Restructuring and Other Charges - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		1 Months Ended		12 Months Ended
	May 31, 2013 t	Mar. 31, 2015 Employees	Mar. 31, 2014	May 31, 2014 t	Jun. 30, 2014 t	Dec. 31, 2014 Employees
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		$ 177	$ 461
Number of employees associated with layoff costs		210
Capacity of lines under review	460,000
Capacity of lines under review period	15 months
Minimum amount of cash payments expected to be paid beyond the end of the current annual period		15
Maximum amount of cash payments expected to be paid beyond the end of the current annual period		20
Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Number of plants permanently shut down and demolished			2
Number of plants temporarily curtailed			2
Rolling Mill [Member]
Restructuring Cost and Reserve [Line Items]
Number of plants permanently shut down and demolished			2
Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		16
Restructuring and other charges, after-tax and noncontrolling interest		11
Number of employees associated with layoff costs		680
Engineered Products and Solutions [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		130
Number of employees associated with layoff costs			110
Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		30
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs		50
Number of employees associated with layoff costs			60
Russia [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		149
Restructuring and other charges, after-tax and noncontrolling interest		142
Sao Luis Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		13
Restructuring and other charges, after-tax and noncontrolling interest		8
Capacity of lines under review		74,000,000,000		85,000
Massena East Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year			84,000
Point Henry Smelter [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year			190,000
Pocos De Caldas Refinery [Member]
Restructuring Cost and Reserve [Line Items]
Capacity of lines under review				62,000	200,000
Massena East, Ny and Point Henry and Yennora, Australia and Portovesme [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in production - result of market conditions, in mt per year			200,000
Other Exit Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		177	461
Restructuring and other charges, after-tax and noncontrolling interest		158	274
Other Miscellaneous Items [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		6	15
Restructuring and other charges, after-tax and noncontrolling interest		3	9
Small Layoff Reserves Related to Prior Periods [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		7	6
Restructuring and other charges, after-tax and noncontrolling interest		6	4
Divested Businesses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			336
Restructuring and other charges, after-tax and noncontrolling interest			189
Smelter Curtailments [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			70
Restructuring and other charges, after-tax and noncontrolling interest			46
Number of employees associated with layoff costs			170
Smelter Curtailments [Member] | Refinery [Member]
Restructuring Cost and Reserve [Line Items]
Number of plants temporarily curtailed			1
Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			33
Restructuring and other charges, after-tax and noncontrolling interest			26
Layoff Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			13
Restructuring and other charges, after-tax and noncontrolling interest			8
Shutdown And Curtailment Actions [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			133
Number of employees associated with layoff costs			1,830
Accelerated depreciation			59
Other asset impairment charges			91
Other exit costs			123
Inventory write-down - permanent shutdown and planned demolition of idled structures			34
Inventory write-down, after-tax and non-controlling interests			20
Shutdown And Curtailment Actions [Member] | Primary Metals [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			1,230
Shutdown And Curtailment Actions [Member] | Global Rolled Products [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			470
Shutdown And Curtailment Actions [Member] | Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			40
Shutdown And Curtailment Actions [Member] | Alumina [Member]
Restructuring Cost and Reserve [Line Items]
Number of employees associated with layoff costs			90
Shutdown And Curtailment Actions [Member] | Australia [Member]
Restructuring Cost and Reserve [Line Items]
Number of facilities accelerated depreciation write off			3
Operating Supplies [Member]
Restructuring Cost and Reserve [Line Items]
Other exit costs			55
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges		47
Other exit costs			38
Supplier And Customer Contract [Member]
Restructuring Cost and Reserve [Line Items]
Other exit costs			30
Restructuring Programs Layoffs 2015 [Member]
Restructuring Cost and Reserve [Line Items]
Total number of employees already laid off		90
Number of positions separated		890
Cash payments made against the layoff reserves		1
Restructuring Programs Layoffs 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Total number of employees already laid off		2,320
Number of positions separated		2,870				2,910
Cash payments made against the layoff reserves		50
Restructuring Programs Layoffs 2013 [Member]
Restructuring Cost and Reserve [Line Items]
Total number of employees already laid off		1,460
Number of positions separated		1,530
Cash payments made against the layoff reserves		$ 3