FINANCIAL DERIVATIVE INSTRUMENTS - Fair Values by Balance Sheet Location (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fuel derivative contracts \| Prepaid expenses and other current assets
Derivatives, Fair Value
Gross amounts of recognized assets	$ 86	$ 352
Gross amounts offset in the balance sheet	15	106
Cash collateral deposits held from counterparties for fuel contracts - current	15	106
Fuel derivative contracts \| Other assets
Derivatives, Fair Value
Gross amounts of recognized assets	137	160
Gross amounts offset in the balance sheet	35	0
Cash collateral deposits held from counterparties for fuel contracts - current	35	0
Fuel derivative contracts \| Accounts and other receivables
Derivatives, Fair Value
Receivable from third parties for fuel contracts	12	34
Interest rate derivatives \| Other assets
Derivatives, Fair Value
Gross amounts of recognized assets	0	14
Designated as Hedging Instrument
Derivatives, Fair Value
Gross amounts of recognized assets	223	526
Gross amounts offset in the balance sheet	0	0
Designated as Hedging Instrument \| Fuel derivative contracts \| Prepaid expenses and other current assets
Derivatives, Fair Value
Gross amounts of recognized assets	86	352
Gross amounts offset in the balance sheet	0	0
Designated as Hedging Instrument \| Fuel derivative contracts \| Other assets
Derivatives, Fair Value
Gross amounts of recognized assets	137	160
Gross amounts offset in the balance sheet	0	0
Designated as Hedging Instrument \| Interest rate derivatives \| Other assets
Derivatives, Fair Value
Gross amounts of recognized assets	0	14
Gross amounts offset in the balance sheet	$ 0	$ 0

Derivative, Cash Receivable (Payable) On Hedge

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- Definition

Amount of obligation to return cash collateral under master netting arrangements offset against derivative assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 10
-Topic 815
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-SubTopic 20
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

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- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483466/210-20-50-3

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
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-Name Accounting Standards Codification
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-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483444/210-20-55-7

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-SubTopic 20
-Topic 860
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481326/860-20-50-4D

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- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

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- Definition

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.

+ References

No definition available.

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