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Fair Value Measurements Available-For-Sale Securities (Details) - USD ($) $ in Thousands | Mar. 31, 2018 | Sep. 30, 2017
--- | --- | ---
Schedule Of Available For Sale Securities [Line Items] |  |
Available For Sale Securities Amortized Cost | $ 83,933 | $ 77,244
Gross Unrealized Gain | 10,229 | 11,203
Gross Unrealized Loss | (497) | (38)
Fair value | 93,665 | 88,409
Available-for-sale Securities, Other Disclosure Items [Abstract] |  |
Available-for-sale Securities, Supplemental Executive Benefit Plans | 46,200 | 42,900
Equity Funds Domestic [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available For Sale Securities Amortized Cost | 25,515 | 25,361
Gross Unrealized Gain | 8,194 | 8,920
Gross Unrealized Loss | (95) | 0
Fair value | 33,614 | 34,281
Equity Funds Foreign [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available For Sale Securities Amortized Cost | 4,138 | 4,581
Gross Unrealized Gain | 2,031 | 2,235
Gross Unrealized Loss | 0 | 0
Fair value | 6,169 | 6,816
Fixed Income Funds [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available For Sale Securities Amortized Cost | 16,548 | 16,391
Gross Unrealized Gain | 0 | 2
Gross Unrealized Loss | (240) | (22)
Fair value | 16,308 | 16,371
Debt Securities [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available For Sale Securities Amortized Cost | 31,295 | 29,074
Gross Unrealized Gain | 4 | 46
Gross Unrealized Loss | (162) | (16)
Fair value | 31,137 | 29,104
Money Market Funds [Member] |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Available For Sale Securities Amortized Cost | 6,437 | 1,837
Gross Unrealized Gain | 0 | 0
Gross Unrealized Loss | 0 | 0
Fair value | $ 6,437 | $ 1,837

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
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