Summary of Significant Accounting Policies - Credit loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Allowance activity
Allowance for doubtful accounts, beginning balance	$ 26	$ 25
Additions charged to expense	53	55
Accounts written-off, net of recoveries	(58)	(49)
Acquisitions, divestitures and other, net	9	(5)
Allowance for doubtful accounts, ending balance	30	26
Accounts receivable, net of allowance	$ 2,633	$ 2,461
Receivables outstanding less than 60 days (as a percent)	90.00%	90.00%
Threshold period to measure receivables	60 days	60 days
Receivables classified as current (as a percent)	0.50%	0.55%
Receivables related to income tax payments in excess of our provision for income taxes	$ 120	$ 150
Federal Fuel Credits Receivable	$ 26	$ 19