Statement of Consolidated Comprehensive Loss (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income (loss)	$ (148)	$ (19)	$ 22	$ 80
Other comprehensive loss, net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	63	79	159	137
Foreign currency translation adjustments	(852)	(872)	(952)	(563)
Net change in unrealized gains on available-for-sale securities	(3)		(2)	2
Net change in unrecognized losses on derivatives	69	134	184	51
Total Other comprehensive loss, net of tax	(723)	(659)	(611)	(373)
Comprehensive loss	(871)	(678)	(589)	(293)
Alcoa [Member]
Net income (loss)	(119)	(2)	30	92
Other comprehensive loss, net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	61	75	156	131
Foreign currency translation adjustments	(603)	(685)	(719)	(441)
Net change in unrealized gains on available-for-sale securities	(3)		(2)	2
Net change in unrecognized losses on derivatives	71	138	184	57
Total Other comprehensive loss, net of tax	(474)	(472)	(381)	(251)
Comprehensive loss	(593)	(474)	(351)	(159)
Noncontrolling Interests [Member]
Net income (loss)	(29)	(17)	(8)	(12)
Other comprehensive loss, net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	2	4	3	6
Foreign currency translation adjustments	(249)	(187)	(233)	(122)
Net change in unrecognized losses on derivatives	(2)	(4)		(6)
Total Other comprehensive loss, net of tax	(249)	(187)	(230)	(122)
Comprehensive loss	$ (278)	$ (204)	$ (238)	$ (134)