Earnings (Loss) Per Share (Schedule of Earnings (Loss) Per Share) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations	$ 344	$ 239	$ 709	$ 422
Earnings (loss) from discontinued operations	0	(8)	(2)	(8)
Net earnings (loss)	$ 344	$ 231	$ 707	$ 414
Weighted average shares - basic	135,589,717	138,619,721	135,752,179	139,626,199
Incremental shares attributable to equity awards	719,441	409,704	747,569	396,357
Weighted average shares - diluted	136,309,158	139,029,425	136,499,748	140,022,556