v3.26.3
Retirement Benefits - Narrative (Details) - USD ($)
 1 Months Ended 12 Months Ended
Aug. 31, 2026
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2024
Defined Benefit Plan Disclosure [Line Items]        
Expense related to defined contribution savings plans   $ 90,000,000 $ 85,000,000 $ 92,000,000
Defined benefit plan, percentage of benefit obligation relating to domestic plan   65.00%    
Recognized settlement and curtailment charges   $ 11,000,000    
Recognized settlement and curtailment charges, net of tax   9,000,000    
Recognized net actuarial losses   18,000,000    
Recognized net actuarial losses, net of tax   $ 14,000,000    
Defined benefit plan, net periodic benefit cost (credit) excluding service cost, statement of income or comprehensive income [extensible enumeration]   Accumulated other comprehensive loss    
Defined benefit plan, accumulated benefit obligation   $ 2,185,000,000 2,771,000,000  
U.S. Plans        
Defined Benefit Plan Disclosure [Line Items]        
Voluntary contribution to U.S. qualified pension plan   0 70,000,000 0
Pension Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Voluntary contribution to U.S. qualified pension plan   15,000,000 88,000,000  
Transfer of pension plan obligations to insurance company $ 247,000,000      
Payment for settlement $ 233,000,000 299,000,000 4,000,000  
Settlement and curtailment charges   11,000,000 1,000,000 0
Defined benefit plan, agreement to transfer   2,330,000,000 2,931,000,000 3,078,000,000
Recognized net actuarial losses   16,000,000 $ 27,000,000 $ (1,000,000)
Estimated future payments, during next fiscal year   $ 35,000,000    
Pension Benefits | U.S. Plans        
Defined Benefit Plan Disclosure [Line Items]        
Discount rate   6.70% 5.35% 5.10%
Pension Benefits | Non-U.S. Plans        
Defined Benefit Plan Disclosure [Line Items]        
Discount rate   4.84% 4.07%  
Other Postretirement Benefits        
Defined Benefit Plan Disclosure [Line Items]        
Voluntary contribution to U.S. qualified pension plan   $ 9,000,000 $ 10,000,000  
Payment for settlement   0 0  
Settlement and curtailment charges   0 0 $ 0
Defined benefit plan, agreement to transfer   36,000,000 41,000,000 45,000,000
Recognized net actuarial losses   2,000,000 $ 2,000,000 $ 1,000,000
Estimated future payments, during next fiscal year   $ 6,000,000    
Other Postretirement Benefits | U.S. Plans        
Defined Benefit Plan Disclosure [Line Items]        
Discount rate   6.30% 5.07%  
Other Postretirement Benefits | Non-U.S. Plans        
Defined Benefit Plan Disclosure [Line Items]        
Discount rate   5.30% 4.45%  
Minimum        
Defined Benefit Plan Disclosure [Line Items]        
Company contribution to defined contribution plan (percentage)   3.00%    
Maximum        
Defined Benefit Plan Disclosure [Line Items]        
Company contribution to defined contribution plan (percentage)   7.00%