LEASES - ADDITIONAL INFORMATION (Details) $ in Millions	3 Months Ended
	Dec. 31, 2019 USD ($) lease extension
Lessee, Lease, Description [Line Items]
ROU asset obtained in exchange for operating lease liability	$ 21.6
ROU asset obtained in exchange for finance lease liability	$ 4.0
Weighted average remaining lease term, operating lease	28 years 1 month 6 days
Weighted average remaining lease term, finance lease	4 years 6 months
Operating lease, discount rate	3.10%
Finance lease, discount rate	4.02%
Number of leases not yet commenced | lease	4
Lease not yet commenced, estimated payments	$ 27.8
Number of options to extend | extension	2
Renewal term	5 years
Solar Property | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	15 years
Renewal term	5 years
Solar Property | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	25 years
Renewal term	10 years
Office Building | Minimum
Lessee, Lease, Description [Line Items]
Term of contract	1 year
Office Building | Maximum
Lessee, Lease, Description [Line Items]
Term of contract	25 years
Meter License
Lessee, Lease, Description [Line Items]
Term of contract	7 years
Equipment
Lessee, Lease, Description [Line Items]
Term of contract	5 years