Retirement Benefits (Assumptions in Calculating Net Periodic Benefit Cost) (Details)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
U.S.
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	7.50%
International
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	5.80%
Defined Benefit Pension Plan | U.S.
Defined Benefit Plan Disclosure [Line Items]
Discount rate – Service cost	3.90%	3.60%	4.50%
Discount rate – Interest cost	3.30%	3.00%	3.60%
Expected return on plan assets	7.50%	8.00%	8.00%
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	2.60%	2.10%	3.40%
Discount rate – Interest cost	2.20%	1.80%	2.90%
Expected return on plan assets	5.80%	6.10%	6.30%
Rate of compensation increase	3.60%	3.50%	3.50%