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) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Dec. 31, 2012
Employees
Pilots
Ground_Mechanics
Jun. 30, 2013
Defined Benefit Pension Plan
Jun. 30, 2013
Defined Benefit Postretirement Medical Benefit Plan
Defined Benefit Plan Disclosure [Line Items]      
Amount contributed to company- sponsored benefit plans   $ 53 $ 61
Estimated future employer contributions to defined benefit plan, current fiscal year   48 50
Number of employees under a national master agreement and various supplemental agreements with local unions affiliated with Teamsters 249,000    
Number of pilots under a collective bargaining agreement with the Independent Pilots Association 2,600    
Majority of ground mechanics not employed under agreements 3,100