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EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016 | Jan. 01, 2018
EMPLOYEE BENEFIT PLANS (Details) [Line Items] |  |  |  |
Defined contribution plan, employer discretionary contribution amount | $ 8,328 | $ 8,714 | $ 8,301 |
Postemployment benefits liability | $ 1,699 | 2,014 |  |
Change in discount rate | 10.00% |  |  |
Tax benefit for amortization of pension cost | $ 342 | 1,170 | 831 |
Defined benefit plan, actuarial gain (loss) | 887 |  |  |
Service cost | $ 14 |  |  |
Adjusted funding target attainment percent |  |  |  | 95.80%
Adjusted funding target attainment percent, threshold |  |  |  | 80.00%
Defined benefit plan, target plan asset allocations | 100.00% |  |  |
Defined benefit plans, estimated future employer contributions in next fiscal year | $ 1,100 |  |  |
Completion period of service | 1 year |  |  |
Maximum compensation of proportion | $ 275 |  |  |
Employee stock ownership plan (ESOP), compensation expense | 9,532 | 5,643 | $ 3,689 |
Employee stock ownership plan (ESOP), deferred shares, fair value | 47,916 | 69,394 |  |
Other Postretirement Benefits Plan [Member] |  |  |  |
EMPLOYEE BENEFIT PLANS (Details) [Line Items] |  |  |  |
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans, net of tax | (60) | (107) |  |
Pension and other postretirement benefit expense | 45 | 41 |  |
Supplemental Employee Retirement Plan [Member] |  |  |  |
EMPLOYEE BENEFIT PLANS (Details) [Line Items] |  |  |  |
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans, net of tax | (3,396) | (12,601) |  |
Company contributions | 3,001 | 4,057 |  |
Defined benefit plan, actuarial gain (loss) | 14,452 | (195) |  |
Defined benefit plan, expected future benefit payments, next twelve months | 1,906 |  |  |
Pension Plan [Member] |  |  |  |
EMPLOYEE BENEFIT PLANS (Details) [Line Items] |  |  |  |
Accumulated other comprehensive income (loss), pension and other postretirement benefit plans, net of tax | (12,985) | (15,539) |  |
Company contributions | 2,449 | 3,747 |  |
Defined benefit plan, actuarial gain (loss) | 7,562 | $ 9,318 |  |
Defined benefit plan, expected future benefit payments, next twelve months | 10,767 |  |  |
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year | $ 3,114 |  |  |

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