Retirement Benefits (Assumptions in Calculating Net Periodic Benefit Cost) (Details)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
U.S.
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	6.75%
International
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	4.73%
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Discount rate – Service cost	3.00%	3.30%	4.30%
Discount rate – Interest cost	2.10%	2.90%	4.00%
Expected return on plan assets	6.80%	7.00%	7.00%
Rate of compensation increase	3.50%	3.50%	3.50%
Defined Benefit Pension Plan | International
Defined Benefit Plan Disclosure [Line Items]
Discount rate – Service cost	1.60%	1.50%	2.50%
Discount rate – Interest cost	1.20%	1.30%	2.20%
Expected return on plan assets	4.70%	5.00%	5.30%
Rate of compensation increase	3.30%	3.30%	3.50%