v3.26.3
Shareowners' Equity - Schedule of Changes in Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Millions
 12 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning of period $ 3,711 $ 3,675 $ 3,743
Other comprehensive income (loss) before reclassifications 151 93 28
Amounts reclassified from accumulated other comprehensive income (loss) 28 22 (10)
Other comprehensive income 179 115 18
End of period 3,554 3,711 3,675
Total accumulated other comprehensive loss, net of tax      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning of period (657) (772) (790)
Other comprehensive income 179 115 18
End of period (478) (657) (772)
Pension and other postretirement benefit plan adjustments, net of tax      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning of period (335) (431) (408)
Other comprehensive income (loss) before reclassifications 205 73 (23)
Amounts reclassified from accumulated other comprehensive income (loss) 23 23 0
Other comprehensive income 228 96 (23)
End of period (107) (335) (431)
Accumulated currency translation adjustments, net of tax      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning of period (281) (297) (365)
Other comprehensive income (loss) before reclassifications (61) 16 66
Amounts reclassified from accumulated other comprehensive income (loss) 0 0 2
Other comprehensive income (61) 16 68
End of period (342) (281) (297)
Accumulated gain (loss), net, cash flow hedge, parent      
AOCI Attributable to Parent, Net of Tax [Roll Forward]      
Beginning of period (41) (44) (17)
Other comprehensive income (loss) before reclassifications 7 4 (15)
Amounts reclassified from accumulated other comprehensive income (loss) 5 (1) (12)
Other comprehensive income 12 3 (27)
End of period $ (29) $ (41) $ (44)