Impact of Non Cash Income Loss from Investments in Affiliates Subsidiaries on Earnings Per Share Diluted.

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Non Cash Income Loss From Investments In Affiliates Subsidiaries

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Non Cash Income Loss from Investments in Affiliates Subsidiaries After Tax and Noncontrolling Interest.

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Percentage of Subsidiary Interest in Joint Venture Divestiture.

No definition available.

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Subsidiary Ownership Percentage in Joint Venture.

No definition available.

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Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

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Subsequent Events - Additional Information (Detail) (Subsequent Event [Member], USD $)			0 Months Ended		0 Months Ended
	Oct. 15, 2014 Alcoa World Alumina and Chemicals [Member]	Oct. 15, 2014 Jamalco Joint Venture [Member]	Oct. 15, 2014 Alcoa [Member]	Oct. 23, 2014 Mt Holly [Member]	Oct. 15, 2014 Minimum [Member]	Oct. 15, 2014 Maximum [Member]
Subsequent Event [Line Items]
Percentage of ownership to sell	100.00%			50.33%
Percentage of ownership by a subsidiary of Alcoa World Alumina and Chemicals		55.00%
Non-cash loss					$ 265,000,000	$ 285,000,000
Non-cash loss after-tax and noncontrolling interest					$ 80,000,000	$ 100,000,000
Non-cash loss per diluted share					$ 0.07	$ 0.09
Percentage of ownership by Alcoa			60.00%