Revenue Recognition - Disaggregation of net sales (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Net sales		$ 2,337	$ 2,389
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period		9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period		1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period		1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01
Disaggregation of Revenue [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period		1 year
Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		$ 1,325	1,287
Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales	[1]	1,012	1,102
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Net sales	[2]	(24)	(14)
Intersegment Eliminations | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		24	14
North America | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		357	349
North America | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		348	386
Europe and Africa | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		433	388
Europe and Africa | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		366	385
Asia-Pacific | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		504	516
Asia-Pacific | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		272	307
South America | Engineered Materials
Disaggregation of Revenue [Line Items]
Net sales		31	34
South America | Acetyl Chain
Disaggregation of Revenue [Line Items]
Net sales		$ 26	$ 24

[1] Excludes intersegment sales of $24 million and $14 million for the three months ended March 31, 2026 and 2025, respectively.

[2] Includes intersegment sales primarily related to the Acetyl Chain.