Restructuring and Other Charges - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended																					1 Months Ended	12 Months Ended	1 Months Ended			12 Months Ended
	May 30, 2013 t	Dec. 31, 2013 Employees t	Dec. 31, 2012	Dec. 31, 2011 Location GeneratingPlant Employees	Dec. 31, 2013 Primary Metals [Member] Employee Employees	Dec. 31, 2012 Primary Metals [Member] Employees	Dec. 31, 2011 Primary Metals [Member] Employees	Dec. 31, 2013 Engineered Products and Solutions [Member] Employees	Dec. 31, 2012 Engineered Products and Solutions [Member] Employees	Dec. 31, 2011 Engineered Products and Solutions [Member] Employees	Dec. 31, 2013 Global Rolled Products [Member] Employees	Dec. 31, 2011 Global Rolled Products [Member] Employees	Dec. 31, 2013 Alumina [Member] Employees	Dec. 31, 2012 Alumina [Member] Employees	Dec. 31, 2011 Alumina [Member] Employees	Dec. 31, 2013 Corporate [Member] Employees	Dec. 31, 2012 Corporate [Member] Employees	Dec. 31, 2011 Corporate [Member] Employees	Dec. 31, 2013 Global Rolled Products Segment [Member] Employees	Dec. 31, 2013 Retirement Of Previously Idled Structure [Member]	Dec. 31, 2013 Write Off Of Capitalized Structure [Member]	Dec. 31, 2011 Rockdale, TX [Member] Potline Location	May 31, 2013 Baie Comeau [Member] Potline t	Dec. 31, 2013 Baie Comeau [Member]	May 31, 2013 Quebec Canada [Member] t	Sep. 30, 2013 Fusina Italy [Member] t Potline	May 31, 2013 Fusina Italy [Member] t	Dec. 31, 2013 Fusina and Massena East [Member]	Dec. 31, 2013 Legal Matter [Member]	Dec. 31, 2012 Legal Matter [Member]	Dec. 31, 2013 Other Exit Costs [Member]	Dec. 31, 2011 Other Exit Costs [Member]	Dec. 31, 2013 Layoff Costs [Member]	Dec. 31, 2012 Layoff Costs [Member]	Dec. 31, 2011 Layoff Costs [Member]	Dec. 31, 2013 Layoff Costs [Member] Primary Metals [Member]	Dec. 31, 2013 Pension Benefits [Member]	Dec. 31, 2013 Asset Impairments and Retirements Costs [Member] Retirement Of Previously Idled Structure [Member]	Dec. 31, 2013 Other Miscellaneous Items [Member]	Dec. 31, 2012 Other Miscellaneous Items [Member]	Dec. 31, 2013 Small Layoff Reserves Related to Prior Periods [Member]	Dec. 31, 2012 Small Layoff Reserves Related to Prior Periods [Member]	Dec. 31, 2013 Pension Costs [Member]	Dec. 31, 2013 Operating Supplies [Member]	Dec. 31, 2011 Operating Supplies [Member]	Dec. 31, 2013 Permanent Shutdown and Planned Demolition of Idled Structures [Member]	Dec. 31, 2011 Permanent Shutdown and Planned Demolition of Idled Structures [Member]	Dec. 31, 2011 Permanent Shutdown and Planned Demolition of Idled Structures [Member] Alcoa, TN [Member] t	Dec. 31, 2011 Permanent Shutdown and Planned Demolition of Idled Structures [Member] Rockdale, TX [Member] t	Dec. 31, 2011 Permanent Shutdown and Planned Demolition of Idled Structures [Member] Remaining Capacity [Member] t	Dec. 31, 2013 Asset Retirement Obligations [Member]	Dec. 31, 2011 Asset Retirement Obligations [Member]	Dec. 31, 2013 Environmental Remediation [Member]	Dec. 31, 2011 Environmental Remediation [Member]	Dec. 31, 2013 Restructuring Programs Layoffs 2013 [Member] Employee	Dec. 31, 2013 Restructuring Programs Layoffs 2012 [Member]	Dec. 31, 2012 Restructuring Programs Layoffs 2012 [Member] Positions	Dec. 31, 2012 Smelter Curtailments [Member] Employees	Dec. 31, 2012 Asset Impairment [Member]	Dec. 31, 2012 Lease and Contract Termination Costs [Member]	Dec. 31, 2012 Portovesme Smelter [Member]	Dec. 31, 2012 Other Asset Impairments [Member]	Dec. 31, 2011 Other Asset Impairments [Member]	Dec. 31, 2012 Spain [Member] Smelter Sites [Member] Employees	Dec. 31, 2011 Asset Impairments [Member]	Dec. 31, 2011 Litigation Matter [Member]	Dec. 31, 2011 Portovesme, Italy [Member] Kmt	Dec. 31, 2011 Aviles, Spain [Member] Kmt	Dec. 31, 2011 La Coruna, Spain [Member] Kmt	Dec. 31, 2013 Restructuring Programs Layoffs 2011 [Member]	Dec. 31, 2012 Restructuring Programs Layoffs 2011 [Member]
Restructuring Cost and Reserve [Line Items]
Pension plan settlement charges		$ 782	$ 172	$ 281																$ 25	$ 13								$ 391	$ 85	$ 245	$ 36	$ 87	$ 47	$ 93	$ 114	$ 9	$ 12	$ 17												$ 58	$ 17	$ 12	$ 18				$ 10					$ 23		$ 127	$ 20
Restructuring and other charges, after-tax and noncontrolling interests		585	106	181																17	25								305	33	183	23	61	29	68			8	12																			7					12		82	8
Number of employees associated with layoff costs		1,110			340			260			250		85			175			590			2	2			1
Restructuring reserve, other adjustment				23																																				4	8	21																	30	6	11	10		10
Restructuring reserve, other adjustment, after-tax				16																																				4	6	15																	30	6	11	8		7
Reduction in production - result of market conditions, in mt per year																							105,000			41,000
Reduction in production - result of market conditions, in kmt per year																									280,000	84,000	44,000																					215,000	76,000	191,000
Number of facilities in which demolition and remediation activities will begin																										3
Reduction in production - result of market conditions, in metric tons per year	460,000	183,000
Number of employees associated with layoff costs				1,600,000,000	550	250	820,000,000		390	20,000,000		470,000,000		85	160,000,000		75	130,000,000																																								170
Pension cost		201	47	93																																							83
Accelerated depreciation																								58
Other asset impairment charges		116	40	150																								18
Inventory write-down - permanent shutdown and planned demolition of idled structures																																												9	6
Inventory write-down, after-tax and non-controlling interests																																												6	4
Other exit costs				5																												1														55	36				48	17	5	18
Other related costs		2
Total number of employees already laid off																																																							1,660									55
Number of positions separated																																																							1,020		800
Cash payments made against the layoff reserves																																																							33	17	16													11	23
Number of U.S. locations permanently shutdown and planned demolition				2,000,000
Other exit costs, after-tax and noncontrolling interests				4																												1																				11		11
Number of U.S. locations permanently shutdown and planned demolition																						2
Number of potlines at facility																						4
Other asset impairment charges																																															127
Capacity for which management approved partial or full curtailment, in kmt																																																																			150,000,000,000	46,000,000,000	44,000,000,000
Number of European smelters, management approved, partial or full curtailment				3,000,000
Capacity of smelters for which management approved partial or full curtailment, in kmt																																																																				93,000,000,000	87,000,000,000
Number of smelters in Spain where curtailment is planned to be temporary				2,000,000
Layoff costs of positions eliminations				33
Layoff costs of positions eliminations, after-tax				31
Number of employees layoff				650,000,000
Minimum amount of cash payments expected to be paid beyond the end of the current annual period		30
Maximum amount of cash payments expected to be paid beyond the end of the current annual period		$ 35