Summary of Significant Accounting Policies - Credit loss (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Allowance activity
Allowance for doubtful accounts, beginning balance	$ 33	$ 28
Additions charged to expense	35	51
Accounts written-off, net of recoveries	(36)	(44)
Acquisitions, divestitures and other, net	(7)	(1)
Allowance for doubtful accounts, ending balance	25	33
Accounts receivable, net of allowance	$ 2,278	$ 2,097
Receivables outstanding less than 60 days (as a percent)	90.00%	90.00%
Threshold period to measure receivables	60 days	60 days
Notes and other receivables, current and noncurrent	$ 451	$ 703
Allowance for notes and other receivables, current and noncurrent	$ 10	$ 8
Receivables classified as current (as a percent)	60.00%	75.00%
Receivables related to income tax payments in excess of our provision for income taxes	$ 166	$ 414
Federal Fuel Credits Receivable	14	20
Cumulative Effect, Period of Adoption, Adjustment [Member] \| Accounting Standards Update 2016-13 [Member]
Allowance activity
Allowance for doubtful accounts, beginning balance	$ (1)
Allowance for doubtful accounts, ending balance		$ (1)

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

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