Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 210	$ 345	$ 548	$ 710
Unrealized gain (loss) on marketable securities		0		0
Foreign currency translation gain (loss)	(11)	(66)	(4)	(17)
Gain (loss) on cash flow hedges	(13)	6	(16)	5
Pension and postretirement benefits gain (loss)	0	0	0	1
Total other comprehensive income (loss), net of tax	(24)	(60)	(20)	(11)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	186	285	528	699
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(1)	(2)	(3)
Comprehensive income (loss) attributable to Celanese Corporation	185	284	526	696
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	209	344	546	707
Unrealized gain (loss) on marketable securities		0		0
Foreign currency translation gain (loss)	(11)	(66)	(4)	(17)
Gain (loss) on cash flow hedges	(13)	6	(16)	5
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(24)	(60)	(20)	(11)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	185	284	526	696
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	185	284	526	696
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	209	344	546	707
Unrealized gain (loss) on marketable securities		0		0
Foreign currency translation gain (loss)	(11)	(66)	(4)	(17)
Gain (loss) on cash flow hedges	(13)	6	(16)	5
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(24)	(60)	(20)	(11)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	185	284	526	696
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	185	284	526	696
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	178	304	489	602
Unrealized gain (loss) on marketable securities		5		5
Foreign currency translation gain (loss)	2	(109)	(16)	(46)
Gain (loss) on cash flow hedges	(3)	5	3	4
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(1)	(99)	(13)	(36)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	177	205	476	566
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	177	205	476	566
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	148	349	393	680
Unrealized gain (loss) on marketable securities		13		13
Foreign currency translation gain (loss)	4	(132)	(20)	(58)
Gain (loss) on cash flow hedges	(3)	6	5	5
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	1	(113)	(15)	(39)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	149	236	378	641
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(1)	(2)	(3)
Comprehensive income (loss) attributable to Celanese Corporation	148	235	376	638
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(534)	(996)	(1,426)	(1,986)
Unrealized gain (loss) on marketable securities		(18)		(18)
Foreign currency translation gain (loss)	5	307	40	121
Gain (loss) on cash flow hedges	19	(17)	8	(14)
Pension and postretirement benefits gain (loss)				(3)
Total other comprehensive income (loss), net of tax	24	272	48	86
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(510)	(724)	(1,378)	(1,900)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	$ (510)	$ (724)	$ (1,378)	$ (1,900)