LONG-TERM DEBT (Details) - Narrative $ / shares in Units, £ in Thousands, $ in Thousands						1 Months Ended			3 Months Ended		6 Months Ended	12 Months Ended
	Oct. 02, 2017 USD ($)	Jan. 17, 2017 USD ($) shares	Oct. 01, 2016 USD ($)	Jul. 14, 2016 USD ($)	Mar. 22, 2016 USD ($)	Aug. 31, 2016 USD ($)	Jul. 31, 2016 USD ($)	Nov. 30, 2012 CAD ($)	Mar. 31, 2018 GBP (£)	Mar. 31, 2017 USD ($) shares	Mar. 31, 2018 USD ($) option	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Mar. 31, 2018 AUD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2018 CAD ($)	Dec. 18, 2017 USD ($)	Sep. 30, 2017 AUD ($)	Sep. 30, 2017 USD ($)	Mar. 31, 2017 AUD ($)	Jul. 31, 2016 AUD ($) loan	May 18, 2016 USD ($)	Mar. 31, 2016 USD ($)	Sep. 30, 2015 USD ($)	Feb. 27, 2014 USD ($)	Feb. 14, 2014 USD ($)	Oct. 21, 2013 property	Dec. 21, 2009 USD ($)
Debt Instrument [Line Items]
Capitalized Fees & Expenses															$ 16,880,000				$ 12,066,000
Long-term debt															1,091,379,000				979,158,000
Face amount						$ 35,092,000																	$ 8,000,000	$ 32,280,000
Underwriting fees and other expense capitalized													$ 10,313,000
Maximum percentage of equity interest of subsidiaries borrowings guaranteed											65.00%
Long-term line of credit															14,896,000
Number of properties refinanced | property																											4
Amount of line note available to purchase common stock in open market						$ 10,908,000
Stock issued during period, shares, employee stock ownership plan (in shares) | shares												621,875
Shares purchased for award value												$ 10,908,000
Weighted average purchase price of shares purchased | $ / shares												$ 17.54
Basis spread on variable rate								1.30%			1.30%
Number of option to extend | option											2
Lease renewal term											5 years
Convert. debt due 2017 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage																												4.00%
Face amount																												$ 100,000,000
Mortgages [Member]
Debt Instrument [Line Items]
Basis spread on variable rate									1.50%
Senior Notes [Member] | Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 275,000,000
Long-term debt															1,000,000,000
Senior Notes [Member] | Senior Notes due 2022, May 2016 Add-On Issuance [Member]
Debt Instrument [Line Items]
Debt issuance costs, net															3,016,000
Issuance price, percentage	101.00%																					98.76%
Face amount																						$ 125,000,000
Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Capitalized Fees & Expenses																	$ 8,472,000
Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Capitalized Fees & Expenses															14,715,000				9,220,000
Debt instrument, interest rate, stated percentage	5.25%																								5.25%
Long-term debt															$ 986,681,000				$ 714,603,000
Face amount																									$ 600,000,000
Debt conversion, original debt, amount				$ 125,000,000
Debt instrument, interest rate, effective percentage									5.25%					5.25%	5.25%	5.25%		5.25%	5.25%
Revolver due 2019 [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity																										$ 250,000,000
Revolver Due 2020 [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity					$ 350,000,000
Convertible Notes 2017 [Member]
Debt Instrument [Line Items]
Debt conversion, converted instrument, amount		$ 173,855,000								$ 173,855,000
Debt conversion, converted instrument, cash received		125,000,000								$ 125,000,000
Issuance of treasury stock in settlement of convertible debt		$ 48,858,000
Debt conversion, converted instrument, shares issued | shares		1,954,993								1,954,993
Debt instrument, interest rate, effective percentage		4.00%
Real estate mortgages [Member]
Debt Instrument [Line Items]
Capitalized Fees & Expenses															$ 0				$ 320,000
Long-term debt															0				23,322,000
Debt instrument, description of variable rate basis											The loans had an interest rate of LIBOR plus 1.50%
Basis spread on variable rate											2.25%
ESOP Loans [Member]
Debt Instrument [Line Items]
Capitalized Fees & Expenses															248,000				310,000
Long-term debt															41,289,000				42,365,000
Basis spread on variable rate											2.50%
Debt instrument, periodic payment, principal			$ 569,000
Capital lease - real estate [Member]
Debt Instrument [Line Items]
Capitalized Fees & Expenses															93,000				105,000
Long-term debt															$ 8,890,000				$ 5,207,000
Debt instrument, interest rate, effective percentage									5.00%					5.00%	5.00%	5.00%		5.00%	5.00%
Non U.S. lines of credit [Member]
Debt Instrument [Line Items]
Capitalized Fees & Expenses															$ 24,000				$ 31,000
Long-term debt															2,101,000				$ 9,371,000
Proceeds from long-term lines of credit								$ 15,000			$ 11,624,000
Long-term line of credit															0
Remaining borrowing capacity															$ 11,624,000	$ 15,000
Term Loan [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, effective percentage									3.85%					3.85%	3.85%	3.85%
Medium-term Notes [Member] | Term Loan Due 2019 [Member]
Debt Instrument [Line Items]
Periodic payment terms, balloon payment to be paid																					$ 37,125,000
Number of loans refinanced with new debt instrument | loan																					2
Revolver Due 2013 [Member]
Debt Instrument [Line Items]
Basis spread on variable rate									1.75%		1.75%
Fair Value, Inputs, Level 1 [Member] | Senior Notes 2022 [Member]
Debt Instrument [Line Items]
Convertible debt, fair value disclosures															$ 1,006,300,000
Libor Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate during period					2.50%
Libor Rate [Member] | Non U.S. lines of credit [Member]
Debt Instrument [Line Items]
Interest rate at period end									3.18%					3.18%	3.18%	3.18%
Bankers Acceptance Rate [Member] | Non U.S. lines of credit [Member]
Debt Instrument [Line Items]
Interest rate at period end									2.87%					2.87%	2.87%	2.87%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term line of credit															$ 0
Maximum borrowing capacity														$ 20,000,000	15,344,000
Revolving Credit Facility [Member] | Revolving Facility, June 2017 [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity														$ 20,000							$ 10,000,000
Revolver due 2019 [Member]
Debt Instrument [Line Items]
Long-term line of credit															14,896,000
Remaining borrowing capacity															320,208,000
Revolver due 2019 [Member] | Letter Of Credit Subfacility [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity					$ 50,000,000
Revolver due 2019 [Member] | Multicurrency Subfacility [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity					$ 50,000,000
Revolver due 2019 [Member] | Margin Rate [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate during period					1.50%
Secured Debt [Member] | Invoice Discounting Arrangement [Member]
Debt Instrument [Line Items]
Long-term line of credit									£ 1,512						$ 2,125,000
Interest rate at period end									2.50%					2.50%	2.50%	2.50%
London Interbank Offered Rate (LIBOR) [Member] | ESOP Loan July 2014 [Member]
Debt Instrument [Line Items]
Basis spread on variable rate											2.50%
Sterling Base Rate [Member] | Secured Debt [Member] | Invoice Discounting Arrangement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate											2.00%
Northcote Holdings Pty. Ltd [Member] | Non U.S. lines of credit [Member] | Line of Credit One [Member]
Debt Instrument [Line Items]
Basis spread on variable rate							2.00%
Debt instrument, interest rate, effective percentage									3.94%					3.94%	3.94%	3.94%
Northcote Holdings Pty. Ltd [Member] | Term Loan [Member]
Debt Instrument [Line Items]
Face amount																					$ 30,000,000
Number of loans | loan																					2
Northcote Holdings Pty. Ltd [Member] | Term Loan May 2014 [Member]
Debt Instrument [Line Items]
Face amount																					$ 10,000,000
Debt instrument, periodic payment, principal							$ 1,250,000
Maximum borrowing capacity																				$ 5,000,000
Maximum borrowing capacity increase																		$ 15,000,000
Northcote Holdings Pty. Ltd [Member] | Term Loan December 2013 and May 2014 [Member]
Debt Instrument [Line Items]
Long-term line of credit														$ 43,375,000	$ 33,277,000
Basis spread on variable rate							2.00%
Debt instrument, interest rate, effective percentage									4.08%					4.08%	4.08%	4.08%
Troy, Ohio [Member]
Debt Instrument [Line Items]
Percentage bearing fixed interest, percentage rate									5.00%					5.00%	5.00%	5.00%
Ocala, Florida [Member]
Debt Instrument [Line Items]
Percentage bearing fixed interest, percentage rate									8.00%					8.00%	8.00%	8.00%