Consolidating Guarantor Financial Information (Schedule of Consolidating Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,586	$ 1,771	$ 4,865	$ 5,466
Cost of sales	(1,172)	(1,255)	(3,575)	(3,914)
Gross profit	414	516	1,290	1,552
Selling, general and administrative expenses	(120)	(129)	(358)	(412)
Amortization of intangible assets	(6)	(5)	(18)	(18)
Research and development expenses	(17)	(18)	(50)	(54)
Other (charges) gains, net	(7)	12	(101)	9
Foreign exchange gain (loss), net	(1)	0	5	2
Gain (loss) on disposition of businesses and assets, net	(3)	(2)	(2)	(4)
Operating profit (loss)	260	374	766	1,075
Equity in net earnings (loss) of affiliates	45	66	134	180
Non-operating pension and other postretirement employee benefit (expense) income	17	25	51	77
Interest expense	(27)	(30)	(87)	(95)
Refinancing expense	0	0	4	0
Interest income	1	2	4	4
Dividend income - equity investments	27	26	89	92
Other income (expense), net	0	(1)	(6)	3
Earnings (loss) from continuing operations before tax	323	462	947	1,336
Income tax (provision) benefit	(53)	(54)	(127)	(216)
Earnings (loss) from continuing operations	270	408	820	1,120
Earnings (loss) from operation of discontinued operations	(6)	(7)	(9)	(9)
Income tax (provision) benefit from discontinued operations	1	1	2	1
Earnings (loss) from discontinued operations	(5)	(6)	(7)	(8)
Net earnings (loss)	265	402	813	1,112
Net (earnings) loss attributable to noncontrolling interests	(2)	(1)	(4)	(4)
Net earnings (loss) attributable to Celanese Corporation	263	401	809	1,108
Write off of Deferred Debt Issuance Cost	0	0	(4)	0
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	277	401	823	1,108
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	(20)	0	(20)	0
Refinancing expense			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	257	401	803	1,108
Income tax (provision) benefit	6	0	6	0
Earnings (loss) from continuing operations	263	401	809	1,108
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)	263	401	809	1,108
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	263	401	809	1,108
Write off of Deferred Debt Issuance Cost			0
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	(3)	0	(3)
Gain (loss) on disposition of businesses and assets, net	0	0	0	0
Operating profit (loss)	0	(3)	0	(3)
Equity in net earnings (loss) of affiliates	267	411	814	1,112
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	(5)	(5)	(24)	(15)
Refinancing expense			4
Interest income	18	13	49	31
Dividend income - equity investments	0	0	0	0
Other income (expense), net	0	0	(3)	0
Earnings (loss) from continuing operations before tax	280	416	832	1,125
Income tax (provision) benefit	(3)	(15)	(9)	(17)
Earnings (loss) from continuing operations	277	401	823	1,108
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)	277	401	823	1,108
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	277	401	823	1,108
Write off of Deferred Debt Issuance Cost			(4)
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	570	565	1,780	1,733
Cost of sales	(444)	(432)	(1,345)	(1,337)
Gross profit	126	133	435	396
Selling, general and administrative expenses	(46)	(46)	(125)	(156)
Amortization of intangible assets	(2)	(1)	(6)	(3)
Research and development expenses	(7)	(7)	(20)	(22)
Other (charges) gains, net	(1)	0	(6)	0
Foreign exchange gain (loss), net	0	0	0	0
Gain (loss) on disposition of businesses and assets, net	(3)	(3)	(7)	(8)
Operating profit (loss)	67	76	271	207
Equity in net earnings (loss) of affiliates	183	286	522	872
Non-operating pension and other postretirement employee benefit (expense) income	15	23	46	70
Interest expense	(37)	(33)	(103)	(93)
Refinancing expense			0
Interest income	23	1	36	5
Dividend income - equity investments	0	0	0	0
Other income (expense), net	1	1	1	1
Earnings (loss) from continuing operations before tax	252	354	773	1,062
Income tax (provision) benefit	2	(10)	(28)	(115)
Earnings (loss) from continuing operations	254	344	745	947
Earnings (loss) from operation of discontinued operations	(6)	(1)	(9)	(2)
Income tax (provision) benefit from discontinued operations	1	0	2	0
Earnings (loss) from discontinued operations	(5)	(1)	(7)	(2)
Net earnings (loss)	249	343	738	945
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	249	343	738	945
Write off of Deferred Debt Issuance Cost			0
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,292	1,483	3,963	4,621
Cost of sales	(1,011)	(1,105)	(3,108)	(3,470)
Gross profit	281	378	855	1,151
Selling, general and administrative expenses	(74)	(83)	(233)	(256)
Amortization of intangible assets	(4)	(4)	(12)	(15)
Research and development expenses	(10)	(11)	(30)	(32)
Other (charges) gains, net	(6)	12	(95)	9
Foreign exchange gain (loss), net	(1)	3	5	5
Gain (loss) on disposition of businesses and assets, net	0	1	5	4
Operating profit (loss)	186	296	495	866
Equity in net earnings (loss) of affiliates	43	64	120	170
Non-operating pension and other postretirement employee benefit (expense) income	2	3	5	8
Interest expense	(9)	(8)	(29)	(25)
Refinancing expense			0
Interest income	4	3	8	7
Dividend income - equity investments	27	25	89	89
Other income (expense), net	(1)	(1)	(4)	3
Earnings (loss) from continuing operations before tax	252	382	684	1,118
Income tax (provision) benefit	(57)	(28)	(96)	(83)
Earnings (loss) from continuing operations	195	354	588	1,035
Earnings (loss) from operation of discontinued operations	0	(6)	0	(7)
Income tax (provision) benefit from discontinued operations	0	1	0	1
Earnings (loss) from discontinued operations	0	(5)	0	(6)
Net earnings (loss)	195	349	588	1,029
Net (earnings) loss attributable to noncontrolling interests	(2)	(1)	(4)	(4)
Net earnings (loss) attributable to Celanese Corporation	193	348	584	1,025
Write off of Deferred Debt Issuance Cost			0
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(276)	(277)	(878)	(888)
Cost of sales	283	282	878	893
Gross profit	7	5	0	5
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)	7	5	0	5
Equity in net earnings (loss) of affiliates	(725)	(1,096)	(2,145)	(3,082)
Non-operating pension and other postretirement employee benefit (expense) income	0	(1)	0	(1)
Interest expense	44	16	89	38
Refinancing expense			0
Interest income	(44)	(15)	(89)	(39)
Dividend income - equity investments	0	1	0	3
Other income (expense), net	0	(1)	0	(1)
Earnings (loss) from continuing operations before tax	(718)	(1,091)	(2,145)	(3,077)
Income tax (provision) benefit	(1)	(1)	0	(1)
Earnings (loss) from continuing operations	(719)	(1,092)	(2,145)	(3,078)
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)	(719)	(1,092)	(2,145)	(3,078)
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (719)	$ (1,092)	(2,145)	$ (3,078)
Write off of Deferred Debt Issuance Cost			$ 0