SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Adoption of ASU 2016-02 and ASU 2018-02 (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 72,481	$ 83,222
Prepaid and other	$ 118,245	118,371	116,862
Property, plant and equipment	991,613	1,042,739	997,489
Current maturities of long-term obligations, net of unamortized debt issuance costs	62,678	64,941	65,309
Accounts payable and accrued liabilities	525,199	537,620	545,707
Operating lease liabilities		55,278	61,331
Long-term obligations, net of unamortized debt issuance costs	1,125,993	$ 1,075,153	1,129,238
Reclassification of stranded income tax effects from AOCI to retained earnings	$ 6,700
Accounting Standards Update 2016-02 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets			83,222
Prepaid and other			(1,383)
Property, plant and equipment			5,876
Current maturities of long-term obligations, net of unamortized debt issuance costs			2,631
Accounts payable and accrued liabilities			20,508
Operating lease liabilities			61,331
Long-term obligations, net of unamortized debt issuance costs			$ 3,245