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EMPLOYEE BENEFIT PLANS, ASSUMED HCCTR (Details) - OPEB [Member] - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
HCCTR | 6.70% | 7.10% | 7.30%
Ultimate HCCTR | 4.80% | 4.80% | 4.80%
Year ultimate HCCTR reached | 2022 | 2022 | 2022
Effect of a 1 percentage point increase in the HCCTR on: |  |  |
Year-end benefit obligation | $ 26,025 | $ 20,965 | $ 18,008
Total service and interest cost | 2,026 | 1,885 | 2,156
Effect of a 1 percentage point decrease in the HCCTR on: |  |  |
Year-end benefit obligation | (20,427) | (16,932) | (14,629)
Total service and interest costs | $ (1,593) | $ (1,493) | $ (1,675)

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- Definition Defined Benefit Plan, Effect of One-Percentage Point Increase in Assumed Health Care Cost Trend Rates [Abstract] + References No definition available. + Details
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- Definition Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits. + 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 (m) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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- Definition The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits. + 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 (m) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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