Retirement Benefits (Schedule of Allocation of Plan Assets, Actual and Target Allocations) (Details) - Defined Benefit Pension Plan [Member]	Sep. 30, 2017	Sep. 30, 2016
UNITED STATES | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	0.20%	4.60%
UNITED STATES | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	64.60%	56.40%
UNITED STATES | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	35.20%	39.00%
UNITED KINGDOM | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	0.10%	0.10%
UNITED KINGDOM | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	46.10%	34.70%
UNITED KINGDOM | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	53.80%	65.20%
JAPAN | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	0.90%	0.90%
JAPAN | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	41.00%	40.00%
JAPAN | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation of Plan Assets	58.10%	59.10%
Minimum [Member] | UNITED STATES | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Minimum [Member] | UNITED STATES | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	41.20%	40.80%
Minimum [Member] | UNITED STATES | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	28.80%	29.20%
Minimum [Member] | UNITED KINGDOM | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Minimum [Member] | UNITED KINGDOM | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	30.00%	25.00%
Minimum [Member] | UNITED KINGDOM | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	45.00%	40.00%
Minimum [Member] | JAPAN | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Minimum [Member] | JAPAN | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	36.00%	36.00%
Minimum [Member] | JAPAN | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	55.00%	55.00%
Maximum [Member] | UNITED STATES | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Maximum [Member] | UNITED STATES | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	81.20%	80.80%
Maximum [Member] | UNITED STATES | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	48.80%	49.20%
Maximum [Member] | UNITED KINGDOM | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%	0.00%
Maximum [Member] | UNITED KINGDOM | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	60.00%	45.00%
Maximum [Member] | UNITED KINGDOM | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	70.00%	80.00%
Maximum [Member] | JAPAN | Other Investment Asset [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	2.00%	2.00%
Maximum [Member] | JAPAN | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	44.00%	44.00%
Maximum [Member] | JAPAN | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	63.00%	63.00%