REVENUE - TIMING OF REVENUE RECOGNITION - BALANCE SHEET (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Billed	$ 110,463	$ 222,297
Unbilled revenues	16,492	13,769
Customers' credit balances and deposits	(30,267)	(33,246)	$ (22,216)	$ (32,586)
Customers accounts receivables & Customers' credit balances and deposits	96,688	202,820
Operating Segments | Natural Gas Distribution
Disaggregation of Revenue [Line Items]
Billed	72,747	78,508
Unbilled revenues	10,583	10,814
Customers' credit balances and deposits	(30,259)	(33,246)
Customers accounts receivables & Customers' credit balances and deposits	53,071	56,076
Operating Segments | Clean Energy Ventures
Disaggregation of Revenue [Line Items]
Billed	7,433	5,566
Unbilled revenues	5,909	2,955
Customers' credit balances and deposits	0	0
Customers accounts receivables & Customers' credit balances and deposits	13,342	8,521
Operating Segments | Energy Services
Disaggregation of Revenue [Line Items]
Billed	20,675	129,199
Unbilled revenues	0	0
Customers' credit balances and deposits	0	0
Customers accounts receivables & Customers' credit balances and deposits	20,675	129,199
Operating Segments | Storage and Transportation
Disaggregation of Revenue [Line Items]
Billed	7,485	7,012
Unbilled revenues	0	0
Customers' credit balances and deposits	(8)	0
Customers accounts receivables & Customers' credit balances and deposits	7,477	7,012
Home Services and Other
Disaggregation of Revenue [Line Items]
Billed	2,123	2,012
Unbilled revenues	0	0
Customers' credit balances and deposits	0	0
Customers accounts receivables & Customers' credit balances and deposits	$ 2,123	$ 2,012