Contingencies and Commitments - Additional Information - 2 (Detail) In Millions, unless otherwise specified	12 Months Ended						12 Months Ended			12 Months Ended				1 Months Ended				1 Months Ended					12 Months Ended						36 Months Ended	12 Months Ended			12 Months Ended					9 Months Ended		12 Months Ended				12 Months Ended				1 Months Ended		12 Months Ended
	Dec. 31, 2013 USD ($) MW t	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2013 EUR (€)	Jun. 12, 2012 USD ($)	Jun. 12, 2012 EUR (€)	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2013 Energy, Raw Materials, and Other Goods and Services [Member] USD ($)	Dec. 31, 2013 Outstanding bank guarantees [Member] Minimum [Member]	Dec. 31, 2013 Outstanding bank guarantees [Member] Maximum [Member]	Dec. 31, 2013 State and Local Jurisdiction [Member] USD ($)	Dec. 31, 2013 State and Local Jurisdiction [Member] BRL	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] BRL	May 31, 2012 Alcoa World Alumina Brasil [Member] USD ($)	May 31, 2012 Alcoa World Alumina Brasil [Member] BRL	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] USD ($)	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] Minimum [Member] USD ($)	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] Maximum [Member] USD ($)	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] Fixed Assets [Member] BRL	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] Fixed Assets [Member] Minimum [Member] USD ($)	Mar. 31, 2013 Alcoa World Alumina Brasil [Member] Fixed Assets [Member] Maximum [Member] USD ($)	Dec. 31, 2013 Estreito Project [Member] USD ($) MWh	Dec. 31, 2013 Estreito Project [Member] BRL	Dec. 31, 2013 Barra Grande [Member] USD ($) MWh	Dec. 31, 2013 Barra Grande [Member] BRL MWh	Dec. 31, 2012 Barra Grande [Member] USD ($)	Dec. 31, 2012 Barra Grande [Member] BRL	Dec. 31, 2002 Alcoa Alumino [Member] t	Dec. 31, 2012 East St. Louis, IL Site [Member] USD ($)	Dec. 31, 2005 East St. Louis, IL Site [Member] USD ($)	Dec. 31, 2013 East St. Louis, IL Site [Member] USD ($)	Dec. 31, 2009 Fusina [Member] USD ($)	Dec. 31, 2009 Portovesme [Member] USD ($)	Dec. 31, 2013 Machadinho and Barra Grande [Member]	Dec. 31, 2013 Serrado Facao and Estreito Projects [Member]	Dec. 31, 2013 Machadinho [Member] MWh	Dec. 31, 2013 Serra Do Facao Project [Member] USD ($)	Dec. 31, 2013 Serra Do Facao Project [Member] BRL	Dec. 31, 2013 Serra Do Facao Project [Member] USD ($) MWh	Dec. 31, 2013 Serra Do Facao Project [Member] BRL MWh	Dec. 31, 2012 Serra Do Facao Project [Member] USD ($)	Dec. 31, 2012 Serra Do Facao Project [Member] BRL	Dec. 31, 2012 Baie Comeau [Member] USD ($)	Dec. 31, 2012 Mosjoen [Member] USD ($)	Dec. 31, 2004 Dampier to Bunbury Natural Gas Pipeline [Member] USD ($)	Dec. 31, 2004 Dampier to Bunbury Natural Gas Pipeline [Member] AUD	Dec. 31, 2013 Dampier to Bunbury Natural Gas Pipeline [Member] Three-Year Equity Call Plan [Member] USD ($)	Dec. 31, 2013 Dampier to Bunbury Natural Gas Pipeline [Member] Three-Year Equity Call Plan [Member] AUD	Dec. 31, 2013 Dampier to Bunbury Natural Gas Pipeline [Member] Three-Year Equity Call Plan [Member] USD ($)	Dec. 31, 2013 Dampier to Bunbury Natural Gas Pipeline [Member] Three-Year Equity Call Plan [Member] AUD	Dec. 31, 2012 Dampier to Bunbury Natural Gas Pipeline [Member] Three-Year Equity Call Plan [Member] USD ($)	Dec. 31, 2012 Dampier to Bunbury Natural Gas Pipeline [Member] Three-Year Equity Call Plan [Member] AUD
Loss Contingencies [Line Items]
Remediation reserve increase (decrease)																														$ 14	$ 15		$ 12	$ 3										$ 25	$ 20
Reserve balance	509	532																												26		24
Disallowed tax credits														220			110			175	0	75
Percentage of penalty of the gross disallowed amount														50.00%
Value added tax receivable															41	82
Estimated range of reasonably possible loss, minimum														155				0	65
Administrative appeal, assessment period														2 years
Total combined assessments	334			242								53	125
Metal sold per month																													2,000
Commitment to taking share of output in associated projects at cost, in years																																			30 years	26 years
Investment percentage																							25.49%	25.49%	42.18%	42.18%											30.99%			34.97%	34.97%					20.00%	20.00%
Assured power from installed capacity																							150	150	160	160											120			65	65
Total investment in project																									143	336	159	326										82	192	82	192	98	200
Estimated project costs																							2,200	5,170														430	1,000
Aluminio's share of project																							560	1,320														150	350
Additional contributions																																						150	350							141	176	29	29	12	12	12	11
Increase in estimated costs to complete project																							130	270
Commitment expended on the project																							540	1,270
Percentage of power self-sufficiency upon completion of project with full operating capacity	70.00%
Total energy demand	690
Temporarily declined in energy demand	260
Partial capacity curtailments of combined smelters	128,000
Initial cash investment																																														17	24
Required plan contributions																																																		40	40
Prepayments made under the agreement for future gas transmission services																																																315	354	315	354
Alcoa's maximum exposure to loss in projects					418	303																																										440	500	440	500
Purchase obligations due in 2014	159								3,319
Purchase obligations due in 2015	157								1,802
Purchase obligations due in 2016	145								1,628
Purchase obligations due in 2017	150								1,552
Purchase obligations due in 2018	149								1,838
Purchase obligations due thereafter	2,091								9,856
Purchase obligations expenditures	163	161	227
Expiration date of unconditional purchase obligations for energy							2015	2036
Operating leases, expense	232	244	255
Long-term operating leases, minimum annual rentals due in 2014	198
Long-term operating leases, minimum annual rentals due in 2015	165
Long-term operating leases, minimum annual rentals due in 2016	135
Long-term operating leases, minimum annual rentals due in 2017	103
Long-term operating leases, minimum annual rentals due in 2018	80
Long-term operating leases, minimum annual rentals due thereafter	244
Guarantees of third party related to project financing	542
Guarantees, expiration date	2019									2014	2022
Guarantees, total amount committed	370
Letters of credit, total amount committed	333
Letters of credit, expiration date	2014
Total amount committed under outstanding surety bonds	$ 170
Surety bonds, expiration date	2014