v3.26.1
DESCRIPTION OF BUSINESS SEGMENTS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details)
€ / shares in Units, $ / shares in Units, € in Millions, shares in Millions, $ in Millions
 1 Months Ended 12 Months Ended 24 Months Ended
Jun. 08, 2026
$ / shares
Jun. 01, 2026
segment
Feb. 09, 2026
EUR (€)
€ / shares
Jun. 30, 2026
USD ($)
Jan. 31, 2026
USD ($)
employee
May 31, 2026
USD ($)
aircraft
location
segment
$ / shares
shares
May 31, 2025
USD ($)
aircraft
$ / shares
shares
May 31, 2024
USD ($)
aircraft
$ / shares
shares
May 31, 2026
USD ($)
location
aircraft
employee
Mar. 31, 2024
USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of reportable segments | segment           2        
Contract assets net of deferred unearned revenue           $ 760 $ 526   $ 760  
Contract liabilities related to advance payments from customers           20 23   $ 20  
Advertising and promotion expenses           436 425 $ 421    
Depreciation and amortization           4,369 4,264 4,287    
Capitalized interest           $ 52 $ 55 81    
Number of aircraft to be permanently retired from service | aircraft           10 12      
Noncash impairment charges           $ 23 $ 21 157    
Noncash impairment charges net of tax           $ 18 $ 16 $ 120    
Noncash impairment charges net of tax per diluted share (in dollars per share) | $ / shares           $ 0.08 $ 0.06 $ 0.48    
Number of aircraft to be permanently retired from service and temporarily idled | aircraft           8        
Number of aircraft engines to be permanently retired from service | aircraft             8      
Number of idle aircraft | aircraft           13     13  
Average idle time           23 months     23 months  
Purchase of treasury stock (in shares) | shares           3.3 10.9 9.8    
Payments for repurchase of common stock           $ 796 $ 3,017 $ 2,500    
Cash dividends declared (in dollars per share) | $ / shares           $ 5.80 $ 5.52 $ 3.78    
Business optimization and realignment costs           $ 366 $ 756 $ 582    
Business optimization costs, net of tax           $ 285 $ 577 $ 444    
Business optimization costs (in dollar per share) | $ / shares           $ 1.19 $ 2.37 $ 1.77    
Business optimization and impairment of property and equipment           $ 14        
Business optimization and realignment costs expense           352 $ 756 $ 582    
Consultation process occur period                 18 months  
Number of employees left or voluntarily leaving | employee                 1,400  
Expected cash expenditures           150     $ 150  
Restructuring and related cost, incurred cost           13 235      
Freight spin off costs           744 56      
Freight spin off costs, net of tax           $ 589 $ 44      
Freight spin off costs (in dollar per share) | $ / shares           $ 2.46 $ 0.18      
Professional fees           $ 738 $ 38      
Debt issuance costs           6 18      
Separation and other costs, net of payments           248 $ 15 $ 0    
Professional services, change in fiscal year           33        
Professional services, change in fiscal year, net of tax           $ 26        
Professional services, change in fiscal year, per diluted share (in dollar per share) | $ / shares           $ 0.11        
Subsequent Event                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of reportable segments | segment   2                
Payments for repurchase of common stock       $ 300            
Cash dividends declared (in dollars per share) | $ / shares $ 1.22                  
Network 2.0 Optimization                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of business locations | location           410     410  
International Operational Transformation Programs                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Business optimization, no. of operational team members | employee         5,000          
Business optimization, number of operational team members, change of location or schedule | employee         800          
Expected to occur over         18 months          
Business optimization costs           $ 147        
2024 Repurchase Program                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Stock repurchase program amount authorized to be repurchased                   $ 5,000
Stock repurchase program amount authorized to be repurchased, remaining available amount           $ 1,300     $ 1,300  
Purchase of treasury stock (in shares) | shares               9.8    
Treasury stock acquired, average cost per share (in dollars per share) | $ / shares               $ 255.34    
Payments for repurchase of common stock               $ 2,500    
Accelerated Share Repurchase Agreement                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Purchase of treasury stock (in shares) | shares           3.3 10.9      
Treasury stock acquired, average cost per share (in dollars per share) | $ / shares           $ 233.07 $ 274.34      
Payments for repurchase of common stock           $ 776 $ 3,000      
Share repurchases benefit per diluted share (in dollars per share) | $ / shares           $ 0.21 $ 0.44      
Accelerated Share Repurchase Agreement | Subsequent Event                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Stock repurchase program amount authorized to be repurchased       $ 1,000            
InPost                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Business combination, price per share (in dollars per share) | € / shares     € 15.60              
Business combination, voting equity interest acquired, percentage     37.00%              
Business combination, price of acquisition, expected | €     € 2,200              
Supply Chain Finance                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Outstanding payment obligations           $ 109 $ 71 $ 94 $ 109  
Boeing 757 Aircraft                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of aircraft to be permanently retired from service | aircraft           4        
Airbus A300 Aircraft                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of aircraft to be permanently retired from service | aircraft           1        
MD-11F aircraft                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of aircraft to be permanently retired from service | aircraft           5        
Boeing 757-200 aircraft                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of aircraft to be permanently retired from service | aircraft             2 22    
Number of aircraft engines to be permanently retired from service | aircraft               7    
Airbus A300-600 aircraft                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of aircraft to be permanently retired from service | aircraft             7      
Boeing MD-11F aircraft                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Number of aircraft to be permanently retired from service | aircraft             3      
Minimum                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Intangible assets amortization periods           1 year        
Minimum | International Operational Transformation Programs                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Business optimization costs, net of pre -tax         $ 225          
Minimum | Wide-body aircraft and related equipment                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Range           18 years     18 years  
Maximum                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Intangible assets amortization periods           15 years        
Maximum | International Operational Transformation Programs                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Business optimization costs, net of pre -tax         $ 325          
Maximum | Wide-body aircraft and related equipment                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Range           30 years     30 years  
Payment Interval One                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Contract with customer, periodic payment term           15 days        
Payment Interval Two                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Contract with customer, periodic payment term           30 days        
Payment Interval Three                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Contract with customer, periodic payment term           45 days        
Payment Interval Four                    
Organization Consolidation And Presentation Of Financial Statements [Line Items]                    
Contract with customer, periodic payment term           90 days