Derivatives and Other Financial Instruments - Additional Information (Detail) kt in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) Member Contract Smelter kt	Dec. 31, 2021 USD ($) kt
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Minimum members required for strategic risk management committee | Member	3
Realized loss reclassed from Other comprehensive (loss) income to earnings	$ (316)	$ (295)
Unrealized gain (loss) in accumulated other comprehensive loss	$ (3,539)	(4,592)
Other derivative contracts estimated term of quoted market prices, in years	10 years
Other derivative beyond market estimated quoted price of aluminum by extrapolating	10 years
Number of new financial contracts | Contract	4
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gain (loss) in accumulated other comprehensive loss	$ 20
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Number of smelters | Smelter	8
Level 1 Derivative Instruments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized loss reclassed from Other comprehensive (loss) income to earnings	$ 35	(10)
Commodity Contract | Level 1 [Member] | Brazil [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instrument, start date	Apr. 30, 2022
Commodity Contract | Level 1 [Member] | Brazil [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instruments, expiration month and year	2023-12
Commodity Contract | Level 1 [Member] | Spain [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instruments, expiration month and year	2022-10
Foreign Exchange Forward | Brazil [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instruments, expiration month and year	2024-12
Foreign Exchange Forward | Norway [Member] | Euro Power Purchases [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instruments, expiration month and year	2026-12
Foreign Exchange Forward | Norway [Member] | Krone Capital Expenditures [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative instruments, expiration month and year	2025-06
Derivatives Designated as Hedging Instruments [Member] | Level 1 Derivative Instruments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized loss reclassed from Other comprehensive (loss) income to earnings	$ 35	$ (10)
Derivatives Designated as Hedging Instruments [Member] | Power Contract [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Aluminum forecast sales | kt	1,683	1,905
Derivatives Designated as Hedging Instruments [Member] | Power Contract [Member] | Cash Flow Hedging [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amount of gain (loss) expected to be recognized into earnings over the next 12 months	$ (195)
Derivatives Designated as Hedging Instruments [Member] | Sales [Member] | Level 1 Derivative Instruments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized loss reclassed from Other comprehensive (loss) income to earnings	40	$ (7)
Derivatives Designated as Hedging Instruments [Member] | Cost of Goods Sold [Member] | Level 1 Derivative Instruments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized loss reclassed from Other comprehensive (loss) income to earnings	$ (5)	$ (3)
Derivatives Not Designated as Hedging Instruments [Member] | Financial Contracts [Member] | Level 3 [Member] | LME Price and Power Price [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contract Termination	Jun. 30, 2026