Pension and Other Postretirement Benefits - Narrative (Details) $ in Millions				1 Months Ended					3 Months Ended	12 Months Ended
	Mar. 11, 2021 USD ($)	Jul. 25, 2019 employee	Nov. 01, 2016 USD ($)	Oct. 31, 2021 USD ($)	Jun. 30, 2019 employee location	Apr. 30, 2019 USD ($)	Mar. 31, 2018 USD ($)	Apr. 30, 2017 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2021
Defined Benefit Plan Disclosure [Line Items]
Labor agreement, number of years covered		4 years			3 years
Number of employees included in labor agreement | employee		560			3,400
Number of locations | location					4
Labor agreement, one time signing bonus												$ 9
Restructuring and other charges											$ 90	$ 182	$ 582
Funded status, percent														76.00%
Average duration for plans' projected cash flows											11 years
Period expected long-term rate of return is applied											5 years
Number of years over actual annual healthcare cost trend experience											20 years
Expected long-term rate of return on plan assets											6.20%	6.00%	5.60%
Health care cost trend rate assumed for next year											5.50%	5.50%	5.50%
Rate to which the cost trend rate gradually declines											4.50%	4.50%	4.50%
Pension contributions											$ 96	$ 257	$ 268
Aggregate cash contribution to pension plan			$ 150
Cash contribution term to pension plan			30 months
Payment for pension and other postretirement benefits						$ 34	$ 66	$ 50
Expenses related to defined contribution plan											$ 66	73	87
Minimum
Defined Benefit Plan Disclosure [Line Items]
Rate to which the cost trend rate gradually declines											2.20%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Rate to which the cost trend rate gradually declines											5.70%
Scenario, forecast
Defined Benefit Plan Disclosure [Line Items]
Contribution next fiscal year										$ 44
Discontinued Operations, Disposed of by Means Other than Sale | Arconic Corportion
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in postretirement benefits liability													42
Restructuring Charges
Defined Benefit Plan Disclosure [Line Items]
Curtailment (charge) benefit													16
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in postretirement benefits liability				$ 125
Curtailment (charge) benefit											$ (6)	0	0
Restructuring and other charges				$ 34								69
Estimated pension contributions and other postretirement benefit payments	$ 110
Other postretirement benefits
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in postretirement benefits liability									$ (39)		(6)
Curtailment (charge) benefit											$ 0	2	58
Number of years over actual annual healthcare cost trend experience											3 years
United States
Defined Benefit Plan Disclosure [Line Items]
Pension contributions											$ 96	227
Payment for pension benefit plan in excess of minimum required											12	25
United States | Scenario, forecast
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets										7.00%
Contribution next fiscal year										$ 35
United States | Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in postretirement benefits liability													(75)
Curtailment (charge) benefit													(17)
United States | Other postretirement benefits | Restructuring Charges
Defined Benefit Plan Disclosure [Line Items]
Curtailment (charge) benefit											$ 23	66
Percent reduction of plan participants											70.00%
Pension Settlement Cost
Defined Benefit Plan Disclosure [Line Items]
Restructuring and other charges											$ 12	$ 8	$ 9