Retirement Benefits (Details 3)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
U.S. Pension Benefit Plans [Member]
Net periodic benefit cost assumptions
Discount rate	3.75%	4.55%	4.50%
Expected return on plan assets	7.50%	7.50%	7.50%
Compensation increase rate	3.50%	3.75%	3.75%
Net benefit obligation assumptions
Discount rate	3.90%	3.75%
Compensation increase rate	3.50%	3.50%
Non-U.S. Pension Benefit Plans [Member]
Net periodic benefit cost assumptions
Discount rate	1.77%	2.67%	3.01%
Expected return on plan assets	5.12%	5.21%	5.31%
Compensation increase rate	2.86%	3.11%	3.16%
Net benefit obligation assumptions
Discount rate	2.30%	1.77%
Compensation increase rate	2.99%	2.86%
U.S. Other Postretirement Benefit Plans [Member]
Net periodic benefit cost assumptions
Discount rate	3.10%	3.85%	3.65%
Net benefit obligation assumptions
Discount rate	3.40%	3.10%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.50%
Health care cost trend rate	6.50%	6.50%
Non-U.S. Other Postretirement Benefit Plans [Member]
Net periodic benefit cost assumptions
Discount rate	2.80%	3.60%	3.50%
Net benefit obligation assumptions
Discount rate	3.20%	2.80%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.50%
Health care cost trend rate		4.95%