The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Amount of the cost of borrowed funds accounted for as interest expense for debt.

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The amount of loss reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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Financial Derivative Instruments - Location and Amount Recognized in Income by Hedging Relationship (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Fuel
Derivative [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	$ 14	$ (2)	$ 36	$ 9
Other (gains)/losses, net
Derivative [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	14		16
Interest Expense
Derivative [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	3	7	4	15
Cash Flow Hedging \| Fuel \| Fuel derivatives
Derivative [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	14	(2)	36	9
Cash Flow Hedging \| Fuel \| Interest rate derivatives
Derivative [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0	0	0
Cash Flow Hedging \| Other (gains)/losses, net \| Fuel derivatives
Derivative [Line Items]
Loss on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring	14		16
Cash Flow Hedging \| Other (gains)/losses, net \| Interest rate derivatives
Derivative [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	0		0
Cash Flow Hedging \| Interest Expense \| Fuel derivatives
Derivative [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0	0	0
Cash Flow Hedging \| Interest Expense \| Interest rate derivatives
Derivative [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	1	1	1	2
Designated as Hedging Instrument \| Fair Value Hedging \| Fuel \| Interest rate derivatives
Derivative [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	0	0	0	0
Designated as Hedging Instrument \| Fair Value Hedging \| Other (gains)/losses, net \| Interest rate derivatives
Derivative [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	0		0
Designated as Hedging Instrument \| Fair Value Hedging \| Interest Expense \| Interest rate derivatives
Derivative [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	(2)	0	(4)	1
Not Designated as Hedging Instrument \| Fuel derivatives
Derivative [Line Items]
Loss on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring	14		16
Not Designated as Hedging Instrument \| Fair Value Hedging \| Fuel \| Interest rate derivatives
Derivative [Line Items]
Interest Expense, Debt	0	0	0	0
Not Designated as Hedging Instrument \| Fair Value Hedging \| Other (gains)/losses, net \| Interest rate derivatives
Derivative [Line Items]
Interest Expense, Debt	0		0
Not Designated as Hedging Instrument \| Fair Value Hedging \| Interest Expense \| Interest rate derivatives
Derivative [Line Items]
Interest Expense, Debt	$ 4	$ 6	$ 7	$ 12