v3.25.2
Benefit Plans Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Other Pension Plan        
Retirement Plan Disclosure        
Defined benefit plan contributions     $ 225  
Pension Benefits        
Retirement Plan Disclosure        
Service cost $ 8 $ 7 24 $ 22
Interest cost 131 145 394 434
Expected return on plan assets 126 (123) 379 (370)
Amortization of prior service cost (22) (22) (67) (67)
Recognized net actuarial loss (44) 25 (131) 75
Total net periodic benefit cost as actuarially determined 35 32 103 94
Total net periodic benefit cost 35 32 103 94
Other Post-retirement Benefits        
Retirement Plan Disclosure        
Defined benefit plan contributions     19  
Service cost 3 3 9 8
Interest cost 3 4 12 15
Expected return on plan assets 0 0 0 0
Amortization of prior service cost (4) (4) (13) (13)
Recognized net actuarial loss 0 0 0 0
Total net periodic benefit cost as actuarially determined 3 3 9 10
Total net periodic benefit cost $ 2 $ 3 $ 8 $ 10