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EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category - USD ($) $ in Thousands | Sep. 30, 2019 | Sep. 30, 2018
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EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | $ 145,319 | $ 150,634
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 104,246 | 82,520
Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 32,297 | 68,114
Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 8,776 | 0
Cash and equivalents [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 2,791 | 27,209
Cash and equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 2,791 | 27,209
Cash and equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Cash and equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Debt instruments [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 3,178 | 14,269
Debt instruments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 182 | 14,269
Debt instruments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 2,996 | 0
Debt instruments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Equity securities [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 72,517 | 41,042
Equity securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 72,517 | 41,042
Equity securities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Equity securities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Commingled funds [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 8,776 | 62,088
Commingled funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Commingled funds [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 62,088
Commingled funds [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 8,776 | 0
Limited partnerships and hedge fund investments [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 18,569 | 6,026
Limited partnerships and hedge fund investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | 0
Limited partnerships and hedge fund investments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 18,569 | 6,026
Limited partnerships and hedge fund investments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 | $ 0
Other Security Investments [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 2,072 |
Other Security Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 1,348 |
Other Security Investments [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 724 |
Other Security Investments [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 0 |
US Government Agencies Debt Securities [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 37,416 |
US Government Agencies Debt Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 27,408 |
US Government Agencies Debt Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | 10,008 |
US Government Agencies Debt Securities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |
EMPLOYEE BENEFIT PLANS (Details) - Pension and post-retirement plan assets by asset category [Line Items] |  |
Defined Benefit Plan, Plan Assets, Amount | $ 0 |

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