Derivative Instruments and Hedging Activities - Part 1 (Details) In Millions, unless otherwise specified				12 Months Ended													12 Months Ended					12 Months Ended
	Dec. 31, 2012 USD ($)	Dec. 31, 2012 Aluminum M Wh [Member] MWh	Dec. 31, 2012 Power MWh [Member] MWh	Dec. 31, 2012 Interest Rate Derivatives Libor USD [Member]	Dec. 31, 2012 Interest Rate Derivatives Euribor EUR [Member]	Dec. 31, 2012 Interest Rate Derivatives Libor GBP [Member]	Dec. 31, 2012 Interest Rate Derivatives Current [Member] Libor USD [Member] USD ($)	Dec. 31, 2012 Interest Rate Derivatives Current [Member] Euribor EUR [Member] USD ($)	Dec. 31, 2012 Interest Rate Derivatives Current [Member] Euribor EUR [Member] EUR (€)	Dec. 31, 2012 Interest Rate Derivatives Current [Member] Libor GBP [Member] USD ($)	Dec. 31, 2012 Interest Rate Derivatives Current [Member] Libor GBP [Member] GBP (£)	Dec. 31, 2012 Interest Rate Derivatives Maximum Libor USD [Member] USD ($)	Dec. 31, 2012 Interest Rate Derivatives Maximum Euribor EUR [Member] USD ($)	Dec. 31, 2012 Interest Rate Derivatives Maximum Euribor EUR [Member] EUR (€)	Dec. 31, 2012 Interest Rate Derivatives Maximum Libor GBP [Member] USD ($)	Dec. 31, 2012 Interest Rate Derivatives Maximum Libor GBP [Member] GBP (£)	Dec. 31, 2012 Cross Currency Swaps Chilean Unidad De Fomento CLF [Member]	Dec. 31, 2012 Cross Currency Swaps Current [Member] Chilean Unidad De Fomento CLF [Member] USD ($)	Dec. 31, 2012 Cross Currency Swaps Current [Member] Chilean Unidad De Fomento CLF [Member] CLF	Dec. 31, 2012 Cross Currency Swaps Maximum Chilean Unidad De Fomento CLF [Member] USD ($)	Dec. 31, 2012 Cross Currency Swaps Maximum Chilean Unidad De Fomento CLF [Member] CLF	Dec. 31, 2012 Foreign Currency Options and Forwards Euro EUR [Member] USD ($)	Dec. 31, 2012 Foreign Currency Options and Forwards Euro EUR [Member] EUR (€)	Dec. 31, 2012 Foreign Currency Options and Forwards Brazilian Real BRL [Member] USD ($)	Dec. 31, 2012 Foreign Currency Options and Forwards Brazilian Real BRL [Member] BRL	Dec. 31, 2012 Foreign Currency Options and Forwards British Pound GBP [Member] USD ($)	Dec. 31, 2012 Foreign Currency Options and Forwards British Pound GBP [Member] GBP (£)	Dec. 31, 2012 Foreign Currency Options and Forwards Chilean Peso CLP [Member] USD ($)	Dec. 31, 2012 Foreign Currency Options and Forwards Chilean Peso CLP [Member] CLP	Dec. 31, 2012 Foreign Currency Options and Forwards Colombian Peso COP [Member] USD ($)	Dec. 31, 2012 Foreign Currency Options and Forwards Colombian Peso COP [Member] COP	Dec. 31, 2012 Foreign Currency Options and Forwards Argentine Peso ARS [Member] USD ($)	Dec. 31, 2012 Foreign Currency Options and Forwards Argentine Peso ARS [Member] ARS	Dec. 31, 2012 Embedded Foreign Currency Derivatives Euro EUR [Member] USD ($)	Dec. 31, 2012 Embedded Foreign Currency Derivatives Euro EUR [Member] EUR (€)	Dec. 31, 2012 Embedded Foreign Currency Derivatives Argentine Peso ARS [Member] USD ($)	Dec. 31, 2012 Embedded Foreign Currency Derivatives Argentine Peso ARS [Member] ARS	Dec. 31, 2012 Embedded Foreign Currency Derivatives Kazakhstani Tenge KZT [Member] USD ($)	Dec. 31, 2012 Embedded Foreign Currency Derivatives Kazakhstani Tenge KZT [Member] KZT	Dec. 31, 2012 Commodity Derivatives Aluminum M Wh [Member]	Dec. 31, 2012 Commodity Derivatives Power MWh [Member]
Derivative Tables [Line Items]
Notional Amount Of Interest Rate Derivatives	$ 3,600						$ 3,413	$ 807	€ 611	$ 109	£ 67	$ 4,272	$ 807	€ 611	$ 112	£ 69
Weighted Average Remaining Term				10 years	9 years	12 years											9 years															1 year	1 year	11 years	11 years	11 years	11 years	4 years	4 years	7 years	3 years
Weighted Average Remaining Term (string type)																						<1	<1	<1	<1	<1	<1	<1	<1	<1	<1
% of Debt Currently Hedged by Index				70.00%	64.00%	86.00%											85.00%
Notional Amount Of Foreign Currency Derivatives																						126	98	83	175	27	17	108	52,575	49	89,928	20	118	2	2	173	849	8	1,195
Notional (CLF)																		$ 267	6	$ 267	6
Notional (MWh)		14,000,000	4,000,000