Number of Solar Renewable Energy Certificates

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DERIVATIVE INSTRUMENTS - ADDITIONAL INFORMATION (Details) certificate in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024 USD ($) certificate	Mar. 31, 2023 USD ($)	Mar. 31, 2024 USD ($) certificate	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($) certificate
Derivative [Line Items]
Derivative, net liability position, aggregate fair value	$ 1.4		$ 1.4		$ 0.1
Treasury Lock \| Interest expense
Derivative [Line Items]
Amount of pre-tax gain (loss) reclassified from OCI into income	$ (0.3)	$ (0.3)	$ (0.7)	$ (0.7)
Physical commodity contracts \| ES
Derivative [Line Items]
Number of SRECs (in certificates) \| certificate	1.4		1.4		1.3