DEBT - Unsecured Long-Term Debt Outstanding (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Long-term debt, gross
Face Amount	$ 550,000	$ 550,000
Unamortized Discount and Debt Issuance Cost	(7,266)	(7,390)
Book Value	542,734	542,610
Less: long-term debt due within one year
Face Amount	0	0
Unamortized Discount and Debt Issuance Cost	0	0
Current portion of long-term debt, net	0	0
Long-term debt
Face Amount	550,000	550,000
Unamortized Discount and Debt Issuance Cost	(7,266)	(7,390)
Long-term debt, net	542,734	542,610
Unsecured Senior Notes due September 29, 2031
Long-term debt, gross
Face Amount	550,000	550,000
Unamortized Discount and Debt Issuance Cost	(7,266)	(7,390)
Book Value	$ 542,734	$ 542,610