Segment Information - Schedule of Operating Results of Arconic's Reportable Segments (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total sales	$ 3,445	$ 3,192
Segment operating profit	400	451
Restructuring and other charges	0	66
Provision for depreciation and amortization	135	126
Assets	18,219		$ 18,718
Operating Segments
Segment Reporting Information [Line Items]
Total sales	3,486	3,225
Assets	15,862		15,321
Intersegment Eliminations
Segment Reporting Information [Line Items]
Intersegment sales	42	34
Third-Party Sales | Operating Segments
Segment Reporting Information [Line Items]
Third-party sales	3,444	3,191
Engineered Products and Solutions
Segment Reporting Information [Line Items]
Segment operating profit	221	247
Restructuring and other charges	1	6
Provision for depreciation and amortization	71	64
Assets	10,561		10,325
Engineered Products and Solutions | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,541	1,487
Engineered Products and Solutions | Intersegment Eliminations
Segment Reporting Information [Line Items]
Intersegment sales	0	0
Engineered Products and Solutions | Third-Party Sales | Operating Segments
Segment Reporting Information [Line Items]
Third-party sales	1,541	1,487
Global Rolled Products
Segment Reporting Information [Line Items]
Segment operating profit	112	136
Restructuring and other charges	(1)	57
Provision for depreciation and amortization	51	50
Assets	4,193		3,955
Global Rolled Products | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,408	1,282
Global Rolled Products | Intersegment Eliminations
Segment Reporting Information [Line Items]
Intersegment sales	42	34
Global Rolled Products | Third-Party Sales | Operating Segments
Segment Reporting Information [Line Items]
Third-party sales	1,366	1,248
Transportation and Construction Solutions
Segment Reporting Information [Line Items]
Segment operating profit	67	68
Restructuring and other charges	0	3
Provision for depreciation and amortization	13	12
Assets	1,108		$ 1,041
Transportation and Construction Solutions | Operating Segments
Segment Reporting Information [Line Items]
Total sales	537	456
Transportation and Construction Solutions | Intersegment Eliminations
Segment Reporting Information [Line Items]
Intersegment sales	0	0
Transportation and Construction Solutions | Third-Party Sales | Operating Segments
Segment Reporting Information [Line Items]
Third-party sales	$ 537	$ 456