Restructuring and Other Charges - Schedule of Restructuring and Other Charges by Reportable Segments, Pretax (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 110	$ 244	$ 571	$ 251
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	107	120	539	126
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	3	124	32	125
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	84	94	415	94
Global Rolled Products [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	23	7	113	10
Engineered Products and Solutions [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 19	$ 4	$ 22