Pension Benefit Obligations - Schedule of Target Allocation and Pension Plan Asset Allocation (Details)	Sep. 30, 2025	Sep. 30, 2024
U.S.
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	100.00%
Percentage of Plan Assets (as percent)	100.00%	100.00%
U.S. | Equities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	18.00%
Percentage of Plan Assets (as percent)	19.00%	24.00%
U.S. | Debt
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	78.00%
Percentage of Plan Assets (as percent)	74.00%	67.00%
U.S. | Cash
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	0.00%
Percentage of Plan Assets (as percent)	2.00%	4.00%
U.S. | Diversified and other
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	4.00%
Percentage of Plan Assets (as percent)	5.00%	5.00%
Int’l
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	100.00%
Percentage of Plan Assets (as percent)	100.00%	100.00%
Int’l | Equities
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	25.00%
Percentage of Plan Assets (as percent)	24.00%	25.00%
Int’l | Debt
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	65.00%
Percentage of Plan Assets (as percent)	64.00%	64.00%
Int’l | Cash
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	3.00%
Percentage of Plan Assets (as percent)	2.00%	2.00%
Int’l | Diversified and other
Defined Benefit Plan Disclosure [Line Items]
Target Allocations (as percent)	7.00%
Percentage of Plan Assets (as percent)	10.00%	9.00%