LONG-TERM DEBT (Details) - Summary of Long-Term Debt - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017
Debt Instrument [Line Items]
Outstanding Balance	$ 1,150,311		$ 1,150,311		$ 992,401
Debt Instrument, Unamortized Premium	1,308		1,308
less: Current portion, Outstanding Balance	(10,739)		(10,739)		(11,078)
Debt Instrument, Unamortized Premium, Current	0		0
Long-term debt, Outstanding Balance	1,139,572		1,139,572		981,323
Debt Instrument, Unamortized Premium, Noncurrent	1,308		1,308
Original Issuer Discount					(1,177)
less: Current portion, Original Issuer Discount					0
Long-term debt, Original Issuer Discount					(1,177)
Capitalized Fees & Expenses	(15,899)		(15,899)		(12,066)
Long-term debt	1,135,720		1,135,720		979,158
less: Current portion	(10,739)		(10,739)		(11,078)
Long-term debt	1,124,981		1,124,981		968,080
Interest Paid	(15,103)	$ (11,784)	(45,994)	$ (34,920)
Amortization of Debt Discount (Premium)	(67)	(67)	(202)	(1,450)
Amortization of Debt Issuance Costs	1,158	828	3,777	2,324
Interest Expense, Debt	$ (16,328)	$ (12,679)	$ (49,973)	$ (38,694)
Senior notes due 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	5.70%	5.50%	5.70%	5.60%
Outstanding Balance	$ 1,000,000		$ 1,000,000		725,000
Debt Instrument, Unamortized Premium	1,308		1,308
Original Issuer Discount					(1,177)
Capitalized Fees & Expenses	(13,932)		(13,932)		(9,220)
Long-term debt	$ 987,376		$ 987,376		$ 714,603
Coupon Interest Rate	5.25%		5.25%		5.25%
Interest Paid	$ (13,125)	$ (9,516)	$ (39,375)	$ (28,547)
Amortization of Debt Discount (Premium)	(67)	(67)	(202)	(202)
Amortization of Debt Issuance Costs	957	462	2,839	1,396
Interest Expense, Debt	(14,149)	(10,045)	(42,416)	(30,145)
Revolver due 2021 [Member]
Debt Instrument [Line Items]
Outstanding Balance	69,912		69,912		$ 144,216
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	(1,556)		(1,556)		(1,951)
Long-term debt	68,356		68,356		142,265
Interest Paid	(1,239)	(1,629)	(3,517)	(3,280)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	141	140	422	422
Interest Expense, Debt	(1,380)	$ (1,769)	(3,939)	$ (3,702)
Real estate mortgages [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period		2.40%		2.40%
Outstanding Balance	0		0		23,642
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	0		0		(320)
Long-term debt	0		0		23,322
Interest Paid	0	$ (142)	(351)	$ (420)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	0	46	320	56
Interest Expense, Debt	$ 0	$ (188)	$ (671)	$ (476)
ESOP Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	5.50%	3.30%	4.70%	4.10%
Outstanding Balance	$ 35,263		$ 35,263		42,675
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	(217)		(217)		(310)
Long-term debt	35,046		35,046		42,365
Interest Paid	(472)	$ (414)	(1,327)	$ (1,147)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	31	29	93	94
Interest Expense, Debt	$ (503)	$ (443)	$ (1,420)	$ (1,241)
Capital lease - real estate [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period	5.60%	5.40%	5.50%	5.40%
Outstanding Balance	$ 8,248		$ 8,248		5,312
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	(86)		(86)		(105)
Long-term debt	$ 8,162		$ 8,162		$ 5,207
Coupon Interest Rate	5.00%		5.00%		5.00%
Interest Paid	$ (42)	$ (72)	$ (533)	$ (227)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	6	7	19	19
Interest Expense, Debt	(48)	(79)	(552)	(246)
Non U.S. lines of credit [Member]
Debt Instrument [Line Items]
Outstanding Balance	0		0		$ 9,402
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	(19)		(19)		(31)
Long-term debt	(19)		(19)		9,371
Interest Paid	(22)	(45)	(33)	(70)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	4	75	11	85
Interest Expense, Debt	(26)	(120)	(44)	(155)
Non U.S. term loans [Member]
Debt Instrument [Line Items]
Outstanding Balance	30,953		30,953		35,943
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	(69)		(69)		(108)
Long-term debt	30,884		30,884		35,835
Interest Paid	(338)	(102)	(1,002)	(560)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	18	68	69	97
Interest Expense, Debt	(356)	(170)	(1,071)	(657)
Other long term debt [Member]
Debt Instrument [Line Items]
Outstanding Balance	5,935		5,935		6,211
Debt Instrument, Unamortized Premium	0		0
Original Issuer Discount					0
Capitalized Fees & Expenses	(20)		(20)		(21)
Long-term debt	5,915		5,915		$ 6,190
Interest Paid	(33)	(64)	(262)	(186)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	1	1	4	7
Interest Expense, Debt	(34)	(65)	(266)	$ (193)
Convert. debt due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period				8.90%
Interest Paid			0	$ (1,167)
Amortization of Debt Discount (Premium)			0	(1,248)
Amortization of Debt Issuance Costs			0	148
Interest Expense, Debt			0	(2,563)
Capitalized Interest [Member]
Debt Instrument [Line Items]
Interest Paid	(168)	(200)	(406)	(684)
Amortization of Debt Discount (Premium)	0	0	0	0
Amortization of Debt Issuance Costs	0	0	0	0
Interest Expense, Debt	$ (168)	$ (200)	$ (406)	$ (684)
Term Loan [Member]
Debt Instrument [Line Items]
Coupon Interest Rate	3.85%		3.85%