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INCOME TAXES, Effective tax rates (Details) - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Effective income tax rates as compared to the U.S. Federal income tax rate |  |  |
U.S. Federal income tax rate (as a percent) | 35.00% | 35.00% | 35.00%
Effect of foreign taxes (as a percent) | 1.80% | (13.80%) | (3.20%)
State income taxes, net of federal tax benefit (as a percent) | 0.60% | 3.20% | 0.80%
U.S. domestic production activities (as a percent) | (2.10%) | (10.40%) | (1.20%)
Other impact of foreign operations | (2.90%) | 14.70% | 4.50%
Other (as a percent) | (1.70%) | (1.60%) | 0.60%
Effective income tax rate (as a percent) | 30.70% | 27.10% | 36.50%
Accrued interest and penalties related to unrecognized tax benefits | $ 2,800 | $ 6,800 |
Reconciliation of the change in gross unrecognized tax benefits |  |  |
Unrecognized tax benefits at the beginning of the period | 9,551 | 11,211 |
Gross decreases - tax positions in prior periods | (1) |  |
Gross decreases - current period effect of tax positions | (170) | (1,173) |
Gross increases - current period effect of tax positions | 300 | 969 |
Expiration of statute of limitations for assessments | (4,907) | (679) |
Settlements |  | (777) |
Unrecognized tax benefits at the end of the period | 4,773 | 9,551 | $ 11,211
Unrecognized tax benefits related to discontinued operations | $ 3,700 | $ 3,800 |

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