Commitments and Contingencies - Noncancelable Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Rent expense	$ 317	$ 354	$ 300
Operating lease liabilities	969	1,010
Operating right-of-use assets obtained in exchange for lease obligations	222	$ 497
2021	251
2022	205
2023	196
2024	151
2025	122
Thereafter	437
Imputed interest	$ 184
Weighted average discount rate	4.00%	4.20%
Weighted-average remaining lease term	7 years 4 months 24 days	7 years 2 months 12 days
Payments for operating leases	$ 309	$ 337
Amount of lease agreements not yet commenced	150
Other assets
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	1,000	1,100
Accrued liabilities
Lessee, Lease, Description [Line Items]
Operating lease liability	209	239
Other liabilities
Lessee, Lease, Description [Line Items]
Operating lease liabilities	$ 969	$ 1,000

Lessor, Operating Lease, Lease Not yet Commenced, Amount

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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.

+ References

No definition available.

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Amount of lessee's undiscounted obligation for lease payment for operating lease due after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent.

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Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use.

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Amount of lessee's right to use underlying asset under operating lease.

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Weighted average discount rate for operating lease calculated at point in time.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Cash payments to lessor's for use of assets under operating leases.

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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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