Unaudited Interim Consolidated Statement Equity - 6 months ended Jun. 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, net of tax		$ 0
Purchases of treasury stock, shares		(888,383)
Purchases of treasury stock, including related fees		$ 0
Stock awards, shares		137,275
Stock awards		$ 0
Purchases of treasury stock, shares	888,383		888,383
Purchases of treasury stock, including related fees	$ (100)		$ (100)
Stock-based compensation, net of tax				33
Net earnings (loss) attributable to Celanese Corporation	707				707
Series A common stock dividends					(136)
Other comprehensive income (loss), net of tax	(11)					(11)
Balance as of the end of the period, shares at Jun. 30, 2018		135,018,148	33,276,096
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2017	412						$ 412
Net earnings (loss) attributable to noncontrolling interests	3						3
(Distributions to) contributions from noncontrolling interests							(8)
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2018	407						$ 407
Total Celanese Corporation stockholders' equity at Jun. 30, 2018	3,380	$ 0	$ (2,131)	$ 208	$ 5,491	$ (188)
Balance as of the end of the period at Jun. 30, 2018	$ 3,787