Unaudited Interim Consolidated Statement Equity - 9 months ended Sep. 30, 2018 - 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) [Member]	Noncontrolling Interest [Member]
Balance as of the beginning of the period, shares at Dec. 31, 2017			135,769,256	32,387,713
Balance as of the beginning of the period at Dec. 31, 2017	$ 3,299
Total Celanese Corporation stockholders' equity at Dec. 31, 2017	$ 2,887		$ 0	$ (2,031)	$ 175	$ 4,920	$ (177)
Stock option exercises, shares			0
Stock option exercises			$ 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	[1]		2,180,758
Purchases of treasury stock, including related fees	$ (250)			$ (250)
Stock-based compensation, net of tax					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							$ 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							$ 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

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