Unaudited Interim Consolidated Statement Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock, Common	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss), Net
Balance as of the beginning of the period (in shares) at Dec. 31, 2023			61,570,314
Balance as of the beginning of the period (in shares) at Dec. 31, 2023		108,906,426
Balance as of the beginning of the period at Dec. 31, 2023		$ 0	$ (5,488)	$ 394	$ 12,929	$ (744)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises, shares		7,947
Stock option exercises		$ 0		1
Stock awards (in shares)		295,913
Stock awards		$ 0
Issuance of treasury stock under stock plans (in shares)			0
Issuance of treasury stock under stock plans			$ 0
Stock-based compensation, net of tax				(12)
Net earnings (loss) attributable to Celanese Corporation	$ 121				121
Common stock dividends					(77)
Other comprehensive income (loss), net of tax	(53)					(53)
Balance as of the end of the period (in shares) at Mar. 31, 2024		109,210,286
Balance as of the end of the period at Mar. 31, 2024	7,071	$ 0	$ (5,488)	383	12,973	(797)
Balance as of the end of the period (in shares) at Mar. 31, 2024			61,570,314
Balance as of the beginning of the period, noncontrolling interest at Dec. 31, 2023	461
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) attributable to noncontrolling interests	3
Distributions/dividends to noncontrolling interests	(4)
Balance as of the end of the period, noncontrolling interest at Mar. 31, 2024	460
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total equity	7,531
Total equity	$ 5,609					(848)
Balance as of the beginning of the period (in shares) at Dec. 31, 2024	61,499,640		61,499,640
Balance as of the beginning of the period (in shares) at Dec. 31, 2024		109,327,556
Balance as of the beginning of the period at Dec. 31, 2024	$ 5,175	$ 0	$ (5,486)	409	11,100	(848)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises, shares		0
Stock option exercises		$ 0		0
Stock awards (in shares)		75,847
Stock awards		$ 0
Issuance of treasury stock under stock plans (in shares)			0
Issuance of treasury stock under stock plans			$ 0
Stock-based compensation, net of tax				4
Net earnings (loss) attributable to Celanese Corporation	(21)				(21)
Common stock dividends					(3)
Other comprehensive income (loss), net of tax	31					31
Balance as of the end of the period (in shares) at Mar. 31, 2025		109,403,403
Balance as of the end of the period at Mar. 31, 2025	$ 5,186	$ 0	$ (5,486)	$ 413	$ 11,076	(817)
Balance as of the end of the period (in shares) at Mar. 31, 2025	61,499,640		61,499,640
Balance as of the beginning of the period, noncontrolling interest at Dec. 31, 2024	$ 434
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) attributable to noncontrolling interests	4
Distributions/dividends to noncontrolling interests	(9)
Balance as of the end of the period, noncontrolling interest at Mar. 31, 2025	429
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total equity	$ 5,615					$ (817)