Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Total Gross Assets & Liabilities [Domain]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	$ 758	$ 635
Advances to/receivables from equity companies	9,233	8,670
Other long-term financial assets	2,112	2,119
Derivative liabilities	908	638
Long-term debt	49,306	25,789
Long-term obligations to equity companies	3,685	4,245
Other long-term financial liabilities	1,073	1,042
Net Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	107	102
Advances to/receivables from equity companies	9,040	8,542
Other long-term financial assets	2,242	2,163
Derivative liabilities	78	70
Long-term debt	45,275	24,672
Long-term obligations to equity companies	3,486	3,988
Other long-term financial liabilities	1,084	1,058
Effect Of Counterparty Netting [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	(571)	(463)
Derivative liabilities	(571)	(463)
Effect Of Collateral Netting [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	(80)	(70)
Derivative liabilities	(259)	(105)
Difference In Carrying Value And Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Advances to/receivables from equity companies	(193)	(128)
Other long-term financial assets	130	44
Long-term debt	(4,031)	(1,117)
Long-term obligations to equity companies	(199)	(257)
Other long-term financial liabilities	11	16
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	637	533
Other long-term financial assets	1,197	1,145
Derivative liabilities	817	568
Long-term debt	49,153	25,652
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	121	102
Advances to/receivables from equity companies	3,152	1,941
Derivative liabilities	91	70
Long-term debt	149	134
Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Advances to/receivables from equity companies	6,081	6,729
Other long-term financial assets	915	974
Long-term debt	4	3
Long-term obligations to equity companies	3,685	4,245
Other long-term financial liabilities	$ 1,073	$ 1,042