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Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Segment
Goodwill [Line Items]
Number of reportable segments | Segment	3
Global Rolled Products [Member]
Goodwill [Line Items]
Segment reporting, goodwill	$ 60
Engineered Products and Solutions [Member]
Goodwill [Line Items]
Segment reporting, goodwill	253
Transportation and Construction Solutions [Member]
Goodwill [Line Items]
Segment reporting, goodwill	$ 18
Arconic [Member]
Goodwill [Line Items]
Number of reportable segments | Segment	3

X

- Definition

Segment reporting reconciling items goodwill assets.

+ References

No definition available.

+ Details

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Namespace Prefix:	arnc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

X

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Details

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Namespace Prefix:
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X

- Details

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Balance Type:
Period Type:

X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

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Namespace Prefix:
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Period Type: