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Summary of Significant Accounting Policies (Tables)
12 Months Ended
Dec. 31, 2021
Accounting Policies [Abstract]  
Marketable securities
The carrying values of investment securities consisted of the following at December 31, 2021 and 2020 (in millions):
December 31, 2021December 31, 2020
Available-for-sale securities 
Time deposits$790 $1,130 
Commercial paper— 
Equity securities26 — 
Debt securities
Total available-for-sale securities826 1,137 
Held-to-maturity securities
Corporate bonds37 — 
Total held-to-maturity securities37 — 
Total investment securities$863 $1,137 
Property, plant and equipment
Estimated useful lives and residual values for our property and equipment are as follows:
Property and Equipment TypeEstimated Useful LifeResidual Value
Aircraft25 years20 %
Inflight entertainment systems
5-10 years
%
Aircraft partsFleet life10 %
Flight equipment leasehold improvementsLower of lease term or economic life%
Ground property and equipment
2-10 years
%
Leasehold improvements—otherLower of lease term or economic life%
Buildings on leased landLease term%