Leases and Capacity Purchase Agreements - Components of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease cost	$ 933	$ 1,038	$ 1,213
Variable and short-term lease cost	1,968	2,548	2,569
Amortization of finance lease assets	88	68	75
Interest on finance lease liabilities	16	85	44
Sublease income	(23)	(32)	(38)
Total lease cost	$ 2,982	$ 3,707	$ 3,863

Variable And Short-Term Lease, Cost

No definition available.

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- Definition

Amount of interest expense on finance lease liability.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
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- Definition

Amount of amortization expense attributable to right-of-use asset from finance lease.

+ References

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- Definition

Amount of lease cost recognized by lessee for lease contract.

+ References

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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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-Publisher FASB
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- Definition

Amount of sublease income excluding finance and operating lease expense.

+ References

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