v3.26.3
Retirement Benefits - Schedule of Net Funded Status (Details) - USD ($)
$ in Millions
 1 Months Ended 12 Months Ended
Aug. 31, 2026
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2024
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]        
Plan assets at beginning of year   $ 2,810    
Plan assets at end of year   2,488 $ 2,810  
Net amount on balance sheet consists of        
Retirement benefits   (336) (406)  
Pension Benefits        
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]        
Benefit obligation at beginning of year   2,931 3,078  
Service cost   38 41 $ 37
Interest cost   137 136 147
Actuarial (gains) losses   (297) (123)  
Plan participant contributions   2 2  
Benefits paid   (161) (208)  
Settlements and curtailments   (299) (5)  
Divestiture   0 0  
Currency translation and other   (21) 10  
Benefit obligation at end of year   2,330 2,931 3,078
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]        
Plan assets at beginning of year   2,810 2,779  
Actual return on plan assets   147 143  
Company contributions   15 88  
Plan participant contributions   2 2  
Benefits paid   (161) (208)  
Settlements and curtailments $ (233) (299) (4)  
Currency translation and other   (26) 10  
Plan assets at end of year   2,488 2,810 2,779
Funded status of plans   158 (121)  
Net amount on balance sheet consists of        
Other assets   435 222  
Compensation and benefits   (20) (20)  
Retirement benefits   (257) (323)  
Net amount on balance sheet   158 (121)  
Other Postretirement Benefits        
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]        
Benefit obligation at beginning of year   41 45  
Service cost   1 1 1
Interest cost   2 2 3
Actuarial (gains) losses   3 4  
Plan participant contributions   6 5  
Benefits paid   (15) (15)  
Settlements and curtailments   0 0  
Divestiture   (2) 0  
Currency translation and other   0 (1)  
Benefit obligation at end of year   36 41 45
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]        
Plan assets at beginning of year   0 0  
Actual return on plan assets   0 0  
Company contributions   9 10  
Plan participant contributions   6 5  
Benefits paid   (15) (15)  
Settlements and curtailments   0 0  
Currency translation and other   0 0  
Plan assets at end of year   0 0 $ 0
Funded status of plans   (36) (41)  
Net amount on balance sheet consists of        
Other assets   0 0  
Compensation and benefits   (6) (6)  
Retirement benefits   (30) (35)  
Net amount on balance sheet   $ (36) $ (41)