EMPLOYEE BENEFIT PLANS - Pension (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
EMPLOYEE BENEFIT PLANS
Accumulated Benefit Obligation	$ 109,731	$ 107,417
Changes in projected benefit obligations
Projected benefit obligation at beginning of year	107,417	111,108
Interest cost	4,266	4,584	$ 4,763
Actuarial loss	15,051	2,741
Benefits paid	(17,003)	(11,016)
Projected benefit obligation at end of year	109,731	107,417	111,108
Change in plan assets
Fair value of plan assets at beginning of year	98,060	108,157
Actual return on plan assets	9,653	(1,324)
Employer contribution	38	2,243
Benefits paid	(17,003)	(11,016)
Fair value of plan assets at end of year	90,748	98,060	$ 108,157
Funded status of the plan at end of year	(18,983)	(9,357)
Amounts Recognized in the Consolidated Balance Sheets
Accrued liabilities	(45)	(44)
Noncurrent liabilities-other	(18,938)	(9,313)
Net amount recognized	(18,983)	(9,357)
Amounts recognized in accumulated other comprehensive income and not yet reflected in net periodic benefit cost
Net actuarial loss	(34,112)	$ (30,144)
Net actuarial loss, which is expected to be amortized in next year's periodic benefit cost	$ 2,300
Weighted average assumptions used for the pension calculations
Discount rate for net periodic benefit costs (as a percent)	4.27%	4.32%	4.80%
Discount rate for year-end obligations (as a percent)	3.64%	4.27%	4.32%
Expected return on plan assets (as a percent)	5.89%	6.26%	6.61%
Components of the net periodic pension expense (benefit)
Interest cost	$ 4,266	$ 4,584	$ 4,763
Expected return on plan assets	(5,616)	(6,855)	(6,789)
Recognized net actuarial loss	2,083	1,308	873
Pension settlement charges	4,964	2,873	1,376
Net pension expense	5,697	$ 1,910	$ 223
Expected benefits to be paid from the Pension Plan
2017	13,976
2018	5,859
2019	6,013
2020	7,094
2021	5,674
2022-2026	33,078
Total	$ 71,694
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)	55.00%
Percentage of Plan Assets	62.00%	59.00%
International equities
Expected benefits to be paid from the Pension Plan
Target Allocation (as a percent)	13.00%
Percentage of Plan Assets	12.00%	13.00%
Fixed income
Expected benefits to be paid from the Pension Plan
Target Allocation (as a percent)	27.00%
Percentage of Plan Assets	21.00%	23.00%
Real estate and other
Expected benefits to be paid from the Pension Plan
Target Allocation (as a percent)	5.00%
Percentage of Plan Assets	5.00%	5.00%