Earnings (Loss) Per Share (Schedule of Earnings (Loss) Per Share) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations		$ 323	$ 225
Earnings (loss) from discontinued operations		(1)	(7)
Net earnings (loss)		$ 322	$ 218
Weighted average shares - basic		113,511,369	119,251,689
Incremental shares attributable to equity awards(1)	[1]	516,776	648,155
Weighted average shares - diluted		114,028,145	119,899,844

[1] Excludes 29 and 63,384 equity award shares for the three months ended March 31, 2021 and 2020, respectively, as their effect would have been antidilutive.