Consolidating Guarantor Financial Information (Schedule of Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2018		Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 703		$ 576	$ 461	$ 638
Trade receivables - third party and affiliates	1,086		986
Non-trade receivables, net	279		244
Inventories, net	1,033		900
Marketable securities, at fair value	31		32
Other assets	48		54
Total current assets	3,180		2,792
Investments in affiliates	981		976
Property, Plant and Equipment, Net	3,699		3,762
Deferred income taxes	170		366
Other assets	413		338
Goodwill	1,064	[1]	1,003
Intangible Assets, Net (Excluding Goodwill)	317		301
Total assets	9,824		9,538
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	229		326
Trade payables - third party and affiliates	819		807
Other liabilities	347		354
Income taxes payable	137		72
Total current liabilities	1,532		1,559
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	3,196		3,315
Deferred income taxes	246		211
Uncertain tax positions	154		156
Benefit obligations	547		585
Other liabilities	206		413
Total noncurrent liabilities	4,349		4,680
Total Celanese Corporation stockholders' equity	3,541		2,887
Noncontrolling interests	402		412
Total equity	3,943		3,299
Total liabilities and equity	9,824		9,538
Parent Guarantor [Member]
Current Assets
Cash and cash equivalents	0		0	0	0
Trade receivables - third party and affiliates	0		0
Non-trade receivables, net	37		38
Inventories, net	0		0
Marketable securities, at fair value	0		0
Other assets	0		0
Total current assets	37		38
Investments in affiliates	3,504		2,850
Property, Plant and Equipment, Net	0		0
Deferred income taxes	0		0
Other assets	0		0
Goodwill	0		0
Intangible Assets, Net (Excluding Goodwill)	0		0
Total assets	3,541		2,888
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	0		0
Trade payables - third party and affiliates	0		0
Other liabilities	0		0
Income taxes payable	0		0
Total current liabilities	0		0
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	0		0
Deferred income taxes	0		0
Uncertain tax positions	0		0
Benefit obligations	0		0
Other liabilities	0		0
Total noncurrent liabilities	0		0
Total Celanese Corporation stockholders' equity	3,541		2,888
Noncontrolling interests	0		0
Total equity	3,541		2,888
Total liabilities and equity	3,541		2,888
Issuer [Member]
Current Assets
Cash and cash equivalents	14		0	5	0
Trade receivables - third party and affiliates	0		0
Non-trade receivables, net	515		482
Inventories, net	0		0
Marketable securities, at fair value	0		0
Other assets	22		60
Total current assets	551		542
Investments in affiliates	4,736		4,283
Property, Plant and Equipment, Net	0		0
Deferred income taxes	17		6
Other assets	1,621		1,295
Goodwill	0		0
Intangible Assets, Net (Excluding Goodwill)	0		0
Total assets	6,925		6,126
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	50		76
Trade payables - third party and affiliates	0		1
Other liabilities	45		71
Income taxes payable	0		0
Total current liabilities	95		148
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	3,326		3,128
Deferred income taxes	0		0
Uncertain tax positions	0		0
Benefit obligations	0		0
Other liabilities	0		0
Total noncurrent liabilities	3,326		3,128
Total Celanese Corporation stockholders' equity	3,504		2,850
Noncontrolling interests	0		0
Total equity	3,504		2,850
Total liabilities and equity	6,925		6,126
Subsidiary Guarantors [Member]
Current Assets
Cash and cash equivalents	46		230	70	51
Trade receivables - third party and affiliates	122		89
Non-trade receivables, net	257		279
Inventories, net	301		277
Marketable securities, at fair value	31		32
Other assets	16		12
Total current assets	773		919
Investments in affiliates	4,729		3,916
Property, Plant and Equipment, Net	1,228		1,145
Deferred income taxes	0		206
Other assets	260		171
Goodwill	314		314
Intangible Assets, Net (Excluding Goodwill)	101		48
Total assets	7,405		6,719
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	176		148
Trade payables - third party and affiliates	303		300
Other liabilities	296		302
Income taxes payable	495		471
Total current liabilities	1,270		1,221
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	1,580		1,254
Deferred income taxes	67		0
Uncertain tax positions	10		1
Benefit obligations	265		277
Other liabilities	105		255
Total noncurrent liabilities	2,027		1,787
Total Celanese Corporation stockholders' equity	4,108		3,711
Noncontrolling interests	0		0
Total equity	4,108		3,711
Total liabilities and equity	7,405		6,719
Non-Guarantors [Member]
Current Assets
Cash and cash equivalents	643		346	386	587
Trade receivables - third party and affiliates	1,098		988
Non-trade receivables, net	444		385
Inventories, net	775		672
Marketable securities, at fair value	0		0
Other assets	57		93
Total current assets	3,017		2,484
Investments in affiliates	860		861
Property, Plant and Equipment, Net	2,471		2,617
Deferred income taxes	175		158
Other assets	479		165
Goodwill	750		689
Intangible Assets, Net (Excluding Goodwill)	216		253
Total assets	7,968		7,227
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	268		369
Trade payables - third party and affiliates	650		598
Other liabilities	298		273
Income taxes payable	104		92
Total current liabilities	1,320		1,332
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	203		233
Deferred income taxes	201		215
Uncertain tax positions	146		157
Benefit obligations	282		308
Other liabilities	142		158
Total noncurrent liabilities	974		1,071
Total Celanese Corporation stockholders' equity	5,272		4,412
Noncontrolling interests	402		412
Total equity	5,674		4,824
Total liabilities and equity	7,968		7,227
Eliminations [Member]
Current Assets
Cash and cash equivalents	0		0	$ 0	$ 0
Trade receivables - third party and affiliates	(134)		(91)
Non-trade receivables, net	(974)		(940)
Inventories, net	(43)		(49)
Marketable securities, at fair value	0		0
Other assets	(47)		(111)
Total current assets	(1,198)		(1,191)
Investments in affiliates	(12,848)		(10,934)
Property, Plant and Equipment, Net	0		0
Deferred income taxes	(22)		(4)
Other assets	(1,947)		(1,293)
Goodwill	0		0
Intangible Assets, Net (Excluding Goodwill)	0		0
Total assets	(16,015)		(13,422)
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	(265)		(267)
Trade payables - third party and affiliates	(134)		(92)
Other liabilities	(292)		(292)
Income taxes payable	(462)		(491)
Total current liabilities	(1,153)		(1,142)
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	(1,913)		(1,300)
Deferred income taxes	(22)		(4)
Uncertain tax positions	(2)		(2)
Benefit obligations	0		0
Other liabilities	(41)		0
Total noncurrent liabilities	(1,978)		(1,306)
Total Celanese Corporation stockholders' equity	(12,884)		(10,974)
Noncontrolling interests	0		0
Total equity	(12,884)		(10,974)
Total liabilities and equity	$ (16,015)		$ (13,422)

[1] There were $0 million of accumulated impairment losses as of September 30, 2018.