Restructuring and Other Charges - Additional Information (Detail)		3 Months Ended		12 Months Ended
	Mar. 31, 2016 Employees	Mar. 31, 2016 USD ($) Employees	Mar. 31, 2015 USD ($) Employees t	Dec. 31, 2015 Employees
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 93,000,000	$ 177,000,000
Restructuring and other charges after tax and noncontrolling interest		61,000,000	158,000,000
Other exit costs		27,000,000
Cash payments made against the layoff reserves		19,000,000
Inventory write down		3,000,000
Inventory write down after tax and noncontrolling interests		2,000,000
Minimum amount of cash payments expected to be paid beyond the end of the current annual period		15,000,000
Maximum amount of cash payments expected to be paid beyond the end of the current annual period		20,000,000
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			5,000,000
Sao Luis Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			16,000,000
Restructuring and other charges after tax and noncontrolling interest			11,000,000
Warrick, IN Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		60,000,000
Restructuring and other charges after tax and noncontrolling interest		39,000,000
Point Comfort Refinery and Wenatchee Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		18,000,000
Restructuring and other charges after tax and noncontrolling interest		11,000,000
Other Miscellaneous Items [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			6,000,000
Restructuring and other charges after tax and noncontrolling interest			3,000,000
Other Adjustments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			7,000,000
Restructuring and other charges after tax and noncontrolling interest			6,000,000
Restructuring Programs Layoffs 2015 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		19,000,000
Restructuring and other charges after tax and noncontrolling interest		$ 14,000,000
Number of positions | Employees	5,050	560		5,200
Cash payments made against the layoff reserves		$ 62,000,000
Approximate number of employees already laid off | Employees	2,750	2,750
Restructuring Programs Layoffs 2015 [Member] | Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees		30
Restructuring Programs Layoffs 2015 [Member] | Engineered Products and Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees		500
Restructuring Programs Layoffs 2015 [Member] | Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees		30
Divested Businesses [Member] | Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			149,000,000
Restructuring and other charges after tax and noncontrolling interest			142,000,000
Restructuring Programs Layoffs 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			13,000,000
Restructuring and other charges after tax and noncontrolling interest			$ 8,000,000
Number of positions | Employees	2,820		210	2,870
Cash payments made against the layoff reserves		$ 2,000,000
Capacity of lines under review | t			74,000,000,000
Approximate number of employees already laid off | Employees	2,590	2,590
Restructuring Programs Layoffs 2014 [Member] | Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees			60
Restructuring Programs Layoffs 2014 [Member] | Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees			30
Restructuring Programs Layoffs 2014 [Member] | Engineered Products and Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees			80
Restructuring Programs Layoffs 2014 [Member] | Transportation and Construction Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees			40
Asset Impairment and Accelerated Depreciation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 70,000,000
Restructuring Programs Layoffs 2016 [Member]
Restructuring Cost and Reserve [Line Items]
Number of positions | Employees	560
Cash payments made against the layoff reserves		$ 2,000,000
Approximate number of employees already laid off | Employees	320	320
Other Adjustments and Other Miscellaneous Charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 4,000,000
Restructuring and other charges after tax and noncontrolling interest		$ 3,000,000