REVENUE - TIMING OF REVENUE RECOGNITION - BALANCE SHEET (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Customer accounts receivable
Billed	$ 195,683	$ 139,263
Unbilled revenues	41,161	6,510
Customers' credit	(19,328)	$ (27,116)
Customers accounts receivables & Customers' credit balances and deposits	217,516
Operating Segments | Natural Gas Distribution
Customer accounts receivable
Billed	104,853
Unbilled revenues	41,161
Customers' credit	(19,328)
Customers accounts receivables & Customers' credit balances and deposits	126,686
Operating Segments | Clean Energy Ventures
Customer accounts receivable
Billed	3,057
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	3,057
Operating Segments | Energy Services
Customer accounts receivable
Billed	81,064
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	81,064
Operating Segments | Midstream
Customer accounts receivable
Billed	4,574
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	4,574
Home Services and Other
Customer accounts receivable
Billed	2,135
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	2,135
Eliminations
Customer accounts receivable
Billed	0
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	$ 0