Consolidating Guarantor Financial Information (Schedule of Consolidating Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,687	$ 1,851
Cost of sales	(1,234)	(1,336)
Gross profit	453	515
Selling, general and administrative expenses	(120)	(147)
Amortization of intangible assets	(6)	(6)
Research and development expenses	(16)	(18)
Other (charges) gains, net	4	0
Foreign exchange gain (loss), net	5	(1)
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	320	343
Equity in net earnings (loss) of affiliates	50	58
Non-operating pension and other postretirement employee benefit (expense) income	17	26
Interest expense	(31)	(33)
Interest income	1	2
Dividend income - equity investments	32	32
Other income (expense), net	(4)	4
Earnings (loss) from continuing operations before tax	385	432
Income tax (provision) benefit	(46)	(65)
Earnings (loss) from continuing operations	339	367
Earnings (loss) from operation of discontinued operations	(1)	(2)
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	(1)	(2)
Net earnings (loss)	338	365
Net (earnings) loss attributable to noncontrolling interests	(1)	(2)
Net earnings (loss) attributable to Celanese Corporation	337	363
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	0	0
Amortization of intangible assets	0	0
Research and development expenses	0	0
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	0	0
Equity in net earnings (loss) of affiliates	337	363
Non-operating pension and other postretirement employee benefit (expense) income	0	0
Interest expense	0	0
Interest income	0	0
Dividend income - equity investments	0	0
Other income (expense), net	0	0
Earnings (loss) from continuing operations before tax	337	363
Income tax (provision) benefit	0	0
Earnings (loss) from continuing operations	337	363
Earnings (loss) from operation of discontinued operations	0	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	0
Net earnings (loss)	337	363
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	337	363
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	0	0
Amortization of intangible assets	0	0
Research and development expenses	0	0
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	0	0
Equity in net earnings (loss) of affiliates	337	360
Non-operating pension and other postretirement employee benefit (expense) income	0	0
Interest expense	(10)	(5)
Interest income	13	8
Dividend income - equity investments	0	0
Other income (expense), net	1	1
Earnings (loss) from continuing operations before tax	341	364
Income tax (provision) benefit	(4)	(1)
Earnings (loss) from continuing operations	337	363
Earnings (loss) from operation of discontinued operations	0	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	0
Net earnings (loss)	337	363
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	337	363
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	624	600
Cost of sales	(458)	(464)
Gross profit	166	136
Selling, general and administrative expenses	(40)	(60)
Amortization of intangible assets	(2)	(2)
Research and development expenses	(6)	(8)
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	(2)	(2)
Operating profit (loss)	116	64
Equity in net earnings (loss) of affiliates	217	267
Non-operating pension and other postretirement employee benefit (expense) income	15	23
Interest expense	(31)	(29)
Interest income	2	2
Dividend income - equity investments	0	0
Other income (expense), net	0	1
Earnings (loss) from continuing operations before tax	319	328
Income tax (provision) benefit	(7)	(37)
Earnings (loss) from continuing operations	312	291
Earnings (loss) from operation of discontinued operations	(1)	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	(1)	0
Net earnings (loss)	311	291
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	311	291
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,373	1,554
Cost of sales	(1,077)	(1,178)
Gross profit	296	376
Selling, general and administrative expenses	(80)	(87)
Amortization of intangible assets	(4)	(4)
Research and development expenses	(10)	(10)
Other (charges) gains, net	4	0
Foreign exchange gain (loss), net	5	(1)
Gain (loss) on disposition of businesses and assets, net	2	2
Operating profit (loss)	213	276
Equity in net earnings (loss) of affiliates	43	53
Non-operating pension and other postretirement employee benefit (expense) income	2	3
Interest expense	(7)	(9)
Interest income	3	2
Dividend income - equity investments	32	32
Other income (expense), net	(5)	2
Earnings (loss) from continuing operations before tax	281	359
Income tax (provision) benefit	(36)	(27)
Earnings (loss) from continuing operations	245	332
Earnings (loss) from operation of discontinued operations	0	(2)
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	(2)
Net earnings (loss)	245	330
Net (earnings) loss attributable to noncontrolling interests	(1)	(2)
Net earnings (loss) attributable to Celanese Corporation	244	328
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(310)	(303)
Cost of sales	301	306
Gross profit	(9)	3
Selling, general and administrative expenses	0	0
Amortization of intangible assets	0	0
Research and development expenses	0	0
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	(9)	3
Equity in net earnings (loss) of affiliates	(884)	(985)
Non-operating pension and other postretirement employee benefit (expense) income	0	0
Interest expense	17	10
Interest income	(17)	(10)
Dividend income - equity investments	0	0
Other income (expense), net	0	0
Earnings (loss) from continuing operations before tax	(893)	(982)
Income tax (provision) benefit	1	0
Earnings (loss) from continuing operations	(892)	(982)
Earnings (loss) from operation of discontinued operations	0	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	0
Net earnings (loss)	(892)	(982)
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (892)	$ (982)