Segment Information - Schedule of Operating Results of Arconic's Reportable Segments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total sales	$ 3,541	$ 3,445
Segment operating profit	447	400
Restructuring and other charges	29	0
Provision for depreciation and amortization	131	134
Operating Segments
Segment Reporting Information [Line Items]
Total sales	3,595	3,501
Intersegment sales
Segment Reporting Information [Line Items]
Total sales	55	57
Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	3,540	3,444
Engineered Products and Solutions
Segment Reporting Information [Line Items]
Segment operating profit	253	209
Restructuring and other charges	14	1
Provision for depreciation and amortization	64	65
Engineered Products and Solutions | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,502	1,426
Engineered Products and Solutions | Intersegment sales
Segment Reporting Information [Line Items]
Total sales	0	0
Engineered Products and Solutions | Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,502	1,426
Global Rolled Products
Segment Reporting Information [Line Items]
Segment operating profit	107	124
Restructuring and other charges	6	(1)
Provision for depreciation and amortization	54	56
Global Rolled Products | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,558	1,538
Global Rolled Products | Intersegment sales
Segment Reporting Information [Line Items]
Total sales	55	57
Global Rolled Products | Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	1,503	1,481
Transportation and Construction Solutions
Segment Reporting Information [Line Items]
Segment operating profit	87	67
Restructuring and other charges	9	0
Provision for depreciation and amortization	13	13
Transportation and Construction Solutions | Operating Segments
Segment Reporting Information [Line Items]
Total sales	535	537
Transportation and Construction Solutions | Intersegment sales
Segment Reporting Information [Line Items]
Total sales	0	0
Transportation and Construction Solutions | Third-party sales | Operating Segments
Segment Reporting Information [Line Items]
Total sales	$ 535	$ 537