Restructuring and Other Charges - Schedule of Restructuring and Other Charges by Reportable Segments, Pretax (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 461	$ 7
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	432	6
Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	29	1
Alumina [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	7
Primary Metals [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	331
Global Rolled Products [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	90	3
Engineered Products and Solutions [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 4	$ 3