v3.26.1
Comprehensive Income (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance $ 839 $ 790 $ 757 $ 675
Other comprehensive income (loss) 5 118 (31) 73
Ending balance 953 812 953 812
Accumulated Other Comprehensive Loss, net        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (225) (292) (189) (247)
Other comprehensive income (loss) 5 118 (31) 73
Ending balance (220) (174) (220) (174)
Foreign Currency Translation Loss        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance     (188) (244)
Other comprehensive income (loss)     (31) 73
Ending balance (219) (171) (219) (171)
Minimum Pension Liability Adjustment        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance     (1) (3)
Other comprehensive income (loss)     0 0
Ending balance $ (1) $ (3) $ (1) $ (3)