INCOME TAXES (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	May 31, 2019
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit), solar investment tax credit, net of deferred taxes							$ (6,000,000)
Federal statutory income tax rate, percent						24.50%
Tax Cuts And Jobs Act Of 2017, income tax benefit		$ 844,000		$ (57,700,000)
Income tax provision (benefit)	$ (1,941,000)	$ (28,534,000)	$ (11,854,000)	$ (47,801,000)
Forecasted effective tax rate			(4.60%)	14.30%
Forecasted tax credits, net of deferred tax						$ 22,000,000
Other reconciling Items, amount			$ 5,400,000	$ 76,600,000
Other reconciling Items, percent			(8.50%)	(23.70%)
Deferred tax assets, operating loss carryforwards, domestic, refundable and receivables	23,000,000		$ 23,000,000			23,000,000
Deferred tax assets, operating loss carryforwards, domestic	24,500,000		24,500,000
ITC carryforward	140,800,000		140,800,000			121,100,000
Valuation allowance	4,000,000		4,000,000			4,000,000
Deferred income taxes
Operating Loss Carryforwards [Line Items]
Income tax provision (benefit)				$ (16,100,000)
Public utilities, remeasurement of deferred income tax, liability						14,300,000
Public utilities, amortization of excess deferred income taxes, liability						890,000
Public utilities, revaluation of deferred income taxes not included in base rates, liability						880,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	135,600,000		135,600,000			136,800,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 403,700,000		$ 403,700,000			$ 578,800,000
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Federal statutory income tax rate, percent					21.00%
Forecasted tax credits, net of deferred tax					$ 46,300,000