Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 402	$ 228	$ 1,112	$ 645
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	370	267	1,066	792
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	0	0	0	1
Foreign currency translation gain (loss)	(35)	42	(52)	148
Gain (loss) on cash flow hedges	4	0	9	(1)
Pension and postretirement benefits gain (loss)	0	(1)	1	4
Other Comprehensive Income (Loss), Net of Tax	(31)	41	(42)	152
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	371	269	1,070	797
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(2)	(4)	(5)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	370	267	1,066	792
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	401	226	1,108	640
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	370	267	1,066	792
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	0	0	0	1
Foreign currency translation gain (loss)	(35)	42	(52)	148
Gain (loss) on cash flow hedges	4	0	9	(1)
Pension and postretirement benefits gain (loss)	0	(1)	1	4
Other Comprehensive Income (Loss), Net of Tax	(31)	41	(42)	152
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	370	267	1,066	792
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	370	267	1,066	792
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	401	226	1,108	640
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	370	267	1,066	792
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	0	0	0	1
Foreign currency translation gain (loss)	(35)	42	(52)	148
Gain (loss) on cash flow hedges	4	0	9	(1)
Pension and postretirement benefits gain (loss)	0	(1)	1	4
Other Comprehensive Income (Loss), Net of Tax	(31)	41	(42)	152
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	370	267	1,066	792
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	370	267	1,066	792
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	343	154	945	486
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	315	218	881	680
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	1	0	6	1
Foreign currency translation gain (loss)	(31)	65	(77)	191
Gain (loss) on cash flow hedges	2	0	6	(1)
Pension and postretirement benefits gain (loss)	0	(1)	1	3
Other Comprehensive Income (Loss), Net of Tax	(28)	64	(64)	194
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	315	218	881	680
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	315	218	881	680
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	349	261	1,029	596
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	313	333	951	829
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	0	0	13	1
Foreign currency translation gain (loss)	(37)	74	(95)	232
Gain (loss) on cash flow hedges	2	0	7	(1)
Pension and postretirement benefits gain (loss)	0	0	1	6
Other Comprehensive Income (Loss), Net of Tax	(35)	74	(74)	238
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	314	335	955	834
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(1)	(2)	(4)	(5)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	313	333	951	829
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(1,092)	(639)	(3,078)	(1,717)
Other comprehensive income (loss), net of tax
Comprehensive income (loss) attributable to Celanese Corporation	(998)	(818)	(2,898)	(2,301)
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	(1)	0	(19)	(3)
Foreign currency translation gain (loss)	103	(181)	224	(571)
Gain (loss) on cash flow hedges	(8)	0	(22)	3
Pension and postretirement benefits gain (loss)	0	2	(3)	(13)
Other Comprehensive Income (Loss), Net of Tax	94	(179)	180	(584)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(998)	(818)	(2,898)	(2,301)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (998)	$ (818)	$ (2,898)	$ (2,301)