Restructuring And Other Charges (Activity And Reserve Balances For Restructuring Charges) (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 reserve beginning balance	$ 116		$ 226		$ 328
Cash payments	(54)		(108)		(221)
Restructuring charges	130		96		199
Other	(58)	[1]	(98)	[1]	(80)	[1]
Restructuring reserve ending balance	134		116		226
Restructuring and other charges	281		207		237
Restructuring and other charges, after-tax and noncontrolling interests	181		130		151
Reserves related to the wire harness and electrical portion of the EES business					26
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	53		160		251
Cash payments	(45)		(93)		(203)
Restructuring charges	93		43		186
Other	(24)	[1]	(57)	[1]	(74)	[1]
Restructuring reserve ending balance	77		53		160
Restructuring and other charges	93				177
Restructuring and other charges, after-tax and noncontrolling interests	68				121
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	63		66		77
Cash payments	(9)		(15)		(18)
Restructuring charges	37		53		13
Other	(34)	[1]	(41)	[1]	(6)	[1]
Restructuring reserve ending balance	57		63		66
Restructuring and other charges	36		46
Restructuring and other charges, after-tax and noncontrolling interests	23		29
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	18
Restructuring and other charges, after-tax and noncontrolling interests			14
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

[1] Other includes reversals of previously recorded restructuring charges and the effects of foreign currency translation. In 2011, Other for other exit costs also included a reclassification of the following restructuring charges: $18 in environmental and $17 in asset retirement obligations, as these liabilities are included in Alcoa's separate reserves for environmental remediation (see Note N) and asset retirement obligations (see Note C), respectively. In 2010, Other for other exit costs also included a reclassification of the following restructuring charges: $30 in asset retirement and $14 in environmental obligations, as these liabilities are included in Alcoa's separate reserves for asset retirement obligations (see Note C) and environmental remediation (see Note N), respectively. In 2009, Other for layoff costs also included a reduction of $26 for reserves related to the wire harness and electrical portion of the EES business as Platinum Equity assumed these obligations (see Note F).