Revenue Recognition Disaggregated Revenue (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Net sales		$ 9,544	$ 10,268	$ 10,926
Intersegment [Member]
Disaggregation of Revenue [Line Items]
Net sales		(78)	(90)	(93)
Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		5,390	5,595	6,135
Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales	[1]	4,154	4,673	4,791
Acetyl Chain | Intersegment [Member]
Disaggregation of Revenue [Line Items]
Net sales		78	90	93
North America [Member] | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		1,456	1,541	1,766
North America [Member] | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		1,442	1,526	1,448
Europe and Africa | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		1,571	1,641	1,941
Europe and Africa | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		1,488	1,613	1,680
Asia Pacific [Member] | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		2,234	2,272	2,274
Asia Pacific [Member] | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		1,123	1,415	1,543
South America [Member] | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		129	141	154
South America [Member] | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		$ 101	$ 119	$ 120

[1] Excludes intersegment sales of $78 million, $90 million and $93 million for the years ended December 31, 2025, 2024 and 2023, respectively.