Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 858	$ 1,213	$ 849
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on marketable securities	0	0	(1)
Foreign currency translation	(16)	(60)	174
Gain (loss) on cash flow hedges	(30)	(10)	(1)
Pension and postretirement benefits	(7)	0	9
Total other comprehensive income (loss), net of tax	(53)	(70)	181
Total comprehensive income (loss), net of tax	805	1,143	1,030
Comprehensive (income) loss attributable to noncontrolling interests	(6)	(6)	(6)
Comprehensive income (loss) attributable to Celanese Corporation	799	1,137	1,024
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	852	1,207	843
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on marketable securities		0	(1)
Foreign currency translation	(16)	(60)	174
Gain (loss) on cash flow hedges	(30)	(10)	(1)
Pension and postretirement benefits	(7)		9
Total other comprehensive income (loss), net of tax	(53)	(70)	181
Total comprehensive income (loss), net of tax	799	1,137	1,024
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	799	1,137	1,024
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	881	1,207	843
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on marketable securities		0	(1)
Foreign currency translation	(16)	(60)	174
Gain (loss) on cash flow hedges	(30)	(10)	(1)
Pension and postretirement benefits	(7)		9
Total other comprehensive income (loss), net of tax	(53)	(70)	181
Total comprehensive income (loss), net of tax	828	1,137	1,024
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	828	1,137	1,024
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	776	1,019	768
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on marketable securities		6	(1)
Foreign currency translation	(39)	(90)	226
Gain (loss) on cash flow hedges	(6)	(2)	(1)
Pension and postretirement benefits	(6)		7
Total other comprehensive income (loss), net of tax	(51)	(86)	231
Total comprehensive income (loss), net of tax	725	933	999
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	725	933	999
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	619	1,205	687
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on marketable securities		13	(1)
Foreign currency translation	(48)	(109)	268
Gain (loss) on cash flow hedges	(4)	(1)	(1)
Pension and postretirement benefits	(7)		10
Total other comprehensive income (loss), net of tax	(59)	(97)	276
Total comprehensive income (loss), net of tax	560	1,108	963
Comprehensive (income) loss attributable to noncontrolling interests	(6)	(6)	(6)
Comprehensive income (loss) attributable to Celanese Corporation	554	1,102	957
Consolidation Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(2,270)	(3,425)	(2,292)
Other comprehensive income (loss), net of tax
Unrealized gain (loss) on marketable securities		(19)	3
Foreign currency translation	103	259	(668)
Gain (loss) on cash flow hedges	40	13	3
Pension and postretirement benefits	20		(26)
Total other comprehensive income (loss), net of tax	163	253	(688)
Total comprehensive income (loss), net of tax	(2,107)	(3,172)	(2,980)
Comprehensive (income) loss attributable to noncontrolling interests	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	$ (2,107)	$ (3,172)	$ (2,980)