Additional charge related to European commission announcement.

No definition available.

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- 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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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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- Definition

Cumulative provision for contract losses not offset against related costs accumulated on the balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 35
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68068069&loc=d3e57777-111642

+ Details

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Period Type:	instant

- Details

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Contingencies and Commitments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2015 EUR (€)	Feb. 21, 2013 USD ($)	Feb. 21, 2013 EUR (€)	Mar. 26, 2012 USD ($)	Mar. 26, 2012 EUR (€)
Loss Contingencies [Line Items]
Management estimate for maximum exposure from class action					$ 110,000,000	€ 85,000,000
Partial reserve	$ 37,000,000	€ 34,000,000
Alcoa Trasformazioni [Member]
Loss Contingencies [Line Items]
Management estimate for maximum exposure from class action			$ 97,000,000	€ 76,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Provision for contract losses			0
Maximum [Member]
Loss Contingencies [Line Items]
Provision for contract losses			$ 97,000,000	€ 76,000,000