Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 338	$ 365
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	341	412
Foreign currency translation gain (loss)	7	49
Gain (loss) on cash flow hedges	(3)	(1)
Pension and postretirement benefits gain (loss)	0	1
Other Comprehensive Income (Loss), Net of Tax	4	49
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	342	414
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(2)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	341	412
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	337	363
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	341	412
Foreign currency translation gain (loss)	7	49
Gain (loss) on cash flow hedges	(3)	(1)
Pension and postretirement benefits gain (loss)		1
Other Comprehensive Income (Loss), Net of Tax	4	49
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	341	412
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	341	412
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	337	363
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	341	412
Foreign currency translation gain (loss)	7	49
Gain (loss) on cash flow hedges	(3)	(1)
Pension and postretirement benefits gain (loss)		1
Other Comprehensive Income (Loss), Net of Tax	4	49
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	341	412
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	341	412
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	311	291
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	299	354
Foreign currency translation gain (loss)	(18)	63
Gain (loss) on cash flow hedges	6	(1)
Pension and postretirement benefits gain (loss)		1
Other Comprehensive Income (Loss), Net of Tax	(12)	63
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	299	354
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	299	354
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	245	330
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	228	402
Foreign currency translation gain (loss)	(24)	74
Gain (loss) on cash flow hedges	8	(1)
Pension and postretirement benefits gain (loss)		1
Other Comprehensive Income (Loss), Net of Tax	(16)	74
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	229	404
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(2)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	228	402
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(892)	(982)
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	(868)	(1,168)
Foreign currency translation gain (loss)	35	(186)
Gain (loss) on cash flow hedges	(11)	3
Pension and postretirement benefits gain (loss)		(3)
Other Comprehensive Income (Loss), Net of Tax	24	(186)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(868)	(1,168)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (868)	$ (1,168)