v3.25.2
Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Balance at beginning of period $ 3,605.0 $ 3,722.0 $ 3,675.0 $ 3,743.0
Other comprehensive income (loss) before reclassifications 89.0 (27.0) 22.0 7.0
Amounts reclassified from accumulated other comprehensive loss 7.0 (4.0) 13.0 (10.0)
Other comprehensive income (loss) 97.0 (31.0) 35.0 (3.0)
Balance at end of period 3,628.0 3,504.0 3,628.0 3,504.0
Total accumulated other comprehensive loss, net of tax        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Balance at beginning of period (833.0) (762.0) (772.0) (790.0)
Other comprehensive income (loss) 96.0 (31.0) 35.0 (3.0)
Balance at end of period (737.0) (793.0) (737.0) (793.0)
Pension and other postretirement benefit plan adjustments, net of tax        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Balance at beginning of period (420.0) (406.0) (431.0) (407.0)
Other comprehensive income (loss) before reclassifications 0.0 0.0 0.0 0.0
Amounts reclassified from accumulated other comprehensive loss 6.0 0.0 17.0 1.0
Other comprehensive income (loss) 6.0 0.0 17.0 1.0
Balance at end of period (414.0) (406.0) (414.0) (406.0)
Accumulated currency translation adjustments, net of tax        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Balance at beginning of period (382.0) (325.0) (296.0) (365.0)
Other comprehensive income (loss) before reclassifications 105.0 (31.0) 19.0 7.0
Amounts reclassified from accumulated other comprehensive loss 0.0 0.0 0.0 2.0
Other comprehensive income (loss) 105.0 (31.0) 19.0 9.0
Balance at end of period (277.0) (356.0) (277.0) (356.0)
Net unrealized losses on cash flow hedges, net of tax        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Balance at beginning of period (31.0) (31.0) (45.0) (18.0)
Other comprehensive income (loss) before reclassifications (16.0) 4.0 3.0 0.0
Amounts reclassified from accumulated other comprehensive loss 1.0 (4.0) (4.0) (13.0)
Other comprehensive income (loss) (15.0) 0.0 (1.0) (13.0)
Balance at end of period $ (46.0) $ (31.0) $ (46.0) $ (31.0)