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		9,937
Stock-based compensation, net of tax				(8)
Stock option exercises		$ 0		(1)
Stock awards, shares		478,997
Stock awards		$ 0
Purchases of treasury stock, shares	(1,972,291)	(1,972,291)	1,972,291
Purchases of treasury stock, including related fees	$ (200)	$ 0	$ (200)
Shares Issued, Shares, Share-based Payment Arrangement, after Forfeiture			(9,937)
Stock-based compensation, net of tax			$ 1
Net earnings (loss) attributable to Celanese Corporation	337				337
Common stock dividends					(70)
Other comprehensive income (loss), net of tax	4					4
Balance as of the end of the period, shares at Mar. 31, 2019		126,612,492	42,285,459
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2018							$ 395
Net earnings (loss) attributable to noncontrolling interests	1						1
(Distributions to) contributions from noncontrolling interests							(4)
Stockholders' Equity Attributable to Noncontrolling Interest at Mar. 31, 2019							392
Total Celanese Corporation stockholders' equity at Mar. 31, 2019	3,047	$ 0	$ (3,048)	224	6,114	(243)
Balance as of the end of the period at Mar. 31, 2019	3,439
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				(12)
Stock option exercises		$ 0		0
Stock awards, shares		383,122
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			0
Stock-based compensation, net of tax			$ 0
Net earnings (loss) attributable to Celanese Corporation	218				218
Common stock dividends					(74)
Other comprehensive income (loss), net of tax	(41)					(41)
Balance as of the end of the period, shares at Mar. 31, 2020		118,228,898	51,127,396
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2019	391						391
Net earnings (loss) attributable to noncontrolling interests	2						2
(Distributions to) contributions from noncontrolling interests							(5)
Stockholders' Equity Attributable to Noncontrolling Interest at Mar. 31, 2020	388						$ 388
Total Celanese Corporation stockholders' equity at Mar. 31, 2020	2,448	$ 0	$ (3,996)	$ 242	$ 6,543	$ (341)
Balance as of the end of the period at Mar. 31, 2020	$ 2,836