	Jan. 31, 2012 Revolving Credit Agreement [Member]	Mar. 31, 2012 Revolving Credit Facility [Member]	Mar. 31, 2012 Two Term Loan Agreements [Member]	Jan. 31, 2012 Two Term Loan Agreements [Member]	Mar. 31, 2012 First Loan Agreement [Member]	Feb. 29, 2012 First Loan Agreement [Member]
Debt Instrument [Line Items]
Repayment of outstanding debt	$ 322	$ 414	$ 33	$ 60
Outstanding debt, interest rate	6.00%
Line of credit facility, amount outstanding					280		100	100			350		100
Contributions to pension plans		$ 213
Applicable margin on LIBOR										1.50%		1.25%
Line of credit facility, expiration date									December 2012	July 2012
Weighted-average interest rate				2.32%
Weighted-average maturity days				172
Revolving credit facility, term						5