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EMPLOYEE BENEFIT PLANS - PENSION AND OTHER POSTEMPLOYMENT BENEFIT PLANS, NARRATIVE (Details) | 12 Months Ended
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Sep. 30, 2024 USD ($) plan | Sep. 30, 2023 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Number of noncontributory defined benefit retirement plans (in plans) | plan | 2 |
Required number of years of service (more than) | 1 year |
Years of service and average compensation, basis period for plan benefits | 60 months |
Amortization period for plan amendment | 8 years |
Pension |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Employer discretionary contributions | $ 0 | $ 0
Employer contributions | 535,000 | 579,000
OPEB |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Employer contributions | 7,846,000 | $ 4,192,000
OPEB | Minimum |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Estimated future employer contributions over the next five years | 5,000,000 |
OPEB | Maximum |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |
Estimated future employer contributions over the next five years | $ 10,000,000 |

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