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Retirement Benefits (Schedule of Allocation of Plan Assets, Actual and Target Allocations) (Details) - Defined Benefit Pension Plan [Member] | Sep. 30, 2017 | Sep. 30, 2016
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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%

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(i) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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