Statement of Consolidated Comprehensive Income (Loss) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income (loss)	$ 44	$ (175)	$ 66	$ (95)
Other comprehensive income (loss), net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	124	52	283	189
Foreign currency translation adjustments	(36)	238	(988)	(325)
Net change in unrealized gains on available-for-sale securities	1	2	(1)	4
Net change in unrecognized losses on derivatives	(49)	(153)	135	(102)
Total Other comprehensive income (loss), net of tax	40	139	(571)	(234)
Comprehensive income (loss)	84	(36)	(505)	(329)
Alcoa [Member]
Net income (loss)	24	(143)	54	(51)
Other comprehensive income (loss), net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	122	50	278	181
Foreign currency translation adjustments	(4)	202	(723)	(239)
Net change in unrealized gains on available-for-sale securities	1	2	(1)	4
Net change in unrecognized losses on derivatives	(50)	(153)	134	(96)
Total Other comprehensive income (loss), net of tax	69	101	(312)	(150)
Comprehensive income (loss)	93	(42)	(258)	(201)
Noncontrolling Interests [Member]
Net income (loss)	20	(32)	12	(44)
Other comprehensive income (loss), net of tax (B):
Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits	2	2	5	8
Foreign currency translation adjustments	(32)	36	(265)	(86)
Net change in unrecognized losses on derivatives	1		1	(6)
Total Other comprehensive income (loss), net of tax	(29)	38	(259)	(84)
Comprehensive income (loss)	$ (9)	$ 6	$ (247)	$ (128)