Schedule of Consolidated VIEs, Carrying Amounts of Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Variable Interest Entity [Line Items]
Cash and cash equivalents (variable interest entities restricted - 2021: $37; 2020: $26)	$ 4,133	$ 5,104	$ 3,633
Other current assets	608	889
Net property (variable interest entities restricted - 2021: $216; 2020: $232)	19,897	20,239
Deferred charges and other assets	1,266	1,249
Total Assets	60,437	61,470
Accrued and other current liabilities	3,431	3,790
Long-Term Debt (variable interest entities nonrecourse - 2021: $6; 2020: $6)	16,200	16,491
Other noncurrent obligations	6,331	6,279
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents (variable interest entities restricted - 2021: $37; 2020: $26)	37	26
Other current assets	41	44
Net property (variable interest entities restricted - 2021: $216; 2020: $232)	216	232
Deferred charges and other assets	17	17
Total Assets	311	319
Accrued and other current liabilities	62	73
Long-Term Debt (variable interest entities nonrecourse - 2021: $6; 2020: $6)	6	6
Other noncurrent obligations	17	18
Total Liabilities	$ 85	$ 97