Statement of Consolidated Comprehensive (Loss) Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net (loss) income	$ (175)	$ 225	$ (95)	$ 968
Other comprehensive income (loss), net of tax:
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	52	63	189	162
Foreign currency translation adjustments	238	(1,459)	(325)	(556)
Unrealized gains on available-for-sale securities:
Unrealized holding gains (losses)	2	(2)	4	(1)
Net amount reclassified to earnings
Net change in unrealized gains on available-for-sale securities	2	(2)	4	(1)
Unrecognized losses on derivatives (N):
Net change from periodic revaluations	(135)	150	(83)	71
Net amount reclassified to earnings	(18)	33	(19)	115
Net change in unrecognized losses on derivatives	(153)	183	(102)	186
Total Other comprehensive income (loss), net of tax	139	(1,215)	(234)	(209)
Comprehensive (loss) income	(36)	(990)	(329)	759
Alcoa
Net (loss) income	(143)	172	(51)	802
Other comprehensive income (loss), net of tax:
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	50	62	181	158
Foreign currency translation adjustments	202	(1,108)	(239)	(386)
Unrealized gains on available-for-sale securities:
Unrealized holding gains (losses)	2	(2)	4	(1)
Net amount reclassified to earnings
Net change in unrealized gains on available-for-sale securities	2	(2)	4	(1)
Unrecognized losses on derivatives (N):
Net change from periodic revaluations	(135)	149	(77)	65
Net amount reclassified to earnings	(18)	32	(19)	114
Net change in unrecognized losses on derivatives	(153)	181	(96)	179
Total Other comprehensive income (loss), net of tax	101	(867)	(150)	(50)
Comprehensive (loss) income	(42)	(695)	(201)	752
Noncontrolling interests
Net (loss) income	(32)	53	(44)	166
Other comprehensive income (loss), net of tax:
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	2	1	8	4
Foreign currency translation adjustments	36	(351)	(86)	(170)
Unrealized gains on available-for-sale securities:
Net amount reclassified to earnings
Unrecognized losses on derivatives (N):
Net change from periodic revaluations		1	(6)	6
Net amount reclassified to earnings		1		1
Net change in unrecognized losses on derivatives		2	(6)	7
Total Other comprehensive income (loss), net of tax	38	(348)	(84)	(159)
Comprehensive (loss) income	$ 6	$ (295)	$ (128)	$ 7