Consolidating Guarantor Financial Information (Schedule of Consolidating Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,844	$ 1,510	$ 3,695	$ 2,981
Cost of sales	(1,323)	(1,145)	(2,659)	(2,266)
Gross profit	521	365	1,036	715
Selling, general and administrative expenses	(136)	(117)	(283)	(220)
Amortization of intangible assets	(7)	(5)	(13)	(9)
Research and development expenses	(18)	(17)	(36)	(34)
Other (charges) gains, net	(3)	(2)	(3)	(57)
Foreign exchange gain (loss), net	3	(4)	2	(4)
Gain (loss) on disposition of businesses and assets, net	(2)	(2)	(2)	(3)
Operating profit (loss)	358	218	701	388
Equity in net earnings (loss) of affiliates	56	38	114	85
Non-operating pension and other postretirement employee benefit (expense) income	26	22	52	44
Interest expense	(32)	(30)	(65)	(59)
Interest income	0	1	2	1
Dividend income - cost investments	34	29	66	58
Other income (expense), net	0	3	4	4
Earnings (loss) from continuing operations before tax	442	281	874	521
Income tax (provision) benefit	(97)	(40)	(162)	(96)
Earnings (loss) from continuing operations	345	241	712	425
Earnings (loss) from operation of discontinued operations	0	(9)	(2)	(9)
Income tax (provision) benefit from discontinued operations	0	1	0	1
Earnings (loss) from discontinued operations	0	(8)	(2)	(8)
Net earnings (loss)	345	233	710	417
Net (earnings) loss attributable to noncontrolling interests	(1)	(2)	(3)	(3)
Net earnings (loss) attributable to Celanese Corporation	344	231	707	414
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	344	231	707	414
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	0	0	0	0
Interest income	0	0	0	0
Dividend income - cost investments	0	0	0	0
Other income (expense), net	0	0	0	0
Earnings (loss) from continuing operations before tax	344	231	707	414
Income tax (provision) benefit	0	0	0	0
Earnings (loss) from continuing operations	344	231	707	414
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)	344	231	707	414
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	344	231	707	414
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	341	233	701	407
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	(5)	(6)	(10)	(12)
Interest income	10	6	18	12
Dividend income - cost investments	0	0	0	0
Other income (expense), net	(1)	(1)	0	(1)
Earnings (loss) from continuing operations before tax	345	232	709	406
Income tax (provision) benefit	(1)	(1)	(2)	8
Earnings (loss) from continuing operations	344	231	707	414
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)	344	231	707	414
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	344	231	707	414
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	586	563	1,168	1,152
Cost of sales	(457)	(459)	(905)	(904)
Gross profit	129	104	263	248
Selling, general and administrative expenses	(51)	(44)	(110)	(78)
Amortization of intangible assets	(1)	(1)	(2)	(2)
Research and development expenses	(7)	(7)	(15)	(14)
Other (charges) gains, net	0	(1)	0	(7)
Foreign exchange gain (loss), net	0	0	0	0
Gain (loss) on disposition of businesses and assets, net	(3)	(2)	(5)	(4)
Operating profit (loss)	67	49	131	143
Equity in net earnings (loss) of affiliates	312	163	586	264
Non-operating pension and other postretirement employee benefit (expense) income	24	20	47	40
Interest expense	(31)	(24)	(60)	(47)
Interest income	2	1	4	2
Dividend income - cost investments	0	0	0	0
Other income (expense), net	0	1	0	1
Earnings (loss) from continuing operations before tax	374	210	708	403
Income tax (provision) benefit	(69)	(8)	(105)	(71)
Earnings (loss) from continuing operations	305	202	603	332
Earnings (loss) from operation of discontinued operations	(1)	0	(1)	0
Income tax (provision) benefit from discontinued operations	0	0	0	0
Earnings (loss) from discontinued operations	(1)	0	(1)	0
Net earnings (loss)	304	202	602	332
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	304	202	602	332
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,566	1,222	3,138	2,399
Cost of sales	(1,171)	(966)	(2,365)	(1,932)
Gross profit	395	256	773	467
Selling, general and administrative expenses	(85)	(73)	(173)	(142)
Amortization of intangible assets	(6)	(4)	(11)	(7)
Research and development expenses	(11)	(10)	(21)	(20)
Other (charges) gains, net	(3)	(1)	(3)	(50)
Foreign exchange gain (loss), net	3	(4)	2	(4)
Gain (loss) on disposition of businesses and assets, net	1	0	3	1
Operating profit (loss)	294	164	570	245
Equity in net earnings (loss) of affiliates	53	34	106	77
Non-operating pension and other postretirement employee benefit (expense) income	2	2	5	4
Interest expense	(8)	(8)	(17)	(15)
Interest income	2	2	4	2
Dividend income - cost investments	32	30	64	59
Other income (expense), net	1	3	4	4
Earnings (loss) from continuing operations before tax	376	227	736	376
Income tax (provision) benefit	(28)	(34)	(55)	(33)
Earnings (loss) from continuing operations	348	193	681	343
Earnings (loss) from operation of discontinued operations	1	(9)	(1)	(9)
Income tax (provision) benefit from discontinued operations	0	1	0	1
Earnings (loss) from discontinued operations	1	(8)	(1)	(8)
Net earnings (loss)	349	185	680	335
Net (earnings) loss attributable to noncontrolling interests	(1)	(2)	(3)	(3)
Net earnings (loss) attributable to Celanese Corporation	348	183	677	332
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(308)	(275)	(611)	(570)
Cost of sales	305	280	611	570
Gross profit	(3)	5	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)	(3)	5	0	0
Equity in net earnings (loss) of affiliates	(994)	(623)	(1,986)	(1,077)
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	12	8	22	15
Interest income	(14)	(8)	(24)	(15)
Dividend income - cost investments	2	(1)	2	(1)
Other income (expense), net	0	0	0	0
Earnings (loss) from continuing operations before tax	(997)	(619)	(1,986)	(1,078)
Income tax (provision) benefit	1	3	0	0
Earnings (loss) from continuing operations	(996)	(616)	(1,986)	(1,078)
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)	(996)	(616)	(1,986)	(1,078)
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (996)	$ (616)	$ (1,986)	$ (1,078)