Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Gross rental expense	$ 777	$ 733
Gross rental expense			$ 875
Sublease income	25	24
Sublease income			21
Operating lease, not yet commenced	0
Finance lease, not yet commenced	0
Gross rental income	$ 1,300	$ 1,400	$ 882
Rental income as percentage of operating revenue	6.00%	7.00%	4.00%

Lessee, Finance Lease, Lease Not Yet Commenced

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- Definition

Lessee, Operating Lease, Lease Not Yet Commenced

+ References

No definition available.

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- Definition

Operating Lease, Lease Income, Percent of Operating Revenue

+ References

No definition available.

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- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

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- References

No definition available.

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- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

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- Definition

Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

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- Definition

The amount of revenue recognized for the period under subleasing arrangements.

+ References

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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

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