Restructuring And Other Charges (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 281	$ 207	$ 237
Restructuring and other charges, after-tax and noncontrolling interests	181	130	151
Number of employees associated with layoff costs	1,600
Other asset impairment charges			13
Number of U.S. locations permanently shutdown and planned demolition	2	5
Asset impairments, after-tax and noncontrolling interests			11
Other exit costs	5	2	19
Other exit costs, after-tax and noncontrolling interests	4	2	10
Cash payments	54	108	221
Total number of employees already laid off			6,600
Layoff costs of positions eliminations	33
Layoff costs of positions eliminations, after-tax	31
Number of employees layoff	650
Number of European smelters management approved partial or full curtailment for	3
Number of smelters in Spain where curtailment is planned to be temporary	2
Asset impairments	150	139	54
Restructuring reserve, other adjustment	23	33
Restructuring reserve, other adjustment, after-tax	16	24
Inventory write-down - permanent shutdown and planned demolition of idled structures		8
Inventory write-down, after-tax and non-controlling interests		5
Reserves related to the wire harness and electrical portion of the EES business			26
Minimum amount of cash payments expected to be paid beyond the end of the current annual period	45
Maximum amount of cash payments expected to be paid beyond the end of the current annual period	50
Engineered Products And Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(3)	18	64
Number of employees associated with layoff costs	20	625	2,980
Flat-Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	19	(11)	65
Number of employees associated with layoff costs	470	25	2,190
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	212	145	30
Number of employees associated with layoff costs	820	75	1,080
Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	39	12	5
Number of employees associated with layoff costs	160	60	180
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	14	43	73
Number of employees associated with layoff costs	130	90	170
Divested Businesses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		22
Restructuring and other charges, after-tax and noncontrolling interests		14
Asset impairments		12
Asset impairments after-tax		8
Warrick, IN [Member]
Restructuring Cost and Reserve [Line Items]
Number of potlines to be shutdown and demolished		1
Rockdale TX [Member]
Restructuring Cost and Reserve [Line Items]
Number of potlines to be shutdown and demolished	2
Number of potlines at facility	4
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	36	46
Restructuring and other charges, after-tax and noncontrolling interests	23	29
Other exit costs	1
Other exit costs, after-tax and noncontrolling interests	1
Cash payments	9	15	18
Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	127
Restructuring and other charges, after-tax and noncontrolling interests	82
Asset impairments		127
Asset impairments after-tax		80
Other Asset Impairments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	23
Restructuring and other charges, after-tax and noncontrolling interests	12
Asset Retirement Obligations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	17
Restructuring and other charges, after-tax and noncontrolling interests		30
Other exit costs	17	30
Other exit costs, after-tax and noncontrolling interests	11	19
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	18
Restructuring and other charges, after-tax and noncontrolling interests		14
Other exit costs	18	14
Other exit costs, after-tax and noncontrolling interests	11	9
Litigation Matter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	20
Restructuring and other charges, after-tax and noncontrolling interests	8
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	93		177
Restructuring and other charges, after-tax and noncontrolling interests	68		121
Cash payments	45	93	203
Write-Off Of Capitalized Business Acquisition Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			18
Restructuring and other charges, after-tax and noncontrolling interests			12
Permanent Shutdown And Planned Demolition Of Idled Structures [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		2
Other asset impairment charges		127
Other exit costs	36	46
Other restructuring activities, after-tax and noncontrolling interests		1
Permanent Shutdown And Planned Demolition Of Idled Structures [Member] | Frederick, MD [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in kmt per year		195
Permanent Shutdown And Planned Demolition Of Idled Structures [Member] | Badin, NC [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in kmt per year		60
Permanent Shutdown And Planned Demolition Of Idled Structures [Member] | Warrick, IN [Member]
Restructuring Cost and Reserve [Line Items]
Reduction of production plan included in asset impairment, kmt		40
Permanent Shutdown And Planned Demolition Of Idled Structures [Member] | Rockdale TX [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in kmt per year	76
Permanent Shutdown And Planned Demolition Of Idled Structures [Member] | Alcoa TN [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in kmt per year	215
Permanent Shutdown And Planned Demolition Of Idled Structures [Member] | Remaining Capacity [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in kmt per year	191
Pension Plan Curtailment Workforce Reductions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			9
Restructuring and other charges, after-tax and noncontrolling interests			6
Businesses Held For Sale [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			41
Restructuring and other charges, after-tax and noncontrolling interests			20
Restructuring Programs (Layoffs), 2011 [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	24
Total number of employees already laid off	380
Number of positions terminated	1,600
Restructuring Programs (Layoffs), 2010 [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		875
Cash payments	7	21
Total number of employees already laid off	790
Number of positions terminated	875
Restructuring Programs (Layoffs), 2010 [Member] | Engineered Products And Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		43
Restructuring and other charges, after-tax and noncontrolling interests		29
Restructuring Programs (Layoffs), 2009 [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs	6,000
Other restructuring activities, after-tax and noncontrolling interests			29
Total number of employees expected to be laid off	5,700
Cash payments	13	60
Reserves related to the wire harness and electrical portion of the EES business			40
Operating Supplies [Member]
Restructuring Cost and Reserve [Line Items]
Inventory write-down - permanent shutdown and planned demolition of idled structures	6
Inventory write-down, after-tax and non-controlling interests	$ 4
Portovesme, Italy [Member]
Restructuring Cost and Reserve [Line Items]
Capacity for which management approved partial or full curtailment, in kmt	150
Aviles, Spain [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of smelters for which management approved partial or full curtailment, in kmt	93
Capacity for which management approved partial or full curtailment, in kmt	46
La Coruna, Spain [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of smelters for which management approved partial or full curtailment, in kmt	87
Capacity for which management approved partial or full curtailment, in kmt	44