Basis of Presentation [Line Items]

No definition available.

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- Definition

Number of operating locations.

+ References

No definition available.

+ Details

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- Definition

Ownership interest in joint venture.

+ References

No definition available.

+ Details

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- Definition

Face amount or stated value per share of common stock.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

The number of countries in which the entity operates as of balance sheet date.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Basis of Presentation - Additional Information (Detail)	12 Months Ended
Basis of Presentation - Additional Information (Detail)	Dec. 31, 2021 Country Location $ / shares	Dec. 31, 2017 $ / shares	Nov. 01, 2016 $ / shares
Basis Of Presentation [Line Items]
Number of countries in which entity operates \| Country	9
Common stock par value	$ 0.01
Aluminum Segment [Member]
Basis Of Presentation [Line Items]
Ownership interest in joint venture	55.00%
AWAC [Member] \| Alumina Limited [Member]
Basis Of Presentation [Line Items]
Non-controlling interest, ownership percentage	40.00%
Parent Co [Member]
Basis Of Presentation [Line Items]
Common stock par value		$ 0.01	$ 0.01
Alcoa Corporation [Member]
Basis Of Presentation [Line Items]
Ownership interest in joint venture	25.10%
Alcoa Corporation [Member] \| AWAC [Member]
Basis Of Presentation [Line Items]
Ownership interest percentage	60.00%
Minimum [Member]
Basis Of Presentation [Line Items]
Number of operating locations \| Location	28
Maximum [Member]
Basis Of Presentation [Line Items]
Percent of equity investments in other entity	50.00%