Segment Information - Schedule of Operating Results of Arconic's Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Total sales	$ 3,691	$ 3,573	$ 7,232	$ 7,018
Segment operating profit	538	432	985	832
Restructuring and other charges	469	10	498	10
Provision for depreciation and amortization	129	136	260	270
Operating Segments
Segment Reporting Information [Line Items]
Total sales	3,745	3,670	7,340	7,171
Intersegment sales
Segment Reporting Information [Line Items]
Total sales	55	61	110	118
Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	3,690	3,609	7,230	7,053
Engineered Products and Solutions
Segment Reporting Information [Line Items]
Segment operating profit	286	224	539	433
Restructuring and other charges	442	8	456	9
Provision for depreciation and amortization	62	65	126	130
Engineered Products and Solutions | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,565	1,474	3,067	2,900
Engineered Products and Solutions | Intersegment sales
Segment Reporting Information [Line Items]
Total sales	0	0	0	0
Engineered Products and Solutions | Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,565	1,474	3,080	3,054
Global Rolled Products
Segment Reporting Information [Line Items]
Segment operating profit	145	111	252	235
Restructuring and other charges	2	2	8	1
Provision for depreciation and amortization	54	59	108	115
Global Rolled Products | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,632	1,634	3,190	3,172
Global Rolled Products | Intersegment sales
Segment Reporting Information [Line Items]
Total sales	55	61	110	118
Global Rolled Products | Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,577	1,573	3,067	2,900
Transportation and Construction Solutions
Segment Reporting Information [Line Items]
Segment operating profit	107	97	194	164
Restructuring and other charges	25	0	34	0
Provision for depreciation and amortization	13	12	26	25
Transportation and Construction Solutions | Operating Segments
Segment Reporting Information [Line Items]
Total sales	548	562	1,083	1,099
Transportation and Construction Solutions | Intersegment sales
Segment Reporting Information [Line Items]
Total sales	0	0	0	0
Transportation and Construction Solutions | Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	$ 548	$ 562	$ 1,083	$ 1,099