Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Accounts and notes receivable, net, allowance for credit losses	$ 223	$ 207
Provision for credit losses	19
Loyalty Program
Disaggregation of Revenue [Line Items]
Change in contract with customer liability	132
Contract with customer liability	6,403	$ 6,271
Deferred revenue recognized	$ 292

Amount of allowance for credit loss of accounts and financing receivables. Includes, but is not limited to, notes and loan receivable.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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-Topic 230
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Amount of expense (reversal of expense) for expected credit loss on accounts receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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