Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Carrying Value
Derivative [Line Items]
Cash and cash equivalents	$ 2,150	$ 1,863
Restricted cash	4	15
Derivatives - current asset	61	14
Noncurrent receivables	20	21
Derivatives - noncurrent asset	33	10
Available-for-sale securities	106	102
Investment in common stock of Alcoa Corporation	0	1,020
Short-term borrowings	38	40
Derivatives - current liability	45	5
Commercial paper	0	0
Derivatives - noncurrent liability	14	3
Contingent payment related to an acquisition	0	78
Long-term debt, less amount due within one year	6,806	8,044
Fair Value
Derivative [Line Items]
Cash and cash equivalents	2,150	1,863
Restricted cash	4	15
Derivatives - current asset	61	14
Noncurrent receivables	20	21
Derivatives - noncurrent asset	33	10
Available-for-sale securities	106	102
Investment in common stock of Alcoa Corporation	0	1,020
Short-term borrowings	38	40
Derivatives - current liability	45	5
Commercial paper	0	0
Derivatives - noncurrent liability	14	3
Contingent payment related to an acquisition	0	78
Long-term debt, less amount due within one year	$ 7,443	$ 8,519