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INCOME TAXES (Tax Reform Act) (Details) - USD ($) $ in Thousands | 2 Months Ended | 3 Months Ended | 7 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Feb. 28, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Dec. 31, 2017
Impact of Tax Reform Act |  |  |  |  |  |  |
Statutory federal rate (as a percent) | 32.74% | 21.00% |  | 21.00% | 21.00% | 21.00% | 35.00%
Reduction of deferred tax liabilities due to Tax Reform Act |  |  | $ 800 |  |  | $ 3,500 | $ 24,500
Tax benefit for change in accumulated other comprehensive income for noncash pension settlement expense |  | $ 0 |  |  | $ 0 |  |
State tax, low end of range of rate (as a percent) |  |  |  |  | 6.00% |  |
State tax, high end of range of rate (as a percent) |  |  |  |  | 6.50% |  |
Effective tax rate (as a percent) |  | 30.30% | 24.50% |  | 28.30% | 18.40% |
Provisional reduction in current income tax expense due Tax Reform Act reflecting use of fiscal year rather than calendar year federal income tax filing |  |  |  |  |  |  | 1,300
Alternative fuel tax credit |  |  |  |  |  |  | $ 1,200
Maximum |  |  |  |  |  |  |
Impact of Tax Reform Act |  |  |  |  |  |  |
Provisional reduction in current income tax expense due Tax Reform Act reflecting use of fiscal year rather than calendar year federal income tax filing |  |  |  |  |  | $ 100 |

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