Segment Information - Schedule of Operating Results of Arconic's Reportable Segment (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Total sales	$ 5,213	$ 5,573	$ 15,455	$ 17,289
Equity (loss) income	(16)	(24)	(54)	(66)
Depreciation, depletion, and amortization	301	305	894	918
Income taxes	137	153	470	644
After-tax operating income (ATOI)	395	410	1,130	1,633
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	5,969	6,459	17,805	20,420
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	757	899	2,355	3,155
Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	5,212	5,560		17,265
Alumina [Member]
Segment Reporting Information [Line Items]
Equity (loss) income	(9)	(9)	(30)	(27)
Depreciation, depletion, and amortization	68	71	197	228
Income taxes	31	85	76	264
After-tax operating income (ATOI)	72	212	189	648
Alumina [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	974	1,303	2,805	4,046
Alumina [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	287	391	879	1,323
Alumina [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	687	912	1,926	2,723
Primary Metals [Member]
Segment Reporting Information [Line Items]
Equity (loss) income	3	(7)	7	(15)
Depreciation, depletion, and amortization	99	106	302	324
Income taxes		(49)	(16)	14
After-tax operating income (ATOI)	56	(59)	111	195
Primary Metals [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,588	1,728	4,778	6,088
Primary Metals [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	440	479	1,388	1,733
Primary Metals [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,148	1,249	3,390	4,355
Global Rolled Products [Member]
Segment Reporting Information [Line Items]
Equity (loss) income	(10)	(8)	(31)	(24)
Depreciation, depletion, and amortization	59	56	170	168
Income taxes	18	28	80	89
After-tax operating income (ATOI)	58	62	194	192
Global Rolled Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,551	1,556	4,556	4,915
Global Rolled Products [Member] \| Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	30	29	88	99
Global Rolled Products [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,521	1,527	4,468	4,816
Engineered Products and Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, and amortization	63	61	190	166
Income taxes	71	71	236	228
After-tax operating income (ATOI)	162	151	504	472
Engineered Products and Solutions [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,406	1,397	4,320	3,933
Engineered Products and Solutions [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,406	1,397	4,320	3,933
Transportation and Construction Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion, and amortization	12	11	35	32
Income taxes	17	18	49	49
After-tax operating income (ATOI)	47	44	132	126
Transportation and Construction Solutions [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	450	475		1,438
Transportation and Construction Solutions [Member] \| Third-Party Sales [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	$ 450	$ 475	$ 1,346	$ 1,438

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(a))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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