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Financial Instruments and Fair Value Measurements - Narrative (Details)	9 Months Ended
	Sep. 30, 2019
Fair Value [Line Items]
Equity stake in Azul	2.00%
Preferred Stock
Fair Value [Line Items]
Equity stake in Azul	8.00%
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 | Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	1 year
U.S. Government and Agency Notes | Minimum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	3 years
Other Fixed-Income Securities | Maximum
Fair Value [Line Items]
Available-for-sale securities remaining maturities	2 years

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