Contingencies and Commitments - Additional Information (Detail) In Millions, unless otherwise specified	1 Months Ended			3 Months Ended		12 Months Ended						1 Months Ended	12 Months Ended						12 Months Ended			3 Months Ended	0 Months Ended		1 Months Ended	3 Months Ended		12 Months Ended		12 Months Ended		0 Months Ended				12 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended			0 Months Ended
	Jul. 31, 2012 Plant	Jun. 12, 2012 USD ($) Installment	Jun. 12, 2012 EUR (€)	Dec. 31, 2013 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Mar. 26, 2012 USD ($)	Mar. 26, 2012 EUR (€)	Jun. 30, 2010 t	Nov. 30, 2006 Curtis v. Alcoa Inc. [Member] Person	Dec. 31, 2011 Scrg Brownfield Recovery Corp Energy Answers Corporation of Puerto Rico [Member] USD ($)	Feb. 21, 2013 Minimum [Member] USD ($)	Feb. 21, 2013 Maximum [Member] USD ($)	Feb. 21, 2013 Maximum [Member] EUR (€)	Feb. 21, 2013 Alcoa Trasformazioni [Member] USD ($)	Feb. 21, 2013 Alcoa Trasformazioni [Member] EUR (€)	Dec. 31, 2013 Alcoa [Member] USD ($)	Dec. 31, 2013 Alcoa [Member] EUR (€)	Dec. 31, 2013 Alumina [Member]	Jun. 30, 2013 Aluminium Bahrain [Member] USD ($)	Oct. 09, 2012 Alba [Member] USD ($) Installment	Feb. 27, 2008 Alba [Member] USD ($)	Feb. 27, 2008 Alba [Member]	Sep. 30, 2012 Alba [Member] USD ($)	Jun. 30, 2012 Alba [Member] USD ($)	Dec. 31, 2013 Alba [Member]	Oct. 09, 2013 Alba [Member] USD ($)	Dec. 31, 2013 Department of Justice [Member] USD ($) Installment	May 31, 2011 Breaches of Warranty [Member] USD ($)	Jan. 20, 2011 Breaches of Warranty [Member] Scrg Brownfield Recovery Corp Energy Answers Corporation of Puerto Rico [Member] USD ($)	Jan. 20, 2011 Punitive Damages [Member] Scrg Brownfield Recovery Corp Energy Answers Corporation of Puerto Rico [Member] USD ($)	Jan. 20, 2011 Property Damages [Member] Scrg Brownfield Recovery Corp Energy Answers Corporation of Puerto Rico [Member] USD ($)	May 31, 2011 Negligence Award [Member] USD ($)	Dec. 31, 2013 Securities and Exchange Commission [Member] USD ($) Installment	Dec. 31, 2013 Department of Justice and Securities Exchange Commission [Member] USD ($)	Dec. 31, 2013 Department of Justice and Securities Exchange Commission [Member] USD ($)	Dec. 31, 2013 Alcoa World Alumina and Chemicals [Member] Country	Dec. 31, 2013 Alcoa World Alumina and Chemicals [Member] Alcoa [Member]	Dec. 31, 2013 Alcoa World Alumina and Chemicals [Member] Alumina [Member]	Nov. 19, 2009 Italian Government [Member] USD ($) Plant	Nov. 19, 2009 Italian Government [Member] EUR (€) Plant	Jul. 31, 2006 Italian Government [Member]	Dec. 31, 2012 Portovesme [Member] Ton
Loss Contingencies [Line Items]
Period of alleged conspiracy, years																									15 years
Damages claimed, value																								$ 1,000
Agreed amount payable on settlement																							85							223						175
Litigation settlement number of installments																							2
Contingency settlement agreement amount paid																							42.5						42.5
Contingency settlement agreement future payable date																												October 9, 2013		AWA agreed to pay a total of $223, including a fine of $209 payable in five equal installments over four years. The first installment of $41.8, plus a one-time administrative forfeiture of $14, will be paid in the first quarter of 2014 (paid on January 22,2014), and the remaining installments of $41.8 each will be paid in the first quarters of 2015-2018.						The Company agreed to a settlement amount of $175, but will be given credit for the $14 one-time forfeiture payment, which is part of the DOJ resolution, resulting in a total cash payment to the SEC of $161 payable in five equal installments over four years. The first installment of $32.2 will be paid to the SEC in the first quarter of 2014 (paid on January 22, 2014), and the remaining installments of $32.2 each will be paid in the first quarters of 2015-2018.
Cash payment for suit settlement																						103				40										161
Restructuring and other charges						782	172	281														103					45
Amount of settlement offer rejected					60
Charges recorded of settlement amount				288	0																																288
Agreement settlement effective date																														Jan. 09, 2014
Number of installments																														5
Number of years in which installments is payable																														4 years
Fine payable over four years period																														209
First installment payable on settlement																														41.8						32.2
One-time administrative forfeiture amount																														14						14
Installments payable in first quarters of 2015																														41.8						32.2
Installments payable in first quarters of 2016																														41.8						32.2
Installments payable in first quarters of 2017																														41.8						32.2
Installments payable in first quarters of 2018																														41.8						32.2
Number of installments																																				5
Number of years in which installments is payable																																				4 years
Legal costs						391	85																														7
Charges in respect of the investigations																																						103
Number of countries																																							7
Percentage owns on settlement																																								60.00%	40.00%
Civil settlement						85
Government investigations and legal charges						384
Percentage to allocate cost of Alba civil settlement and all legal fees																			85.00%	85.00%	15.00%
Percentage of civil settlement and all legal costs associated with civil suit and government investigations																			60.00%	60.00%	40.00%
Retired former employees involved in class action												13,000
Trial length, number of days						8 days
Court granted motion for judgment regarding Plaintiffs													20																			13	6	10	10
Damages awarded to plaintiff, pre-judgment interest																															2
Management estimate for maximum exposure from class action									110	85							97	76
Provision for contract losses														0	97	76
Number of years operating under a power supply structure																																												10 years
Charge related to European Commission announcement																																										250	173
Number of smelters	2																																									2	2
Write-off of receivable																																										20	14
Establishment reserve																																										230	159
Recovery amount		375	303
Reduction in recovery amount		65	53
Payments to Italian Government		310	250
Payments to Italian Government, installments amount		69	50
Number of installments, litigation payment		5	5
Litigation reserve		219	159																0
Range of reasonable possible loss, minimum		219	159
Range of reasonable possible loss, maximum		418	303
Noncurrent asset																			$ 126	€ 91
Amount of curtailment, metric-tons-per-year											44,000																																		150,000