Consolidating Guarantor Financial Information (Schedule of Consolidating Statements of Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	$ 265	$ 402	$ 813	$ 1,112
Unrealized gain (loss) on marketable securities		0		0
Foreign currency translation gain (loss)	(7)	(35)	(11)	(52)
Gain (loss) on cash flow hedges	(32)	4	(48)	9
Pension and postretirement benefits gain (loss)	0	0	0	1
Total other comprehensive income (loss), net of tax	(39)	(31)	(59)	(42)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	226	371	754	1,070
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(2)	(1)	(4)	(4)
Comprehensive income (loss) attributable to Celanese Corporation	224	370	750	1,066
Parent Guarantor [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	263	401	809	1,108
Unrealized gain (loss) on marketable securities		0		0
Foreign currency translation gain (loss)	(7)	(35)	(11)	(52)
Gain (loss) on cash flow hedges	(32)	4	(48)	9
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(39)	(31)	(59)	(42)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	224	370	750	1,066
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	224	370	750	1,066
Issuer [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	277	401	823	1,108
Unrealized gain (loss) on marketable securities		0		0
Foreign currency translation gain (loss)	(7)	(35)	(11)	(52)
Gain (loss) on cash flow hedges	(32)	4	(48)	9
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(39)	(31)	(59)	(42)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	238	370	764	1,066
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	238	370	764	1,066
Subsidiary Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	249	343	738	945
Unrealized gain (loss) on marketable securities		1		6
Foreign currency translation gain (loss)	(52)	(31)	(68)	(77)
Gain (loss) on cash flow hedges	(12)	2	(9)	6
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(64)	(28)	(77)	(64)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	185	315	661	881
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	185	315	661	881
Non-Guarantors [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	195	349	588	1,029
Unrealized gain (loss) on marketable securities		0		13
Foreign currency translation gain (loss)	(67)	(37)	(87)	(95)
Gain (loss) on cash flow hedges	(12)	2	(7)	7
Pension and postretirement benefits gain (loss)				1
Total other comprehensive income (loss), net of tax	(79)	(35)	(94)	(74)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	116	314	494	955
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(2)	(1)	(4)	(4)
Comprehensive income (loss) attributable to Celanese Corporation	114	313	490	951
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Net earnings (loss)	(719)	(1,092)	(2,145)	(3,078)
Unrealized gain (loss) on marketable securities		(1)		(19)
Foreign currency translation gain (loss)	126	103	166	224
Gain (loss) on cash flow hedges	56	(8)	64	(22)
Pension and postretirement benefits gain (loss)				(3)
Total other comprehensive income (loss), net of tax	182	94	230	180
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(537)	(998)	(1,915)	(2,898)
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	0	0	0
Comprehensive income (loss) attributable to Celanese Corporation	$ (537)	$ (998)	$ (1,915)	$ (2,898)