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SHAREHOLDERS' EQUITY - AOCI Components (Details) - USD ($) $ in Thousands | Jun. 30, 2019 | Sep. 30, 2018
--- | --- | ---
After-tax amounts: |  |
Accumulated other comprehensive income (loss) | $ (16,085) | $ 16,550
Unrealized Appreciation on Equity Securities |  |
Pre-tax amounts: |  |
Accumulated other comprehensive income (loss) | 0 | 44,023
After-tax amounts: |  |
Accumulated other comprehensive income (loss) | 0 | 29,071
Defined Benefit Pension Plan |  |
Pre-tax amounts: |  |
Accumulated other comprehensive income (loss) | (20,818) | (21,693)
After-tax amounts: |  |
Accumulated other comprehensive income (loss) | (16,085) | (12,521)
Accumulated Other Comprehensive Income (Loss) |  |
Pre-tax amounts: |  |
Accumulated other comprehensive income (loss) | (20,818) | 22,330
After-tax amounts: |  |
Accumulated other comprehensive income (loss) | $ (16,085) | $ 16,550

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