Restructuring and Other Charges - Schedule of Restructuring and Other Charges by Reportable Segments, Pretax (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 151	$ 2	$ 402	$ 27
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	150	3	276	14
Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	1	(1)	126	13
Alumina [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges				1
Primary Metals [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	150	3	244	9
Global Rolled Products [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			10	1
Engineered Products and Solutions [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			$ 22	$ 3