Quarterly report pursuant to Section 13 or 15(d)

EMPLOYEE BENEFIT PLANS - Additional Information (Detail)

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EMPLOYEE BENEFIT PLANS - Additional Information (Detail)
$ in Millions
 3 Months Ended
Dec. 31, 2007
USD ($)
Mar. 31, 2022
USD ($)
employee
Mar. 31, 2021
USD ($)
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Defined Benefit Plan Disclosure [Line Items]          
Curtailment gain, before tax   $ 33      
Curtailment gain, after tax   $ 24      
Multiemployer Plans, Payment Term   41 years      
National Master Agreement And Various Supplemental Agreements          
Defined Benefit Plan Disclosure [Line Items]          
Number of employees covered | employee   327,000      
Independent Pilots Association          
Defined Benefit Plan Disclosure [Line Items]          
Number of employees covered | employee   3,200      
Teamsters Local 2727          
Defined Benefit Plan Disclosure [Line Items]          
Number of employees covered | employee   1,700      
International Association Of Machinists And Aerospace Workers          
Defined Benefit Plan Disclosure [Line Items]          
Number of employees covered | employee   3,300      
UPS/IBT Plan          
Defined Benefit Plan Disclosure [Line Items]          
Actuarial gain (loss)     $ 6,400    
Reduction of the liability for coordinating benefits     5,100    
Gain from other updated actuarial assumptions     $ 1,300    
Defined Benefit Pension Plan          
Defined Benefit Plan Disclosure [Line Items]          
Multi-employer Plans, Withdrawal Obligation, Fair Value Disclosure   $ 849   $ 963  
Defined Benefit Pension Plan | Central States Pension Fund          
Defined Benefit Plan Disclosure [Line Items]          
Payment of withdrawal liability $ 6,100        
Pension liability         $ 5,500
Defined Benefit Pension Plan | Long term debt          
Defined Benefit Plan Disclosure [Line Items]          
Multiemployer Plans, Withdrawal Obligation, Present Value   828   830  
Defined Benefit Pension Plan | Other current liabilities          
Defined Benefit Plan Disclosure [Line Items]          
Multiemployer Plans, Withdrawal Obligation, Present Value   8   $ 8  
Defined Benefit Pension Plan | U.S. Pension Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Amount contributed to company- sponsored benefit plans   31      
Estimated future employer contributions to defined benefit plan, current fiscal year   2,000      
U.S. Postretirement Medical Benefits | U.S. Pension Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Amount contributed to company- sponsored benefit plans   14      
Estimated future employer contributions to defined benefit plan, current fiscal year   $ 264