Segment and Geographic Area Information - Sales by Major Product Grouping (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Product Information [Line Items]
Consolidated sales	$ 5,585	$ 5,765	$ 5,849	$ 5,833	$ 5,898	$ 5,833	$ 5,963	$ 6,006	$ 23,032	$ 23,700	$ 24,951
Alumina [Member]
Product Information [Line Items]
Consolidated sales									3,151	2,962	3,350
Primary Aluminum [Member]
Product Information [Line Items]
Consolidated sales									6,194	7,121	7,907
Flat-Rolled Aluminum [Member]
Product Information [Line Items]
Consolidated sales									7,106	7,378	7,642
Investment Castings [Member]
Product Information [Line Items]
Consolidated sales									1,807	1,747	1,700
Alcoa Fastening Systems [Member]
Product Information [Line Items]
Consolidated sales									1,505	1,414	1,313
Architectural Aluminum Systems [Member]
Product Information [Line Items]
Consolidated sales									977	970	973
Aluminum Wheels [Member]
Product Information [Line Items]
Consolidated sales									702	692	656
Other Extruded Aluminum and Forged Products [Member]
Product Information [Line Items]
Consolidated sales									1,015	955	1,010
Other [Member]
Product Information [Line Items]
Consolidated sales									$ 575	$ 461	$ 400