Earnings (Loss) Per Share (Schedule of Earnings (Loss) Per Share) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations		$ 110	$ 210	$ 335	$ 548
Earnings (loss) from discontinued operations		(3)	(1)	(10)	(2)
Net earnings (loss)		$ 107	$ 209	$ 325	$ 546
Weighted average shares - basic		118,339,872	125,289,967	118,795,780	126,409,926
Incremental shares attributable to equity awards(1)	[1]	427,761	557,927	581,735	701,120
Weighted average shares - diluted		118,767,633	125,847,894	119,377,515	127,111,046

[1] Excludes 120,210 and 0 equity award shares for the three months ended June 30, 2020 and 2019, respectively, as their effect would have been antidilutive. Excludes 89,241 and 0 equity award shares for the six months ended June 30, 2020 and 2019, respectively, as their effect would have been antidilutive.