v3.26.1
FINANCIAL INSTRUMENTS - Additional Information (Details)
€ in Millions, $ in Millions
6 Months Ended 12 Months Ended
Mar. 31, 2026
EUR (€)
Sep. 30, 2024
EUR (€)
Mar. 31, 2026
USD ($)
Sep. 30, 2025
EUR (€)
Mar. 31, 2025
EUR (€)
Sep. 30, 2019
EUR (€)
Derivative Instruments, Gain (Loss) [Line Items]            
Fair value of long-term debt compared with carrying value | $     $ 798      
Collateral already posted, aggregate fair value | $     0      
Collateral held from counterparties | $     0      
Level 2            
Derivative Instruments, Gain (Loss) [Line Items]            
Fair value of long-term debt | $     $ 7,500      
Senior Notes            
Derivative Instruments, Gain (Loss) [Line Items]            
Debt, face amount | €           € 1,500
Repayments of debt | €   € 500        
Senior Notes | Due October 2025            
Derivative Instruments, Gain (Loss) [Line Items]            
Repayments of debt | € € 500          
Notes interest rate, percentage     1.25%      
Senior Notes | Due March 2031            
Derivative Instruments, Gain (Loss) [Line Items]            
Debt, face amount | €       € 500 € 500  
Notes interest rate, percentage       3.00% 3.00%  
Senior Notes | Due March 2037            
Derivative Instruments, Gain (Loss) [Line Items]            
Debt, face amount | €       € 500 € 500  
Notes interest rate, percentage       3.50% 3.50%  
Foreign Exchange Contract            
Derivative Instruments, Gain (Loss) [Line Items]            
Notional amount of foreign currency hedge positions | $     $ 4,300