Earnings (Loss) Per Share (Schedule of Earnings (Loss) Per Share) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations		$ 856	$ 902	$ 306
Earnings (loss) from discontinued operations		(13)	(2)	(2)
Net earnings (loss)		$ 843	$ 900	$ 304
Weighted average shares - basic		137,902,667	144,939,433	150,838,050
Incremental shares attributable to equity awards	[1]	414,728	728,748	1,449,905
Weighted average shares - diluted		138,317,395	145,668,181	152,287,955
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		29	836	2,903

[1] Excludes 29, 836 and 2,903 equity award shares for the years ended December 31, 2017, 2016 and 2015, respectively, as their effect would have been antidilutive.