EMPLOYEE BENEFIT PLANS - Pension (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
EMPLOYEE BENEFIT PLANS
Accumulated Benefit Obligation	$ 109,976	$ 109,731
Changes in projected benefit obligations
Projected benefit obligation at beginning of year	109,731	107,417
Interest cost	4,053	4,266	$ 4,584
Actuarial loss	3,633	15,051
Benefits paid	(7,441)	(17,003)
Projected benefit obligation at end of year	109,976	109,731	107,417
Change in plan assets
Fair value of plan assets at beginning of year	90,748	98,060
Actual return on plan assets	9,470	9,653
Employer contribution	39	38
Benefits paid	(7,441)	(17,003)
Fair value of plan assets at end of year	92,816	90,748	$ 98,060
Funded status of the plan at end of year	(17,160)	(18,983)
Amounts Recognized in the Consolidated Balance Sheets
Accrued liabilities	(45)	(45)
Noncurrent liabilities-other	(17,115)	(18,938)
Net amount recognized	(17,160)	(18,983)
Amounts recognized in accumulated other comprehensive income and not yet reflected in net periodic benefit cost
Net actuarial loss	(28,873)	$ (34,112)
Net actuarial loss, which is expected to be amortized in next year's periodic benefit cost	$ 1,800
Weighted average assumptions used for the pension calculations
Discount rate for net periodic benefit costs (as a percent)	3.64%	4.27%	4.32%
Discount rate for year-end obligations (as a percent)	3.79%	3.64%	4.27%
Expected return on plan assets (as a percent)	6.17%	5.89%	6.26%
Components of the net periodic pension expense (benefit)
Interest cost	$ 4,053	$ 4,266	$ 4,584
Expected return on plan assets	(5,130)	(5,616)	(6,855)
Recognized net actuarial loss	2,891	2,083	1,308
Pension settlement charges	1,640	4,964	2,873
Net pension expense	3,454	$ 5,697	$ 1,910
Expected benefits to be paid from the Pension Plan
2018	16,050
2019	6,844
2020	7,222
2021	5,591
2022	6,383
2023-2027	32,723
Total	$ 74,813
Target Allocation (as a percent)	100.00%
Percentage of Plan Assets	100.00%	100.00%
U.S. equities
Expected benefits to be paid from the Pension Plan
Target Allocation (as a percent)	45.00%
Percentage of Plan Assets	50.00%	62.00%
International equities
Expected benefits to be paid from the Pension Plan
Target Allocation (as a percent)	20.00%
Percentage of Plan Assets	16.00%	12.00%
Fixed income
Expected benefits to be paid from the Pension Plan
Target Allocation (as a percent)	35.00%
Percentage of Plan Assets	34.00%	21.00%
Real estate and other
Expected benefits to be paid from the Pension Plan
Percentage of Plan Assets		5.00%