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Retirement Plans (Accumulated and Projected Benefit Obligations) (Details) - USD ($) $ in Millions | Sep. 30, 2018 | Sep. 30, 2017
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Pension Plans with accumulated benefit obligations in excess of plan assets |  |
Projected benefit obligation | $ 6.2 | $ 379.5
Accumulated benefit obligation | 6.2 | 379.5
Fair value of plan assets | 5.0 | 364.2
Pension plans with plan assets in excess of accumulated benefit obligations |  |
Projected benefit obligation | 327.1 | 1.0
Accumulated benefit obligation | 327.1 | 1.0
Fair value of plan assets | $ 338.5 | $ 2.1

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- Definition Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2417-114920 + Details
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