Other Noncurrent Liabilities and Deferred Credits - Schedule of Other Noncurrent Liabilities and Deferred Credits (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Environmental remediation (N)	$ 554	$ 473
Asset retirement obligations (C)	551	587
Income taxes (T)	521	377
Accrued compensation and retirement costs	329	346
Fair value of derivative contracts (X)	208	376
Liability related to the resolution of a legal matter (N)	148	222
Contingent payment related to an acquisition (F)	130	130
Deferred alumina sales revenue	84	93
Deferred credit related to derivative contract (X)		62
Other	213	230
Other noncurrent liabilities and deferred credits, total	$ 2,738	$ 2,896

Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable after twelve months or beyond the next operating cycle if longer.

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