Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended
	Feb. 29, 2012	Jan. 31, 2012	Dec. 31, 2011
Subsequent Event [Line Items]
Repaid outstanding principal		$ 322
Proceeds from term loan		350
Interest rate on notes issued		6.00%
Revolving credit agreement, credit facility	100	100
Revolving credit facility, expiration date			2012
Defined Benefit Plan, Contribution To Pension Plan		95
Amount borrowed under the credit facility	100
Aluminio [Member]
Subsequent Event [Line Items]
Proceeds from term loan		$ 280
Weighted-average interest rate		2.32%
Debt instrument weighted-average maturity period, in days		172
5.375% Notes, Due 2013 [Member]
Subsequent Event [Line Items]
Interest rate on notes issued			5.375%
Debt instrument, maturity date			2013
LIBOR Plus [Member]
Subsequent Event [Line Items]
LIBOR plus margin	1.25%	1.50%
Term Loans [Member]
Subsequent Event [Line Items]
Debt instrument, maturity date		July 2012
Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Debt instrument, maturity date			July 25, 2016
Revolving credit facility, expiration date		December 2012