Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 7,155	$ 6,140	$ 5,389
Cost of sales	(5,183)	(4,629)	(3,984)
Gross profit	1,972	1,511	1,405
Selling, general and administrative expenses	(546)	(496)	(378)
Amortization of intangible assets	(24)	(20)	(9)
Research and development expenses	(72)	(73)	(78)
Other (charges) gains, net	9	(59)	(8)
Foreign exchange gain (loss), net	0	(1)	(1)
Gain (loss) on disposition of businesses and assets, net	(5)	(5)	3
Operating profit (loss)	1,334	857	934
Equity in net earnings (loss) of affiliates	233	183	155
Non-operating pension and other postretirement employee benefit (expense) income	(62)	44	(41)
Interest expense	(125)	(122)	(120)
Refinancing expense	(1)	0	(6)
Interest income	6	2	2
Dividend income - equity investments	117	108	108
Other income (expense), net	8	3	(2)
Earnings (loss) from continuing operations before tax	1,510	1,075	1,030
Income tax (provision) benefit	(292)	(213)	(122)
Earnings (loss) from continuing operations	1,218	862	908
Earnings (loss) from operation of discontinued operations	(5)	(16)	(3)
Gain (loss) on disposition of discontinued operations	0	0	0
Income tax (provision) benefit from discontinued operations	0	3	1
Earnings (loss) from discontinued operations	(5)	(13)	(2)
Net earnings (loss)	1,213	849	906
Net (earnings) loss attributable to noncontrolling interests	(6)	(6)	(6)
Net earnings (loss) attributable to Celanese Corporation	1,207	843	900
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0	0
Cost of sales	0	0	0
Gross profit	0	0	0
Selling, general and administrative expenses	0	0	0
Amortization of intangible assets	0	0	0
Research and development expenses	0	0	0
Other (charges) gains, net	0	0	0
Foreign exchange gain (loss), net	0	0	0
Gain (loss) on disposition of businesses and assets, net	0	0	0
Operating profit (loss)	0	0	0
Equity in net earnings (loss) of affiliates	1,207	843	898
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0
Interest expense	0	0	0
Refinancing expense	0	0	0
Interest income	0	0	0
Dividend income - equity investments	0	0	0
Other income (expense), net	0	0	0
Earnings (loss) from continuing operations before tax	1,207	843	898
Income tax (provision) benefit	0	0	2
Earnings (loss) from continuing operations	1,207	843	900
Earnings (loss) from operation of discontinued operations	0	0	0
Gain (loss) on disposition of discontinued operations	0	0	0
Income tax (provision) benefit from discontinued operations	0	0	0
Earnings (loss) from discontinued operations	0	0	0
Net earnings (loss)	1,207	843	900
Net (earnings) loss attributable to noncontrolling interests	0	0	0
Net earnings (loss) attributable to Celanese Corporation	1,207	843	900
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0	0
Cost of sales	0	0	0
Gross profit	0	0	0
Selling, general and administrative expenses	0	0	0
Amortization of intangible assets	0	0	0
Research and development expenses	0	0	0
Other (charges) gains, net	0	0	0
Foreign exchange gain (loss), net	(3)	0	0
Gain (loss) on disposition of businesses and assets, net	0	0	0
Operating profit (loss)	(3)	0	0
Equity in net earnings (loss) of affiliates	1,202	867	939
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0
Interest expense	(30)	(20)	(16)
Refinancing expense	(1)	0	(4)
Interest income	45	25	12
Dividend income - equity investments	0	0	0
Other income (expense), net	5	(3)	(1)
Earnings (loss) from continuing operations before tax	1,218	869	930
Income tax (provision) benefit	(11)	(26)	(32)
Earnings (loss) from continuing operations	1,207	843	898
Earnings (loss) from operation of discontinued operations	0	0	0
Gain (loss) on disposition of discontinued operations	0	0	0
Income tax (provision) benefit from discontinued operations	0	0	0
Earnings (loss) from discontinued operations	0	0	0
Net earnings (loss)	1,207	843	898
Net (earnings) loss attributable to noncontrolling interests	0	0	0
Net earnings (loss) attributable to Celanese Corporation	1,207	843	898
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	2,387	2,240	2,162
Cost of sales	(1,898)	(1,723)	(1,658)
Gross profit	489	517	504
Selling, general and administrative expenses	(213)	(189)	(113)
Amortization of intangible assets	(8)	(4)	(5)
Research and development expenses	(30)	(32)	(32)
Other (charges) gains, net	0	(6)	0
Foreign exchange gain (loss), net	0	0	0
Gain (loss) on disposition of businesses and assets, net	(10)	(8)	(8)
Operating profit (loss)	228	278	346
Equity in net earnings (loss) of affiliates	1,033	591	653
Non-operating pension and other postretirement employee benefit (expense) income	(28)	60	2
Interest expense	(118)	(104)	(94)
Refinancing expense	0	0	(2)
Interest income	7	4	4
Dividend income - equity investments	0	0	0
Other income (expense), net	1	2	1
Earnings (loss) from continuing operations before tax	1,123	831	910
Income tax (provision) benefit	(106)	(62)	(53)
Earnings (loss) from continuing operations	1,017	769	857
Earnings (loss) from operation of discontinued operations	3	(2)	(2)
Gain (loss) on disposition of discontinued operations	0	0	0
Income tax (provision) benefit from discontinued operations	(1)	1	0
Earnings (loss) from discontinued operations	2	(1)	(2)
Net earnings (loss)	1,019	768	855
Net (earnings) loss attributable to noncontrolling interests	0	0	0
Net earnings (loss) attributable to Celanese Corporation	1,019	768	855
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	5,954	5,013	4,322
Cost of sales	(4,471)	(4,014)	(3,427)
Gross profit	1,483	999	895
Selling, general and administrative expenses	(333)	(307)	(265)
Amortization of intangible assets	(16)	(16)	(4)
Research and development expenses	(42)	(41)	(46)
Other (charges) gains, net	9	(53)	(8)
Foreign exchange gain (loss), net	3	(1)	(1)
Gain (loss) on disposition of businesses and assets, net	5	3	17
Operating profit (loss)	1,109	584	588
Equity in net earnings (loss) of affiliates	220	166	146
Non-operating pension and other postretirement employee benefit (expense) income	(34)	(16)	(43)
Interest expense	(33)	(30)	(29)
Refinancing expense	0	0	0
Interest income	10	5	5
Dividend income - equity investments	113	111	107
Other income (expense), net	3	4	(2)
Earnings (loss) from continuing operations before tax	1,388	824	772
Income tax (provision) benefit	(176)	(125)	(36)
Earnings (loss) from continuing operations	1,212	699	736
Earnings (loss) from operation of discontinued operations	(8)	(14)	(1)
Gain (loss) on disposition of discontinued operations	0	0	0
Income tax (provision) benefit from discontinued operations	1	2	1
Earnings (loss) from discontinued operations	(7)	(12)	0
Net earnings (loss)	1,205	687	736
Net (earnings) loss attributable to noncontrolling interests	(6)	(6)	(6)
Net earnings (loss) attributable to Celanese Corporation	1,199	681	730
Consolidation Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(1,186)	(1,113)	(1,095)
Cost of sales	1,186	1,108	1,101
Gross profit	0	(5)	6
Selling, general and administrative expenses	0	0	0
Amortization of intangible assets	0	0	0
Research and development expenses	0	0	0
Other (charges) gains, net	0	0	0
Foreign exchange gain (loss), net	0	0	0
Gain (loss) on disposition of businesses and assets, net	0	0	(6)
Operating profit (loss)	0	(5)	0
Equity in net earnings (loss) of affiliates	(3,429)	(2,284)	(2,481)
Non-operating pension and other postretirement employee benefit (expense) income	0	0	0
Interest expense	56	32	19
Refinancing expense	0	0	0
Interest income	(56)	(32)	(19)
Dividend income - equity investments	4	(3)	1
Other income (expense), net	(1)	0	0
Earnings (loss) from continuing operations before tax	(3,426)	(2,292)	(2,480)
Income tax (provision) benefit	1	0	(3)
Earnings (loss) from continuing operations	(3,425)	(2,292)	(2,483)
Earnings (loss) from operation of discontinued operations	0	0	0
Gain (loss) on disposition of discontinued operations	0	0	0
Income tax (provision) benefit from discontinued operations	0	0	0
Earnings (loss) from discontinued operations	0	0	0
Net earnings (loss)	(3,425)	(2,292)	(2,483)
Net (earnings) loss attributable to noncontrolling interests	0	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (3,425)	$ (2,292)	$ (2,483)