Goodwill and Intangible Assets, net (Schedule of Goodwill) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($)
Goodwill [Line Items]
As of December 31, 2020	$ 1,166
Acquisitions	6
Exchange rate changes	(41)
As of March 31, 2019	1,131	[1]
Goodwill, Impaired, Accumulated Impairment Loss	0
Engineered Materials
Goodwill [Line Items]
As of December 31, 2020	768
Acquisitions	4
Exchange rate changes	(28)
As of March 31, 2019	744	[1]
Acetate Tow
Goodwill [Line Items]
As of December 31, 2020	149
Acquisitions	0
Exchange rate changes	0
As of March 31, 2019	149	[1]
Acetyl Chain
Goodwill [Line Items]
As of December 31, 2020	249
Acquisitions	2
Exchange rate changes	(13)
As of March 31, 2019	$ 238	[1]

[1] There were no accumulated impairment losses as of September 30, 2021.