Retirement Benefits - Schedule of Significant Assumptions Used in Determining Net Periodic Benefit Cost (Income) and Benefit Obligations (Details)	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, ultimate health care cost trend rate	5.00%	0.00%
U.S. Plans | Pension Benefits
Net periodic benefit cost assumptions
Discount rate	4.35%	3.90%	3.75%
Expected return on plan assets	7.50%	7.50%	7.50%
Compensation increase rate	3.50%	3.50%	3.50%
U.S. Plans | Other Postretirement Benefits
Net periodic benefit cost assumptions
Discount rate	4.15%	3.40%	3.10%
Expected return on plan assets	0.00%	0.00%	0.00%
Compensation increase rate	0.00%	0.00%	0.00%
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, ultimate health care cost trend rate	5.50%
Non-U.S. Plans | Pension Benefits
Net periodic benefit cost assumptions
Discount rate	2.48%	2.30%	1.77%
Expected return on plan assets	5.22%	5.19%	5.12%
Compensation increase rate	3.02%	2.99%	2.86%
Non-U.S. Plans | Other Postretirement Benefits
Net periodic benefit cost assumptions
Discount rate	3.30%	3.20%	2.80%
Expected return on plan assets	0.00%	0.00%	0.00%
Compensation increase rate	0.00%	0.00%	0.00%