REPORTING SEGMENT AND OTHER OPERATIONS DATA - RECONCILIATION OF SEGMENT ASSETS TO CONSOLIDATED (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 6,610,094	$ 6,261,416
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	6,729,345	6,378,335
Operating Segments | Natural Gas Distribution
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	4,226,035	4,030,686
Operating Segments | Clean Energy Ventures
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	1,047,726	1,015,065
Operating Segments | Energy Services
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	446,017	333,064
Operating Segments | Storage and Transportation
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	1,009,567	999,520
Home Services and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	145,887	159,068
Intercompany Assets
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ (265,138)	$ (275,987)