EMPLOYEE BENEFIT PLANS - COMPONENTS OF NET PERIODIC COST (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Pension | ||||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | ||||
| Service cost | $ 1,245 | $ 1,381 | $ 3,734 | $ 4,142 |
| Interest cost | 3,964 | 3,858 | 11,891 | 11,575 |
| Expected return on plan assets | (6,137) | (5,925) | (18,411) | (17,775) |
| Recognized actuarial loss | 38 | 301 | 115 | 902 |
| Prior service credit amortization | 0 | 0 | 0 | 0 |
| Net periodic benefit (credit) cost | (890) | (385) | (2,671) | (1,156) |
| OPEB | ||||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | ||||
| Service cost | 272 | 273 | 816 | 819 |
| Interest cost | 2,699 | 2,096 | 8,095 | 6,290 |
| Expected return on plan assets | (2,259) | (2,346) | (6,778) | (7,039) |
| Recognized actuarial loss | 2,796 | 1,792 | 8,388 | 5,378 |
| Prior service credit amortization | (3,270) | (3,270) | (9,810) | (9,810) |
| Net periodic benefit (credit) cost | $ 238 | $ (1,455) | $ 711 | $ (4,362) |
| X | ||||||||||
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|