Financial Derivative Instruments - Premiums for Fuel Derivative Contracts (Details) - Fuel derivatives - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Designated as Hedging Instrument \| Fuel and oil
Derivative [Line Items]
Premium expense recognized in income on derivatives	$ 14	$ 13	$ 29	$ 38
Not Designated as Hedging Instrument \| Other (gains)/losses, net
Derivative [Line Items]
Premium expense recognized in income on derivatives	$ 10	$ 11	$ 21	$ 11

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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