Contingencies and Commitments (Details) € in Millions, $ in Millions		1 Months Ended				3 Months Ended				6 Months Ended
	Jun. 15, 2023 USD ($)	Jul. 31, 2024 USD ($)	Jul. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2023 EUR (€)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) location	Jun. 30, 2022 USD ($)	Mar. 31, 2023 EUR (€)	Sep. 30, 2022 USD ($)	Jun. 26, 2020 entity derivative
Loss Contingencies [Line Items]
Number of cleanup locations | location										30
Remediation reserve balance					$ 16	$ 17				$ 17
Remediation reserve balance, classified as a current liability					6	6				6
Payments related to remediation expenses applied against the reserve						2				2
Income tax reserve						0			$ 0	20	$ 0
Judgement from legal proceedings				$ 74
Reversal of previously recorded litigation amount	$ 25					25				25
Guarantees of third party related to project financing						5				5
Combined fair value of guarantees					6	6				6
Coverage limit					80
Total amount committed under outstanding surety bonds						43				43
Surety bonds, amount outstanding						22				22
Bank Loan Obligations
Loss Contingencies [Line Items]
Letters of credit, total amount						117				117
Other Noncurrent Liabilities and Deferred Credits | Separation Agreement
Loss Contingencies [Line Items]
Guarantees of third party related to project financing					$ 1,040	1,040				1,040
Lehman Brothers International (Europe) (“LBIE”) Claims
Loss Contingencies [Line Items]
Judgement from legal proceedings	$ 40
Number of entities | entity														2
Number of derivative transactions | derivative														2
Amount reserved													$ 65
Lehman Brothers International (Europe) (“LBIE”) Claims | Subsequent Event
Loss Contingencies [Line Items]
Payments for legal settlements			$ 15
Lehman Brothers International (Europe) (“LBIE”) Claims | Subsequent Event | Forecast
Loss Contingencies [Line Items]
Payments for legal settlements		$ 25
Foreign Tax Authority | Ministry of the Economy, Finance and Industry, France | Tax Years 2010 Through 2012
Loss Contingencies [Line Items]
Assessment amount				$ 19			$ 19					€ 18
Income tax reserve							$ 20	€ 19
Alcoa Corporation Workers Compensation Claims
Loss Contingencies [Line Items]
Letters of credit, total amount outstanding						52				52
Arconic Corporation Environmental Obligations
Loss Contingencies [Line Items]
Letters of credit, total amount outstanding						$ 17				$ 17
Maximum | Recurring Costs of Managing Hazardous Substances and Environmental Programs
Loss Contingencies [Line Items]
Percentage of cost of goods sold (as a percent)										1.00%