FINANCING ACTIVITIES - Narrative (Details)			3 Months Ended	12 Months Ended
	Jan. 09, 2023	Feb. 28, 1997 USD ($)	Dec. 31, 2022 USD ($) aircraft	Dec. 31, 2022 USD ($) aircraft	Dec. 31, 2021 USD ($) $ / shares	Dec. 31, 2020 USD ($)	Jan. 01, 2022 USD ($)	Jul. 31, 2020 USD ($)	Jun. 08, 2020 USD ($)	May 04, 2020 USD ($)	May 01, 2020 USD ($) $ / shares	Feb. 29, 2020 USD ($)	Dec. 31, 2019 USD ($)	Nov. 30, 2017 USD ($)	Nov. 30, 2016 USD ($)	Oct. 03, 2007 USD ($) Mortgages
Debt Instrument [Line Items]
Initial conversion price (in USD per share) | $ / shares					$ 38.48
Loss on extinguishment of debt				$ 193,000,000	$ 28,000,000	$ 0
Equity feature of partial extinguishment of convertible notes					(92,000,000)
Long-term debt			$ 8,097,000,000	8,097,000,000
Decrease in AOCI			(10,687,000,000)	(10,687,000,000)	(10,414,000,000)	(8,876,000,000)							$ (9,832,000,000)
Payments of long-term debt and finance lease obligations				2,437,000,000	612,000,000	839,000,000
Minimum level of liquidity required			1,500,000,000	1,500,000,000
Outstanding letters of credit			162,000,000	162,000,000
Net book value of assets pledged as collateral for the Company's secured borrowings, primarily aircraft and engines			2,000,000,000	2,000,000,000
Aircraft
Debt Instrument [Line Items]
Net book value of assets pledged as collateral for the Company's secured borrowings, primarily aircraft and engines			296,000,000	296,000,000
Capital in excess of par value
Debt Instrument [Line Items]
Equity feature of partial extinguishment of convertible notes					(92,000,000)
Decrease in AOCI			(4,037,000,000)	(4,037,000,000)	(4,224,000,000)	(4,191,000,000)							$ (1,581,000,000)
Cumulative Effect, Period of Adoption, Adjustment
Debt Instrument [Line Items]
Decrease in AOCI					245,000,000	0
Cumulative Effect, Period of Adoption, Adjustment | Capital in excess of par value
Debt Instrument [Line Items]
Decrease in AOCI					300,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Credit outstanding			0	0	0
Maximum borrowing capacity			$ 1,500,000,000	$ 1,500,000,000
Convertible Notes
Debt Instrument [Line Items]
Term (in years)				5 years
Effective interest rate (as a percent)			1.90%	1.90%
Accrued Interest				$ 34,000,000	110,000,000
Non-cash amortization of the debt discount				0	73,000,000
Non-cash amortization of debt issuance costs				12,000,000	9,000,000
Convertible Notes | Accounting Standards Update 2020-06
Debt Instrument [Line Items]
Long-term debt							$ 300,000,000
Convertible Notes | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)							1.25%
Convertible Notes | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2020-06 | Capital in excess of par value
Debt Instrument [Line Items]
Decrease in AOCI							$ 300,000,000
Convertible Debt And Unsecured Debt
Debt Instrument [Line Items]
Accrued Interest				28,000,000
Payments of long-term debt and finance lease obligations				3,100,000,000	905,000,000
Principal repayment				2,256,000,000
Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 1,000,000,000	$ 1,000,000,000
Total 5.125 Notes due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Principal amount						$ 2,000,000,000
5.125 Unsecured Notes due 2027
Debt Instrument [Line Items]
Face amount of debt									$ 1,300,000,000
Term (in years)						364 days
5.125% Notes due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			5.125%	5.125%		5.125%
Principal amount			$ 1,727,000,000	$ 1,727,000,000	2,000,000,000			$ 700,000,000
Accrued Interest				4,000,000
Principal repayment				$ 272,000,000
5.25% Notes due 2025
Debt Instrument [Line Items]
Face amount of debt						$ 1,550,000,000				$ 1,250,000,000
Term (in years)						364 days
5.25% Notes due 2025 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			5.25%	5.25%		5.25%
Principal amount			$ 1,302,000,000	$ 1,302,000,000	1,550,000,000			$ 300,000,000
Accrued Interest				4,000,000
Principal repayment				$ 248,000,000
4.75% Notes due 2023
Debt Instrument [Line Items]
Face amount of debt						$ 1,250,000,000			$ 500,000,000	$ 750,000,000
Interest rate stated in the debt agreement (as a percent)										4.75%
Term (in years)						364 days
4.75% Notes due 2023 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			4.75%	4.75%
Principal amount			$ 0	$ 0	1,250,000,000
Accrued Interest				19,000,000
Principal repayment				$ 1,250,000,000
Amended 364-Day Term Loan Credit Facility
Debt Instrument [Line Items]
Aircrafts secured to debt transactions | aircraft			83	83
Amended 364-Day Term Loan Credit Facility | LIBOR
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			100.00%	100.00%
Amended 364-Day Term Loan Credit Facility | LIBOR | Minimum
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			100.00%	100.00%
Amended 364-Day Term Loan Credit Facility | New York Fed Bank Rate
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			50.00%	50.00%
Amended 364-Day Term Loan Credit Facility | Base Rate | Minimum
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			100.00%	100.00%
Amended 364-Day Term Loan Credit Facility | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			10.00%	10.00%
2.625% Notes due 2030
Debt Instrument [Line Items]
Face amount of debt												$ 500,000,000
2.625% Notes due 2030 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)												2.625%
Principal amount			$ 500,000,000	$ 500,000,000	500,000,000
2.75% Notes due 2022
Debt Instrument [Line Items]
Face amount of debt														$ 300,000,000
Interest rate stated in the debt agreement (as a percent)														2.75%
2.75% Notes due 2022 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			2.75%	2.75%
Principal amount			$ 0	$ 0	300,000,000
Pass Through Certificates due 2022 - 6.24%
Debt Instrument [Line Items]
Face amount of debt																$ 500,000,000
Number of mortgages on secured aircraft | Mortgages																16
Pass Through Certificates Series A
Debt Instrument [Line Items]
Face amount of debt																$ 412,000,000
Interest rate stated in the debt agreement (as a percent)																6.15%
Pass Through Certificates Series B
Debt Instrument [Line Items]
Face amount of debt																$ 88,000,000
Interest rate stated in the debt agreement (as a percent)																6.65%
7.375% Debentures due 2027
Debt Instrument [Line Items]
Face amount of debt		$ 100,000,000
Interest rate stated in the debt agreement (as a percent)		7.375%
7.375% Debentures due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			7.375%	7.375%
Principal amount			$ 114,000,000	$ 114,000,000	116,000,000
1.25% Convertible Notes due 2025
Debt Instrument [Line Items]
Conversion ratio (in shares)			0.0259909
Initial conversion price (in USD per share) | $ / shares											$ 38.48
If-converted value exceeded principal amount				$ 201,000,000
1.25% Convertible Notes due 2025 | Subsequent Event
Debt Instrument [Line Items]
Conversion ratio (in shares)	0.0261250
1.25% Convertible Notes due 2025 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			1.25%	1.25%
1.25% Convertible Notes due 2025 | Convertible Notes
Debt Instrument [Line Items]
Face amount of debt											$ 2,300,000,000
Interest rate stated in the debt agreement (as a percent)											1.25%
Principal amount			$ 1,611,000,000	$ 1,611,000,000	1,842,000,000
Accrued Interest				1,000,000	92,000,000
Principal repayment				$ 486,000,000	203,000,000
Unsecured Senior Notes Due 2027 - 3.45%
Debt Instrument [Line Items]
Face amount of debt														$ 300,000,000
Interest rate stated in the debt agreement (as a percent)														3.45%
Unsecured Senior Notes Due 2027 - 3.45% | Treasury Rate
Debt Instrument [Line Items]
Spread on variable rate (as a percent)		0.20%
3.00% Notes due 2026
Debt Instrument [Line Items]
Face amount of debt															$ 300,000,000
Interest rate stated in the debt agreement (as a percent)															3.00%
3.00% Notes due 2026 | Unsecured Debt
Debt Instrument [Line Items]
Interest rate stated in the debt agreement (as a percent)			3.00%	3.00%
Principal amount			$ 300,000,000	$ 300,000,000	$ 300,000,000