v3.20.2

Restructuring and Other Charges - Restructuring Reserve (Details) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($) employee	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) employee claimants	Sep. 30, 2019 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2019 USD ($)
Restructuring Reserve [Roll Forward]
Beginning balance				$ 21	$ 4			$ 4
Cash payments				(18)				(15)
Restructuring charges				29				32
Other				(10)				0
Ending balance		$ 24		24				21
Restructuring and other charges		(3)	$ (64)	(61)	(104)
Separation-related adjustments (A)		8		324
Restructuring and other charges (E)		$ 3	64	$ 61	104
Number of employees separated | employee		30		440
Forecast
Restructuring Reserve [Roll Forward]
Cash payments	$ (12)					$ (1)	$ (11)
Hard Alloy Extrusions Plant in South Korea
Restructuring Reserve [Roll Forward]
Gain (Loss) on Disposition of Business				$ 25
Aluminum Rolling Mill in Brazil
Restructuring Reserve [Roll Forward]
Restructuring and other charges			(59)		(59)
Gain (Loss) on Disposition of Business				25
Operating segments
Restructuring Reserve [Roll Forward]
Restructuring and other charges		$ 0	(62)	(6)	(99)
Rolled Products [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges		(1)	(61)	(15)	(69)
Building and Construction Systems [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges		0	(2)	(6)	(31)
Extrusions [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges		(1)	(1)	(27)	(1)
Corporate Segment
Restructuring Reserve [Roll Forward]
Restructuring and other charges		(3)	(2)	(67)	(5)
Layoff costs
Restructuring Reserve [Roll Forward]
Beginning balance				20	1			1
Cash payments				(16)				(12)
Restructuring charges				26				30
Other				(9)				1
Ending balance		23		23				20
Restructuring and other charges		(1)		(18)
Separation-related adjustments (A)				2
Layoff costs | Building and Construction System and Extrustions [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges				$ (8)
Number of employees separated | claimants				140
Other costs
Restructuring Reserve [Roll Forward]
Beginning balance				$ 1	3			3
Cash payments				(2)				(3)
Restructuring charges				3				2
Other				(1)				(1)
Ending balance		1		1				$ 1
Restructuring and other charges		(1)		(7)	(2)
Separation-related adjustments (A)				0
Other costs | Building and Construction System and Extrustions [Member]
Restructuring Reserve [Roll Forward]
Restructuring and other charges				(11)
Spin-off
Restructuring Reserve [Roll Forward]
Restructuring and other charges		$ 0	$ (2)	(2)	$ (5)
Separation-related adjustments (A)				$ 2

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