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SHAREHOLDERS' EQUITY - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023
--- | --- | --- | ---
Accumulated Other Comprehensive Income (Loss) |  |  |
Pre-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | $ 49,401 | $ (8,294) | $ (10,407)
After-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | 44,964 | (6,350) | (7,981)
Unrealized pension actuarial gain (loss) on defined benefit pension plans |  |  |
Pre-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | 3,336 | (7,632) | (10,407)
After-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | 4,470 | (5,838) | (7,981)
Unrealized Loss on Available-for-Sale Securities |  |  |
Pre-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | 383 | (662) | 0
After-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | 296 | (512) | 0
Unrealized gain on foreign currency translation adjustment |  |  |
Pre-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | 45,682 | 0 | 0
After-tax amounts: |  |  |
Unrealized pension actuarial gain (loss) on defined benefit pension plans | $ 40,198 | $ 0 | $ 0

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- Definition Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, attributable to parent. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners). + References No definition available. + Details
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