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INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2021 | Sep. 30, 2020
Income Tax Examination [Line Items] |  |
Valuation allowance increase (decrease) | $ 601 | $ 999
Undistributed earnings of foreign subsidiaries | 143,058 |
Deferred tax assets, valuation allowance | 10,425 | 9,824
Potential tax benefits impact on effective tax rate | 1,106 |
Liability for uncertainty in income taxes, current | 100 | 77
Domestic Tax Authority |  |
Income Tax Examination [Line Items] |  |
Operating loss carryforwards | 0 | 0
Tax credit carryforward amount | 5,933 | 5,954
Domestic Tax Authority | Capital Loss Carryforward |  |
Income Tax Examination [Line Items] |  |
Tax credit carryforward amount | 10,327 | 10,500
Non-U.S. Tax Authority |  |
Income Tax Examination [Line Items] |  |
Operating loss carryforwards | 8,332 | 9,671
State and Local Jurisdiction |  |
Income Tax Examination [Line Items] |  |
Operating loss carryforwards | $ 139,894 | $ 124,191

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