Consolidated Statements of Equity - USD ($) $ in Millions	Total		Series A Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Noncontrolling Interests [Member]	InfraServ Gmbh & Co. Hoechst KG [Member]
Cumulative Effect on Retained Earnings, Net of Tax						$ 0
Balance as of the beginning of the period, shares at Dec. 31, 2014			152,902,710	13,266,625
Balance as of the beginning of the period at Dec. 31, 2014								$ 260
Balance as of the beginning of the year at Dec. 31, 2014			$ 0	$ (611)	$ 103	3,491	$ (165)
Stock option exercises, net of tax			$ 0		5
Stock option exercises, shares			94,147
Purchases of treasury stock, shares			(6,649,865)
Purchases of treasury stock			$ 0
Stock awards, shares			435,305
Stock awards			$ 0
Purchases of treasury stock, shares	6,640,601	[1]		6,649,865
Purchases of treasury stock, including related fees	$ (420)			$ (420)
Stock-based compensation, net of tax					28
Net earnings (loss) attributable to Celanese Corporation	304					304
Series A common stock dividends						(174)
Other comprehensive income (loss), net of tax	(183)						(183)
Balance as of the end of the year at Dec. 31, 2015	2,378		$ 0	$ (1,031)	136	3,621	(348)
Balance as of the end of the period, shares at Dec. 31, 2015			146,782,297	19,916,490
Net earnings (loss) attributable to noncontrolling interests	(19)							(19)
(Distributions to) contributions from noncontrolling interests								210
Balance as of the end of the period at Dec. 31, 2015								451
Total equity at Dec. 31, 2015	$ 2,829
Dividends, Share-based Compensation, Paid-in-kind						0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									$ 0
Cumulative Effect on Retained Earnings, Net of Tax						0
Stock option exercises, net of tax			$ 0		13
Stock option exercises, shares			194,872
Purchases of treasury stock, shares			(7,034,420)
Purchases of treasury stock			$ 0
Stock awards, shares			717,698
Stock awards			$ 0
Purchases of treasury stock, shares	7,034,420			7,034,420
Purchases of treasury stock, including related fees	$ (500)			$ (500)
Stock-based compensation, net of tax					8
Net earnings (loss) attributable to Celanese Corporation	900					900
Series A common stock dividends						(201)
Other comprehensive income (loss), net of tax	(10)						(10)
Balance as of the end of the year at Dec. 31, 2016	2,588		$ 0	$ (1,531)	157	4,320	(358)
Balance as of the end of the period, shares at Dec. 31, 2016			140,660,447	26,950,910
Net earnings (loss) attributable to noncontrolling interests	6							6
(Distributions to) contributions from noncontrolling interests								(24)
Balance as of the end of the period at Dec. 31, 2016	433							433
Total equity at Dec. 31, 2016	$ 3,021
Dividends, Share-based Compensation, Paid-in-kind						0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									0
Cumulative Effect on Retained Earnings, Net of Tax						(1)
Stock option exercises, net of tax			$ 0		1
Stock option exercises, shares			20,151
Purchases of treasury stock, shares			(5,436,803)
Purchases of treasury stock			$ 0
Stock awards, shares			525,461
Stock awards			$ 0
Purchases of treasury stock, shares	5,436,803			5,436,803
Purchases of treasury stock, including related fees	$ (500)			$ (500)
Stock-based compensation, net of tax					23
Net earnings (loss) attributable to Celanese Corporation	843					843
Series A common stock dividends						(241)
Other comprehensive income (loss), net of tax	181						181
Balance as of the end of the year at Dec. 31, 2017	2,887		$ 0	$ (2,031)	$ 175	4,920	$ (177)
Balance as of the end of the period, shares at Dec. 31, 2017			135,769,256	32,387,713
Net earnings (loss) attributable to noncontrolling interests	6							6
(Distributions to) contributions from noncontrolling interests								(27)
Balance as of the end of the period at Dec. 31, 2017	412							$ 412
Total equity at Dec. 31, 2017	$ 3,299
Dividends, Share-based Compensation, Paid-in-kind						$ (1)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									$ (6)

[1] The year ended December 31, 2015 excludes 9,264 shares withheld from an executive officer to cover statutory minimum withholding requirements for personal income taxes related to the vesting of restricted stock. Restricted stock awards are considered outstanding at the time of issuance. Accordingly, the shares withheld are treated as treasury shares.