Earnings (Loss) Per Share (Schedule of Earnings (Loss) Per Share) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations		$ 1,997	$ 858	$ 1,212
Earnings (loss) from discontinued operations		(12)	(6)	(5)
Net earnings (loss) attributable to Celanese Corporation		$ 1,985	$ 852	$ 1,207
Weighted average shares - basic		117,817,445	123,925,697	134,305,269
Incremental shares attributable to equity awards	[1]	663,931	726,062	1,111,589
Weighted average shares - diluted		118,481,376	124,651,759	135,416,858
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		4,313	45	0

[1] Excludes 4,313, 45 and 0 equity award shares for the years ended December 31, 2020, 2019 and 2018, respectively, as their effect would have been antidilutive.