Consolidated Statements of Equity - USD ($) $ in Millions	Total		Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net [Member]	Noncontrolling Interests [Member]	InfraServ Gmbh & Co. Hoechst KG [Member]
Cumulative Effect on Retained Earnings, Net of Tax						$ (1)
Balance as of the beginning of the period, shares at Dec. 31, 2016			140,660,447	26,950,910
Balance as of the beginning of the period at Dec. 31, 2016								$ 433
Balance as of the beginning of the year at Dec. 31, 2016			$ 0	$ (1,531)	$ 157	4,320	$ (358)
Stock option exercises, net of tax			$ 0		1
Stock option exercises, shares			20,151
Purchases of treasury stock, shares			(5,436,803)
Purchases of treasury stock			$ 0
Stock awards, shares			525,461
Stock awards			$ 0
Purchases of treasury stock, shares	5,436,803			5,436,803
Purchases of treasury stock, including related fees	$ (500)			$ (500)
Stock-based compensation, net of tax				0	23
Net earnings (loss) attributable to Celanese Corporation	843					843
Common stock dividends						(241)
Other comprehensive income (loss), net of tax	181						181
Balance as of the end of the year at Dec. 31, 2017	2,887		$ 0	$ (2,031)	175	4,920	(177)
Balance as of the end of the period, shares at Dec. 31, 2017			135,769,256	32,387,713
Net earnings (loss) attributable to noncontrolling interests	(6)							6
(Distributions to) contributions from noncontrolling interests								(27)
Balance as of the end of the period at Dec. 31, 2017								412
Total equity at Dec. 31, 2017	$ 3,299
Dividend, Share-based Payment Arrangement, Paid-in-Kind						(1)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									$ (6)
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture				0
Cumulative Effect on Retained Earnings, Net of Tax						0
Stock option exercises, net of tax			$ 0		0
Stock option exercises, shares			0
Purchases of treasury stock, shares			(7,935,392)
Purchases of treasury stock			$ 0
Stock awards, shares			261,985
Stock awards			$ 0
Purchases of treasury stock, shares	7,933,692	[1]		7,935,392
Purchases of treasury stock, including related fees	$ (817)			$ (818)
Stock-based compensation, net of tax				0	58
Net earnings (loss) attributable to Celanese Corporation	1,207					1,207
Common stock dividends						(280)
Other comprehensive income (loss), net of tax	(70)						(70)
Balance as of the end of the year at Dec. 31, 2018	2,984		$ 0	$ (2,849)	233	5,847	(247)
Balance as of the end of the period, shares at Dec. 31, 2018			128,095,849	40,323,105
Net earnings (loss) attributable to noncontrolling interests	(6)							6
(Distributions to) contributions from noncontrolling interests								(23)
Balance as of the end of the period at Dec. 31, 2018	395							395
Total equity at Dec. 31, 2018	$ 3,379
Dividend, Share-based Payment Arrangement, Paid-in-Kind						0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									0
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture				0
Cumulative Effect on Retained Earnings, Net of Tax						0
Stock option exercises, net of tax			$ 0		(1)
Stock option exercises, shares			14,045
Purchases of treasury stock, shares			(9,166,267)
Purchases of treasury stock			$ 0
Stock awards, shares			611,580
Stock awards			$ 0
Purchases of treasury stock, shares	9,166,267			9,166,267
Purchases of treasury stock, including related fees	$ (1,000)			$ (1,000)
Stock-based compensation, net of tax				3	22
Net earnings (loss) attributable to Celanese Corporation	852					852
Common stock dividends						(300)
Other comprehensive income (loss), net of tax	(53)						(53)
Balance as of the end of the year at Dec. 31, 2019	2,507		$ 0	$ (3,846)	$ 254	6,399	$ (300)
Balance as of the end of the period, shares at Dec. 31, 2019			119,555,207	49,417,965
Net earnings (loss) attributable to noncontrolling interests	(6)							6
(Distributions to) contributions from noncontrolling interests								(10)
Balance as of the end of the period at Dec. 31, 2019	391							$ 391
Total equity at Dec. 31, 2019	$ 2,898
Dividend, Share-based Payment Arrangement, Paid-in-Kind						$ 0
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests									$ 0
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture				(71,407)

[1] Excludes 1,700 common shares reacquired pursuant to an employee clawback agreement.