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Income tax expense, payment of interest and penalties.

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Percentage of deferred tax asset exclusive of reversing temporary differences.

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Percentage of the effect of unrecognized tax benefit, if recorded.

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Percentage of temporary tax differences that reverse within the carryforward period.

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Unamortized tax deductible goodwill resulting from intercompany stock sales and reorganizations.

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Unamortized tax deduction rate on goodwill.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences, classified as other.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign tax credit carryforwards.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the income tax rates.

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Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

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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.

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The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to increase (decrease) in foreign income tax contingency.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

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Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return.

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Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Contingency [Line Items]
Tax benefit (charge) realized from exercise of employee stock options		$ 0	$ 2,000,000	$ 8,000,000
Unamortized tax-deductible goodwill resulting from intercompany stock sales and reorganizations		$ 23,000,000
Unamortized tax-deduction rate on goodwill		25.00%
Percentage of temporary tax differences that reverse within the carryforward period		(59.00%)
Percentage of deferred tax asset exclusive of reversing temporary differences		(41.00%)
Discrete income tax charge for valuation allowances	$ 1,267,000,000	$ 1,267,000,000
Foreign tax credits	128,000,000	128,000,000	15,000,000
Net deferred tax assets other	(184,000,000)	$ (184,000,000)	(311,000,000)
Foreign tax credits carry forward period		10 years
Valuation allowance	302,000,000	$ 302,000,000	134,000,000		$ 135,000,000
Cumulative valuation allowance	427,000,000	427,000,000
Valuation allowance	1,940,000,000	$ 1,940,000,000	$ 1,291,000,000	$ 1,151,000,000	$ 1,252,000,000
Percentage of tax rate decreased		(15.70%)	(1.00%)	78.80%
Noncontrolling interest	26,000,000	$ 26,000,000	$ 2,085,000,000
Income tax benefit for operational losses related to certain foreign jurisdictions that are excluded from the estimated annual effective tax rate calculation		$ 450,000,000
Percentage of the effect of unrecognized tax benefit, if recorded		6.00%	7.00%	4.00%
Interest or penalties recognized		$ 0	$ 0	$ 0
Income related to accrued interest and penalties		0	1,000,000	$ 0
Amount accrued for payment of interest and penalties	2,000,000	2,000,000	1,000,000
Alcoa Corporation [Member]
Income Tax Contingency [Line Items]
Discrete income tax charge for valuation allowances		1,267,000,000
Foreign tax credits	302,000,000	302,000,000
Net deferred tax assets other	(2,000,000)	$ (2,000,000)
Minimum [Member]
Income Tax Contingency [Line Items]
Percentage of tax rate decreased		15.25%
Maximum [Member]
Income Tax Contingency [Line Items]
Percentage of tax rate decreased		34.00%
Internal Revenue Service IRS [Member] \| Alcoa Corporation [Member]
Income Tax Contingency [Line Items]
Net deferred tax assets	925,000,000	$ 925,000,000
Luxembourg [Member]
Income Tax Contingency [Line Items]
Discrete income tax charge for valuation allowances		42,000,000
Valuation allowance	280,000,000	280,000,000
Luxembourg [Member] \| Alcoa Corporation [Member]
Income Tax Contingency [Line Items]
Net deferred tax assets	42,000,000	42,000,000
Federal Tax Services of Russia [Member]
Income Tax Contingency [Line Items]
Net deferred tax assets	19,000,000	19,000,000
Canada Revenue Agency [Member]
Income Tax Contingency [Line Items]
Net deferred tax assets	20,000,000	20,000,000
Australia [Member]
Income Tax Contingency [Line Items]
Valuation allowance	93,000,000	93,000,000
Spain [Member]
Income Tax Contingency [Line Items]
Valuation allowance	163,000,000	$ 163,000,000
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Foreign tax credits carry forward period		10 years
Decrease to the net deferred tax asset and noncash charge to earnings		$ 52,000,000
Noncontrolling interest	$ 31,000,000	$ 31,000,000
Foreign Tax Authority [Member] \| Minimum [Member]
Income Tax Contingency [Line Items]
Foreign tax credits expiry period		2017
Foreign Tax Authority [Member] \| Maximum [Member]
Income Tax Contingency [Line Items]
Foreign tax credits expiry period		2026
Iceland And Suriname [Member]
Income Tax Contingency [Line Items]
Discrete income tax charge for valuation allowances			141,000,000
Suriname [Member]
Income Tax Contingency [Line Items]
Valuation allowance			$ 85,000,000
Suriname [Member] \| Minimum [Member]
Income Tax Contingency [Line Items]
Foreign tax credits expiry period			2016
Suriname [Member] \| Maximum [Member]
Income Tax Contingency [Line Items]
Foreign tax credits expiry period			2022
Iceland [Member]
Income Tax Contingency [Line Items]
Valuation allowance			$ 56,000,000
Iceland [Member] \| Minimum [Member]
Income Tax Contingency [Line Items]
Foreign tax credits expiry period			2017
Iceland [Member] \| Maximum [Member]
Income Tax Contingency [Line Items]
Foreign tax credits expiry period			2023