Consolidating Guarantor Financial Information (Schedule of Consolidating Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,771	$ 1,566	$ 5,466	$ 4,547
Cost of sales	(1,255)	(1,183)	(3,914)	(3,449)
Gross profit	516	383	1,552	1,098
Selling, general and administrative expenses	(129)	(133)	(412)	(353)
Amortization of intangible assets	(5)	(5)	(18)	(14)
Research and development expenses	(18)	(19)	(54)	(53)
Other (charges) gains, net	12	0	9	(57)
Foreign exchange gain (loss), net	0	4	2	0
Gain (loss) on disposition of businesses and assets, net	(2)	(1)	(4)	(4)
Operating profit (loss)	374	229	1,075	617
Equity in net earnings (loss) of affiliates	66	50	180	135
Non-operating pension and other postretirement employee benefit (expense) income	25	23	77	67
Interest expense	(30)	(32)	(95)	(91)
Interest income	2	1	4	2
Dividend income - cost investments	26	24	92	82
Other income (expense), net	(1)	(6)	3	(2)
Earnings (loss) from continuing operations before tax	462	289	1,336	810
Income tax (provision) benefit	(54)	(57)	(216)	(153)
Earnings (loss) from continuing operations	408	232	1,120	657
Earnings (loss) from operation of discontinued operations	(7)	(5)	(9)	(14)
Income tax (provision) benefit from discontinued operations	1	1	1	2
Earnings (loss) from discontinued operations	(6)	(4)	(8)	(12)
Net earnings (loss)	402	228	1,112	645
Net (earnings) loss attributable to noncontrolling interests	(1)	(2)	(4)	(5)
Net earnings (loss) attributable to Celanese Corporation	401	226	1,108	640
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	401	226	1,108	640
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	401	226	1,108	640
Income tax (provision) benefit	0	0	0	0
Earnings (loss) from continuing operations	401	226	1,108	640
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)	401	226	1,108	640
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	401	226	1,108	640
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	(3)	0	(3)	0
Gain (loss) on disposition of businesses and assets, net	0	0	0	0
Operating profit (loss)	(3)	0	(3)	0
Equity in net earnings (loss) of affiliates	411	233	1,112	640
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0	0
Interest expense	(5)	(5)	(15)	(17)
Interest income	13	7	31	19
Dividend income - cost investments	0	0	0	0
Other income (expense), net	0	(2)	0	(3)
Earnings (loss) from continuing operations before tax	416	233	1,125	639
Income tax (provision) benefit	(15)	(7)	(17)	1
Earnings (loss) from continuing operations	401	226	1,108	640
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)	401	226	1,108	640
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	401	226	1,108	640
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	565	527	1,733	1,679
Cost of sales	(432)	(407)	(1,337)	(1,311)
Gross profit	133	120	396	368
Selling, general and administrative expenses	(46)	(54)	(156)	(132)
Amortization of intangible assets	(1)	(1)	(3)	(3)
Research and development expenses	(7)	(9)	(22)	(23)
Other (charges) gains, net	0	0	0	(7)
Foreign exchange gain (loss), net	0	0	0	0
Gain (loss) on disposition of businesses and assets, net	(3)	(2)	(8)	(6)
Operating profit (loss)	76	54	207	197
Equity in net earnings (loss) of affiliates	286	175	872	439
Non-operating pension and other postretirement employee benefit (expense) income	23	20	70	60
Interest expense	(33)	(28)	(93)	(75)
Interest income	1	1	5	3
Dividend income - cost investments	0	0	0	0
Other income (expense), net	1	0	1	1
Earnings (loss) from continuing operations before tax	354	222	1,062	625
Income tax (provision) benefit	(10)	(68)	(115)	(139)
Earnings (loss) from continuing operations	344	154	947	486
Earnings (loss) from operation of discontinued operations	(1)	0	(2)	0
Income tax (provision) benefit from discontinued operations	0	0	0	0
Earnings (loss) from discontinued operations	(1)	0	(2)	0
Net earnings (loss)	343	154	945	486
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	343	154	945	486
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,483	1,314	4,621	3,713
Cost of sales	(1,105)	(1,042)	(3,470)	(2,974)
Gross profit	378	272	1,151	739
Selling, general and administrative expenses	(83)	(79)	(256)	(221)
Amortization of intangible assets	(4)	(4)	(15)	(11)
Research and development expenses	(11)	(10)	(32)	(30)
Other (charges) gains, net	12	0	9	(50)
Foreign exchange gain (loss), net	3	4	5	0
Gain (loss) on disposition of businesses and assets, net	1	1	4	2
Operating profit (loss)	296	184	866	429
Equity in net earnings (loss) of affiliates	64	45	170	122
Non-operating pension and other postretirement employee benefit (expense) income	3	3	8	7
Interest expense	(8)	(8)	(25)	(23)
Interest income	3	2	7	4
Dividend income - cost investments	25	26	89	85
Other income (expense), net	(1)	(4)	3	0
Earnings (loss) from continuing operations before tax	382	248	1,118	624
Income tax (provision) benefit	(28)	17	(83)	(16)
Earnings (loss) from continuing operations	354	265	1,035	608
Earnings (loss) from operation of discontinued operations	(6)	(5)	(7)	(14)
Income tax (provision) benefit from discontinued operations	1	1	1	2
Earnings (loss) from discontinued operations	(5)	(4)	(6)	(12)
Net earnings (loss)	349	261	1,029	596
Net (earnings) loss attributable to noncontrolling interests	(1)	(2)	(4)	(5)
Net earnings (loss) attributable to Celanese Corporation	348	259	1,025	591
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(277)	(275)	(888)	(845)
Cost of sales	282	266	893	836
Gross profit	5	(9)	5	(9)
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)	5	(9)	5	(9)
Equity in net earnings (loss) of affiliates	(1,096)	(629)	(3,082)	(1,706)
Non-operating pension and other postretirement employee benefit (expense) income	(1)	0	(1)	0
Interest expense	16	9	38	24
Interest income	(15)	(9)	(39)	(24)
Dividend income - cost investments	1	(2)	3	(3)
Other income (expense), net	(1)	0	(1)	0
Earnings (loss) from continuing operations before tax	(1,091)	(640)	(3,077)	(1,718)
Income tax (provision) benefit	(1)	1	(1)	1
Earnings (loss) from continuing operations	(1,092)	(639)	(3,078)	(1,717)
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)	(1,092)	(639)	(3,078)	(1,717)
Net (earnings) loss attributable to noncontrolling interests	0	0	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (1,092)	$ (639)	$ (3,078)	$ (1,717)