Unaudited Interim Consolidated Statement Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]
Balance as of the beginning of the period, shares at Dec. 31, 2017		135,769,256	32,387,713
Total Celanese Corporation stockholders' equity at Dec. 31, 2017		$ 0	$ (2,031)	$ 175	$ 4,920	$ (177)
Stock option exercises, shares		0
Stock option exercises		$ 0		0
Purchases of treasury stock, shares		(2,180,758)
Purchases of treasury stock		$ 0
Stock awards, shares		143,011
Stock awards		$ 0
Purchases of treasury stock, shares	2,179,058		2,180,758
Purchases of treasury stock, including related fees	$ (250)		$ 250
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			0
Stock-based compensation, net of tax			$ 0	47
Net earnings (loss) attributable to Celanese Corporation	1,108				1,108
Common stock dividends					209
Other comprehensive income (loss), net of tax	(42)					(42)
Balance as of the end of the period, shares at Sep. 30, 2018		133,731,509	34,568,471
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2017							$ 412
Net earnings (loss) attributable to noncontrolling interests	4						4
(Distributions to) contributions from noncontrolling interests							14
Stockholders' Equity Attributable to Noncontrolling Interest at Sep. 30, 2018							402
Total Celanese Corporation stockholders' equity at Sep. 30, 2018	3,541	$ 0	$ (2,281)	222	5,819	(219)
Balance as of the end of the period at Sep. 30, 2018	3,943
Balance as of the beginning of the period, shares at Jun. 30, 2018		135,018,148	33,276,096
Total Celanese Corporation stockholders' equity at Jun. 30, 2018		$ 0	$ (2,131)	208	5,491	(188)
Stock option exercises				0
Purchases of treasury stock, shares		(1,292,375)
Purchases of treasury stock		$ 0
Stock awards, shares		5,736
Stock awards		$ 0
Purchases of treasury stock, shares			1,292,375
Purchases of treasury stock, including related fees			$ 150
Stock-based compensation, net of tax				14
Net earnings (loss) attributable to Celanese Corporation	401				401
Common stock dividends					73
Other comprehensive income (loss), net of tax	(31)					(31)
Balance as of the end of the period, shares at Sep. 30, 2018		133,731,509	34,568,471
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2018							407
Net earnings (loss) attributable to noncontrolling interests	1						1
(Distributions to) contributions from noncontrolling interests							6
Stockholders' Equity Attributable to Noncontrolling Interest at Sep. 30, 2018							402
Total Celanese Corporation stockholders' equity at Sep. 30, 2018	3,541	$ 0	$ (2,281)	222	5,819	(219)
Balance as of the end of the period at Sep. 30, 2018	3,943
Balance as of the beginning of the period, shares at Dec. 31, 2018		128,095,849	40,323,105
Balance as of the beginning of the period at Dec. 31, 2018	3,379
Total Celanese Corporation stockholders' equity at Dec. 31, 2018	$ 2,984	$ 0	$ (2,849)	233	5,847	(247)
Stock option exercises, shares		14,045
Stock option exercises		$ 0		(1)
Purchases of treasury stock, shares		(7,334,433)
Purchases of treasury stock		$ 0
Stock awards, shares		557,842
Stock awards		$ 0
Purchases of treasury stock, shares	7,334,433		7,334,433
Purchases of treasury stock, including related fees	$ (775)		$ 775
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			(42,778)
Stock-based compensation, net of tax			$ 2	12
Net earnings (loss) attributable to Celanese Corporation	809				809
Common stock dividends					225
Other comprehensive income (loss), net of tax	(59)					(59)
Balance as of the end of the period, shares at Sep. 30, 2019		121,333,303	47,614,760
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2018	395						395
Net earnings (loss) attributable to noncontrolling interests	4						4
(Distributions to) contributions from noncontrolling interests							7
Stockholders' Equity Attributable to Noncontrolling Interest at Sep. 30, 2019	392						392
Total Celanese Corporation stockholders' equity at Sep. 30, 2019	2,747	$ 0	$ (3,622)	244	6,431	(306)
Balance as of the end of the period at Sep. 30, 2019	3,139
Balance as of the beginning of the period, shares at Jun. 30, 2019		123,740,349	45,170,482
Total Celanese Corporation stockholders' equity at Jun. 30, 2019		$ 0	$ (3,347)	233	6,245	(267)
Stock option exercises				0
Purchases of treasury stock, shares		(2,444,278)
Purchases of treasury stock		$ 0
Stock awards, shares		37,232
Stock awards		$ 0
Purchases of treasury stock, shares			2,444,278
Purchases of treasury stock, including related fees			$ 275
Stock-based compensation, net of tax				11
Net earnings (loss) attributable to Celanese Corporation	263				263
Common stock dividends					77
Other comprehensive income (loss), net of tax	(39)					(39)
Balance as of the end of the period, shares at Sep. 30, 2019		121,333,303	47,614,760
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2019							390
Net earnings (loss) attributable to noncontrolling interests	2						2
(Distributions to) contributions from noncontrolling interests							0
Stockholders' Equity Attributable to Noncontrolling Interest at Sep. 30, 2019	392						$ 392
Total Celanese Corporation stockholders' equity at Sep. 30, 2019	2,747	$ 0	$ (3,622)	$ 244	$ 6,431	$ (306)
Balance as of the end of the period at Sep. 30, 2019	$ 3,139