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 9 Months Ended
Sep. 30, 2017
USD ($)
Employees
Sep. 30, 2017
USD ($)
Employees
Jun. 30, 2017
Dec. 31, 2016
USD ($)
Employees
Dec. 31, 2007
USD ($)
Defined Benefit Plan Disclosure [Line Items]          
Defined benefit plan, net actuarial gain $ 569        
Defined benefit plan, curtailments 1,525        
Defined benefit plan, net actuarial loss $ 956        
Defined benefit plan, assumptions used calculating benefit obligation, discount rate     3.20%    
Defined benefit plan,actual return on plan assets     2.75%    
Actuarial gain loss corridor threshold 10.00% 10.00%      
Multiemployer Plans, Payment Term   45 years      
Number of employees under a national master agreement and various supplemental agreements with local unions affiliated with Teamsters | Employees       268,000  
Number of pilots under a collective bargaining agreement with the Independent Pilots Association | Employees 2,600 2,600      
Majority of ground mechanics not employed under agreements | Employees 3,000 3,000      
Central States Pension Fund          
Defined Benefit Plan Disclosure [Line Items]          
Withdrawal liability         $ 6,100
Pension liability $ 4,000 $ 4,000      
Multiemployer Plans, Pension [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Multi-employer Plans, Withdrawal Obligation, Fair Value Disclosure 891 891   $ 861  
Other noncurrent liabilities | Multiemployer Plans, Pension [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Multiemployer Plans, Withdrawal Obligation, Present Value 861 861   866  
Other current liabilities | Multiemployer Plans, Pension [Member]          
Defined Benefit Plan Disclosure [Line Items]          
Multiemployer Plans, Withdrawal Obligation, Present Value $ 7 $ 7   $ 6  
Minimum [Member] | Employees          
Defined Benefit Plan Disclosure [Line Items]          
Employer contribution percentage   3.00%      
Minimum [Member] | Non-union employees          
Defined Benefit Plan Disclosure [Line Items]          
Employer contribution percentage   5.00%      
Maximum [Member] | Employees          
Defined Benefit Plan Disclosure [Line Items]          
Employer contribution percentage   8.00%      
Maximum [Member] | Non-union employees          
Defined Benefit Plan Disclosure [Line Items]          
Employer contribution percentage   8.00%      
U.S. Pension Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Amount contributed to company- sponsored benefit plans   $ 2,359      
International Pension Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Estimated future employer contributions to defined benefit plan, current fiscal year   18      
U.S. Postretirement Medical Benefits          
Defined Benefit Plan Disclosure [Line Items]          
Amount contributed to company- sponsored benefit plans   $ 226      
Estimated future employer contributions to defined benefit plan, current fiscal year   15