Financial Instruments and Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Fair Value [Line Items]
Carrying value of investment	$ 92
Unrealized gain (loss) on derivative asset	$ (24)	$ 3
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 \| Maximum
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 Agency Notes
Fair Value [Line Items]
Available-for-sale securities remaining maturities	3 years
Other Fixed-Income Securities
Fair Value [Line Items]
Available-for-sale securities remaining maturities	2 years
Azul
Fair Value [Line Items]
Equity stake in Azul	2.00%
Gain (loss) on equity securities	$ (293)	$ 14
Carrying value of investment	$ 92
Azul \| Preferred Stock
Fair Value [Line Items]
Equity stake in Azul	8.00%

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Equity Securities, Ownership Percentage

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Fair Value [Line Items]

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714

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- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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