Unaudited Interim Consolidated Statement Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]
Balance as of the beginning of the period, shares at Dec. 31, 2018		128,095,849	40,323,105
Total Celanese Corporation stockholders' equity at Dec. 31, 2018		$ 0	$ (2,849)	$ 233	$ 5,847	$ (247)
Stock option exercises, shares		14,045
Stock-based compensation, net of tax				1
Stock option exercises		$ 0		(1)
Stock awards, shares		520,610
Stock awards		$ 0
Purchases of treasury stock, shares	(4,890,155)	(4,890,155)	4,890,155
Purchases of treasury stock, including related fees	$ (500)	$ 0	$ (500)
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			(42,778)
Stock-based compensation, net of tax			$ 2
Net earnings (loss) attributable to Celanese Corporation	546				546
Common stock dividends					(148)
Other comprehensive income (loss), net of tax	(20)					(20)
Balance as of the end of the period, shares at Jun. 30, 2019		123,740,349	45,170,482
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2018							$ 395
Net earnings (loss) attributable to noncontrolling interests	2						2
(Distributions to) contributions from noncontrolling interests							(7)
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2019							390
Total Celanese Corporation stockholders' equity at Jun. 30, 2019	2,864	$ 0	$ (3,347)	233	6,245	(267)
Balance as of the end of the period at Jun. 30, 2019	3,254
Balance as of the beginning of the period, shares at Mar. 31, 2019		126,612,492	42,285,459
Total Celanese Corporation stockholders' equity at Mar. 31, 2019		$ 0	$ (3,048)	224	6,114	(243)
Stock option exercises, shares		4,108
Stock-based compensation, net of tax				9
Stock option exercises		$ 0
Stock awards, shares		41,613
Stock awards		$ 0
Purchases of treasury stock, shares		(2,917,864)	2,917,864
Purchases of treasury stock, including related fees		$ 0	$ (300)
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			(32,841)
Stock-based compensation, net of tax			$ 1
Net earnings (loss) attributable to Celanese Corporation	209				209
Common stock dividends					(78)
Other comprehensive income (loss), net of tax	(24)					(24)
Balance as of the end of the period, shares at Jun. 30, 2019		123,740,349	45,170,482
Stockholders' Equity Attributable to Noncontrolling Interest at Mar. 31, 2019							392
Net earnings (loss) attributable to noncontrolling interests	1						1
(Distributions to) contributions from noncontrolling interests							(3)
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2019							390
Total Celanese Corporation stockholders' equity at Jun. 30, 2019	2,864	$ 0	$ (3,347)	233	6,245	(267)
Balance as of the end of the period at Jun. 30, 2019	3,254
Balance as of the beginning of the period, shares at Dec. 31, 2019		119,555,207	49,417,965
Balance as of the beginning of the period at Dec. 31, 2019	2,898
Total Celanese Corporation stockholders' equity at Dec. 31, 2019	$ 2,507	$ 0	$ (3,846)	254	6,399	(300)
Stock option exercises, shares		0
Stock-based compensation, net of tax				(2)
Stock option exercises		$ 0		0
Stock awards, shares		442,520
Stock awards		$ 0
Purchases of treasury stock, shares	(1,709,431)	(1,709,431)	1,709,431
Purchases of treasury stock, including related fees	$ (150)	$ 0	$ (150)
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			(44,370)
Stock-based compensation, net of tax			$ 1
Net earnings (loss) attributable to Celanese Corporation	325				325
Common stock dividends					(148)
Other comprehensive income (loss), net of tax	(46)					(46)
Balance as of the end of the period, shares at Jun. 30, 2020		118,288,296	51,083,026
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2019	391						391
Net earnings (loss) attributable to noncontrolling interests	4						4
(Distributions to) contributions from noncontrolling interests							(13)
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2020	382						382
Total Celanese Corporation stockholders' equity at Jun. 30, 2020	2,487	$ 0	$ (3,995)	252	6,576	(346)
Balance as of the end of the period at Jun. 30, 2020	2,869
Balance as of the beginning of the period, shares at Mar. 31, 2020		118,228,898	51,127,396
Total Celanese Corporation stockholders' equity at Mar. 31, 2020		$ 0	$ (3,996)	242	6,543	(341)
Stock option exercises, shares		0
Stock-based compensation, net of tax				10
Stock option exercises		$ 0
Stock awards, shares		59,398
Stock awards		$ 0
Purchases of treasury stock, shares		0	0
Purchases of treasury stock, including related fees		$ 0	$ 0
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			(44,370)
Stock-based compensation, net of tax			$ 1
Net earnings (loss) attributable to Celanese Corporation	107				107
Common stock dividends					(74)
Other comprehensive income (loss), net of tax	(5)					(5)
Balance as of the end of the period, shares at Jun. 30, 2020		118,288,296	51,083,026
Stockholders' Equity Attributable to Noncontrolling Interest at Mar. 31, 2020							388
Net earnings (loss) attributable to noncontrolling interests	2						2
(Distributions to) contributions from noncontrolling interests							(8)
Stockholders' Equity Attributable to Noncontrolling Interest at Jun. 30, 2020	382						$ 382
Total Celanese Corporation stockholders' equity at Jun. 30, 2020	2,487	$ 0	$ (3,995)	$ 252	$ 6,576	$ (346)
Balance as of the end of the period at Jun. 30, 2020	$ 2,869