Earnings (Loss) Per Share - Schedule of Earnings (Loss) Per Share (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2026	Mar. 31, 2025
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations		$ 45	$ (19)
Earnings (loss) from discontinued operations		(1)	(5)
Net earnings (loss)		$ 44	$ (24)
Weighted average shares - basic (in shares)		109,663,939	109,421,035
Incremental shares attributable to equity awards(1)	[1]	315,008	0
Weighted average shares - diluted		109,978,947	109,421,035
Antidilutive securities excluded from computation of earnings per share, amount			167,276

[1] Excludes anti-dilutive incremental shares attributable to equity awards as follows: Three Months Ended
March 31, 20262025(In shares )Options to purchase shares of Common Stock828,128 535,179 Equity award shares8,098 75,147