Consolidating Guarantor Financial Information (Schedule of Consolidating Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,193	$ 1,592	$ 2,653	$ 3,279
Cost of sales	(951)	(1,169)	(2,063)	(2,403)
Gross profit	242	423	590	876
Selling, general and administrative expenses	(114)	(118)	(239)	(238)
Amortization of intangible assets	(6)	(6)	(11)	(12)
Research and development expenses	(18)	(17)	(35)	(33)
Other (charges) gains, net	(21)	(98)	(27)	(94)
Foreign exchange gain (loss), net	1	1	0	6
Gain (loss) on disposition of businesses and assets, net	(1)	1	(1)	1
Operating profit (loss)	83	186	277	506
Equity in net earnings (loss) of affiliates	31	39	88	89
Non-operating pension and other postretirement employee benefit (expense) income	27	17	55	34
Interest expense	(27)	(29)	(55)	(60)
Refinancing expense	0	(4)	0	(4)
Interest income	1	2	3	3
Dividend income - equity investments	32	30	69	62
Other income (expense), net	0	(2)	2	(6)
Earnings (loss) from continuing operations before tax	147	239	439	624
Income tax (provision) benefit	(35)	(28)	(100)	(74)
Earnings (loss) from continuing operations	112	211	339	550
Earnings (loss) from operation of discontinued operations	(4)	(2)	(11)	(3)
Income tax (provision) benefit from discontinued operations	1	1	1	1
Earnings (loss) from discontinued operations	(3)	(1)	(10)	(2)
Net earnings (loss)	109	210	329	548
Net (earnings) loss attributable to noncontrolling interests	(2)	(1)	(4)	(2)
Net earnings (loss) attributable to Celanese Corporation	107	209	325	546
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Research and development expenses	0	0	0	0
Other (charges) gains, net	0	0	0	0
Foreign exchange gain (loss), net	0	0	0	0
Gain (loss) on disposition of businesses and assets, net	0	0	0	0
Operating profit (loss)	0	0	0	0
Equity in net earnings (loss) of affiliates	110	209	336	546
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	(4)	0	(12)	0
Refinancing expense		0		0
Interest income	0	0	0	0
Dividend income - equity investments	0	0	0	0
Other income (expense), net	0	0	0	0
Earnings (loss) from continuing operations before tax	106	209	324	546
Income tax (provision) benefit	1	0	1	0
Earnings (loss) from continuing operations	107	209	325	546
Earnings (loss) from operation of discontinued operations	0	0	0	0
Income tax (provision) benefit from discontinued operations	0	0	0	0
Earnings (loss) from discontinued operations	0	0	0	0
Net earnings (loss)	107	209	325	546
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	107	209	325	546
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Research and development expenses	0	0	0	0
Other (charges) gains, net	0	0	0	0
Foreign exchange gain (loss), net	0	0	0	0
Gain (loss) on disposition of businesses and assets, net	0	0	0	0
Operating profit (loss)	0	0	0	0
Equity in net earnings (loss) of affiliates	111	210	333	547
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	(10)	(9)	(19)	(19)
Refinancing expense		(4)		(4)
Interest income	9	18	22	31
Dividend income - equity investments	0	0	0	0
Other income (expense), net	(1)	(4)	7	(3)
Earnings (loss) from continuing operations before tax	109	211	343	552
Income tax (provision) benefit	1	(2)	(7)	(6)
Earnings (loss) from continuing operations	110	209	336	546
Earnings (loss) from operation of discontinued operations	0	0	0	0
Income tax (provision) benefit from discontinued operations	0	0	0	0
Earnings (loss) from discontinued operations	0	0	0	0
Net earnings (loss)	110	209	336	546
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	110	209	336	546
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	462	586	1,022	1,210
Cost of sales	(408)	(443)	(868)	(901)
Gross profit	54	143	154	309
Selling, general and administrative expenses	(36)	(39)	(90)	(79)
Amortization of intangible assets	(2)	(2)	(4)	(4)
Research and development expenses	(8)	(7)	(15)	(13)
Other (charges) gains, net	(5)	(5)	(13)	(5)
Foreign exchange gain (loss), net	0	0	(1)	0
Gain (loss) on disposition of businesses and assets, net	(2)	(2)	(4)	(4)
Operating profit (loss)	1	88	27	204
Equity in net earnings (loss) of affiliates	137	122	325	339
Non-operating pension and other postretirement employee benefit (expense) income	25	16	50	31
Interest expense	(25)	(35)	(55)	(66)
Refinancing expense		0		0
Interest income	5	11	15	13
Dividend income - equity investments	0	0	0	0
Other income (expense), net	(1)	0	0	0
Earnings (loss) from continuing operations before tax	142	202	362	521
Income tax (provision) benefit	(23)	(23)	(18)	(30)
Earnings (loss) from continuing operations	119	179	344	491
Earnings (loss) from operation of discontinued operations	(4)	(2)	(4)	(3)
Income tax (provision) benefit from discontinued operations	1	1	1	1
Earnings (loss) from discontinued operations	(3)	(1)	(3)	(2)
Net earnings (loss)	116	178	341	489
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	116	178	341	489
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,033	1,298	2,236	2,671
Cost of sales	(822)	(1,020)	(1,768)	(2,097)
Gross profit	211	278	468	574
Selling, general and administrative expenses	(78)	(79)	(149)	(159)
Amortization of intangible assets	(4)	(4)	(7)	(8)
Research and development expenses	(10)	(10)	(20)	(20)
Other (charges) gains, net	(16)	(93)	(14)	(89)
Foreign exchange gain (loss), net	1	1	1	6
Gain (loss) on disposition of businesses and assets, net	1	3	3	5
Operating profit (loss)	105	96	282	309
Equity in net earnings (loss) of affiliates	29	34	80	77
Non-operating pension and other postretirement employee benefit (expense) income	2	1	5	3
Interest expense	(3)	(13)	(8)	(20)
Refinancing expense		0		0
Interest income	2	1	6	4
Dividend income - equity investments	32	30	68	62
Other income (expense), net	2	2	(5)	(3)
Earnings (loss) from continuing operations before tax	169	151	428	432
Income tax (provision) benefit	(17)	(3)	(80)	(39)
Earnings (loss) from continuing operations	152	148	348	393
Earnings (loss) from operation of discontinued operations	0	0	(7)	0
Income tax (provision) benefit from discontinued operations	0	0	0	0
Earnings (loss) from discontinued operations	0	0	(7)	0
Net earnings (loss)	152	148	341	393
Net (earnings) loss attributable to noncontrolling interests	(2)	(1)	(4)	(2)
Net earnings (loss) attributable to Celanese Corporation	150	147	337	391
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(302)	(292)	(605)	(602)
Cost of sales	279	294	573	595
Gross profit	(23)	2	(32)	(7)
Selling, general and administrative expenses	0	0	0	0
Amortization of intangible assets	0	0	0	0
Research and development expenses	0	0	0	0
Other (charges) gains, net	0	0	0	0
Foreign exchange gain (loss), net	0	0	0	0
Gain (loss) on disposition of businesses and assets, net	0	0	0	0
Operating profit (loss)	(23)	2	(32)	(7)
Equity in net earnings (loss) of affiliates	(356)	(536)	(986)	(1,420)
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	15	28	39	45
Refinancing expense		0		0
Interest income	(15)	(28)	(40)	(45)
Dividend income - equity investments	0	0	1	0
Other income (expense), net	0	0	0	0
Earnings (loss) from continuing operations before tax	(379)	(534)	(1,018)	(1,427)
Income tax (provision) benefit	3	0	4	1
Earnings (loss) from continuing operations	(376)	(534)	(1,014)	(1,426)
Earnings (loss) from operation of discontinued operations	0	0	0	0
Income tax (provision) benefit from discontinued operations	0	0	0	0
Earnings (loss) from discontinued operations	0	0	0	0
Net earnings (loss)	(376)	(534)	(1,014)	(1,426)
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (376)	$ (534)	$ (1,014)	$ (1,426)