LONG-TERM DEBT - Summary of Interest Expense Incurred (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Cash interest, capitalized interest	$ (65)	$ 0
Cash interest	14,939	15,298
Amort. Debt Discount	67	68
Amort. Debt Issuance Costs & Other Fees	1,205	1,163
Total Interest Expense	$ 16,211	$ 16,529
Senior notes due 2022
Debt Instrument [Line Items]
Effective Interest Rate	5.70%	5.70%
Cash interest, including amounts capitalized	$ 13,125	$ 13,125
Amort. Debt Discount	67	68
Amort. Debt Issuance Costs & Other Fees	951	951
Total Interest Expense	14,143	14,144
Revolver due 2025
Debt Instrument [Line Items]
Cash interest, including amounts capitalized	1,382	933
Amort. Debt Discount	0	0
Amort. Debt Issuance Costs & Other Fees	232	141
Total Interest Expense	1,614	$ 1,074
ESOP Loans
Debt Instrument [Line Items]
Effective Interest Rate		5.50%
Cash interest, including amounts capitalized	0	$ 488
Amort. Debt Discount	0	0
Amort. Debt Issuance Costs & Other Fees	0	31
Total Interest Expense	$ 0	$ 519
Capital lease - real estate
Debt Instrument [Line Items]
Effective Interest Rate	5.60%	5.60%
Cash interest, including amounts capitalized	$ 61	$ 115
Amort. Debt Discount	0	0
Amort. Debt Issuance Costs & Other Fees	6	6
Total Interest Expense	67	121
Non US lines of credit
Debt Instrument [Line Items]
Cash interest, including amounts capitalized	4	7
Amort. Debt Discount	0	0
Amort. Debt Issuance Costs & Other Fees	4	4
Total Interest Expense	8	11
Non US term loans
Debt Instrument [Line Items]
Cash interest, including amounts capitalized	272	448
Amort. Debt Discount	0	0
Amort. Debt Issuance Costs & Other Fees	12	27
Total Interest Expense	284	475
Other long term debt
Debt Instrument [Line Items]
Cash interest, including amounts capitalized	160	182
Amort. Debt Discount	0	0
Amort. Debt Issuance Costs & Other Fees	0	3
Total Interest Expense	$ 160	$ 185