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Derivatives and Other Financial Instruments - Schedule of Reconciliation of Activity for Derivative Contracts (Detail) - USD ($) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2016 | Jun. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Fair value measurement, Assets, Purchases, sales, issuances, and settlements | $ 0 | $ 0
Embedded Aluminum Derivative [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Fair value measurement, Assets, Beginning balance | 988,000,000 | 1,135,000,000
Fair value measurement, Assets, Sales | (3,000,000) | (10,000,000)
Fair value measurement, Assets, Cost of goods sold | (30,000,000) | (61,000,000)
Fair value measurement, Assets, Other income, net | (4,000,000) | (8,000,000)
Fair value measurement, Assets, Other comprehensive income | (215,000,000) | (336,000,000)
Fair value measurement, Assets, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Assets, Other | 9,000,000 |
Fair value measurement, Assets, Other |  | 25,000,000
Fair value measurement, Assets, Ending balance | 745,000,000 | 745,000,000
Fair value measurement, Assets, Sales | 0 | 0
Fair value measurement, Assets, Cost of goods sold | 0 | 0
Fair value measurement, Assets, Other income , net | (4,000,000) | (8,000,000)
Fair value measurement, Liabilities, Beginning balance | 161,000,000 | 169,000,000
Fair value measurement, Liabilities, Sales | (3,000,000) | (5,000,000)
Fair value measurement, Liabilities, Other comprehensive income | 38,000,000 | 32,000,000
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements | 32,000,000 | 32,000,000
Fair value measurement, Liabilities, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Liabilities, Ending balance | 228,000,000 | 228,000,000
Fair value measurement, Liabilities, Sales | 0 | 0
Fair value measurement, Liabilities, Cost of goods sold | 0 | 0
Embedded Credit Derivative [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Fair value measurement, Liabilities, Beginning balance | 33,000,000 | 35,000,000
Fair value measurement, Liabilities, Cost of goods sold | (2,000,000) | (3,000,000)
Fair value measurement, Liabilities, Other income, net | 2,000,000 | 1,000,000
Fair value measurement, Liabilities, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Liabilities, Ending balance | 33,000,000 | 33,000,000
Fair value measurement, Liabilities, Sales | 0 | 0
Fair value measurement, Liabilities, Cost of goods sold | 0 | 0
Fair value measurement, Liabilities, Other income, net | 2,000,000 | 1,000,000
Energy Contracts [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Fair value measurement, Assets, Beginning balance | 6,000,000 | 2,000,000
Fair value measurement, Assets, Other income, net |  | 2,000,000
Fair value measurement, Assets, Other comprehensive income | 37,000,000 | 39,000,000
Fair value measurement, Assets, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Assets, Other | 6,000,000 |
Fair value measurement, Assets, Other |  | 6,000,000
Fair value measurement, Assets, Ending balance | 49,000,000 | 49,000,000
Fair value measurement, Assets, Sales | 0 | 0
Fair value measurement, Assets, Cost of goods sold | 0 | 0
Fair value measurement, Assets, Other income , net |  | 2,000,000
Fair value measurement, Liabilities, Beginning balance | 11,000,000 | 4,000,000
Fair value measurement, Liabilities, Other income, net |  | (1,000,000)
Fair value measurement, Liabilities, Other comprehensive income | (8,000,000) |
Fair value measurement, Liabilities, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Liabilities, Other | 6,000,000 |
Fair value measurement, Liabilities, Other |  | 6,000,000
Fair value measurement, Liabilities, Ending balance | 9,000,000 | 9,000,000
Fair value measurement, Liabilities, Sales | 0 | 0
Fair value measurement, Liabilities, Cost of goods sold | $ 0 | 0
Fair value measurement, Liabilities, Other income, net |  | $ (1,000,000)

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- Definition Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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