Consolidating Guarantor Financial Information (Schedule of Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 497	$ 439	$ 703	$ 576
Trade receivables - third party and affiliates	947	1,017
Non-trade receivables, net	335	301
Inventories, net	994	1,046
Marketable securities, at fair value	26	31
Other assets	44	40
Total current assets	2,843	2,874
Investments in affiliates	970	979
Property, Plant and Equipment, Net	3,585	3,719
Operating Lease, Right-of-Use Asset	206	0
Deferred income taxes	98	84
Other assets	344	290
Goodwill	1,054	1,057
Intangible Assets, Net (Excluding Goodwill)	314	310
Total assets	9,414	9,313
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	368	561
Trade payables - third party and affiliates	764	819
Other liabilities	358	343
Income taxes payable	43	56
Total current liabilities	1,533	1,779
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	3,359	2,970
Deferred income taxes	269	255
Uncertain tax positions	169	158
Benefit obligations	523	564
Operating Lease, Liability, Noncurrent	182	0
Other liabilities	240	208
Total noncurrent liabilities	4,742	4,155
Total Celanese Corporation stockholders' equity	2,747	2,984	3,541
Noncontrolling interests	392	395
Total equity	3,139	3,379	3,943
Total liabilities and equity	9,414	9,313
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	46	40
Inventories, net	0	0
Marketable securities, at fair value	0	0
Other assets	0	0
Total current assets	46	40
Investments in affiliates	4,006	3,503
Property, Plant and Equipment, Net	0	0
Operating Lease, Right-of-Use Asset	0
Deferred income taxes	0	0
Other assets	1	0
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	0	0
Total assets	4,053	3,543
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	1,280	544
Trade payables - third party and affiliates	25	13
Other liabilities	0	1
Income taxes payable	1	0
Total current liabilities	1,306	558
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
Operating Lease, Liability, Noncurrent	0
Other liabilities	0	1
Total noncurrent liabilities	0	1
Total Celanese Corporation stockholders' equity	2,747	2,984
Noncontrolling interests	0	0
Total equity	2,747	2,984
Total liabilities and equity	4,053	3,543
Issuer [Member]
Current Assets
Cash and cash equivalents	0	0	14	0
Trade receivables - third party and affiliates	0	0
Non-trade receivables, net	1,082	551
Inventories, net	0	0
Marketable securities, at fair value	0	0
Other assets	31	24
Total current assets	1,113	575
Investments in affiliates	5,135	4,820
Property, Plant and Equipment, Net	0	0
Operating Lease, Right-of-Use Asset	0
Deferred income taxes	0	0
Other assets	1,674	1,658
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	0	0
Total assets	7,922	7,053
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	251	333
Trade payables - third party and affiliates	1	1
Other liabilities	79	87
Income taxes payable	0	0
Total current liabilities	331	421
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	3,502	3,104
Deferred income taxes	26	15
Uncertain tax positions	2	0
Benefit obligations	0	0
Operating Lease, Liability, Noncurrent	0
Other liabilities	55	10
Total noncurrent liabilities	3,585	3,129
Total Celanese Corporation stockholders' equity	4,006	3,503
Noncontrolling interests	0	0
Total equity	4,006	3,503
Total liabilities and equity	7,922	7,053
Subsidiary Guarantors [Member]
Current Assets
Cash and cash equivalents	87	30	46	230
Trade receivables - third party and affiliates	102	96
Non-trade receivables, net	1,771	797
Inventories, net	337	329
Marketable securities, at fair value	26	31
Other assets	17	10
Total current assets	2,340	1,293
Investments in affiliates	4,241	4,678
Property, Plant and Equipment, Net	1,373	1,289
Operating Lease, Right-of-Use Asset	54
Deferred income taxes	0	0
Other assets	194	142
Goodwill	399	399
Intangible Assets, Net (Excluding Goodwill)	127	132
Total assets	8,728	7,933
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	914	465
Trade payables - third party and affiliates	295	342
Other liabilities	190	267
Income taxes payable	495	475
Total current liabilities	1,894	1,549
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	1,678	1,679
Deferred income taxes	84	85
Uncertain tax positions	6	6
Benefit obligations	237	250
Operating Lease, Liability, Noncurrent	43
Other liabilities	94	99
Total noncurrent liabilities	2,142	2,119
Total Celanese Corporation stockholders' equity	4,692	4,265
Noncontrolling interests	0	0
Total equity	4,692	4,265
Total liabilities and equity	8,728	7,933
Non-Guarantors [Member]
Current Assets
Cash and cash equivalents	410	409	643	346
Trade receivables - third party and affiliates	958	1,040
Non-trade receivables, net	705	697
Inventories, net	706	765
Marketable securities, at fair value	0	0
Other assets	73	37
Total current assets	2,852	2,948
Investments in affiliates	839	855
Property, Plant and Equipment, Net	2,212	2,430
Operating Lease, Right-of-Use Asset	152
Deferred income taxes	100	86
Other assets	426	461
Goodwill	655	658
Intangible Assets, Net (Excluding Goodwill)	187	178
Total assets	7,423	7,616
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	555	258
Trade payables - third party and affiliates	556	583
Other liabilities	297	258
Income taxes payable	53	88
Total current liabilities	1,461	1,187
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	104	127
Deferred income taxes	161	157
Uncertain tax positions	161	152
Benefit obligations	286	314
Operating Lease, Liability, Noncurrent	139
Other liabilities	126	138
Total noncurrent liabilities	977	888
Total Celanese Corporation stockholders' equity	4,593	5,146
Noncontrolling interests	392	395
Total equity	4,985	5,541
Total liabilities and equity	7,423	7,616
Eliminations [Member]
Current Assets
Cash and cash equivalents	0	0	$ 0	$ 0
Trade receivables - third party and affiliates	(113)	(119)
Non-trade receivables, net	(3,269)	(1,784)
Inventories, net	(49)	(48)
Marketable securities, at fair value	0	0
Other assets	(77)	(31)
Total current assets	(3,508)	(1,982)
Investments in affiliates	(13,251)	(12,877)
Property, Plant and Equipment, Net	0	0
Operating Lease, Right-of-Use Asset	0
Deferred income taxes	(2)	(2)
Other assets	(1,951)	(1,971)
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	0	0
Total assets	(18,712)	(16,832)
Current Liabilities
Short-term borrowings and current installments of long-term debt - third party and affiliates	(2,632)	(1,039)
Trade payables - third party and affiliates	(113)	(120)
Other liabilities	(208)	(270)
Income taxes payable	(506)	(507)
Total current liabilities	(3,459)	(1,936)
Noncurrent Liabilities
Long-term debt, net of unamortized deferred financing costs	(1,925)	(1,940)
Deferred income taxes	(2)	(2)
Uncertain tax positions	0	0
Benefit obligations	0	0
Operating Lease, Liability, Noncurrent	0
Other liabilities	(35)	(40)
Total noncurrent liabilities	(1,962)	(1,982)
Total Celanese Corporation stockholders' equity	(13,291)	(12,914)
Noncontrolling interests	0	0
Total equity	(13,291)	(12,914)
Total liabilities and equity	$ (18,712)	$ (16,832)