Retirement Benefits - Schedule of Significant Assumptions Used in Determining Benefit Obligations (Details)	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Expected gross health care cost trend rate	4.97%
Pension Benefits | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.35%	5.10%	6.10%
Compensation increase rate	3.50%	3.60%
Health care cost trend rate	0.00%	0.00%
Pension Benefits | Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.07%	3.87%
Compensation increase rate	2.85%	3.22%
Health care cost trend rate	0.00%	0.00%
Other Postretirement Benefits | U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.07%	4.91%
Compensation increase rate	0.00%	0.00%
Health care cost trend rate	7.53%	14.35%
Expected gross health care cost trend rate	0.00%
Other Postretirement Benefits | Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.45%	4.45%
Compensation increase rate	0.00%	0.00%
Health care cost trend rate	4.50%	4.50%