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INCOME TAXES - Schedule of effective income tax rate reconciliation (Details) | 12 Months Ended
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Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Income Tax Disclosure [Abstract] |  |  |
U.S. Federal income tax provision rate | 21.00% | 21.00% | 21.00%
State and local taxes, net of Federal benefit | 4.70% | 7.80% | 9.10%
Non-U.S. taxes - foreign permanent items and taxes | 3.00% | 4.20% | 3.10%
Change in tax contingency reserves | 0.20% | 0.20% | (1.10%)
Impact of foreign rate change on deferred tax balances | 2.80% | 0.00% | 0.00%
Tax Reform-Repatriation of Foreign Earnings and GILTI | 0.40% | 0.30% | 1.60%
Change in valuation allowance | 0.40% | (2.60%) | 5.00%
Other non-deductible/non-taxable items, net | 0.004 | 0.013 | 0.059
Non-deductible officer's compensation | 4.00% | 5.40% | 8.20%
Research and U.S. foreign tax credits | (0.10%) | 1.40% | (6.40%)
Share based compensation | (2.00%) | 0.00% | 0.60%
Other | 1.10% | (0.80%) | (2.10%)
Effective tax provision (benefit) rate | 35.90% | 38.20% | 44.90%

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