Unaudited Interim Consolidated Statement Equity - USD ($)	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, 2017		135,769,256	32,387,713
Total Celanese Corporation stockholders' equity at Dec. 31, 2017		$ 0	$ (2,031,000,000)	$ 175,000,000	$ 4,920,000,000	$ (177,000,000)
Stock option exercises, shares		0
Stock option exercises		$ 0		0
Purchases of treasury stock, shares		0
Purchases of treasury stock		$ 0
Stock awards, shares		86,454
Stock awards		$ 0
Purchases of treasury stock, shares	0		0
Purchases of treasury stock, including related fees	$ 0		$ 0
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures			0
Stock-based compensation, net of tax			$ 0	17,000,000
Net earnings (loss) attributable to Celanese Corporation	363,000,000				363,000,000
Common stock dividends					63,000,000
Other comprehensive income (loss), net of tax	49,000,000					49,000,000
Balance as of the end of the period, shares at Mar. 31, 2018		135,855,710	32,387,713
Stockholders' Equity Attributable to Noncontrolling Interest at Dec. 31, 2017							$ 412,000,000
Net earnings (loss) attributable to noncontrolling interests	2,000,000						2,000,000
(Distributions to) contributions from noncontrolling interests							2,000,000
Stockholders' Equity Attributable to Noncontrolling Interest at Mar. 31, 2018							412,000,000
Total Celanese Corporation stockholders' equity at Mar. 31, 2018	3,253,000,000	$ 0	$ (2,031,000,000)	192,000,000	5,220,000,000	(128,000,000)
Balance as of the end of the period at Mar. 31, 2018	3,665,000,000
Balance as of the beginning of the period, shares at Dec. 31, 2018		128,095,849	40,323,105
Balance as of the beginning of the period at Dec. 31, 2018	3,379,000,000
Total Celanese Corporation stockholders' equity at Dec. 31, 2018	$ 2,984,000,000	$ 0	$ (2,849,000,000)	233,000,000	5,847,000,000	(247,000,000)
Stock option exercises, shares		9,937
Stock option exercises		$ 0		(1,000,000)
Purchases of treasury stock, shares		(1,972,291)
Purchases of treasury stock		$ 0
Stock awards, shares		478,997
Stock awards		$ 0
Purchases of treasury stock, shares	1,972,291		1,972,291
Purchases of treasury stock, including related fees	$ (200,000,000)		$ 200,000,000
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures			(9,937)
Stock-based compensation, net of tax			$ 1,000,000	(8,000,000)
Net earnings (loss) attributable to Celanese Corporation	337,000,000				337,000,000
Common stock dividends					70,000,000
Other comprehensive income (loss), net of tax	4,000,000					4,000,000
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	395,000,000						395,000,000
Net earnings (loss) attributable to noncontrolling interests	1,000,000						1,000,000
(Distributions to) contributions from noncontrolling interests							4,000,000
Stockholders' Equity Attributable to Noncontrolling Interest at Mar. 31, 2019	392,000,000						$ 392,000,000
Total Celanese Corporation stockholders' equity at Mar. 31, 2019	3,047,000,000	$ 0	$ (3,048,000,000)	$ 224,000,000	$ 6,114,000,000	$ (243,000,000)
Balance as of the end of the period at Mar. 31, 2019	$ 3,439,000,000