Earnings (Loss) Per Share (Schedule of Earnings (Loss) Per Share) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Amounts attributable to Celanese Corporation
Earnings (loss) from continuing operations	$ 407	$ 230	$ 1,116	$ 652
Earnings (loss) from discontinued operations	(6)	(4)	(8)	(12)
Net earnings (loss)	$ 401	$ 226	$ 1,108	$ 640
Weighted average shares - basic	134,519,301	136,579,077	135,336,704	138,599,330
Incremental shares attributable to equity awards	980,089	372,846	1,050,999	388,991
Weighted average shares - diluted	135,499,390	136,951,923	136,387,703	138,988,321

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