Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 345	$ 233	$ 710	$ 417
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	284	311	696	525
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0	1	0	1
Foreign currency translation	(66)	78	(17)	106
Gain (loss) on cash flow hedges	6	1	5	(1)
Pension and postretirement benefits	0	0	1	5
Other Comprehensive Income (Loss), Net of Tax	(60)	80	(11)	111
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	285	313	699	528
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(2)	(3)	(3)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	284	311	696	525
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	344	231	707	414
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	284	311	696	525
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0	1	0	1
Foreign currency translation	(66)	78	(17)	106
Gain (loss) on cash flow hedges	6	1	5	(1)
Pension and postretirement benefits			1	5
Other Comprehensive Income (Loss), Net of Tax	(60)	80	(11)	111
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	284	311	696	525
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	284	311	696	525
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	344	231	707	414
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	284	311	696	525
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0	1	0	1
Foreign currency translation	(66)	78	(17)	106
Gain (loss) on cash flow hedges	6	1	5	(1)
Pension and postretirement benefits			1	5
Other Comprehensive Income (Loss), Net of Tax	(60)	80	(11)	111
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	284	311	696	525
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	284	311	696	525
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	304	202	602	332
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	205	300	566	462
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	5	1	5	1
Foreign currency translation	(109)	96	(46)	126
Gain (loss) on cash flow hedges	5	1	4	(1)
Pension and postretirement benefits			1	4
Other Comprehensive Income (Loss), Net of Tax	(99)	98	(36)	130
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	205	300	566	462
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	205	300	566	462
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	349	185	680	335
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	235	304	638	496
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	13	1	13	1
Foreign currency translation	(132)	119	(58)	158
Gain (loss) on cash flow hedges	6	1	5	(1)
Pension and postretirement benefits			1	6
Other Comprehensive Income (Loss), Net of Tax	(113)	121	(39)	164
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	236	306	641	499
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(2)	(3)	(3)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	235	304	638	496
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(996)	(616)	(1,986)	(1,078)
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	(724)	(915)	(1,900)	(1,483)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	(18)	(3)	(18)	(3)
Foreign currency translation	307	(293)	121	(390)
Gain (loss) on cash flow hedges	(17)	(3)	(14)	3
Pension and postretirement benefits			(3)	(15)
Other Comprehensive Income (Loss), Net of Tax	272	(299)	86	(405)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(724)	(915)	(1,900)	(1,483)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (724)	$ (915)	$ (1,900)	$ (1,483)