Quarterly report [Sections 13 or 15(d)]

EMPLOYEE BENEFIT PLANS - Additional Information (Details)

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EMPLOYEE BENEFIT PLANS - Additional Information (Details)
$ in Millions
 3 Months Ended
Mar. 31, 2025
USD ($)
employee
Dec. 31, 2024
USD ($)
Defined Benefit Plan Disclosure [Line Items]    
Multiemployer plans, payment term 38 years  
National Master Agreement and Various Supplemental Agreements    
Defined Benefit Plan Disclosure [Line Items]    
Number of employees covered | employee 314,000  
Teamsters    
Defined Benefit Plan Disclosure [Line Items]    
Number of employees covered | employee 10,000  
Independent Pilots Association    
Defined Benefit Plan Disclosure [Line Items]    
Number of employees covered | employee 3,300  
Teamsters Local 2727    
Defined Benefit Plan Disclosure [Line Items]    
Number of employees covered | employee 1,900  
International Association Of Machinists And Aerospace Workers    
Defined Benefit Plan Disclosure [Line Items]    
Number of employees covered | employee 3,000  
Other current liabilities    
Defined Benefit Plan Disclosure [Line Items]    
Withdrawal liability $ 17 $ 19
Defined Benefit Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Multi-employer plans, withdrawal obligation, fair value 653 651
Defined Benefit Pension Plan | Long term debt    
Defined Benefit Plan Disclosure [Line Items]    
Multiemployer plans, withdrawal obligation, present value 802 804
Defined Benefit Pension Plan | Other current liabilities    
Defined Benefit Plan Disclosure [Line Items]    
Multiemployer plans, withdrawal obligation, present value 9 $ 9
U.S | Defined Benefit Pension Plan    
Defined Benefit Plan Disclosure [Line Items]    
Amount contributed to company- sponsored benefit plans 13  
Estimated future employer contributions to defined benefit plan, current fiscal year 1,200  
U.S | U.S. Postretirement Medical Benefits    
Defined Benefit Plan Disclosure [Line Items]    
Amount contributed to company- sponsored benefit plans 54  
Estimated future employer contributions to defined benefit plan, current fiscal year $ 167