Pension Plan and Retirement Benefits - Cost Assumptions (Details)	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Other Postretirement Benefit Plan
Assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	2.75%	2.50%	3.13%
Pension Plans Defined Benefit Us [Member]
Assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	2.63%	2.25%	2.88%
Expected return on plan assets (as a percent)	5.25%	7.25%	7.25%
Rate of compensation increase (as a percent)	2.50%	2.50%	2.50%
Pension Plans Defined Benefit Non Us [Member]
Assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	2.00%	1.50%	1.70%
Expected return on plan assets (as a percent)	3.00%	2.00%	2.20%