Segment and Geographic Area Information - Schedule of Segment ATOI to Consolidated Net (Loss) Income Attributable to Alcoa (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Total segment ATOI	$ 325	$ 351
Interest expense	(120)	(115)
Noncontrolling interests	(19)	21
Consolidated net (loss) income attributable to Alcoa	(178)	149
Unallocated Amounts (Net of Tax) [Member]
Segment Reporting Information [Line Items]
Impact of LIFO	(7)	(2)
Interest expense	(78)	(75)
Noncontrolling interests	19	(21)
Corporate expense	(67)	(67)
Restructuring and other charges	(321)	(5)
Other	$ (49)	$ (32)