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Retirement Benefits (Schedule of Allocation of Plan Assets, Actual and Target Allocations) (Details) - Defined Benefit Pension Plan [Member] | Sep. 30, 2019 | Sep. 30, 2018
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United States [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 100.00% | 100.00%
United States [Member] | Equity Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 60.60% | 65.10%
United States [Member] | Equity Securities [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 41.40% | 41.50%
United States [Member] | Equity Securities [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 81.40% | 81.50%
United States [Member] | Debt Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 37.90% | 33.10%
United States [Member] | Debt Securities [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 28.60% | 28.50%
United States [Member] | Debt Securities [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 48.60% | 48.50%
United States [Member] | Other Investment Asset [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 1.50% | 1.80%
United States [Member] | Other Investment Asset [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 0.00% | 0.00%
United States [Member] | Other Investment Asset [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 0.00% | 0.00%
United Kingdom |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 100.00% | 100.00%
United Kingdom | Equity Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 41.60% | 44.80%
United Kingdom | Equity Securities [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 30.00% | 30.00%
United Kingdom | Equity Securities [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 60.00% | 60.00%
United Kingdom | Debt Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 57.80% | 54.80%
United Kingdom | Debt Securities [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 45.00% | 45.00%
United Kingdom | Debt Securities [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 70.00% | 70.00%
United Kingdom | Other Investment Asset [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 0.60% | 0.40%
United Kingdom | Other Investment Asset [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 0.00% | 0.00%
United Kingdom | Other Investment Asset [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 0.00% | 0.00%
Japan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 100.00% | 100.00%
Japan | Equity Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 41.40% | 41.00%
Japan | Equity Securities [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 36.00% | 36.00%
Japan | Equity Securities [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 44.00% | 44.00%
Japan | Debt Securities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 57.70% | 58.10%
Japan | Debt Securities [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 55.00% | 55.00%
Japan | Debt Securities [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 63.00% | 63.00%
Japan | Other Investment Asset [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of Plan Assets | 0.90% | 0.90%
Japan | Other Investment Asset [Member] | Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 0.00% | 0.00%
Japan | Other Investment Asset [Member] | Maximum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Target Allocation Ranges | 2.00% | 2.00%

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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/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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