Restructuring and Other Charges - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended			1 Months Ended
	May 31, 2013 t	Dec. 31, 2014 Employees	Dec. 31, 2013 Employees	Dec. 31, 2012	Aug. 31, 2013 Potline	Jun. 30, 2014 t	May 31, 2014 t	Aug. 31, 2014 t
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 1,168	$ 782	$ 172
Restructuring and other charges, after-tax and noncontrolling interest			585	106
Number of employees associated with layoff costs		1,120	1,110
Capacity of lines under review	460,000
Capacity of lines under review period	15 months
Other layoff cost including reclassification in pension cost		246	185	26
Accelerated depreciation		204	58
Other exit costs		183
Other asset impairment charges		406	116	40
Minimum amount of cash payments expected to be paid beyond the end of the current annual period		15
Maximum amount of cash payments expected to be paid beyond the end of the current annual period		20
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			340
Number of employees associated with layoff costs		1,210		250
Engineered Products and Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		550	260
Number of employees associated with layoff costs				390
Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		45	250
Number of employees associated with layoff costs		470
Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			85
Number of employees associated with layoff costs		80		85
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		465	175
Number of employees associated with layoff costs		30		75
Global Rolled Products Segment [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			590
Retirement Of Previously Idled Structure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			25
Restructuring and other charges, after-tax and noncontrolling interest			17
Write Off Of Capitalized Structure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			13
Restructuring and other charges, after-tax and noncontrolling interest			25
Alumina and Primary Metals Segments [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		60
Divested Businesses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		332
Restructuring and other charges, after-tax and noncontrolling interest		163
Baie Comeau [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year	105,000
Number of potlines to be shutdown and demolished	2				1
Quebec Canada [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year					41,000
Reduction in production - result of market conditions, in mt per year	280,000
Fusina Italy [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year	44,000
Capacity of lines under review					84,000
Fusina and Massena East [Member]
Restructuring Cost and Reserve [Line Items]
Other asset impairment charges			18
Massena East Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year		84,000
Point Henry Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year		190,000
Pocos De Caldas Refinery [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of lines under review						200,000	62,000
Sao Luis Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of lines under review							85,000
Massena East, Ny and Point Henry and Yennora, Australia and Portovesme [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year		200,000
Portovesme Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year								150,000
Legal Matter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			391	85
Restructuring and other charges, after-tax and noncontrolling interest			305	33
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		1,168	245
Restructuring and other charges, after-tax and noncontrolling interest		703	183
Other layoff cost including reclassification in pension cost		180	84	5
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		51	87	47
Restructuring and other charges, after-tax and noncontrolling interest		36	61	29
Other layoff cost including reclassification in pension cost		66	101	21
Pension Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			9
Asset Impairments and Retirements Costs [Member] | Retirement Of Previously Idled Structure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			12
Restructuring and other charges, after-tax and noncontrolling interest			8
Other Miscellaneous Items [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		18	17
Restructuring and other charges, after-tax and noncontrolling interest		11	12
Restructuring reserve, other adjustment				4
Restructuring reserve, other adjustment, after-tax				4
Small Layoff Reserves Related to Prior Periods [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		28
Restructuring and other charges, after-tax and noncontrolling interest		21
Restructuring reserve, other adjustment			8	21
Restructuring reserve, other adjustment, after-tax			6	15
Pension Costs [Member]
Restructuring Cost and Reserve [Line Items]
Other layoff cost including reclassification in pension cost		26	92
Operating Supplies [Member]
Restructuring Cost and Reserve [Line Items]
Inventory write-down - permanent shutdown and planned demolition of idled structures		67	9
Inventory write-down, after-tax and non-controlling interests		47	6
Permanent Shutdown and Planned Demolition of Idled Structures [Member]
Restructuring Cost and Reserve [Line Items]
Other exit costs			55
Asset Retirement Obligations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		95	58
Other exit costs		95	48
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		47	12
Other exit costs		42	5
Restructuring Programs Layoffs 2013 [Member]
Restructuring Cost and Reserve [Line Items]
Total number of employees already laid off		1,530	1,660
Number of positions separated		1,440
Cash payments made against the layoff reserves		39	33
Restructuring Programs Layoffs 2012 [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions separated				800
Cash payments made against the layoff reserves		3	17	16
Smelter Curtailments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges				10
Restructuring and other charges, after-tax and noncontrolling interest				7
Number of employees associated with layoff costs				170
Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		34	3
Restructuring and other charges, after-tax and noncontrolling interest		26	2
Restructuring reserve, other adjustment				30
Restructuring reserve, other adjustment, after-tax				30
Lease and Contract Termination Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, other adjustment				6
Restructuring reserve, other adjustment, after-tax				6
Portovesme Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, other adjustment				11
Restructuring reserve, other adjustment, after-tax				11
Other Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, other adjustment				10
Restructuring reserve, other adjustment, after-tax				8
Spain [Member] | Smelter Sites [Member]
Restructuring Cost and Reserve [Line Items]
Total number of employees already laid off				55
Restructuring reserve, other adjustment				10
Restructuring reserve, other adjustment, after-tax				7
Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			114
Number of employees associated with layoff costs		1,790
Exit Costs [Member] | Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			550
Supplier And Customer Contract [Member]
Restructuring Cost and Reserve [Line Items]
Other exit costs		46	2
Restructuring Programs Layoffs 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Total number of employees already laid off		2,910
Number of positions separated		2,185
Cash payments made against the layoff reserves		141
Asset Impairment And Accelerated Depreciation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		2
Restructuring and other charges, after-tax and noncontrolling interest		2
Divested Businesses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		693
Restructuring and other charges, after-tax and noncontrolling interest		443
Temporary Curtailment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		68
Restructuring and other charges, after-tax and noncontrolling interest		$ 45