Arconic Inc Separation Transaction and Discontinued Operations - Summary of Results of Discontinued Operations (Details) - Arconic Corportion - Discontinued Operations, Disposed of by Means Other than Sale $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales	$ 1,575
Cost of goods sold	1,293
Selling, general administrative, research and development and other expenses	106
Provision for depreciation and amortization	58
Restructuring and other credits	(18)
Operating income from discontinued operations	136
Interest expense, net	7
Other expense, net	41
Income from discontinued operations	88
Provision for income taxes	38
Income from discontinued operations after income taxes	$ 50