Investments and Fair Value Measurements - Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Fair Value [Line Items]
Investments in securities accounted for under the equity method	$ 126
Asset-backed Securities \| Minimum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
Asset-backed Securities \| Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	15 years
Corporate Debt
Fair Value [Line Items]
Available-for-sale securities remaining maturities	3 years
CDARS
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
U.S. Government and Other Securities
Fair Value [Line Items]
Available-for-sale securities remaining maturities	3 years
Fixed Income Securities
Fair Value [Line Items]
Available-for-sale securities remaining maturities	2 years
Azul
Fair Value [Line Items]
Equity stake	2.00%
Carrying value of investment	$ 385
Azul \| Preferred Stock
Fair Value [Line Items]
Equity stake	8.00%
Republic
Fair Value [Line Items]
Ownership stake	19.00%
ManaAir
Fair Value [Line Items]
Ownership stake	49.90%
Champlain
Fair Value [Line Items]
Ownership stake	40.00%
Fulcrum
Fair Value [Line Items]
Ownership interest	0.07
Carrying value of other investment	$ 51
Fulcrum \| Preferred Stock
Fair Value [Line Items]
Ownership interest	0.08

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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