Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 109	$ 210	$ 329	$ 548
Foreign currency translation gain (loss)	(6)	(11)	(8)	(4)
Gain (loss) on cash flow hedges	1	(13)	(38)	(16)
Total other comprehensive income (loss), net of tax	(5)	(24)	(46)	(20)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	104	186	283	528
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(2)	(1)	(4)	(2)
Comprehensive income (loss) attributable to Celanese Corporation	102	185	279	526
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	107	209	325	546
Foreign currency translation gain (loss)	(6)	(11)	(8)	(4)
Gain (loss) on cash flow hedges	1	(13)	(38)	(16)
Total other comprehensive income (loss), net of tax	(5)	(24)	(46)	(20)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	102	185	279	526
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	102	185	279	526
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	110	209	336	546
Foreign currency translation gain (loss)	(6)	(11)	(8)	(4)
Gain (loss) on cash flow hedges	1	(13)	(38)	(16)
Total other comprehensive income (loss), net of tax	(5)	(24)	(46)	(20)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	105	185	290	526
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	105	185	290	526
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	116	178	341	489
Foreign currency translation gain (loss)	15	2	(29)	(16)
Gain (loss) on cash flow hedges	3	(3)	2	3
Total other comprehensive income (loss), net of tax	18	(1)	(27)	(13)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	134	177	314	476
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	134	177	314	476
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	152	148	341	393
Foreign currency translation gain (loss)	18	4	(36)	(20)
Gain (loss) on cash flow hedges	2	(3)	2	5
Total other comprehensive income (loss), net of tax	20	1	(34)	(15)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	172	149	307	378
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(2)	(1)	(4)	(2)
Comprehensive income (loss) attributable to Celanese Corporation	170	148	303	376
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(376)	(534)	(1,014)	(1,426)
Foreign currency translation gain (loss)	(27)	5	73	40
Gain (loss) on cash flow hedges	(6)	19	34	8
Total other comprehensive income (loss), net of tax	(33)	24	107	48
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(409)	(510)	(907)	(1,378)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	$ (409)	$ (510)	$ (907)	$ (1,378)