Segment Information - Schedule of Operating Results of Arconic's Reportable Segments (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total sales	$ 3,236	$ 3,138	$ 9,689	$ 9,427
Depreciation and amortization	133	127	388	377
Adjusted EBITDA	535	515	1,640	1,607
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	3,263	3,171	9,770	9,539
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	36	30	107	88
Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	3,227	3,141	9,663	9,451
Engineered Products and Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	68	63	198	190
Adjusted EBITDA	312	296	928	930
Engineered Products and Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,476	1,406	4,445	4,320
Engineered Products and Solutions [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,476	1,406	4,445	4,320
Global Rolled Products [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	52	52	153	152
Adjusted EBITDA	140	143	475	461
Global Rolled Products [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	1,270	1,315	3,858	3,873
Global Rolled Products [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intersegment sales	36	30	107	88
Global Rolled Products [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	1,234	1,285	3,751	3,785
Transportation and Construction Solutions [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization	13	12	37	35
Adjusted EBITDA	83	76	237	216
Transportation and Construction Solutions [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total sales	517	450	1,467	1,346
Transportation and Construction Solutions [Member] | Third-Party Sales [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Third-party sales	$ 517	$ 450	$ 1,467	$ 1,346