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Derivatives and Other Financial Instruments - Schedule of Reconciliation of Activity for Derivative Contracts (Detail) - Jun. 30, 2015 - USD ($) $ in Millions | Total | Total
--- | --- | ---
Embedded Aluminum Derivative [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Fair value measurement, Assets, Beginning balance | $ 201 | $ 266
Fair value measurement, Assets, Sales | 7 | 13
Fair value measurement, Assets, Cost of goods sold | (24) | (45)
Fair value measurement, Assets, Other income, net | (2) | (1)
Fair value measurement, Assets, Other comprehensive income (loss) | 494 | 451
Fair value measurement, Assets, Purchases, sales, issuances, and settlements | 0 | 0
Fair value measurement, Assets, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Assets, Foreign currency translation | 4 | (4)
Fair value measurement, Assets, Ending balance | 680 | 680
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) | (1)
Fair value measurement, Liabilities, Beginning balance | 425 | 376
Fair value measurement, Liabilities, Sales | (5) | (11)
Fair value measurement, Liabilities, Cost of goods sold | 0 | 0
Fair value measurement, Liabilities, Other comprehensive income (loss) | (122) | (67)
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements | 0 | 0
Fair value measurement, Liabilities, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Liabilities, Foreign currency translation | 0 | 0
Fair value measurement, Liabilities, Ending balance | 298 | 298
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 | 16 | 18
Fair value measurement, Liabilities, Cost of goods sold | 0 | 0
Fair value measurement, Liabilities, Other income, net | 3 | 1
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements | 0 | 0
Fair value measurement, Liabilities, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Liabilities, Foreign currency translation | 0 | 0
Fair value measurement, Liabilities, Ending balance | 19 | 19
Fair value measurement, Liabilities, Sales | 0 | 0
Fair value measurement, Liabilities, Cost of goods sold | 0 | 0
Fair value measurement, Liabilities, Other income, net | 3 | 1
Energy Contracts [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Fair value measurement, Assets, Beginning balance | 8 | 2
Fair value measurement, Assets, Other comprehensive income (loss) | (8) | (2)
Fair value measurement, Assets, Purchases, sales, issuances, and settlements | 0 | 0
Fair value measurement, Assets, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Assets, Sales | 0 | 0
Fair value measurement, Assets, Cost of goods sold | 0 | 0
Fair value measurement, Liabilities, Cost of goods sold | 0 | 0
Fair value measurement, Liabilities, Other comprehensive income (loss) | 9 | 9
Fair value measurement, Liabilities, Purchases, sales, issuances, and settlements | 0 | 0
Fair value measurement, Liabilities, Transfers into and/or out of Level 3 | 0 | 0
Fair value measurement, Liabilities, Foreign currency translation | 0 | 0
Fair value measurement, Liabilities, Ending balance | 9 | 9
Fair value measurement, Liabilities, Sales | 0 | 0
Fair value measurement, Liabilities, Cost of goods sold | $ 0 | $ 0

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