Retirement Benefits (Schedule of Assumptions Used) (Details)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Pension Plan [Member] | UNITED STATES
Weighted-average assumptions to determine benefit obligation at September 30:
Discount rate	3.80%	3.65%	4.39%
Weighted-average assumptions to determine periodic benefit costs for years ending September 30:
Discount rate	3.65%	4.39%	4.40%
Long-term rate of return on plan assets	7.38%	7.62%	7.62%
Defined Benefit Pension Plan [Member] | UNITED KINGDOM
Weighted-average assumptions to determine benefit obligation at September 30:
Discount rate	2.56%	2.28%	3.75%
Rate of compensation increase	3.60%	3.40%	3.40%
Weighted-average assumptions to determine periodic benefit costs for years ending September 30:
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Service Cost	2.33%	3.86%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Interest Cost	2.24%	3.63%	4.10%
Rate of compensation increase	3.40%	3.40%	3.50%
Long-term rate of return on plan assets	4.75%	5.00%	5.50%
Defined Benefit Pension Plan [Member] | JAPAN
Weighted-average assumptions to determine benefit obligation at September 30:
Discount rate	0.58%	0.46%	0.97%
Rate of compensation increase	2.00%	2.02%	2.00%
Weighted-average assumptions to determine periodic benefit costs for years ending September 30:
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Service Cost	0.59%	1.27%	1.10%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Interest Cost	0.45%	0.59%	1.10%
Rate of compensation increase	2.02%	2.00%	2.00%
Long-term rate of return on plan assets	2.50%	3.00%	3.00%
Other Postretirement Benefit Plans [Member]
Weighted-average assumptions to determine benefit obligation at September 30:
Discount rate	3.78%	3.63%	4.01%
Weighted-average assumptions to determine periodic benefit costs for years ending September 30:
Discount rate	3.63%	4.01%	4.40%