LEASES - RIGHT-OF-USE ASSETS AND LEASE LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Noncurrent
Operating lease assets	$ 168,520	$ 173,928
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Utility plant, at cost	Utility plant, at cost
Finance lease assets	$ 21,913	$ 13,489
Total lease assets	190,433	187,417
Current
Operating lease liabilities	$ 4,562	$ 4,300
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Current maturities of long-term debt	Current maturities of long-term debt
Finance lease liabilities	$ 6,538	$ 5,393
Noncurrent
Operating lease liabilities	$ 138,382	$ 141,363
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Long-term debt	Long-term debt
Finance lease liabilities	$ 23,752	$ 14,742
Total lease liabilities	$ 173,234	$ 165,798