Restructuring and Other Charges - Schedule of Restructuring and Other Charges by Reportable Segments, Pretax (Detail) € in Millions, $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2015 EUR (€)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 735	€ 150	$ 1,195	$ 1,168	$ 782
Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			1,112	1,129	349
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			83	39	433
Alumina [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			233	287	11
Primary Metals [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			691	553	295
Global Rolled Products [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			131	266	15
Engineered Products and Solutions [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			49	13	12
Transportation and Construction Solutions [Member] | Operating Segments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			$ 8	$ 10	$ 16