Consolidating Guarantor Financial Information (Schedule of Consolidating Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,460	$ 1,687
Cost of sales	(1,112)	(1,234)
Gross profit	348	453
Selling, general and administrative expenses	(125)	(120)
Amortization of intangible assets	(5)	(6)
Research and development expenses	(17)	(16)
Other (charges) gains, net	(6)	4
Foreign exchange gain (loss), net	(1)	5
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	194	320
Equity in net earnings (loss) of affiliates	57	50
Non-operating pension and other postretirement employee benefit (expense) income	28	17
Interest expense	(28)	(31)
Interest income	2	1
Dividend income - equity investments	37	32
Other income (expense), net	2	(4)
Earnings (loss) from continuing operations before tax	292	385
Income tax (provision) benefit	(65)	(46)
Earnings (loss) from continuing operations	227	339
Earnings (loss) from operation of discontinued operations	(7)	(1)
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	(7)	(1)
Net earnings (loss)	220	338
Net (earnings) loss attributable to noncontrolling interests	(2)	(1)
Net earnings (loss) attributable to Celanese Corporation	218	337
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	0	0
Amortization of intangible assets	0	0
Research and development expenses	0	0
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	0	0
Equity in net earnings (loss) of affiliates	226	337
Non-operating pension and other postretirement employee benefit (expense) income	0	0
Interest expense	(8)	0
Interest income	0	0
Dividend income - equity investments	0	0
Other income (expense), net	0	0
Earnings (loss) from continuing operations before tax	218	337
Income tax (provision) benefit	0	0
Earnings (loss) from continuing operations	218	337
Earnings (loss) from operation of discontinued operations	0	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	0
Net earnings (loss)	218	337
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	218	337
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	0	0
Cost of sales	0	0
Gross profit	0	0
Selling, general and administrative expenses	0	0
Amortization of intangible assets	0	0
Research and development expenses	0	0
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	0	0
Equity in net earnings (loss) of affiliates	222	337
Non-operating pension and other postretirement employee benefit (expense) income	0	0
Interest expense	(9)	(10)
Interest income	13	13
Dividend income - equity investments	0	0
Other income (expense), net	8	1
Earnings (loss) from continuing operations before tax	234	341
Income tax (provision) benefit	(8)	(4)
Earnings (loss) from continuing operations	226	337
Earnings (loss) from operation of discontinued operations	0	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	0
Net earnings (loss)	226	337
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	226	337
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	560	624
Cost of sales	(460)	(458)
Gross profit	100	166
Selling, general and administrative expenses	(54)	(40)
Amortization of intangible assets	(2)	(2)
Research and development expenses	(7)	(6)
Other (charges) gains, net	(8)	0
Foreign exchange gain (loss), net	(1)	0
Gain (loss) on disposition of businesses and assets, net	(2)	(2)
Operating profit (loss)	26	116
Equity in net earnings (loss) of affiliates	188	217
Non-operating pension and other postretirement employee benefit (expense) income	25	15
Interest expense	(30)	(31)
Interest income	10	2
Dividend income - equity investments	0	0
Other income (expense), net	1	0
Earnings (loss) from continuing operations before tax	220	319
Income tax (provision) benefit	5	(7)
Earnings (loss) from continuing operations	225	312
Earnings (loss) from operation of discontinued operations	0	(1)
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	(1)
Net earnings (loss)	225	311
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	225	311
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	1,203	1,373
Cost of sales	(946)	(1,077)
Gross profit	257	296
Selling, general and administrative expenses	(71)	(80)
Amortization of intangible assets	(3)	(4)
Research and development expenses	(10)	(10)
Other (charges) gains, net	2	4
Foreign exchange gain (loss), net	0	5
Gain (loss) on disposition of businesses and assets, net	2	2
Operating profit (loss)	177	213
Equity in net earnings (loss) of affiliates	51	43
Non-operating pension and other postretirement employee benefit (expense) income	3	2
Interest expense	(5)	(7)
Interest income	4	3
Dividend income - equity investments	36	32
Other income (expense), net	(7)	(5)
Earnings (loss) from continuing operations before tax	259	281
Income tax (provision) benefit	(63)	(36)
Earnings (loss) from continuing operations	196	245
Earnings (loss) from operation of discontinued operations	(7)	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	(7)	0
Net earnings (loss)	189	245
Net (earnings) loss attributable to noncontrolling interests	(2)	(1)
Net earnings (loss) attributable to Celanese Corporation	187	244
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net sales	(303)	(310)
Cost of sales	294	301
Gross profit	(9)	(9)
Selling, general and administrative expenses	0	0
Amortization of intangible assets	0	0
Research and development expenses	0	0
Other (charges) gains, net	0	0
Foreign exchange gain (loss), net	0	0
Gain (loss) on disposition of businesses and assets, net	0	0
Operating profit (loss)	(9)	(9)
Equity in net earnings (loss) of affiliates	(630)	(884)
Non-operating pension and other postretirement employee benefit (expense) income	0	0
Interest expense	24	17
Interest income	(25)	(17)
Dividend income - equity investments	1	0
Other income (expense), net	0	0
Earnings (loss) from continuing operations before tax	(639)	(893)
Income tax (provision) benefit	1	1
Earnings (loss) from continuing operations	(638)	(892)
Earnings (loss) from operation of discontinued operations	0	0
Income tax (provision) benefit from discontinued operations	0	0
Earnings (loss) from discontinued operations	0	0
Net earnings (loss)	(638)	(892)
Net (earnings) loss attributable to noncontrolling interests	0	0
Net earnings (loss) attributable to Celanese Corporation	$ (638)	$ (892)