v3.26.1
Employee Benefit Plans - Schedule of Components of Pension and Other Postretirement Benefit Costs for Continuing Operation (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Defined Benefit Plan Disclosure [Line Items]        
Service cost     $ 28  
Settlement gain $ (2)   (2)  
Curtailment loss       $ 1
Total net periodic benefit costs     30  
Pension Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 1 $ 1 3 3
Interest cost 3 3 9 9
Expected return on plan assets (3) (2) (8) (7)
Settlement gain (2) 0 (2) 0
Actuarial gain (3) 0 (3) 0
Curtailment loss     0 1
Total net periodic benefit costs (4) 2 (1) 6
Other Postretirement Benefits Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 1 1 1 1
Interest cost 0 0 1 1
Expected return on plan assets 0 0 0 0
Settlement gain 0 0 0 0
Actuarial gain 0 0 0 0
Curtailment loss     0 0
Total net periodic benefit costs $ 1 $ 1 $ 2 $ 2