Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Total Gross Assets & Liabilities [Domain]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	$ 2,750	$ 1,441
Advances to/receivables from equity companies	8,894	9,179
Other long-term financial assets	2,407	2,179
Derivative liabilities	3,565	1,697
Long-term debt	46,891	50,392
Long-term obligations to equity companies	3,337	3,530
Other long-term financial liabilities	972	964
Net Carrying Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	393	153
Advances to/receivables from equity companies	8,603	8,812
Other long-term financial assets	2,597	2,304
Derivative liabilities	558	213
Long-term debt	43,515	45,502
Long-term obligations to equity companies	3,038	3,253
Other long-term financial liabilities	1,029	1,008
Effect Of Counterparty Netting [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	(2,357)	(1,282)
Derivative liabilities	(2,357)	(1,282)
Effect Of Collateral Netting [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	0	(6)
Derivative liabilities	(650)	(202)
Difference In Carrying Value And Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Advances to/receivables from equity companies	(291)	(367)
Other long-term financial assets	190	125
Long-term debt	(3,376)	(4,890)
Long-term obligations to equity companies	(299)	(277)
Other long-term financial liabilities	57	44
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	2,156	1,247
Other long-term financial assets	1,104	1,235
Derivative liabilities	2,806	1,443
Long-term debt	46,787	50,263
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative assets	594	194
Advances to/receivables from equity companies	3,167	3,275
Derivative liabilities	759	254
Long-term debt	100	125
Level 3 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Advances to/receivables from equity companies	5,727	5,904
Other long-term financial assets	1,303	944
Long-term debt	4	4
Long-term obligations to equity companies	3,337	3,530
Other long-term financial liabilities	$ 972	$ 964