WORLDWIDE PANDEMIC - Narrative (Details) $ / shares in Units, $ in Millions					3 Months Ended	9 Months Ended	12 Months Ended
	Apr. 23, 2026	Jan. 15, 2026	Apr. 20, 2025	Jun. 01, 2020 employee	Sep. 30, 2021 USD ($) aircraft employee $ / shares	Sep. 30, 2021 USD ($) aircraft employee $ / shares	Dec. 31, 2020 USD ($)
COVID - 19
Unusual or Infrequent Item, or Both [Line Items]
Voluntary separation program 2020 participants					4,200	4,200
Number of employees who participated in extended emergency time off during 2020				11,000	1,000	1,000
Total employees who participated in extended emergency time off During 2020, who were still on emergency time off at December 31, 2020				500
Number of days before the end of their term				90 days
Employees who elected conversion in extended emergency time off						300
Extended emergency time off accrual for employees who accepted through 2020 | $					$ 369	$ 405	$ 1,400
Extended emergency time off reversal for employees who accepted through March 31, 2021 | $						140
Proceeds from PSP2 payroll support program | $					$ 763	$ 2,700
Aircrafts in long-term storage | aircraft					24	24
COVID - 19 | Minimum
Unusual or Infrequent Item, or Both [Line Items]
Extended emergency time off, period				6 months
COVID - 19 | Minimum | Option to Convert to Voluntary Separation Program 2020
Unusual or Infrequent Item, or Both [Line Items]
Extended emergency time off, period				12 months
Years of service				10 years
COVID - 19 | Maximum
Unusual or Infrequent Item, or Both [Line Items]
Extended emergency time off, period				18 months
COVID - 19 | Maximum | Option to Convert to Voluntary Separation Program 2020
Unusual or Infrequent Item, or Both [Line Items]
Extended emergency time off, period				18 months
COVID - 19 | Maximum | Pilots
Unusual or Infrequent Item, or Both [Line Items]
Extended emergency time off, period				5 years
United States Department of Treasury | PSP1 Payroll Support Program
Unusual or Infrequent Item, or Both [Line Items]
Strike price (in USD per share) | $ / shares					$ 36.47	$ 36.47
United States Department of Treasury | PSP1 Payroll Support Program | Notes Payable, Other Payables
Unusual or Infrequent Item, or Both [Line Items]
Stated interest rate					1.00%	1.00%
United States Department of Treasury | PSP1 Payroll Support Program | Notes Payable, Other Payables | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Forecast
Unusual or Infrequent Item, or Both [Line Items]
Variable rate (as a percent)			2.00%
United States Department of Treasury | PSP2 Payroll Support Program
Unusual or Infrequent Item, or Both [Line Items]
Strike price (in USD per share) | $ / shares					$ 46.28	$ 46.28
Expiration period (in years)						5 years
United States Department of Treasury | PSP2 Payroll Support Program | Notes Payable, Other Payables
Unusual or Infrequent Item, or Both [Line Items]
Stated interest rate					1.00%	1.00%
United States Department of Treasury | PSP2 Payroll Support Program | Notes Payable, Other Payables | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Forecast
Unusual or Infrequent Item, or Both [Line Items]
Variable rate (as a percent)		2.00%
United States Department of Treasury | PSP3 Payroll Support Program
Unusual or Infrequent Item, or Both [Line Items]
Strike price (in USD per share) | $ / shares					$ 58.51	$ 58.51
Expiration period (in years)						5 years
United States Department of Treasury | PSP3 Payroll Support Program | Notes Payable, Other Payables
Unusual or Infrequent Item, or Both [Line Items]
Stated interest rate					1.00%	1.00%
United States Department of Treasury | PSP3 Payroll Support Program | Notes Payable, Other Payables | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Forecast
Unusual or Infrequent Item, or Both [Line Items]
Variable rate (as a percent)	2.00%