Consolidated Statements of Equity - USD ($) $ in Millions	Total		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, 2015			146,782,297	19,916,490
Balance as of the beginning of the period at Dec. 31, 2015								$ 451
Balance as of the beginning of the year at Dec. 31, 2015			$ 0	$ (1,031)	$ 136	3,621	$ (348)
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
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
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
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)
Cumulative Effect on Retained Earnings, Net of Tax						0
Stock option exercises, net of tax			$ 0		0
Stock option exercises, shares			0
Purchases of treasury stock, shares			(7,935,392)
Purchases of treasury stock			$ 0
Stock awards, shares			261,985
Stock awards			$ 0
Purchases of treasury stock, shares	7,933,692	[1]		7,935,392
Purchases of treasury stock, including related fees	$ (817)			$ (818)
Stock-based compensation, net of tax					58
Net earnings (loss) attributable to Celanese Corporation	1,207					1,207
Common stock dividends						(280)
Other comprehensive income (loss), net of tax	(70)						(70)
Balance as of the end of the year at Dec. 31, 2018	2,984		$ 0	$ (2,849)	$ 233	5,847	$ (247)
Balance as of the end of the period, shares at Dec. 31, 2018			128,095,849	40,323,105
Net earnings (loss) attributable to noncontrolling interests	6							6
(Distributions to) contributions from noncontrolling interests								(23)
Balance as of the end of the period at Dec. 31, 2018	395							$ 395
Total equity at Dec. 31, 2018	$ 3,379
Dividends, Share-based Compensation, Paid-in-kind						$ 0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									$ 0

[1] Excludes 1,700 common shares reacquired pursuant to an employee clawback agreement.