SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - ADDITIONAL INFORMATION (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Jul. 31, 2021 Megawatt	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2024 USD ($)
Finite-Lived Intangible Assets [Line Items]
Operating revenues		$ 488,361	$ 467,210
Loans receivable in other noncurrent assets		56,700		$ 53,600
BPU
Finite-Lived Intangible Assets [Line Items]
Number of megawatts | Megawatt	5
Financial Asset, Not Past Due
Finite-Lived Intangible Assets [Line Items]
Loans receivable in other current assets		$ 18,800		18,100
Minimum
Finite-Lived Intangible Assets [Line Items]
Loans receivable, term		3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Loans receivable, term		10 years
ES
Finite-Lived Intangible Assets [Line Items]
Operating revenues		$ 4,900	$ 9,500
Deferred revenue		$ 51,600		$ 22,300